Hammerusersguide.pdf

HAMMER

™

USER ’S GUIDE

HYDRAULIC TRANSIENT MODELING SOFTWARE

Copyright © 1986-2003 Haestad Methods, Inc. All rights reserved. HAMMER User’s Guide. This documentation was prepared by the Haestad Methods and Environmental Hydraulics Group staffs and it includes material from previous papers, theses, and reports. This documentation is published by Haestad Methods, Inc. (“Haestad”), and is intended solely for use in conjunction with Haestad’s software. This documentation is available to all current Licensees in print and electronic format. No one may copy, photocopy, reproduce, translate, or convert to any electronic or machine-readable form, in whole or in part, the printed documentation without the prior written approval of Haestad. Licensee may download the electronic documentation from Haestad’s web site and make that documentation available solely on licensee’s intranet. Licensee may print the electronic documentation, in part or in whole, for personal use. No one may translate, alter, sell, or make available the electronic documentation on the Internet, transfer the documentation by FTP, or display any of the documentation on any web site without the prior written approval of Haestad. Trademarks The following are registered trademarks of Haestad Methods, Inc.: CulvertMaster, Cybernet, Darwin, FlowMaster, Graphical HEC-1, Haestad Methods, PondPack, PumpMaster, SewerCAD, StormCAD, WaterCAD, and WaterGEMS. The following are trademarks of Haestad Methods, Inc.: HEC-Pack, HAMMER, and GISConnect. AutoCAD is a registered trademark of Autodesk, Inc. ESRI is a registered trademark of Environmental Systems Research Institute, Inc. Microsoft, Windows, Visual Studio, Word, and Excel, are registered trademarks of Microsoft Corporation. All other brands, company or product names, or trademarks belong to their respective holders. HAMMER is based on technology originally created by Environmental Hydraulics Group, Inc. http://www.ehg-inc.com

37 Brookside Road Waterbury, CT 06708-1499 USA Phone: +1-203-755-1666 Fax: +1-203-597-1488 E-mail: [email protected] Internet: http://www.haestad.com

Contents Chapter 1: Orientation and Installation

1

What is HAMMER? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1 About EHG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2 Capabilities of HAMMER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2 Installing HAMMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3 Minimum System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3 Installing Haestad Methods Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5 Troubleshooting Setup or Uninstallation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6 Software Registration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6 Upgrades and the Globe Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7 Network Licensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7 Registering Network Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-8 Requesting a Permanent Network License . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-8 Installation Guide for Network License Versions . . . . . . . . . . . . . . . . . . . . . . .1-10 Network Deployment Folder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-12 Learning HAMMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-12 Frequently Asked Questions—How Do I?. . . . . . . . . . . . . . . . . . . . . . . . . . . .1-12 Tutorials and Sample Projects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-12 Haestad Methods Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-13 Contacting Haestad Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-13 Sales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-13 Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-14 Engineering Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-15 Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-15 Your Suggestions Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-15

Chapter 2: HAMMER Main Window

17

Main Window Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-17 Main Window: HAMMER Modeler. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-18 Output Windows: HAMMER Viewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-20 HAMMER Menus and Shortcut Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-21 File Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-22 Edit Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-23 View Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-24 Tools Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-25

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Contents-i

Help Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27 Format Graph Shortcut Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27 Format Display Shortcut Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29 Using the Online Help, Online Book, and Help Pane . . . . . . . . . . . . . . . . . . . Online Book (PDF). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Online Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ONLINE HELP INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ONLINE HELP SEARCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ONLINE HELP FAVORITES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ONLINE HELP TOPICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NAVIGATION ARROWS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2-30 2-30 2-31 2-32 2-33 2-34 2-35 2-36

Hammer Dialog Boxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Project Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REPORT POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REPORT TIMES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REPORT PATHS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PREFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OTHER OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Run Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WaterCAD/WaterGEMS Import Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . Import EPANET File Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Import Surge 2000 File Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SURGE TO HAMMER FIELD-TO-FIELD CONVERSION . . . . . . . . . . . . . . . . . .

2-37 2-38 2-38 2-39 2-40 2-41 2-42 2-43 2-44 2-45 2-47 2-48 2-49

Bladder Surge Tank (Surge) to Gas Vessel (HAMMER) . . . . . . . . . . . . . . . . 2-49 Closed Surge Tank (Surge) to Gas Vessel (HAMMER) . . . . . . . . . . . . . . . . . 2-51 One-Way Open-Surge Tank (Surge) to Simple-Surge Tank (HAMMER) . . . . 2-52 Open-Surge Tank (Surge) to Simple Surge Tank (HAMMER) . . . . . . . . . . . . 2-53 Pressure Valve (Surge) to SAV/SRV (HAMMER). . . . . . . . . . . . . . . . . . . . . . 2-54 Rupture Disk (Surge) to Rupture Disk (HAMMER) . . . . . . . . . . . . . . . . . . . . 2-56 Single-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER) . . . . . . . . . 2-57 Surge-Anticipation Valve (Surge) to SAV/SRV (HAMMER) . . . . . . . . . . . . . . 2-58 Two-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER) . . . . . . . . . . . 2-60 Three-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER). . . . . . . . . . 2-61

Search Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FlexUnits Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color Mapping Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Color Map Settings Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Choose Color Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Global HAMMER Options Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . COLORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TOOLTIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FILE I/O. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OTHER OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HAMMER Viewer Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Animation Control Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Font Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents-ii

2-62 2-63 2-63 2-65 2-66 2-67 2-67 2-69 2-69 2-70 2-71 2-72 2-73 2-74

HAMMER User's Guide

Copy Paths Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-74 HAMMER Toolbars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-75 File Tools (Modeler Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-75 Edit Tools (Modeler Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-75 Run Control (Modeler Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-75 Display Tools (Modeler Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-75 Output Graphics (Modeler Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-76 Help (Modeler Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-76 Hydraulic Elements (Modeler Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-76 Boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-77 Control Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-77 Protection Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-78 Rotating Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-79 HAMMER Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-79

Chapter 3: Quick Start Lessons

81

Lesson 1: Pipeline Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-82 Part 1—Creating or Importing a Steady-State Model . . . . . . . . . . . . . . . . . . .3-82 CREATING A MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-82 IMPORTING A STEADY-STATE MODEL FROM EPANET . . . . . . . . . . . . . . . . . .3-89 Part 2—Selecting the Transient Events to Model . . . . . . . . . . . . . . . . . . . . . .3-90 Part 3—Configuring the HAMMER Project . . . . . . . . . . . . . . . . . . . . . . . . . . .3-90 Part 4—Performing a Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-93 ANALYSIS WITHOUT SURGE PROTECTION EQUIPMENT . . . . . . . . . . . . . . . . .3-93 Reviewing your Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-96 Analysis with Surge-Protection Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 3-97

Part 5—Animating Transient Results at Points and along Profiles . . . . . . . .3-100 Part 6—Adding Comments to Generate Report-Ready Graphs . . . . . . . . . .3-103 Lesson 2: Working with Data from External Sources . . . . . . . . . . . . . . . . . .3-104 Part 1—Exporting an Input or Output File to a HAMMER Datastore. . . . . . .3-105 CREATING A HAMMER INPUT DATASTORE . . . . . . . . . . . . . . . . . . . . . . . .3-105 CREATING AN OUTPUT DATASTORE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-107 Part 2—Importing a HAMMER Datastore . . . . . . . . . . . . . . . . . . . . . . . . . . .3-109 Part 3—Importing Haestad Methods Models Using WaterObjects . . . . . . . . 3-113 Part 4—Importing from Other Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-114 IMPORTING FROM EPANET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-114 IMPORTING FROM PIPE2000 OR SURGE2000 . . . . . . . . . . . . . . . . . . . . . . 3-115 Lesson 3: Network Risk Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-115 Part 1—Importing and Verifying the Initial Steady-States . . . . . . . . . . . . . . . 3-116 Part 2—Selecting the Key Transient Events to Model. . . . . . . . . . . . . . . . . . 3-119 Part 3—Performing a Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-119 ANALYSIS WITHOUT SURGE PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . 3-119 ANALYSIS WITH SURGE-PROTECTION EQUIPMENT . . . . . . . . . . . . . . . . . . . .3-124 Part 4—Color-Coding Maps, Profiles, and Point Histories . . . . . . . . . . . . . .3-128 Part 5—Adding Comments to Generate Report-Ready Graphs . . . . . . . . . .3-131

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Chapter 4: Starting a HAMMER Project

137

File Management and Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HAMMER Input and Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HAMMER Datastore and Access Connections . . . . . . . . . . . . . . . . . . . . . . WaterObjects Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Additional Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Multiple Sessions and Submodels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-137 4-137 4-138 4-138 4-138 4-139

Import and Export Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importing/Exporting EPANET v.2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importing/Exporting to a GIS or Database Using the HAMMER Datastore . Importing from WaterGEMS/WaterCAD Using WaterObjects . . . . . . . . . . . Importing PIPE2000 or Surge2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-139 4-140 4-141 4-141 4-142

Project Management and Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Global HAMMER Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Project Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PROJECT SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-142 4-142 4-143 4-144

Determining Pressure Wave Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-144 Determining the Run Duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-144

UNIT SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LIQUID PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VAPOR PRESSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SELECTING THE FRICTION METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4-145 4-146 4-146 4-147

Steady-State Friction Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-147 Quasi-Steady Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-148 Transient or Unsteady Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-148

Drawing Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-149 FlexUnits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Display Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NUMBER OF DIGITS DISPLAYED AFTER DECIMAL POINT . . . . . . . . . . . . . . . ROUNDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scientific Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Minimum and Maximum Allowed Value . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 5: Layout and Editing Tools

4-149 4-150 4-151 4-151 4-151 4-151 4-152

153

HAMMER Modeler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Creating New Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Morphing Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Selecting Hydraulic Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Editing Hydraulic Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Moving Hydraulic Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Copying/Cutting/Pasting/Deleting Elements . . . . . . . . . . . . . . . . . . . . . . . .

5-153 5-154 5-155 5-155 5-156 5-156 5-156

Finding Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-157 View Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-158 Pan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-158

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HAMMER User's Guide

Zoom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-158 Drawing Pane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-158 Screen Layout (Format Display) Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-159

Chapter 6: Hydraulic Element Reference

161

Overview of Hydraulic Element Properties. . . . . . . . . . . . . . . . . . . . . . . . . . .6-161 Pipes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-163 Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-164 System Boundaries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-164 Control Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-166 Flow-Control Valve Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-166 Flow-Control Valves as Sources of Hydraulic Transients . . . . . . . . . . . . . . .6-167 Flow-Control Valve Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-168 Orifice Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-170 Rotating Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-171 Pump Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-171 PUMP INERTIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-173 SPECIFIC SPEED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-174 FIRST-QUADRANT AND FOUR-QUADRANT REPRESENTATIONS . . . . . . . . . . .6-175 VARIABLE-SPEED PUMPS (VSP OR VFD) . . . . . . . . . . . . . . . . . . . . . . . . . .6-176 Pump Element Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-177 Turbine Element Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-180 Protection Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-181 Check Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-181 Pressure Relief and Other Regulating Valves . . . . . . . . . . . . . . . . . . . . . . . .6-181 Protective Equipment Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-183 Gas Vessels and Surge Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-185

Chapter 7: Modeling Capabilities

189

Hydraulic Transient Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-189 Rigid-Column Simulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-190 Elastic Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-191 Data Requirements and Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . .7-192 Infrastructure and Risk Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-192 Water Column Separation and Vapor Pockets . . . . . . . . . . . . . . . . . . . . . . . .7-193 Global Adjustment to Vapor Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-193 Global Adjustment to Pipe Elevations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-194 Global Adjustment to Wave Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-194 Automatic Selection of the Time Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-195 Check Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-195 Orifice Demand and Intrusion Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-196 Numerical Model Calibration and Validation . . . . . . . . . . . . . . . . . . . . . . . . .7-197 HAMMER User's Guide

Contents-v

Gathering Field Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-199 Timing and Shape of Transient Pressure Pulses. . . . . . . . . . . . . . . . . . . . . 7-199

Chapter 8: Presenting Your Results

201

Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Using Time or Head to Trigger Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Text Output File Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Predefined Report Formats in Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8-202 8-202 8-202 8-203

Hydraulic Element Labels and Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Using Your Organization’s Name and Logo . . . . . . . . . . . . . . . . . . . . . . . . . System Colors and Display Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hydraulic Element Labels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hydraulic Element Colors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8-206 8-206 8-206 8-207 8-207

Generating Color Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-208 Profile Plots along a Path (or Walk) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-210 Walking the Path (or Profile Setup) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-210 Path or Profile Plot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-211 Time History Graphs at a Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-211 Graph Formatting and Annotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Graph Formatting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Output Variable Formatting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Adding Annotations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . No Need for Print Previews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8-212 8-212 8-213 8-214 8-214

Animating Maps, Profiles and Point Histories . . . . . . . . . . . . . . . . . . . . . . . 8-215

Chapter A: Frequently Asked Questions

219

Overview: “How Do I” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-219 Import/Export Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transitioning from Steady-State Models to HAMMER . . . . . . . . . . . . . . . . . SCENARIO MANAGEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DEMAND ALTERNATIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTROL VALVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PUMPS AND PUMP CURVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IN SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importing Data from WaterCAD/WaterGEMS Models . . . . . . . . . . . . . . . . . Importing EPANET Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Importing Surge2000 and PIPE2000 Data . . . . . . . . . . . . . . . . . . . . . . . . . Importing from a Database Using the HAMMER Datastore. . . . . . . . . . . . . Additional Considerations When Working with Large Model Files. . . . . . . .

A-219 A-220 A-220 A-221 A-221 A-222 A-222 A-223 A-223 A-223 A-223 A-224

Modeling Tips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-224 How Do I Set Up a HAMMER Project? . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-225 Modeling a Hydropneumatic Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-227 Modeling a Pumped Groundwater Well . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-227

Contents-vi

HAMMER User's Guide

Modeling Parallel Pipes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modeling Pumps in Parallel and Series. . . . . . . . . . . . . . . . . . . . . . . . . . . . Modeling Hydraulically Close Tanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Top-Feed/Bottom Gravity Discharge Tank. . . . . . . . . . . . . . . . . . . . . . . . . . Estimating Hydrant Discharge Using Flow Emitters . . . . . . . . . . . . . . . . . . Modeling Variable-Speed Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A-228 A-228 A-228 A-228 A-230 A-230

How Do I Access the Knowledge Base? . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-231 Display Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . How Do I Display my Organization’s Name and Logo? . . . . . . . . . . . . . . . How Do I Control Element and Label Display? . . . . . . . . . . . . . . . . . . . . . . How Do I Color-Code Elements? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . How Do I Reuse Sets of Hydraulic Elements? . . . . . . . . . . . . . . . . . . . . . . How Do I Copy a Path from One HAMMER Project to Another? . . . . . . . .

A-231 A-232 A-232 A-232 A-233 A-233

Editing Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-233

Appendix B: HAMMER Theory and Practice

235

Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-236 Overview of Hydraulic Transients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . History of Solution Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Causes of Transient Initiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Impacts of Transients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design of Protective Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B-236 B-237 B-239 B-242 B-244

Hydraulic Transient Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conservation of Energy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Governing Equations for Steady-State Flow . . . . . . . . . . . . . . . . . . . . . . . . CONSERVATION OF MASS AT STEADY STATE . . . . . . . . . . . . . . . . . . . . . . CONSERVATION OF ENERGY AT STEADY STATE . . . . . . . . . . . . . . . . . . . . Governing Equations for Unsteady (or Transient) Flow . . . . . . . . . . . . . . . CONTINUITY EQUATION FOR UNSTEADY FLOW . . . . . . . . . . . . . . . . . . . . . MOMENTUM EQUATION FOR UNSTEADY FLOW . . . . . . . . . . . . . . . . . . . . . METHOD OF CHARACTERISTICS (MOC) . . . . . . . . . . . . . . . . . . . . . . . . . . Rigid Column Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rigid Column versus Elastic Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elastic Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B-244 B-245 B-246 B-247 B-248 B-248 B-248 B-249 B-250 B-252 B-255 B-256

Water System Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Celerity and Pipe Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wave Propagation and Characteristic Time . . . . . . . . . . . . . . . . . . . . . . . . Wave Reflection and Transmission Pipelines . . . . . . . . . . . . . . . . . . . . . . . Type of Networks and Pumping Systems . . . . . . . . . . . . . . . . . . . . . . . . . . Putting It All Together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B-257 B-257 B-261 B-262 B-264 B-266

Pump Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-267 Pump Characteristics and Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-267 Variable-Speed Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-269

HAMMER User's Guide

Contents-vii

Constant-Horsepower Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-270 Valve Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Valve Selection and Sizing Considerations . . . . . . . . . . . . . . . . . . . . . . . . . Typical Valve Bodies and Pistons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Closing Characteristics of Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flow-Decreasing Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B-271 B-271 B-273 B-274 B-276

Friction and Minor Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-277 Hazen-Williams Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-277 Darcy-Weisbach Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-278 SWAMEE AND JAIN EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-279 COLEBROOK-WHITE EQUATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-280 Manning’s Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-280 CHÉZY’S EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-281 Minor Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-282 Quasi-Steady Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-283 Unsteady or Transient Friction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-285 Developing a Surge-Control Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-286 Piping System Design and Layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-286 Protection Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-288 Approaches to Surge Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-289 SYSTEM-IMPROVEMENT METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-292 FLOW-SUPPLEMENT APPROACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-292 TWO-WAY SURGE TANK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-292 ONE-WAY SURGE TANK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-294 GAS VESSEL OR AIR CHAMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-294 INCREASE OF INERTIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-296 Pump Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-297 CHECK VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-297 BOOSTER PUMP BYPASS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-297 Surge-Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-299 Operation and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-305 Engineer’s Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-306 Roughness Values—Manning’s Equation . . . . . . . . . . . . . . . . . . . . . . . . . . B-307 Roughness Values—Darcy-Weisbach Equation (Colebrook-White) . . . . . . B-308 Roughness Values—Hazen-Williams Equation . . . . . . . . . . . . . . . . . . . . . . B-309 Typical Roughness Values for Pressure Pipes . . . . . . . . . . . . . . . . . . . . . . B-310 Fitting Loss Coefficients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-311 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-312

Appendix C: About Haestad Methods

317

Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-317 WaterGEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-318 WaterCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-318 SewerCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-318 StormCAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-319 PondPack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-319 Contents-viii

HAMMER User's Guide

FlowMaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-320 CulvertMaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-320 Haestad Press . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-320 Training and Certification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-321 Accreditations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-321 Internet Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-321 Instant Account Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-322 CivilQuiz.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-322

Chapter D: Environmental Hydraulics Group

323

Water Networks and Transmission Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . D-323 Deep Sewers and Tunnels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-325 Hydraulic Testing and Forensic Engineering . . . . . . . . . . . . . . . . . . . . . . . . D-326 Pump Station Upgrades and NPHS Testing . . . . . . . . . . . . . . . . . . . . . . . . D-327 Expert Witness and Break Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . D-327 Field and Lab Tests for Disinfection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-328 Hydropower and Cogeneration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-329 Mining and Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-329

Index

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Contents-ix

Contents-x

HAMMER User's Guide

Chapter

1

Orientation and Installation Thank you for purchasing HAMMER. At Haestad Methods, we pride ourselves in providing the very best engineering software available. Our goal is to make software that is easy to install and use, yet so powerful and intuitive that it anticipates your needs without getting in your way. When you first use HAMMER, the intuitive interface and interactive dialog boxes will guide you. If you need more information, use the online help by pressing the F1 key or selecting help from the Help menu. Help text regarding the area of the program in which you are working will be displayed. In addition to Help resources, three other sources of information are available:

1.1

•

Printed User’s Guide—The printed manual provides Quick Start lessons and it can be used away from the computer to review HAMMER features and theory.

•

Online Book—The online text, which is available with each new software version you download, includes information about the HAMMER interface and hypertext links to help navigate the information more easily. (For more information, see “Using the Online Help, Online Book, and Help Pane”.)

•

Internet Resources—The Haestad Methods WaterTalk forum is a free service where anyone can ask questions (from novice to expert level), and get answers from other users. Engineers and experts from Haestad Methods and Environmental Hydraulics Group often post answers to questions. To sign up for WaterTalk, visit http://www.haestad.com/forums.

What is HAMMER? HAMMER is a powerful yet easy-to-use program that helps engineers analyze complex pumping systems and piping networks as they transition from one steady state to another. Hydraulic transients only last from seconds to a few minutes, but they can damage a system or cause significant operational difficulties. For example,

HAMMER User's Guide

1-1

What is HAMMER? HAMMER’s name is due to the loud “water hammer” noise which can be heard when sudden hydraulic transients occur. HAMMER helps engineers understand their pumping and piping networks better, enabling them to design safe and economical surge-control systems. HAMMER is based on technology originally created by Environmental Hydraulics Group Inc. (EHG), the water hammer specialists, and backed by a long-term collaboration between EHG and Haestad Methods. Haestad Methods and EHG are committed to continuously improving HAMMER.

1.1.1

About EHG Environmental Hydraulics Group, Inc. (EHG), has a proven track record of advanced consulting projects and break investigations involving water, sewage, oil/fuel, slurries, and steam for the public, mining and industrial sectors world wide. EHG is led by Dr. Alan Fok, P.Eng., a designated Hydraulics Specialist (1983) who founded the firm in 1987 after completing his water hammer Ph.D. EHG’s clients are governments, legal firms, and consulting engineers requiring expert assistance or reviews based on the highest level of technical expertise and most advanced numerical modeling technologies (http:// www.ehg-inc.com).

1.1.2

Capabilities of HAMMER HAMMER’s graphical interface makes it easy to quickly lay out a complex network of pipes, tanks, pumps, and surge control equipment. If you already have a steadystate model of your system, HAMMER can import its data and results automatically to save you time and eliminate transcription errors. You can use HAMMER to

1-2

•

Reduce the risk of transient-related damage to maximize operator safety and reduce the frequency of service interruptions to customers.

•

Reduce daily wear and tear on pumping and piping systems to maximize the useful life of infrastructure.

•

Reduce the risk of water contamination during subatmospheric transient pressures, during which groundwater and pollutants could be sucked into the pipe.

•

Reduce the number and severity of high transient pressure shocks, where applicable. High transient pressures can loosen joints or grow cracks, increasing leaks and unaccounted-for water (UFW).

HAMMER User's Guide

Orientation and Installation •

Prepare operation checklists for use in emergencies such as power failures, pipe breaks, and component (valve, pump) and/or control failures.

•

Develop standards to ensure major water users do not damage the water system. Information can be provided to industries to avoid sudden water takings or load rejection. Safe speeds to open or close fire hydrants can be provided to the fire and waterworks department.

•

Provide additional information (with respect to steady-state models) to help select pumps, locate elevated tanks, and size air valves. Transient Tip: Usually, hydraulic systems operate at a steady state of dynamic equilibrium and changes in flow take minutes to hours. “Normal” hydraulic transients may occur several times a day as pumps start or stop. “Emergency” transients may only occur once every month, year, or decade when power fails or pipes break. Hydraulic transients and surge-protection needs must be considered in the context of a water utility’s risk management and environmental protection plan.

1.2

Installing HAMMER Before installing HAMMER, it is important to understand that it is intended for use by engineers and expert users. HAMMER should not be installed on a computer used as a network server or on a computer used for heavy multitasking. HAMMER uses advanced numerical computation methods to represent pipelines or networks as a large system of equations. Since HAMMER’s performance during a run is proportional to the processor’s speed and floating-point throughput, it has been optimized to use virtually 100% of system resources. Transient Tip: Unlike steady-state programs, which may solve from one to a few dozen time steps (e.g., 24 for an hourly extended-period simulation), HAMMER typically solves hundreds to hundreds of thousands of time steps, each requiring hundreds of calculations.

1.2.1

Minimum System Requirements A powerful personal computer or workstation is required to run HAMMER. It is best not to run other large programs simultaneously. Depending on each run’s configuration, HAMMER may require very large amounts of RAM and disk space. It is essential to configure a HAMMER run to avoid placing undue demands on your computer, especially when generating output, as described in “Lesson 3: Network Risk Reduction” on page 3-115.

HAMMER User's Guide

1-3

Installing HAMMER Animation is a powerful way to visualize the impacts of transients and a fast graphics card is ideal to ensure smooth motion when animating HAMMER results. We suggest the following minimum and recommended system requirements to avoid significant delays: Minimum (e.g., occasional use for simple pipelines) Processor:

Pentium III – 1 GHz

RAM:

256 megabytes

Hard Disk:

100 megabytes of free storage space, with additional room for data files

Display:

800 x 600 resolution at 256 colors

Recommended (e.g., regular use for entire networks) Processor:

Pentium IV or Athlon XP – 2 to 3 GHz

RAM:

512 megabytes or more (adding RAM is an economical way to boost performance for large pipe networks)

Hard Disk:

500 megabytes of free storage space (or more depending on data files)

Display:

1280 x 1024 resolution at 256 colors or more, 64 megabyte graphics card or better (dual displays are helpful to visualize complex networks by letting you see HAMMER and another application, like WaterCAD, on separate monitors at the same time)

While Haestad Methods’ software will perform adequately given the minimum system requirements, performance will only improve with a faster system. Our products are designed to perform at optimal levels with a fast processor and ample amounts of RAM memory and free disk space. We highly recommend running HAMMER on the best system possible to maximize its potential, especially for larger network models containing thousands of pipes. An engineer’s time is valuable and we have designed our software to help make the most of that time.

1-4

HAMMER User's Guide

Orientation and Installation

1.2.2

Installing Haestad Methods Products Note:

Windows 2000 and XP are the only supported operating systems.

For Windows 2000 and Windows XP, follow these steps to install a single-user license copy of HAMMER: 1. Place the CD in your CD-ROM drive (commonly the d: or e: drive). 2. If the Autorun feature of the operating system is enabled, setup will begin automatically. Proceed to step six. 3. If Autorun is disabled, click the Start button on the task bar, select Run, and type d:\setup (use the actual drive letter of the CD-ROM drive if it is not the d: drive), and then click OK. 4. Follow the instructions of the Setup Wizard. Note:

You can choose not to activate the software immediately but you can only run the inactivated software a few times before you are required to activate it. Activation is completely anonymous and no personal information will be sent to Haestad Methods. During activation, the product ID, registration number, and a nonunique hardware identification are sent to Haestad Methods. This information is used strictly for the purposes of validating the license for your product. The hardware identification does not include any personal information about you, any information about other software or data that may reside on your PC, or any information about the specific make or model of your PC. This information is sent over the Internet in an encrypted form and stored at Haestad Methods in a controlled environment.

5. After the installation finishes, you are prompted to register the software online or by telephone using the Registration Wizard. Haestad Methods’ products come with an uninstallation option. After a single-user license copy of HAMMER is installed on a computer, it must be uninstalled before a new installation or upgrade of HAMMER can occur. To uninstall the program, click Start > Program Files > Haestad Methods > HAMMER > Uninstall HAMMER.

HAMMER User's Guide

1-5

Installing HAMMER

1.2.3

Troubleshooting Setup or Uninstallation Because of the multitasking capabilities of Windows, you may have applications running in the background that make it difficult for the setup routines to determine the configuration of your current system. If you have difficulties during the installation (setup) or uninstallation process, please try these steps before contacting our technical support staff: •

Restart your PC.

•

Verify that there are no other programs running. You can see applications currently in use by pressing Ctrl+Shift+Esc in Windows. Exit any applications that are running.

•

Run setup or uninstall again without running any other program first.

If these steps fail to successfully install or uninstall the product, contact our support staff.

1.2.4

Software Registration During the installation of the program, a dialog box will prompt you to register the software. Please note that the label with your registration information is on the inside of the back cover of the manual. Although this software is not copy protected, registration is required to unlock the software capabilities for the hydraulic features that you have licensed. All registration information must be entered into the Registration dialog box exactly as it appears on the label: •

Company

•

City

•

State/Country

•

Product ID

•

Registration Number

After you have registered the software, you can check your current registration status by opening the registration dialog box in the software itself. To open the Registration dialog box:

1-6

•

Select Help > About.

•

Click the Registration button in the About dialog box.

HAMMER User's Guide

Orientation and Installation The current registration status (number of licenses, expiration date, feature level, etc.) will be displayed.

1.2.5

•

You can use the Copy button to place the registration information in the Windows Clipboard so that you can paste it into another Windows application.

•

You can also use the Print button to print the information shown in the Registration Form dialog box.

Upgrades and the Globe Button When you click the Registration button on the Help > About HAMMER dialog box, the current registration status (number of licenses, expiration date, feature level, etc.) is displayed. To upgrade to higher feature levels or additional licenses, contact our sales team today and request information about our ClientCare® program. We will provide the information you need to get up and running in no time! Note:

Use the Globe button to keep your investment current.

Haestad Methods makes it easy to stay up to date with the latest advances in our software. Software maintenance releases can be downloaded from the Haestad Methods’ Web site quickly and easily if you are a subscriber to our ClientCare Program. Just click the Globe icon on the tool palette to launch your preferred Web browser and open the Haestad Methods’ ClientCare Web site. You can download the correct upgrade to bring your software up to date. The ClientCare program also gives you access to our extensive KnowledgeBase™ for answers to Frequently Asked Questions (FAQ). Contact the Haestad Methods sales team for more information about ClientCare.

1.3

Network Licensing Network versions of this product are available. If you purchased a network version, your program will run at any workstation located on your network if a floating license key is available for use. Floating licenses allow one or more concurrent users of a particular application to access and use the full capabilities of the software, if the number of concurrent licenses does not exceed the number allowed under the terms of the license sale. Once the number of concurrent users equals the licensed number, new application sessions will run in a limited demo mode. Network licensing is implemented using Rainbow Industries SentinelLM™ license manager. Administrators should refer to the SentinelLM™ System Administrators Guide for details on implementing network licensing at your location.

HAMMER User's Guide

1-7

Network Licensing

1.3.1

Registering Network Programs During the installation of the network deployment folder, a dialog box will appear asking you to register the software. The label with your registration information is on the inside back cover of the manual. This registration data is required to enable the software capabilities for the hydraulic network size and features that you have licensed. All registration information must be entered into the Registration dialog box exactly as it appears on the label. •

Company

•

City

•

State/Country

•

Product ID

•

Registration Number

After you have registered the software, you can view the current registration and floating license usage status at any of the workstations that have the product software installed on it. To open the registration dialog box: •

Select Help > About.

•

Click the Registration button.

The current registration status (number of floating licenses, expiration date, feature level, etc.) will be displayed. If all available floating licenses are in current use, the software will run in demo mode. Network administrators may activate network licenses and upgrade the features served by their floating licenses by requesting a permanent license from Haestad Methods.

1.3.2

Requesting a Permanent Network License System administrators who are responsible for managing network license versions of Haestad Methods’ software must activate their organization’s floating licenses by obtaining a permanent license file from Haestad Methods.

1-8

HAMMER User's Guide

Orientation and Installation Note:

Haestad Methods uses SentinelLM™ License Manager software from Rainbow Technologies to manage network licensing for this application. For more information concerning the administration of the Haestad Methods floating network licensing, please see the Sentinel online documentation that installed with your network license server software.

To acquire a network license file, the administrator must first generate the network locking codes for the computer that will be acting as the network license server. To get your license server locking code, use the SentinelLM™ echoid utility. This is installed with the license server software on the computer acting as the network license host for this application. Note:

The echoid utility must be run from the same computer that will act as the license server host for this particular Haestad Methods application.

Write down the values for the locking codes that are posted in the echoid utility’s message box. Be certain to record these values accurately, as they will be used by Haestad Methods to generate a custom license file keyed to the specific license server’s hardware signature. Once issued, a license key-code may not be installed on another machine. You will not be able to transport the license server to another network machine without obtaining new lock codes. With echoid values in hand, start the Haestad Methods product application on any workstation located on the network served by the license manager. You can even install and run the Haestad Methods application from the same computer that will be acting as the license server host computer. Caution:

The permanent license file that is generated depends on the IP address and HostName of the computer from which the lock code was produced. The issued license will not operate on any computer without the same IP address and HostName. If the license server software is moved to a computer without the same IP address and HostName, it will be necessary to obtain a new, permanent network license file from Haestad Methods. A replacement/relocation network license fee will be applied for the new license file. Please select the server for the license manager carefully, to avoid this process and fee.

Request a permanent license for the product by e-mailing or faxing to:

HAMMER User's Guide

1-9

Network Licensing

E-mail:

[email protected]

Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

Mail:

Haestad Methods 37 Brookside Road Waterbury, 06708-1499 USA

Include the following information in your correspondence: Note:

1.3.3

The registration information and product ID are on the inside of the back cover of the user manual that shipped with your product or on the ClientCare certificate you received.

•

Product name

•

Build number

•

Registration number

•

Product ID

•

Lock code 1

•

Lock code 2

•

Name of the registered user of the software

•

Attention—the name of the person who is to receive the permanent license file

•

Company

•

City

•

State

Installation Guide for Network License Versions To set up a Haestad Methods’ software product for operation as a network-licensed version: 1. Place the CD in your CD-ROM drive (commonly the d: or e: drive). 2. If the Autorun feature of the operating system is enabled, setup will begin automatically. If Autorun is disabled, click the Start button on the task bar, select Run, and type d:\setup (use the actual drive letter of the CD-ROM drive if it is not the d: drive). Click OK.

1-10

HAMMER User's Guide

Orientation and Installation 3. To perform the following steps, you must have full administrator privileges for the target network-based installation folders. Follow the instructions of the Setup Wizard, which will guide you through the installation of two components. –

Network Deployment Folder—A directory installed on a network node that is available from all client workstations on which the license product will be installed. Users of the floating licenses will invoke the network-based installation utility, SETUP.EXE, which will install and configure the application to each client workstation.

–

Network License Manager and Utilities—The license manager service executable file that will automatically monitor availability and distribute network floating licenses to client applications as they are started up across the license hosting LAN. The license manager may be installed on any shared node in the network, but is generally located on a network server machine.

4. Start the license server. The license manager runs as a service and can be manually controlled via the Windows NT Control Panel > Services group. 5. Announce the availability of the product via e-mail. Instruct interested users to install the product by using the Start > Run menu command and browsing to the network deployment folder installed in step 3 to run SETUP.EXE. The license server ships with special 30-day licenses that will allow users to begin using the application immediately. 6. Obtain a permanent license file for the application. A permanent license file must be obtained from Haestad Methods within 30 days of receipt of the product package. Request a permanent license file by following these steps: a. At the host computer on which the license server will run, use the echoid utility (\Haestad\AdminTools\echoid) via the Locking Codes menu option to determine the locking codes that will be used to generate license keys for your network. The license key file will be configured specifically for the license server machine installation. Write these locking codes down. b. Request a permanent network license for the product. See “Requesting a Permanent Network License” on page 1-8. 7. Use the lslic utility located in the AdminTools directory to modify the permanent license file managed by the network license server. After the license key file requested above is received via e-mail from Haestad Methods, save the file attachment to a computer folder on any computer resident on the network serviced by the running license server. For future convenience, safety, and ease of support, it is recommended that the license file be saved in the license manager tools directory, AdminTools. This utility must be run from the operating system prompt. Enter lslic -F , where is the name of the license file attachment e-mailed by Haestad Methods and saved to the hard-drive. This step will install the new license key into the license file, lservrc, located on the same computer and in the same directory where the license server resides.

HAMMER User's Guide

1-11

Learning HAMMER Once these steps are completed, floating licenses will be available to concurrent users via the network. Should the number of users exceed the number of license keys available, the unlicensed client sessions will continue to run in demo mode.

1.3.4

Network Deployment Folder Interested users may install the complete product via the network-deployment folder using the Windows Start > Run command. Browse to the deployment directory, and run SETUP.EXE to install the program to a client workstation.

1.4

Learning HAMMER In addition to the online help and documentation, there are many ways to quickly learn HAMMER:

1.4.1

•

“Frequently Asked Questions—How Do I?” on page 1-12

•

“Tutorials and Sample Projects” on page 1-12

•

“Haestad Methods Workshops” on page 1-13

Frequently Asked Questions—How Do I? “How Do I?” is an easily referenced topic in HAMMER’s online documentation. It is a listing of commonly asked questions about HAMMER. To use it click Help > How Do I? and a listing of topics will appear. Click the topic of your choice for a detailed explanation.

1.4.2

Tutorials and Sample Projects You can explore sample projects to investigate HAMMER’s capabilities further: 1. Select File > Open to access the Open Project File dialog box. 2. Choose HAMsam??.HIF (where ?? is a number) from the Samples directory and click Open. These are working models, so you can explore the systems and see how different elements are modeled. First, calculate the system by using the GO button on the main toolbar to see how the system behaves. Then, click Tools > Viewer > Graphics to look at sample graphs (.GRP) and animations (.ANI).

1-12

HAMMER User's Guide

Orientation and Installation

1.4.3

Haestad Methods Workshops Haestad Methods offers a variety of workshops dealing with water-distribution modeling topics. These provide theory, modeling insights, and hands-on practice with software instruction. These workshops are held at various locations and discounted pricing is available to purchasers of Haestad Methods software. For more information about our workshops (such as instructors, schedules, pricing, and locations), please contact our sales department or visit our Web site at http:// www.haestad.com for current workshop schedules and locations. We will be glad to answer any questions you may have regarding the workshops and our other products and services. Haestad Methods offers a range of other training services including on-site, on-line, and on-campus training. For detailed information on the availability of these options, visit http://www.haestad.com/education.

1.5

Contacting Haestad Methods For information on contacting Haestad Methods, see:

1.5.1

•

“Sales” on page 1-13

•

“Technical Support” on page 1-14

•

“Engineering Support” on page 1-15

•

“Addresses” on page 1-15

Sales Haestad Methods’ professional staff is ready to answer your questions. Please contact your sales representative with any questions regarding Haestad Methods’ latest products and prices: Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

E-mail:

[email protected]

HAMMER User's Guide

1-13

Contacting Haestad Methods

1.5.2

Technical Support We hope that everything runs smoothly and you never have a need for our technical support staff. However, if you do need support, our highly skilled staff offers their services seven days a week and may be contacted by phone, fax, and the Internet. For information on the various levels of support we offer, contact our sales team and request information about our ClientCare program. When calling for support, in order to assist our technicians in troubleshooting your problem, please be in front of your computer and have the following information: •

Operating system your computer is running (Windows 2000 or Windows XP).

•

Name and build number of the Haestad Methods software. The build number can be determined by clicking Help > About HAMMER. The build number is the number in brackets located in the lower-left corner of the dialog box that opens.

•

A note of exactly what you were doing when you encountered the problem.

•

Any error messages or other information displayed on your screen.

When e-mailing or faxing for support, please provide additional details as follows so we can provide a timely and accurate response: •

Company name, address, and phone number

•

A detailed explanation of your concerns

•

The FORERR.LOG file located in the \Comp subfolder of the product directory

You can contact our support staff during the hours shown below:

1-14

Monday – Friday:

9:00 AM EST to 8:00 PM EST

Saturday – Sunday:

9:00 AM EST to 5:00 PM EST

Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

E-mail:

[email protected]

HAMMER User's Guide

Orientation and Installation

1.5.3

Engineering Support Technical-support questions pertain to the correct use of your HAMMER software's features and capabilities. Engineering support is also available to help you develop particular surge control designs or written recommendations. Consider engineering support whenever project requirements exceed your in-house capabilities or the available staff time. In addition to Haestad Methods training courses, project-specific coaching or collaborations can help you reach the next level of expertise in hydraulic transients.

1.5.4

Addresses Use this address information to contact us: Internet

http://www.haestad.com

E-mail:

[email protected] [email protected] [email protected]

1.6

Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

Mail:

Haestad Methods 37 Brookside Road Waterbury, 06708-1499 USA

Your Suggestions Count At Haestad Methods, we strive to continually provide you with sophisticated software and documentation. We are very interested in hearing your suggestions for improving our products, our online help system and our printed manuals. Your feedback will guide us in developing products that will make you more productive. Please let us hear from you ([email protected])!

HAMMER User's Guide

1-15

Your Suggestions Count

1-16

HAMMER User's Guide

Chapter

2

HAMMER Main Window If you are already familiar with standard Microsoft Windows interfaces or other Haestad Methods software, such as WaterCAD or WaterGEMS, you will find HAMMER to be intuitive and comfortable. Even if you are not accustomed to Windows, just a few minutes of exploring HAMMER should be enough to acquaint yourself with its flexibility and power. Note:

You can also explore each component by moving the cursor over it and then holding it still for a little while (i.e., hovering), to display Tool Tip help text describing each particular item.

This section describes the program’s main windows, menus, toolbars, and online help to let you use HAMMER quickly and efficiently.

2.1

Main Window Components HAMMER has two alternative modes: Main Window or Modeler mode and Viewer mode. In Modeler mode, you can assemble hydraulic models in the Main Window or import them from other models or databases. In Viewer mode, you can display, annotate and animate current (or previous) HAMMER simulation results as well as generate and print tables and reports. You will normally begin a new project using Modeler, but you can also run Viewer separately if you only need to examine results or animations. To start HAMMER from the start menu, select: Start > All Programs > Haestad Methods > HAMMER > HAMMER You can open the Viewer from within Modeler using Tools > Viewer > Graphics (for graphs or animations) or Tools > Viewer > Output Database (for tables or reports). HAMMER has the following Main Window (Modeler) components: •

Menus, Tool Bar, and Status Bar

•

Drawing and Element Panes

HAMMER User's Guide

2-17

Main Window Components Viewer Mode

2.1.1

•

Graphing and Annotation Tools and Shortcut Menus

•

Animation Controller

Main Window: HAMMER Modeler It is useful to keep HAMMER’s fundamental purpose in mind while exploring the Main Window. HAMMER simulates hydraulic systems made of various hydraulic elements (e.g., pipes or valves) connected together at particular end points (or nodes) to form paths (also known as profiles in WaterCAD) and/or networks. The Main Window is used to input element data and to specify the locations (points or paths) for which output is required. The following figure shows the areas of HAMMER’s Main Window (without showing any model data):

Title bar

Element selector pane

Menus Tool bar (buttons)

Drawing pane Element data pane

Status bar

The components of the Main Window are: •

2-18

Title Bar—The title bar for the Main Window displays the current folder and input file name. If the file has been modified since it was last saved, the title bar displays [Modified].

HAMMER User's Guide

HAMMER Main Window •

Menus—Each menu item can be accessed from the keyboard by holding down the Alt key and pressing the underlined letter on the menu. Some frequently used commands can also be accessed using toolbar buttons or shortcut key combinations. Shortcuts are invoked by holding down the Ctrl key and pressing the letter shown to the right of some menu entries (e.g., Ctrl+S to save).

•

Model and Element Toolbars—The left-hand-side buttons are used to manage files and to set view and simulation parameters. Buttons used to set the display (zoom, color-code), some of which are inactive prior to a run, are shown in the middle. The right-hand-side buttons are used to select hydraulic elements to drop onto the Drawing Pane. Note:

Individual buttons are provided for the two most common items (node and link), followed by drop-down lists for each element type: system boundaries (reservoir icon shown), control equipment (orifice icon shown), protection equipment (air valve icon shown), and rotating equipment (pump icon shown). For more information, see “Hydraulic Element Reference” on page 6161.

•

Drawing Pane—The Drawing Pane displays the hydraulic elements forming the system to be analyzed. It is the main interactive area for creating elements, editing their parameters, and mapping key results for each one. After selecting a suitable background color, you can copy the contents of the current Drawing Pane view to the Windows clipboard (using the camera button on the toolbar) to create figures describing your system in your favorite graphics software.

•

Display Tabs—Click the Properties tab to display properties of the currentlyselected hydraulic element. a. Element Selector Pane—The element selector pane sorts elements alphabetically to help you find and select them easily. The drop-down list shows all elements by default, but it can be restricted to display a single type of element, such as pipes, nodes, system boundaries, control equipment, protection equipment, or rotating equipment. b. Element Data Pane—The element data pane provides a name, data-entry field, and unit (if applicable) for each attribute of the currently selected hydraulic element. The number and types of fields are different for each hydraulic element.

•

Status Bar—The Status Bar located along the bottom of HAMMER’s Main Window displays useful information about the current state of your HAMMER model, such as the cursor position, units, zoom percentage, display setting, and whether the project file has been saved or computed recently.

HAMMER User's Guide

2-19

Main Window Components

2.1.2

Output Windows: HAMMER Viewer During a hydraulic transient simulation, HAMMER calculates how three fundamental and interrelated variables change over time: head (or pressure), flow (or velocity), and volume (of air or vapor) at each particular point in the system. The HAMMER Viewer displays the results of these calculations as graphs, animations, tables, and reports. After a transient model has been run, select Tools > Viewer > Graphics from the main menu to display the graphics Viewer. The following figure shows the graphics Viewer after running a sample file. The components of the HAMMER Viewer are: •

Title Bar—Similar to the Main window’s title bar but showing the output file name. It can be toggled on and off within each graph window to maximize the available display area.

•

Menus—Similar to the Main window but showing only applicable commands.

•

Paths—In HAMMER, a continuously connected pipe run is called a Path (red label, top left in the viewer). This is analogous to a profile in WaterCAD. The Viewer displays the number of interior points and the length of the current Path from its start (From Point) to its end (To Point).

•

Time Histories—In HAMMER, results at a point of interest are called a time History (red label, middle left). The Viewer displays the number of time steps in the current history and its location or end point.

Profile control

Point control

Select location to display

Select output variables to display

Select type of display

Looking from left to right, the Viewer allows you to select the locations (point histories or pipeline profiles) for which to display one or more of the result variables (head, flow, or volume) as plots or animations:

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HAMMER Main Window •

Clicking Plot automatically displays the selected variables on a graph so you can annotate, save, and print it.

•

Clicking Animate displays the selected variables on a graph and automatically loads the compact Animation Controller so you can animate all on-screen graphs. You can also save the screen layouts you prepare (as an .ANI file) for use in future presentations.

The components of the Animation Controller are:

Speed and frame sliders

Time step

2.2

Clock (HH:MM:SS)

Play controls

•

Play Controls—Like other media devices, these controls let you play forward or backward, stop, or advance by a single frame forward or backward.

•

Menus—Similar to those on the Viewer but only showing applicable commands.

•

Time Value—Shows the time step or frame for which results are currently displayed onscreen for point histories or path (profile) graphs (not shown).

•

Clock—The large, easy-to-read clock displays minutes, seconds, and hundredths of a second. Transient pressure pulses can travel fast enough to require this degree of simulation and display accuracy.

•

Sliders—Control animation speed (in frames per second) and frame position. Manipulate them during an animation to jump ahead or change speed.

HAMMER Menus and Shortcut Menus Although the toolbars and shortcut keys provide quick and easy access to commonly used features, the menu system provides comprehensive access to HAMMER properties and behaviors. Since toolbar buttons and shortcut keys do not exist for all of these features, the menus are a logical choice for exploring all areas of HAMMER. This section will introduce you to the features you can access using the menus and the corresponding toolbar buttons and shortcut keys (where available).

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HAMMER Menus and Shortcut Menus A typical HAMMER modeling project begins by laying out the system in the Main Window (with dozens of menu and toolbar items) and ends by reviewing output using the HAMMER Viewer or Animation Controller (with a minimum number of menu and toolbar items). Note the following special features: •

The menus show only the options required to accomplish tasks or to access model features which may be needed in the part of the program you are using.

•

Nearly every item is available either from the main menu or from shortcut menus opened by right-clicking items or graphs.

•

Menus and title bars can be hidden to maximize the portion of the graph window available for plots or animations. This is useful during presentations or for large systems.

Commands are grouped under top-level menus:

2.2.1

•

File Menu—manage projects and the resulting graphs and animations.

•

Edit Menu—modify or annotate system data or graphs.

•

View Menu—pan, zoom, and other graphic controls.

•

Tools Menu—change settings or start the Viewer or Animation Controller.

•

Help Menu—access online help or documentation.

File Menu Certain menu commands are only available in HAMMER Modeler or Viewer mode. Commands are grouped under several categories separated by horizontal bars in the menu. For example, the file management category provides menu commands to create, open, run, save, rename, and close files, as described in the following:

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•

New (Ctrl + N)—Creates a new project file and opens a dialog box where you can select a drive, directory, and file name for your new project file.

•

Open (Ctrl + O)—Loads an existing project file from disk. A dialog box opens so you can choose the name and location of the file.

•

Close (Ctrl + F4)—Closes the current project file, but not the HAMMER program, allowing you to load another project file.

•

Save (Ctrl + S)—Saves the current project file to disk, overwriting any previous version with the same name, if any. Remember to save often to avoid losing your work if a problem occurs.

•

Save As—Saves the current project file to disk under a different filename. A dialog box will open prompting you to enter the drive, directory, and new file name for your project.

HAMMER User's Guide

HAMMER Main Window •

Project Summary—Displays the Summary tab of the Project Options dialog box. This information includes the project title, run duration, and other data.

•

Run (Ctrl + R)—Runs the HAMMER file that is currently open. A dialog box prompts you to choose the name and location of the output files and whether you want to generate animation data. You can also run a model by right-clicking anywhere in the Drawing Pane and clicking Run, clicking Compute (if it is currently displayed) on the Status bar, or using the GO button on the toolbar.

The import – export category provides commands to exchange data with other applications, as follows: •

Import > Network—Imports network data from other hydraulic models such as EPANET 2.0, Surge2000 (and PIPE 2000), and WaterCAD and WaterGEMS. You may need to supply information not imported from these models prior to running HAMMER.

•

Export > Network—Exports network data to the EPANET 2.0 steady-state model.

•

Export > Database—Exports a HAMMER input or output (results) file to a Microsoft Access database in HAMMER datastore format, complete with predefined, customizable tabular reports.

The utility category includes the print, recent files, and exit commands. These are only available by right-clicking in a graph window.

2.2.2

•

Page Setup—In HAMMER Viewer mode, in a graph, right-click and select Page Setup to open a dialog to select the paper size, orientation, printer name, and the page margins.

•

Print—In HAMMER Viewer mode, in a graph, right-click and select Print to print the contents of the current graph window. HAMMER does not currently support printing from the Main Window, but it is possible to capture the contents of the Drawing Pane and copy them to the Windows clipboard (click the Capture Screen button).

•

Exit (Alt + F4)—Closes the current project file and then closes HAMMER.

Edit Menu The edit menu provides commands to select, locate, and modify network models and their hydraulic elements. As with the File menu, menu commands are grouped into categories separated by horizontal bars.

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HAMMER Menus and Shortcut Menus Note:

Menu commands used in Modeler or Viewer mode are only displayed in these modes. For example, commands used to modify element data in Modeler mode are not shown in Viewer mode to avoid a situation where input data does not correspond to the output graphs and tables generated by HAMMER.

The cut and paste category includes the following menu commands, available in both Modeler and Viewer modes, as follows: •

Cut (Ctrl + X)—Deletes the selected item or group of items and places it on the Windows clipboard. This item can be pasted back into HAMMER or other programs. You can also right-click any element and select Cut.

•

Copy (Ctrl + C)—Copies the selected item or group of items and places it on the Windows clipboard. This item can be pasted back into HAMMER or other programs. You can also right-click any element and select Copy.

•

Paste (Ctrl + V)—Inserts the items on the Windows Clipboard into the Drawing Pane at the current cursor position and selects them. The same items can be pasted repeatedly to replicate similar pump suction and discharge piping, for example. You can also right-click any location and select Paste.

•

Delete (Delete)—Deletes an item or group of items permanently. You can also right-click any element and select Delete. Note:

You can select hydraulic elements in the Drawing Pane using the Select toolbar button. There are two ways to select a group of elements: clicking on each item while holding down the Shift key or using a Selection Window. To use a Selection Window, click and hold the left mouse button, and move the cursor until the rectangle includes the required items, and then let go of the button to select them.

The search and select category includes the following menu commands:

2.2.3

•

Find (Ctrl + F)—Finds any type of element using its label or description and selects it in the Drawing Pane. The find command is case sensitive.

•

Find Next (F3)—Repeats a search to find any type of element using its label or description.

•

Select All (Ctrl + A)—Selects every element in the Drawing Pane. You can also select or deselect individual elements using the mouse.

View Menu •

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Pan—After clicking this toolbar icon, hold down the left mouse button to move the drawing within the Drawing Pane.

HAMMER User's Guide

HAMMER Main Window

2.2.4

•

Zoom In (Ctrl + numpad +)—Enlarges the current view of the drawing using the location you click as the center of the next view.

•

Zoom Out (Ctrl + numpad -)—Reduces the current view of the drawing using the location you click as the center of the next view

•

Zoom Window—Only available as a toolbar icon. Activates the userdefined zoom tool. This tool lets you select the corners of the area within the drawing pane that you wish to enlarge. You can also click in any area of the drawing pane to zoom into that location.

•

Normalize Symbol Size—Resizes all symbols in the Drawing Pane to a convenient size for the current window. These symbol sizes persist when the zoom level changes.

•

Zoom Extents—Resets the drawing pane zoom factor such that all elements are displayed in the drawing pane.

•

Lock Drawing Pane—Toggles the Drawing Pane lock on or off. When the Drawing Pane is locked, you can select hydraulic elements to modify their parameters or inspect their results, but you cannot change their coordinates using the mouse. This is useful to prevent accidental movement or deletion of hydraulic elements.

•

Anti-Alias—Turns on (and off) the anti-aliasing feature to let you display lines more smoothly.

Tools Menu The external tool manager category includes the following menu items to start external programs: •

Start WaterCAD/WaterGEMS—Starts the WaterCAD or WaterGEMS software.

•

Start EPANET—Starts the EPANET program identified in the File I/O tab in the Global HAMMER options dialog box (Tools > Global HAMMER Options).

•

Start Text Editor—Starts the text editor of your choice to review HAMMER output text files (based on the path and executable identified in the File I/O tab in the Global HAMMER Options).

•

View Reports/Logs—Starts the text editor of your choice and loads the output logs generated by HAMMER during each run. The report includes detailed point histories and path output for key variables. The output log includes warnings and errors as well as preselected output tables as the run progresses. The error log includes messages only if HAMMER terminates abnormally.

The output manager category includes the following menu commands to compare the results of different HAMMER project files:

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HAMMER Menus and Shortcut Menus •

Viewer > Graphics—Opens a dialog box from which you can select a HAMMER output, graph, or animation file to open using the graphics Viewer. The graphics Viewer lets you generate graphs and animations from output files (.HOF).

•

Viewer > Output Database—Starts Microsoft Access and prompts you for a HAMMER output database to open (defaults to the most recently completed run). The predefined tabular and summary reports provide a quick understanding of your results and they are fully customizable.

The output variable category provides menu commands to specify and work with output to create graphs and animations. •

Generate Animations—Generates the HAMMER output file (.HOF) required to view animations and automatically launches the Animation Controller. Since this can be time consuming for large systems, this command allows you to defer this step until you have already inspected summary output and graphics after a successful HAMMER run.

•

Animation Controller—Launches the Animation Controller, which allows you to open current or previously generated HAMMER output files (.HOF) or animation files (.ANI) and view graphs and animations onscreen.

•

Copy Paths—Copies paths from another HAMMER project file to the current project file.

•

Reset Results—Resets the results of the previous run and turns off color coding.

•

Capture Screen—Copies the contents of the Drawing Pane to the Windows clipboard. This is only available as a toolbar button.

The settings category includes the following menu commands to configure the HAMMER workspace and runs:

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•

Global HAMMER Options—Opens a tabbed dialog box in which you specify key HAMMER settings and options for colors, tool tips, default directories and programs, and fonts. You can also right-click anywhere in the Drawing Pane and select Global HAMMER Options.

•

Project Options—Opens a tabbed dialog box in which you specify runspecific settings and options including project summary, report points, report times, report paths, and other preferences and options. You can also right-click anywhere in the Drawing Pane and select Project Options.

•

FlexUnits—Opens a dialog box in which you can globally change the units used in HAMMER for specific attributes. You can also right-click anywhere in the Drawing Pane and select FlexUnits.

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HAMMER Main Window

2.2.5

Help Menu The Help menu contains online documentation for HAMMER, and includes the information contained in the printed documentation as well as updated information and built-in tutorials. The following menu items can also be accessed from the Help menu. •

Contents (F1)—Opens the Table of Contents for the online help. For more information, see “Using the Online Help, Online Book, and Help Pane” on page 2-30.

•

Index—Opens the online help at the index.

•

Search—Opens the online help at the search tab.

•

Release Notes—Provides the latest information on the current version of HAMMER. Like a README file, it includes information about new features, tips, performance tuning, and other general information.

•

Services—Opens an Internet browser to Haestad Methods’ Web site or a local page that provides an overview of the services and products offered by Haestad Methods (including training) and EHG. The local page, accessed by selecting Contents, provides links to frequently updated Haestad Methods Internet sites.

The introduction to HAMMER category provides access to resources for learning HAMMER: •

Welcome to HAMMER—Accesses the interactive tutorials, which guide you through many of the program’s features. Tutorials are a great way to become familiar with new features.

•

Using HAMMER—Opens a help topic with an Introduction to HAMMER and related information.

•

How Do I?—Provides instructions for tasks commonly performed within the program, as well as frequently asked questions.

The notices category provides access to the most up-to-date information about HAMMER:

2.2.6

•

Update from Haestad.com—Connects to http://www.haestad.com to check for updates.

•

About HAMMER—Opens a dialog box displaying product and registration information. (For more information, see “Software Registration” on page 1-6.)

Format Graph Shortcut Menu These menu commands are only available from within the HAMMER Viewer. Open this menu by right-clicking on a graph axis.

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HAMMER Menus and Shortcut Menus The formatting category includes the following menu commands to format the contents of the output variable graphs (in Viewer) to obtain report-ready figures: •

Format Graph—Opens a dialog to select the axis titles and labels, major and minor grid lines, tick marks, background color, and outline style.

•

Format Data—Opens a dialog to select the line type, color, and thickness for each output variable (head, flow, or volume) displayed in the current graph. For the currently selected output variable, you can specify an offset value to create a new line parallel to it; for example, to show a pipeline’s surge pressure tolerance. You can also limit your formatting selections to a Line Segment, to show different pipe materials along a pipeline, for example. Note:

A Line Segment is a portion of the dependent variable (head, flow, or volume) bounded by two user-selected values of the independent variable (on the x-axis). You can subdivide output variables into several Line Segments.

•

Format Shades—Opens a dialog to create and modify Differential Shades between any two output variables (head, flow, or volume). You can select the color and opacity of each Differential Shade. You can toggle each Differential Shade on or off to improve animation performance or to reduce the size of a graph when printing to a file.

•

Copy Settings—Copies the settings for the current graph to the Windows clipboard.

•

Paste Settings—Modifies the current graph using the settings previously copied to the Windows clipboard.

•

Copy Symbols—Copies all symbols in the current graph pane to the Windows clipboard.

•

Paste Symbols—Pastes the symbols previously copied to the Windows clipboard into the current graph pane.

The edit category includes the following menu commands:

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•

Copy Data—Copies the output variable line data shown in the current graph pane so you can paste it into another graph.

•

Paste Data (–)—Clears the contents of the current graph pane, then pastes the output variable line data previously copied to the Windows clipboard into the current graph pane.

•

Paste Data (+)—Pastes the output variable line data previously copied to the Windows clipboard into the current graph pane so you can compare the results of two HAMMER project files. All results are displayed at the correct scale using the units set for the graph.

HAMMER User's Guide

HAMMER Main Window The draw category includes the following menu commands, which are available in the Viewer only:

2.2.7

•

Draw Lines—Draws vertical, horizontal, or diagonal lines and allows you to specify their line type, color, and thickness.

•

Draw Text—Allows you to enter vertical or horizontal text labels.

•

Draw Symbols—Displays a graphical list of hydraulic symbols you can insert into the current graph pane.

Format Display Shortcut Menu These menu commands are only available from within the HAMMER Viewer by right-clicking anywhere except the graph axes. •

FlexUnits—Opens the FlexUnits manager, from which you can select the units of measurement, display precision, and whether or not to use scientific notation. Please note that changes made to FlexUnits take effect throughout the current HAMMER project.

The graph display category includes the following menu commands to adapt the appearance of each graph for use on-screen or as a printed figure: •

Show Frame (Ctrl + F)—Toggles the display of the frames that convert an onscreen plot to a report-ready figure, complete with your company logo, project number, date, and a title block.

•

Page View (Ctrl + V)—Toggles the display of the page outline to help you visualize how it will look after printing. With HAMMER figures, what you see is what you get (WYSIWYG) so there is no need for a print preview command.

•

Lock Aspect Ratio (Ctrl + L)—Toggles the display of the frames between figure format, in which the length and width are scaled to the paper size, and on-screen format, for which you can set the length and width by dragging the corner of the graph window.

•

Show Title Bar (Ctrl + T)—Toggles the display of the graph window’s title bar. Turn title bars off to maximize the display area; for example, when animating.

The print and save category includes the following menu commands to specify printing options: •

Page Setup—Opens a dialog box in which you can select a printer, set page orientation, and set margin widths.

•

Print (Ctrl + P)—Prints the current graph according to the graph display options currently shown in the graph window.

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Using the Online Help, Online Book, and Help Pane •

Save (Ctrl + S)—Saves the current graph file to disk, overwriting any previous version of the same name. Remember to save your work often.

•

Save As—Saves the current graph file to disk under a different filename. A dialog box prompts you to enter the drive, directory, and new file name.

The data sources category includes the following menu commands to specify or modify data sources:

2.3

•

Set Data From—Opens an .RPT file and plots the selected variables in the current graph window, after deleting the current graph contents.

•

Add Data From—Opens an .RPT file and plots the selected variables in the current graph window, without deleting the current graph contents. Useful for comparing the results of two similar HAMMER projects.

•

Close (Ctrl + F4)—Closes the current graph window without saving its contents.

Using the Online Help, Online Book, and Help Pane HAMMER provides two ways to get help: the Online Book and Online Help, which can be updated and be available for download with new product releases.

2.3.1

Online Book (PDF) Note:

On-screen display of graphics in .PDF files is dependent on the zoom level you use. For better viewing of graphics in Adobe Acrobat Reader, try using 167% and 208% zoom.

HAMMER includes an Adobe Acrobat online book (.PDF) in the installation directory. The online book is designed so that you can view it on screen or print page ranges. Use the bookmarks, index, and search in the Adobe Acrobat Reader to find the topic you want.

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HAMMER Main Window

2.3.2

Online Help For help menu commands, see “Help Menu” on page 2-27. To open the online help for browsing, select Help > Contents. Use the table of contents or index or perform a search to locate the information you need. You can also save a list of favorite help topics for quick reference.

Click Hide/Show to hide or show the Contents tab

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Using the Online Help, Online Book, and Help Pane

Online Help Index Use the Index tab to search the online help index. For most searches, the index provides results more efficiently than the Search tab.

Type the keyword you want to find

Click a topic and click Display to display the selected topic

Click a Related Topic button to see and select topics related to the current one

To use the index: 1. Type the word (called keywords) you want to find. 2. Select the topic you want to see and click Display. The topic you selected displays in the help window. Keywords are highlighted. 3. If your keyword pertains to more than one topic, you are prompted to select the topic you want. Click the topic to select it and click Display.

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HAMMER Main Window

Online Help Search Use the Search tab to search for all instances of a word or words in the help system. •

If you enter more than one word, the online help will return only those topics that contain all of the words you enter, though those topics might not have the words all together or in the order you specify.

•

If you enter more than one word inside quotation marks, the online help search returns only topics with the complete phrase as typed.

To search for words: 1. Type the words (called keywords) you want to find. 2. Click List Topics. 3. Click the topic you want to highlight it. 4. Click Display. The topic you selected displays in the help window; keywords are highlighted.

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Using the Online Help, Online Book, and Help Pane

Keywords are highlighted in the text

Click a topic and click Display to display the selected topic

Type the keywords you want to find and click List Topics

Online Help Favorites You can use the Favorites tab to create a list of topics you frequently use.

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•

Click the Add button in the Favorites tab to add the current topic to your list of favorites.

•

Click Display to display the contents of the selected favorite topic in the help window.

•

Click Remove to remove the selected favorite topic from the Favorites tab.

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HAMMER Main Window

Click Add to add the current topic to the Favorites tab

If you want to print part of the online help, consider opening the online book, which is set up for printing.

Online Help Topics Online help topics can be navigated by using hypertext and Related Topics. Hypertext:

Hypertext is underlined blue text that is clickable. Clicking hypertext displays the destination topic for that hypertext link. Click Back to return to your location before you clicked the hypertext.

Related Topics:

Related Topics is a button that displays at the end of some help topics. If there is more than one related topic, click the button to see a list of the related topics. This list is hypertext. You can click an item in

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Using the Online Help, Online Book, and Help Pane the list to display the related topic. If there is only one related topic, click the button to display that related topic. Click Back to return to where you were before you clicked the hypertext.

Click Back to return to the previous help topic

Click the Related Topic button to see and select topics related to the current one

Navigation Arrows In addition to the standard HTML Help navigation tools, HAMMER online help includes forward and backward arrows at the bottom-left of every topic that let you navigate sequentially through the online help file. While the online book (.PDF) is better suited to this kind of navigation, these buttons may be particularly helpful if you are reviewing the HAMMER lessons online (for more information, see “Quick Start Lessons” on page 3-81).

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HAMMER Main Window

Navigation buttons at the bottom-left of every topic

2.4

Hammer Dialog Boxes HAMMER provides dialog boxes for the following items: •

“Project Options” on page 2-38

•

“Run Dialog Box” on page 2-44

•

“WaterCAD/WaterGEMS Import Dialog Box” on page 2-45

•

“Import EPANET File Dialog Box” on page 2-47

•

“Import Surge 2000 File Dialog Box” on page 2-48

•

“Search Dialog Box” on page 2-62

•

“FlexUnits Dialog Box” on page 2-63

•

“Color Mapping Box” on page 2-63

•

“Color Map Settings Dialog Box” on page 2-65

•

“Choose Color Dialog Box” on page 2-66

•

“Global HAMMER Options Dialog Box” on page 2-67

•

“HAMMER Viewer Dialog Box” on page 2-72

•

“Animation Control Dialog Box” on page 2-73

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Hammer Dialog Boxes

2.4.1

•

“Font Dialog Box” on page 2-74

•

“Copy Paths Dialog Box” on page 2-74

Project Options The Project Options dialog box includes the following tabs: •

“Summary” on page 2-38

•

“Report Points” on page 2-39

•

“Report Times” on page 2-40

•

“Report Paths” on page 2-41

•

“Preferences” on page 2-42

•

“Other Options” on page 2-43

Summary The summary tab lets you set the system parameters. Title:

Description of the model.

Run Duration:

Period of time simulated by the model.

Time:

Choose steps or seconds for modeling time.

Specific Gravity:

Comparison of a substance’s density to the density of water.

Pressure Wave Speed:

Speed for the liquid being conveyed, the pipe material selected and its dimension ratio (DR), bedding, and other factors.

Vapor Pressure:

Pressure below which a liquid changes phase and become a gas (steam for water), at a given temperature and elevation.

For more information, see “Project Setup” on page 4-143.

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HAMMER Main Window

Report Points Report:

Report by All Points, Specific Points, or No Points.

Specific Points:

Report for points that you manually specify.

System:

Contains elements you do not necessarily want in your report. Click the < > move buttons to move selected elements between the System and Report columns. Ctrl+click or Shift+click to select more than one element at a time.

Report:

Contains those elements that you want in your report.

For more information, see “Project Setup” on page 4-143.

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Hammer Dialog Boxes

Report Times Report Periodically:

Report at equal intervals of time (default).

Report Specific Times:

Specify report for selected time steps. Start time denotes the initial time step limit for reporting, Max time denotes the final time step for reporting. Click the < > move buttons to move selected time steps between the System and Report columns. Ctrl+click or Shift+click to select more than one element at a time. Time steps in the System column are excluded from the report; those in the Report column are included.

Report All Times:

Reports the result for all time steps.

Report No Times:

No report based on time steps.

Period:

Period denotes the number of simulation time steps between consecutive-output data (if Report Periodically is selected).

For more information, see “Project Setup” on page 4-143.

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HAMMER Main Window

Report Paths Report Path:

A continuously-connected pipe run is called a path (or profile in WaterCAD). Set the paths to be included in the report using the Add Path, Remove Path, Rename Path, and Show Path buttons.

Add Path:

Lets you add a continuously-connected pipe run.

Remove Path:

Lets you delete a continuously-connected pipe run.

Rename Path:

Lets you change the name for a path.

Show Path:

Lists the elements in the connected pipe run, selects them in the Drawing Pane and zooms in.

System Pipes:

Lists the pipes available for inclusion in a path.

Report Pipes:

Lists the pipes in the path that are included in the report.

Valid Path:

Shown in green, indicates the pipes follow a logical sequence and constitute a valid path.

Fix Path:

Shown in red, indicates the pipes sequence is incorrect.

For more information, see “Project Setup” on page 4-143.

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Hammer Dialog Boxes

Preferences Initial Flow Consistency Value: Flow changes that exceed the specified value are listed in the output log as a location at which water hammer occurs as soon as simulation begins. The default value is 0.02 cfs. Initial Head Consistency Value: Head changes that exceed the specified value are listed in the output log as a location at which water hammer occurs as soon as simulation begins. The default value is 0.1 ft.

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Friction Coefficient Criterion:

For pipes whose Darcy-Weisbach friction coefficient exceeds this criterion, an asterisk appears beside the coefficient in the pipe information table in the output log. The default value is 0.02.

Decrement in All Pipe Elev:

Decreases the elevation of each pipe by the amount specified. Use a negative value to raise the pipes. By default, elevations are not adjusted. (Permissible units are m and ft.)

Show Extreme Heads After:

Sets the time to start output of the maximum and minimum heads for a run. You can set these to show beginning at time = 0 (right away), after the first maximum or minimum, or after a specified time delay.

HAMMER User's Guide

HAMMER Main Window Report History after Time:

Set the time at which reporting begins. The default value is 0.02.

Friction Method:

Select Steady, Quasi-Steady, or Unsteady friction methods. For more information, see “Selecting the Friction Method” on page 4-147.

For more information, see “Selecting the Friction Method” on page 4-147.

Other Options Other options lets you set the appearance of HAMMER. For more information, see “Text Output File Options” on page 8-202.

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Hammer Dialog Boxes

2.4.2

Run Dialog Box The Run dialog box lets you control the output created by a HAMMER calculation. For more information, see “File Menu” on page 2-22.

2-44

Browse:

Click Browse to navigate to the folder where you want to store the generated files.

File Name:

Type the filename you want to use for output.

Generate Animation Data:

Select this check box to generate animation data for selected report paths and points.

Generate Output Database:

Select this check box to generate an output database.

Full:

Select a Full Type of Run to create a simulation with specified conditions and parameters.

Data Check:

Select a Data Check Type of Run to quickly validate your model. This lets you check for data-entry errors and modeling problems without committing to a lengthy run calculation.

HAMMER User's Guide

HAMMER Main Window

2.4.3

WaterCAD/WaterGEMS Import Dialog Box Use this dialog box to import model data and steady-state results from WaterCAD or WaterGEMS into HAMMER. For more information, see “Part 1—Importing and Verifying the Initial Steady-States” on page 3-116. File > Open:

Click File > Open or click the Ellipsis (…) button to select the WaterCAD or WaterGEMS database (.MDB) file you want to import. The path and filename of what you import displays in the Project field.

Scenario:

If the project you are importing has more than one scenario, use the drop-down menu to select the scenario that you want to analyze in HAMMER.

Units:

Select the units you want to use for the project. (Permissible units are cfs, ft. and cms, m.)

Time Step:

Select the time step you want to use.

Create HAMMER Input File:

Click Create HAMMER Input File to create a HAMMER file from your WaterCAD/GEMS project.

Steady State/Extended Period: If you have selected Extended Period, a set of extended period options become available for editing. These are Start Time, Duration, and Hydraulic Time Step. Otherwise, HAMMER uses steady-state for the basis of calculations. Start Time:

Set the beginning time for the analysis.

Duration:

Set how long the analysis lasts.

Hydraulic Time Step:

Set the increments over which the model will be measured.

Run Simulation:

Click Run Simulation to run the Steady State or Extended Period scenario that you imported.

HAMMER User's Guide

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Hammer Dialog Boxes

Table 2-1: Element Conversions from WaterObjects to HAMMER WaterCAD/WaterGEMS

HAMMER Equivalence

Junctions Junction with positive demand

Consumption

Junction with negative demand

Reservoir

Junction with zero demand (0 or 1 branches)

Dead end

Junction with zero demand (2+ branches)

Junction

Tanksa Tank (variable-area)

Variable-area surge tank

Tank (constant-area)

Simple surge tank

Pipes Pipe

Pipe

Reservoirs Reservoir

Reservoir

Pumps

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Pump (constant-power pump curve)

Constant-speed, between 2 pipes – no pump curve

Pump (design-point – 1 point)

Constant-speed, between 2 pipes – pump curve

Pump (standard – 3 point)

Constant-speed, between 2 pipes – pump curve

HAMMER User's Guide

HAMMER Main Window Table 2-1: Element Conversions from WaterObjects to HAMMER (Cont’d) WaterCAD/WaterGEMS

HAMMER Equivalence

Pump (standard-extended)

Constant-speed, between 2 pipes – pump curve

Pump (custom-extended)

Constant-speed, between 2 pipes – pump curve

Pump (multiple-point)

Constant-speed, between 2 pipes – pump curve

Valves PRV (pressure-reducer valve)

Valve of various types between 2 pipes

PSV (pressure-sustaining valve)

Valve of various types between 2 pipes

PBV (pressure-breaker valve)

Orifice between 2 pipes

FCV (flow-control valve)

Valve of various types between 2 pipes

TCV (throttle-control valve)

Orifice between 2 pipes

GPV (general-purpose valve)

Orifice between 2 pipes

a. You can convert any surge tank to a reservoir (either representation is hydraulically correct) if the liquid level of the surge tank will not change due to transient inflows or outflows.

2.4.4

Import EPANET File Dialog Box The Import EPANET File dialog box lets you to choose the EPANET input and report files you import into an existing or a new HAMMER file. Because HAMMER needs steady-state run results, including flow values, to calculate transients, the EPANET report file is required. For more information, see “Importing/Exporting EPANET v.2.0” on page 4-140. •

EPANET Report File—Browse to select an .RPT file. The .RPT file is generated by developing a report on an EPANET model run in the EPANET editor.

•

EPANET Network File—Browse to select an .INP file. The .INP file is generated by exporting an EPANET .NET file to a network .INP file.

•

Output HAMMER File—Browse to select the name of the new hammer file (*.HIF) to which the data is transferred from the EPANET files.

•

Mode—Lets you select whether the file to which EPANET data is being written is a new file or existing file that you want to update.

HAMMER User's Guide

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Hammer Dialog Boxes

2.4.5

•

Existing Hammer File—Browse to select the name of the existing hammer file (.HIF) to which the data is transferred from the EPANET files. To enable this selection, you must first set Mode to Update.

•

Recent Imports—Lists the files recently imported from EPANET.

•

Import—Imports the file chosen.

•

Close—Closes the dialog box without importing any files.

Import Surge 2000 File Dialog Box The Import Surge 2000 File dialog box lets you to choose the Surge files you import into a HAMMER file. For more information, see “Surge to HAMMER Field-to-Field Conversion” on page 2-49 and “Importing PIPE2000 or Surge2000” on page 4-142.

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•

Surge Output File—Browse to select the output file generated by Surge (.OT2).

•

Surge Input File—Browse to select the input file generated by Surge (.DT2).

•

Output Hammer File—Browse to select the name of the HAMMER file (.HIF) to which surge information will be written.

•

Import—Imports the file into HAMMER.

•

Close—Closes the dialog box without importing anything.

HAMMER User's Guide

HAMMER Main Window

Surge to HAMMER Field-to-Field Conversion Consider the following when converting to HAMMER from Surge 2000. •

“Bladder Surge Tank (Surge) to Gas Vessel (HAMMER)” on page 2-49

•

“Closed Surge Tank (Surge) to Gas Vessel (HAMMER)” on page 2-51

•

“One-Way Open-Surge Tank (Surge) to Simple-Surge Tank (HAMMER)” on page 2-52

•

“Open-Surge Tank (Surge) to Simple Surge Tank (HAMMER)” on page 2-53

•

“Pressure Valve (Surge) to SAV/SRV (HAMMER)” on page 2-54

•

“Rupture Disk (Surge) to Rupture Disk (HAMMER)” on page 2-56

•

“Single-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER)” on page 2-57

•

“Surge-Anticipation Valve (Surge) to SAV/SRV (HAMMER)” on page 2-58

•

“Two-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER)” on page 2-60

•

“Three-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER)” on page 2-61

Bladder Surge Tank (Surge) to Gas Vessel (HAMMER) Table 2-2: Surge—Bladder Surge Tank Code

Description

Units

x1

Diameter

m, ft

x2

Initial fluid level

m, ft

x3

Initial gas volume

m3, ft3

x4

Expansion contstant

none

x5

Set pressure or head

m, ft

x6

Inflow resistance

none

x7

Outflow resistance

none

HAMMER User's Guide

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Hammer Dialog Boxes Table 2-3: HAMMER—Gas Vessel Code

Description

Units

y1

Diameter of orifice or throat

mm, in

y2

Initial volume of gas or tank volume

m3, ft3

y3

Exponent of gas law

none

y4

Ratio of losses

none

y5

Headloss coefficient (outflow)

none

y6

Bladder

yes/no

y7

Tank volume

m3, ft3

y8

Preset pressure

m, ft

Table 2-4: Mappings Code

Map

y1

x1

y2

x3

y3

x4

y4

x6 / x7

y5

x7

y6

Yes

y7

x3

y8

x5

• X2 is not used, since HAMMER does not track tank geometry of liquid level.

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HAMMER User's Guide

HAMMER Main Window Closed Surge Tank (Surge) to Gas Vessel (HAMMER) Table 2-5: Surge—Closed Surge Tank Code

Description

Units

x1

Diameter

m, ft

x2

Initial fluid level

m, ft

x3

Initial gas volume

m3,ft3

x4

Gas expansion contstant

none

x5

Inflow resistance

m, ft

x6

Outflow resistance

none

Table 2-6: HAMMER—Gas Vessel Code

Description

Units

y1

Diameter of orifice or throat

mm, in

y2

Initial volume of gas or tank volume

m3, ft3

y3

Exponent of gas law

none

y4

Ratio of losses

none

y5

Headloss coefficient (outflow)

none

y6

Bladder

yes/no

y7

Tank volume

m3, ft3

y8

Preset pressure

m, ft

Table 2-7: Mappings Code

Map

y1

x1

y2

x3

y3

x4

y4

x5 / x6

HAMMER User's Guide

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Hammer Dialog Boxes Table 2-7: Mappings Code

Map

y5

x6

y6

No

y7

n/a

y8

n/a

• X2 is not used, since HAMMER does not track tank geometry of liquid level.

One-Way Open-Surge Tank (Surge) to Simple-Surge Tank (HAMMER) Table 2-8: Surge—One-Way Open Surge Tank Code

Description

Units

x1

Diameter

m, ft

x2

Maximum fluid level

m, ft

x3

Inflow resistance

none

x4

Outflow resistance

none

x5

Check-valve resistance

N, lb

x6

Check-valve time

sec.

Table 2-9: HAMMER—Simple Surge Tank Code

2-52

Description

Units

y1

Initial water level

m, ft

y2

Diameter

mm, in

y3

Diameter of orifice

mm, in

y4

Elevation of top of tank

m, ft

y5

Check valve installed

yes/no

y6

Ratio of losses

none

y7

Headloss coefficient (outflow)

none

y8

Weir coefficient

n/a

HAMMER User's Guide

HAMMER Main Window Table 2-10: Mappings Code

Map

y1

n/a x2

y2

x1

y3

n/a

y4

n/a x2

y5

Yes

y6

x3 / x4

y7

x4

y8

n/a

• X5 and X6 are not used, since HAMMER does not account for check-valve resistance.

Open-Surge Tank (Surge) to Simple Surge Tank (HAMMER) Table 2-11: Surge—Open Surge Tank Code

Description

Units

x1

Diameter

m, ft

x2

Maximum fluid level

m, ft

x3

Inflow resistance

none

x4

Outflow resistance

none

Table 2-12: HAMMER—Simple Surge Tank Code

Description

Units

y1

Initial water level

m, ft

y2

Diameter

mm, in

y3

Diameter of orifice

mm, in

y4

Elevation of top of tank

m, ft

HAMMER User's Guide

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Hammer Dialog Boxes Table 2-12: HAMMER—Simple Surge Tank Code

Description

Units

y5

Check valve installed

yes/no

y6

Ratio of losses

none

y7

Headloss coefficient (outflow)

none

y8

Weir coefficient

n/a

Table 2-13: Mappings Code

Map

y1

n/a

y2

x1

y3

n/a

y4

x2

y5

No

y6

x3 / x4

y7

x4

y8

n/a

• HAMMER can track tank-overflow rate using y4 and y8, but Surge does not.

Pressure Valve (Surge) to SAV/SRV (HAMMER) Table 2-14: Surge—Pressure-Relief Valve Code

2-54

Description

Units

x1

Opening pressure

kPa, psi

x2

Opening time

sec.

x3

Closing pressure

kPa, psi

x4

Closing time

sec.

HAMMER User's Guide

HAMMER Main Window Table 2-14: Surge—Pressure-Relief Valve Code

Description

Units

x5

External head

m, ft

x6

Sensing node

none

x7

Inflow resistance

none

x8

Outflow resistance

none

Table 2-15: HAMMER—SAV/SRV Code

Description

Units

y1

Type of valve

SAV/SRV…

y2

SAV Diameter

mm, in

y3

SRV Diameter

mm, in

y4

SAV threshold pressure

m, ft

y5

SRV threshold pressure

m, ft

y6

SAV open time

sec.

y7

SAV fully-open time

sec.

y8

SAV closing time

sec.

y9

Type of SAV

needle …

y10

SAV Cv at full opening

n/a

y11

SRV spring constant

n/a

Table 2-16: Mappings Code

Map

y1

SRV

y2

n/a

y3

n/a

y4

n/a

y5

x1

HAMMER User's Guide

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Hammer Dialog Boxes Table 2-16: Mappings Code

Map

y6

n/a

y7

n/a

y8

n/a

y9

n/a

y10

n/a

y11

n/a

• HAMMER SRV uses a spring constant, y11, not a pre-set opening time, x2. For the same reason, there is no need for x3 and x4; the spring closes the valve. • x5, external head, is not used in HAMMER. Instead, connect SRV to suction piping (the default connection is to atmosphere). • x6, x7, and x8 are not used in HAMMER. HAMMER assumes the valve is piloted locally, so there is no need to describe losses in a sensing line.

Rupture Disk (Surge) to Rupture Disk (HAMMER) Table 2-17: Surge—Rupture Disk Code

Description

Units

x1

Opening pressure

kPa, psi

x2

Inflow resistance

none

x3

Outflow resistance

none

Table 2-18: HAMMER—Rupture Disk Code

2-56

Description

Units

y1

Typical flow

m3/sec., cfs

y2

Pressure

m, ft

y3

Threshold pressure

m, ft

HAMMER User's Guide

HAMMER Main Window Table 2-19: Mappings Code

Map

y1

n/a

y2

n/a

y3

x1

• x2 and x3 are not used because HAMMER assumes connecting lines are not limiting, unless you model them as such using small diameter pipes. HAMMER has y1 and y2 that can be used to account for the orifice and those two connecting pipes, if any. • Surge does not appear to have a Cv or other flow-versus-pressure-drop coefficient.

Single-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER) Table 2-20: Surge—Single-Stage Air-Vacuum Valve Code

Description

Units

x1

Outflow diameter

mm, in

x2

Outflow diameter

mm, in

x3

Initial air volume

m3, ft3

Table 2-21: HAMMER—Air Valve Code

Description

Units

y1

Initial air volume

m3, ft3

y2

Outflow diameter (< TV)

mm, in

y3

Transition volume

m3, ft3

y4

Outflow diameter (≥ TV)

mm, in

y5

Inflow diameter

mm, in

HAMMER User's Guide

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Hammer Dialog Boxes Table 2-22: Mappings Code

Map

y1

x3

y2

x1 (=x2)

y3

n/a

y4

x1 (=x2)

y5

x1 (=x2)

Surge-Anticipation Valve (Surge) to SAV/SRV (HAMMER) Table 2-23: Surge—Surge-Anticipation Valve Code

Description

Units

x1

Opening pressure

kPa, psi

x2

Opening time

sec.

x3

Full-open time

sec.

x4

Closing time

sec.

x5

External head

m, ft

x6

Sensing node

none

x7

Inflow resistance

none

x8

Outflow resistance

none

Table 2-24: HAMMER—SAV/SRV Code

2-58

Description

Units

y1

Type of valve

SAV/SRV…

y2

SAV Diameter

mm, in

y3

SRV Diameter

mm, in

y4

SAV threshold pressure

m, ft

y5

SRV threshold pressure

m, ft

y6

SAV open time

sec.

HAMMER User's Guide

HAMMER Main Window Table 2-24: HAMMER—SAV/SRV Code

Description

Units

y7

SAV fully-open time

sec.

y8

SAV closing time

sec.

y9

Type of SAV

needle …

y10

SAV Cv at full opening

n/a

y11

SRV spring constant

n/a

Table 2-25: Mappings Code

Map

y1

SAV

y2

n/a

y3

n/a

y4

x1

y5

n/a

y6

x2

y7

x3

y8

x4

y9

n/a

y10

n/a

y11

n/a

• x5, external head, is not used in HAMMER. Instead, connect SAV to suction piping (the default connection is to atmosphere). • x6, sensing node, is not used in HAMMER. Instead, HAMMER assumes that the valve is piloted locally. Note that SAV pilots are rarely more than 10 m away, so the wave travel time of 0.01 seconds may be less than a simulation time step. • x7 and x8, inflow and outflow resistance, are not used in HAMMER, but these can probably be converted to y10, SAV Cv at full opening.

HAMMER User's Guide

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Hammer Dialog Boxes Two-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER) Table 2-26: Surge—Two-Stage Air-Vacuum Valve Code

Description

Units

x1

Outflow diameter

mm, in

x2

Outflow diameter

mm, in

x3

Initial air volume

m3, ft3

Table 2-27: HAMMER—Air Valve Code

Description

Units

y1

Initial air volume

m3, ft3

y2

Outflow diameter (< TV)

mm, in

y3

Transition volume

m3, ft3

y4

Outflow diameter (≥ TV)

mm, in

y5

Inflow diameter

mm, in

Table 2-28: Mappings

2-60

Code

Map

y1

x3

y2

x2

y3

n/a

y4

x2

y5

x1

HAMMER User's Guide

HAMMER Main Window Three-Stage Air-Vacuum Valve (Surge) to Air Valve (HAMMER) Table 2-29: Surge—Two-Stage Air-Vacuum Valve Code

Description

Units

x1

Inflow diameter

mm, in

x2

First outflow diameter

mm, in

x3

Second outflow diameter

mm, in

x4

Switch value

depends on

x5

Switch flag

flow/pr./vol.

x6

Initial air volume

m3, ft3

Table 2-30: HAMMER—Air Valve Code

Description

Units

y1

Initial air volume

m3, ft3

y2

Outflow diameter (< TV)

mm, in

y3

Transition volume

m3, ft3

y4

Outflow diameter (≥ TV)

mm, in

y5

Inflow diameter

mm, in

Table 2-31: Mappings Code

Map

y1

x6

y2

x3

y3

x4 (volume)

y4

x2

y5

x1

• x5 is not used in HAMMER. Instead, you must convert flow or pressure (possibly obtained from a trial HAMMER simulation) to an equivalent y3 transition volume.

HAMMER User's Guide

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Hammer Dialog Boxes

2.4.6

Search Dialog Box Use the Search dialog box to quickly locate any element in the drawing by its label. For more information, see “Finding Elements” on page 5-157.

2-62

Enter the Label:

Type the element name for which you are searching.

Search for Node/Pipe:

Select whether the element that you are searching for is a node or a pipe.

By Label/Node:

Select whether you want to search for the pipe by its label name or by the node name.

Find:

Click Find to being the search for the item you specified.

HAMMER User's Guide

HAMMER Main Window

2.4.7

FlexUnits Dialog Box Select the units, system, precision, and scientific notation displayed for each attribute. Click in a cell to change an attribute or setting. For example, to change the Unit for Flow, click the Unit cell in row 6 and select the unit you want to use from the dropdown list. For more information, see “FlexUnits” on page 4-149.

2.4.8

System: SI:

If System: SI displays, then HAMMER is using the metric system. Click System: SI if you want to change the units to U.S. customary.

System: US:

If System: US displays, then HAMMER is using the U.S. customary system. Click System: US if you want to change the units to SI.

Color Mapping Box The Color Mapping box is only available after you click Go and run your model. This option lets you color code items. The color coding is available for pipes and nodes. For more information, see “Part 4—Color-Coding Maps, Profiles, and Point Histories” on page 3-128. The following are the attributes available for color coding of pipes: •

Off—Select this if you do not want to color code your pipes based on any attribute.

•

Maximum/Minimum Head—Color codes the maximum or minimum transient head experienced at any point in the pipe throughout the simulation period.

HAMMER User's Guide

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Hammer Dialog Boxes •

Maximum/Minimum Flow—Color codes the maximum or minimum transient flow experienced at any point in the pipe throughout the simulation period. Note that the initial flow direction at time zero is considered as positive flow.

•

Maximum Vapor Volume—Color codes the maximum vapor volume, if any, that occurred at all locations in the pipe at any time during the simulation.

•

Maximum Air Volume—Color codes the maximum air volume, if any, that occurred at all locations in the pipe at any time during the simulation.

The following are the attributes available for color coding of nodes: •

Off—Select this if you do not want to color code your nodes based on any attribute.

•

Maximum/Minimum Head—Color codes the maximum or minimum transient head experienced at the nodes resulting from a transient in any pipe linked with the node.

•

Maximum/Minimum Pressure—Color codes the maximum or minimum transient pressure experienced at the nodes resulting from a transient in any pipe linked with the node.

•

Maximum Vapor Volume—Color codes the maximum vapor volume, if any, that occurred at a node at any time during the simulation.

•

Maximum Air Volume—Color codes the maximum air volume, if any, that occurred at a node at any time during the simulation.

Click Scales to open the Color Map Settings dialog box. Click Legend and then click the Drawing Pane to place a legend that describes the color coding.

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HAMMER User's Guide

HAMMER Main Window

2.4.9

Color Map Settings Dialog Box Color Map Settings Dialog Box lets you set the color coding for pipes or nodes. The title bar shows the name of the attribute for which color coding settings are displayed. Color Setting: •

%—Percentage value of the attribute being color coded. 100% is maximum value among all elements during the period of simulation or the Maximum Value and Minimum Value you enter.

•

Color—The color that corresponds to the percentage and value associated with an attribute. This color is displayed for the selected percentage. Click a color to open it and display the Choose Color dialog box (see “Choose Color Dialog Box” on page 2-66).

•

Value—Absolute value of the attribute being color coded.

Buttons: •

Add—Adds a new set point for the range of color.

•

Delete—Deletes an existing set point and color.

•

Presets—Lets you select an existing, previously saved color-code range.

•

Save Preset—Lets you save the current color coding as a preset for use later on.

•

Delete Preset—Lets you delete any existing preset. Click Delete Preset and you are prompted to select the preset you want to delete.

Scale Type: •

Quartile, Quintile, Decile, and Percentile correspond to upper and lower range limits of 25, 20, 10 and 1 percent, respectively.

•

You can also click Custom (Percent) to use the Low Percent and High Percent sliders or Custom (Value) to enter the limiting values directly.

Scale Limits: •

Default Minimum—Displays the minimum attribute value from the entire simulation.

•

Default Maximum—Displays the maximum attribute value from the entire simulation.

•

Minimum Value—User-specified minimum value that is available if you choose Custom (Value) as the Scale Type.

HAMMER User's Guide

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Hammer Dialog Boxes

2.4.10

•

Maximum Value—User-specified maximum value that is available if you choose Custom (Value) as the Scale Type.

•

Low Percent/High Percent—A visual representation of the scale chosen based on scale type and limits.

Choose Color Dialog Box The Choose Color dialog box lets you select a color for use in the color map.

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•

Swatches—Comprise predefined colors. Click a one of the color squares to select it

•

HSB—Lets you define a color based on hue, saturation, and brightness. Hue is the value of the pure color (such as orange) based on 360 degrees of a standard color wheel (values are from 0 to 359 inclusive), saturation is them amount of gray in the color (0% is gray and 100% is pure color), and brightness is the amount of light in the color (zero brightness is black and 100% is white).

•

RGB—Lets you define a color based on the amount of transmitted red, green, and blue light it contains (values for each range from 0 to 255 inclusive). For example, 255, 255, 255 is white and 0, 0, 0 is black.

HAMMER User's Guide

HAMMER Main Window Click OK to apply that color to your color map. Click Cancel to close the dialog box without making a change and click Reset to set the color options to their defaults.

2.4.11

Global HAMMER Options Dialog Box The Global HAMMER Options include: •

“Colors” on page 2-67

•

“Tooltips” on page 2-69

•

“Tabs” on page 2-69

•

“File I/O” on page 2-70

•

“Other Options” on page 2-71

For more information, see “Global HAMMER Options” on page 4-142.

Colors To change colors, click the color you want to change, or click the Ellipsis (…) button that corresponds to the item whose color you want to change. Rubber Band:

This is the color of the border of the bounding box that you draw when you click and drag to select elements in the Drawing Pane.

Handle:

This is the color for the rectangle that goes around a selected element.

Highlight:

The color for selected pipes.

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Hammer Dialog Boxes Background:

The color for the main display.

Node:

The color for all of the individual nodes in the model

Line:

The color of the lines in the model

Text:

The color of the text in the model.

When changing colors, you can choose a predefined color from a drop-down list or enter the RGB values for the color. After you change a color, click the Close button in the top-right of the Color Editor dialog box to save your change.

Set an RGB value

2-68

Click the Close button to save your changes Pick a color

HAMMER User's Guide

HAMMER Main Window

Tooltips Use the Tooltips tab to control how tooltips display in HAMMER. Initial Delay:

Set the time it takes for the tooltips to open after you move the mouse over an element in a dialog box. (Unit is milliseconds.)

Enable Tooltips:

Set this to True if you want to use tooltips or False if you want tooltips turned off and not to display in HAMMER.

Tabs Show Properties On Create:

Shows the property pane or tabs at the right of the Drawing Pane when you're creating an element. This has no effect if the tabs are already shown.

Show Properties On Select:

Shows the property pane or tabs at the right Drawing Pane when you're selecting an element. Similarly, it has no effect if the tabs are already shown.

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Hammer Dialog Boxes

File I/O This tab lets you set default directories used by HAMMER for Data Path, Output Path, and Report Path. Specify a default path and directory by clicking Browse, navigating to and selecting the location you want to use.

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•

Microsoft Access EXE, Epanet EXE, and Text Editor EXE let you set the location of these program files that HAMMER can use.

•

The location of the Microsoft Access database allows you to open tabular reports generated by HAMMER, and the default text editor is used when you open ASCII .RPT or .OUT files. Wordpad and Notepad are examples of text editors.

•

Epanet EXE must display the path to the EPANET directory on your computer before you can import or export EPANET files.

HAMMER User's Guide

HAMMER Main Window

Other Options Default Font:

Select a font to be used for all projects using the Default Font drop down menu. A range of font types are available.

Anti-Alias:

Set this to True to enhance the appearance of straight lines in the HAMMER Drawing Pane.

Show Startup Dialog:

Set this to True to display the Welcome to HAMMER dialog box when you open HAMMER.

Optimized Anim. Performance: Set this to True to minimize the amount of RAM required for animations or set this to False to maximize the speed with which the animation can be made ready.

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Hammer Dialog Boxes

2.4.12

HAMMER Viewer Dialog Box For more information on the HAMMER Viewer, see “Output Windows: HAMMER Viewer” on page 2-20. File > Open:

Select a HAMMER output (.HOF), graph (.GRP), or animation (.ANI) file you want to use.

Settings:

The settings menu lets you anti-alias plots and animations for smoother lines and show (or not) a company logo and name on the plots and animations. For more information about logos and company names, see “Using Your Organization’s Name and Logo” on page 8-206.

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Tools:

The tools menu lets you select the logo and company name that is called from the Settings menu. The logo must be a .GIF file.

Path Profile:

Select the path profile you want to plot or animate.

Time History:

Select the element where the profile ends.

Graph Type:

Select the output variables you want plotted in the graph.

Animate:

Creates a graph that can be animated to visualize model results.

HAMMER User's Guide

HAMMER Main Window Plot:

2.4.13

Makes a static graph suitable for reports.

Animation Control Dialog Box Use the animation control buttons (reverse, forward, stop, fast reverse, and fast forward) to control the animation. File > Save Animation/As:

Saves the location and size of every HAMMER graph window currently shown on the screen in a HAMMER animation file (.ANI). You may be prompted to save all active graphs first. It is faster to open an animation file from the HAMMER Viewer than to open each graph file and reposition each one manually.

View Menu:

Use the View menu to set whether you want the full or compact version of the Animation Control dialog box.

Speed:

Set the number of frames shown per second.

Frame:

Set the current frame in your animation.

Animation control buttons

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Hammer Dialog Boxes

2.4.14

Font Dialog Box Set the font family, style, and size you want to use in a HAMMER graph. (To open a HAMMER graph, click Tools > Viewer > Graphics.) You should use font families that are installed on your computer. These are installed in your Winnt\Fonts or \Windows\Fonts directories (and perhaps in other locations if you purchased fonts or font software).

2.4.15

Copy Paths Dialog Box If two HAMMER project files share pipes, you can copy the path information from one project file to the other. For more information, see “How Do I Copy a Path from One HAMMER Project to Another?” on page A-233.

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Source:

The HAMMER project file where the path you want to copy is defined.

Target:

The HAMMER project file to which you want to copy the path information.

Browse:

Click Browse to select the Source and Target HAMMER files.

New Paths:

Select the check boxes of paths that you want to copy from the source project.

Existing Paths:

Paths that already exist in the destination project are listed.

HAMMER User's Guide

HAMMER Main Window

2.5

HAMMER Toolbars There are two tool panes in HAMMER: utility and element. The utility tool pane contains buttons to manage projects, work with data,m and present results.

2.5.1

2.5.2

2.5.3

2.5.4

File Tools (Modeler Only) •

New (Ctrl + N)—Creates a new project.

•

Open (Ctrl + O)—Opens an existing project.

•

Save (Ctrl + S)—Saves the current project.

Edit Tools (Modeler Only) •

Cut (Ctrl + X)—Deletes the selected item or group of items and places it on the Windows clipboard. This item can be pasted back into HAMMER or other programs.

•

Copy (Ctrl + C)—Copies the selected item or group of items and places it on the Windows clipboard. This items can be pasted back into HAMMER or other programs.

•

Paste (Ctrl + V)—Inserts the item on the Windows Clipboard into the Drawing Pane at the current cursor position and selects them. The same items can be pasted repeatedly to replicate similar pump suction and discharge piping, for example.

Run Control (Modeler Only) •

Go (Ctrl + R)—Runs the currently open HAMMER project file. A dialog box opens so you can choose the name and location of the output files and whether you want to generate an output database or animation data.

•

Project Options—Displays the Project Options dialog box. This includes the project title, units, and other useful information.

Display Tools (Modeler Only) •

Select—After clicking this toolbar icon, move the cursor over any hydraulic element in the Drawing Pane and click to select it.

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Hydraulic Elements (Modeler Only)

2.5.5

2.5.6

•

Pan—After clicking this toolbar icon, hold down the left mouse button and move the mouse to reposition the Drawing Pane window.

•

Zoom Window or Zoom In—Magnifies an area of the Drawing Pane centered on the cursor (left click). Magnify an area of the drawing by holding down the left mouse button, moving the cursor, and releasing it to define the Zoom Window.

•

Zoom Out—Reduces the magnification of an area of the Drawing Pane centered on the cursor (left click) so you can see more of a large drawing.

•

Normalize Symbol Size—Resizes all symbols and text in the Drawing Pane to a convenient size for the current window. These symbol sizes persist when the zoom level changes.

•

Zoom Extents—Zooms to the full extent of the workspace so that every hydraulic element is contained in the Drawing Pane.

Output Graphics (Modeler Only) •

Sticky—Toggle sticky mode. While in sticky mode, the current mouse function remains active until you change it by clicking a toolbar button.

•

Capture—Captures the contents of the Drawing Pane and copies it to the Windows clipboard. You can paste various views into a graphical editor to generate compound figures, such as a large-scale view with a small-scale inset showing the overall location in the network.

•

Map Selection—Provides a choice of the maximum or minimum hydraulic transient heads or flows, or the maximum vapor or air volumes, and automatically produces a customizable color-coded map in the Drawing Pane. You can color-code pipes, nodes, or both.

Help (Modeler Only) Haestad Online—Provides instant access to a wealth of information on Haestad’s Web sites and forums using your internet connection. HAMMER Help—Opens the HAMMER Help utility.

2.6

Hydraulic Elements (Modeler Only) The hydraulic element toolbar has two fundamental icons (node and link) followed by four types of elements grouped together:

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HAMMER Main Window

2.6.1

2.6.2

•

“Boundaries” on page 2-77

•

“Control Equipment” on page 2-77

•

“Protection Equipment” on page 2-78

•

“Rotating Equipment” on page 2-79

Boundaries •

Junction—Junctions can be located at system boundaries or between other hydraulic elements.

•

Consumption—Consumption nodes can be located at system boundaries or between other hydraulic elements.

•

Dead End—A dead end can be used to represent a permanently closed valve or a blind flange end connection in the system.

•

Periodic Head/Flow—A versatile hydraulic boundary condition which allows you to specify a constant head (pressure), flow, or any time-dependent variation, including periodic changes that repeat indefinitely until the end of the simulation.

•

Manhole—A pressurized pipe connected to atmosphere that can accept any user-defined inflow pattern or hydrograph. Useful in representing surcharged sewer systems.

•

Reservoir—A reservoir is assumed to have a very large surface area such that it maintains a constant hydraulic grade line while supplying or accepting any amount of flow to or from the system, respectively.

Control Equipment These hydraulic elements are selected from the drop-down menu. •

Orifice to Atmosphere—A constant-diameter orifice which releases flow from the system to atmospheric pressure in proportion to the transient head at the orifice location.

•

Orifice at Branch End—A Y-shaped pipe fitting with a branch at the end of which is an orifice discharging flow from the system to atmospheric pressure in proportion to the transient head at the orifice location.

•

Orifice between 2 Pipes—A fixed-diameter orifice which breaks pressure, useful for representing choke stations on high-head pipelines.

•

Rating Curve—A boundary element which releases flow from the system to atmosphere based on a custom-defined rating curve relating head (pressure) and flow.

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Hydraulic Elements (Modeler Only)

2.6.3

•

Valve to Atmosphere—A valve which releases flow from the system to atmospheric pressure based on its Cv curve and position (if open).

•

Valve of Check Type between 2 Pipes—A check valve only allows flow in one direction. This element is useful to simulate a by-pass line with check valve.

•

Valve of Check Type at Wye Branch—A Y-shaped pipe fitting with a check valve in one of the branches.

•

Valve of Various Types between 2 Pipes—A versatile element which can represent a wide range of common valves complete with detailed stroke data and Cv relationships.

•

Valve with Linear Area Change between 2 Pipes—An ideal valve useful for verifying best-case assumptions or representing motorized valves.

Protection Equipment These hydraulic elements are selected from the drop-down menu.

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•

Air Valve—An air-release valve which allows air to exit the system to atmospheric pressure (but prevents fluid from escaping).

•

Air Valve (Slow-Closing) between 2 Pipes—An air-release valve with a damped closure mechanism to minimize valve slam–related transient pressures.

•

SAV/SRV at End of 1 Pipe—A surge-anticipator valve (SAV) or surgerelief valve (SRV) at the end of a pipe releases fluid from the system to atmospheric pressure.

•

SAV/SRV between 2 Pipes—A surge-anticipator valve (SAV) or surgerelief valve (SRV) at the end of a pipe releases fluid from the system to another part of the system, such as a reservoir or suction piping system.

•

Surge Tank (Simple)—A cylindrical tank which allows fluid to enter the pipeline when pressures drop and returns fluid to the tank when pressures increase.

•

Surge Tank (Differential) between 2 Pipes—A specialized surge tank within a larger tank which provides a fast response.

•

Surge Tank (Variable Area)—A tank with user-specified geometry which allows fluid to enter the pipeline when pressures drop and to return to the tank when pressures increase.

HAMMER User's Guide

HAMMER Main Window

2.6.4

•

Gas Vessel—A pressure vessel connected to the system and containing fluid in its lower portion and a pressurized gas, usually air, in the top portion. A flexible and expandable bladder is sometimes used to keep the gas and fluid separate.

•

Rupture Disk between 2 Pipes—A plate which blocks the entire crosssectional area of a pipe, forming a dead end in the system unless a specified pressure is exceeded, in which case it bursts and allows fluid to exit the system via the second pipe segment.

Rotating Equipment These hydraulic elements are selected from the drop-down menu.

2.7

•

Shut After Time Delay, between 2 Pipes—A pump between two pipe segments which shuts down after a user-specified time delay. Useful to simulate a power failure.

•

Constant Speed between 2 Pipes - No Pump Curve—A simplified constant-speed pump element between two pipe segments.

•

Constant Speed at Reservoir - Pump Curve—A constant-speed pump directly connected to a reservoir of fluid, which supports user-defined pump curves.

•

Constant Speed, between 2 Pipes - Pump Curve—A constant-speed pump between two pipes, which supports user-defined pump curves.

•

Variable Speed, between 2 Pipes—A variable-speed (or torque) pump between two pipes. Also known as a variable-frequency drive or VFD.

•

Turbine between 2 Pipes—A turbine between two pipes.

HAMMER Status Bar The HAMMER status bar, at the bottom of the program’s Main Window, displays useful information about the current state of the Drawing Pane and HAMMER model file. Its several useful components are described separately below. General Status Information:

HAMMER User's Guide

General status information includes messages that relate to your current activities. These messages contain such information as menu command descriptions and indications regarding the progress of an executing command.

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HAMMER Status Bar

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Cursor Location and Zoom:

The status bar displays the current X and Y coordinates for the cursor’s position within the Drawing pane, complete with their current unit of measurement. A list box next to the coordinates allows you to select a particular zoom level for the Drawing pane.

Show Tab Button:

The Show Tab button toggles the Properties tab on or off (to maximize the amount of screen space available to the Drawing Pane).

Unit System Status:

The unit system button on the task bar indicates the unit system that is currently active: Système International (S.I. metric) or U.S. customary (English). It does not indicate changes to units of individual variable fields. If you use this box to change the unit system, the dimension of every variable will be converted automatically throughout HAMMER.

Calculation Results Status:

In Modeler mode, if the current calculation results are out of date or otherwise invalid, an indicator appears in the status bar signifying that the results no longer match the state of your input data. If the results are currently valid, no such indicator appears.

File Status:

If changes have been made since the last time the project file was saved, an image of a diskette appears in the status pane. If the file is currently in a saved state, no image appears.

HAMMER User's Guide

Chapter

3

Quick Start Lessons

Note:

You can perform these lessons in sequence, since each lesson uses what you learned in the previous ones, or do the lessons in any order using the catch-up files located in the \Haestad\HAMR\Lesson#\Catch-up folder, where # is the lesson number.

HAMMER is a very efficient and powerful tool for simulating hydraulic transients in pipelines and networks. The quick-start lessons give you hands-on experience with many of HAMMER’s features and capabilities. These detailed lessons will help you to explore and understand the following topics: 1. Pipeline Protection using HAMMER—by assembling a pipeline using the graphical editor and performing two hydraulic transient analyses; without protection and with protection. In Lesson 2, you will also be able to import the same pipeline data from an EPANET file. 2. Working with Data from External Sources—by importing hydraulic model data from EPANET, PIPE2000/Surge2000, WaterCAD/WaterGEMS using WaterObjects technology, or GIS and databases using the HAMMER Datastore. 3. Network Risk Reduction using HAMMER—by importing a water distribution network model from WaterCAD/WaterGEMS and performing a hydraulic transient analysis using advanced surge protection and presentation methods. Another way to become acquainted with HAMMER is to run and experiment with the sample files, located in the \Haestad\HAMR\Samples folder. Remember, you can press the F1 key to access the context-sensitive help at any time.

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Lesson 1: Pipeline Protection

3.1

Lesson 1: Pipeline Protection In this lesson, you will use HAMMER to perform a numerical simulation of hydraulic transients in a water transmission main and, based on the results of your analysis, recommend suitable surge-protection equipment to protect this system from damage. You can do this in three steps: 1. You need to analyze the system as it was designed (without any surge-protection equipment) to determine its vulnerability to transient events. 2. You can select and model different surge-protection equipment to control transient pressures and predict the time required for friction to attenuate the transient energy. 3. You can present your results graphically to explain your surge-control strategy and recommendations for detailed design.

3.1.1

Part 1—Creating or Importing a Steady-State Model You can create an initial steady-state model of your system within HAMMER directly, using the advanced HAMMER Modeler interface, or import one from an existing steady-state model created using other software. In this lesson, you will assemble a hydraulic transient model using both methods to learn their respective advantages and note the similarities between them.

Creating a Model HAMMER is an extremely efficient tool for laying out a water-transmission pipeline or even an entire distribution network. It is easy to prepare a schematic model and let HAMMER take care of the link-node connectivity and element labels, which are assigned automatically. Only pipe lengths must be entered manually to complete the layout. You may need to input additional data for some hydraulic elements prior to a run. Note:

Regardless of the screen coordinates entered or displayed in the element editor, HAMMER analyzes the system using the pipe lengths entered. If you import data from another model, HAMMER uses and displays the lengths from the corresponding field, not the XYZ coordinates (if any).

The water system is described as follows: a water-pumping station draws water from a nearby reservoir (383 m normal water level) and conveys 468 L/s along a dedicated transmission pipeline to a reservoir (456 m normal water level) for a total static lift of 456 – 383 = 73 m. The elevation of the constant-speed pump is 363 m and its speed is

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Quick Start Lessons 1760 rpm. Transmission main data are given in “Table 3-1: Nodes and Elevations”on page 3-84 and “Table 3-2: Link (Pipe) Properties and Steady State HGL”on page 3-86. Other data will be discussed below, as you add or modify each hydraulic element in this system. To create a hydraulic model using the HAMMER Modeler interface: 1. Start HAMMER from the Windows start menu using Start > Programs > Haestad Methods > HAMMER > HAMMER or double-click the HAMMER desktop icon (if any). 2. Click File > New to start a new project. This starts HAMMER’s graphical element editor, so you can draw the system by inserting hydraulic elements. 3. Set the default unit system for this project to SI. Click the button labeled U.S., which is displayed near the right end of the status bar (to the right of the Show Tabs button), so that it displays: SI.

If this button displays U.S., click it so that SI displays

4. Add a node. a. Click Add Node. b. Move the cursor over the drawing pane and click to insert a node. HAMMER automatically names this node J1.

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Lesson 1: Pipeline Protection c. Select the node and rename it by entering Res1 in the label field of the element editor pane.

Enter the name of the node

d. Click Select Object. e. Right-click this node and select Convert Type > Boundaries > Reservoir. 5. Add three more nodes to the right of Res1 and rename them PJ1, PMP1, and PJ2. 6. Convert PMP1 to a pump by selecting right-clicking it and selecting Convert Type > Rotating Equipment > Constant Speed between 2 Pipes - No Pump Curve. Table 3-1: Nodes and Elevations

3-84

Node Name

Elevation (m)

Description (Optional)

Res1

383

Source reservoir

PJ1

363

Suction

PMP1

363

Pump

PJ2

363

Pump discharge

J1

408

Feedermain

J2

395

Feedermain

J3

395

Feedermain

HAMMER User's Guide

Quick Start Lessons Table 3-1: Nodes and Elevations (Cont’d) Node Name

Elevation (m)

Description (Optional)

J4

386

Feedermain

J5

380

Feedermain

J6

420

Feedermain

Res2

456

Receiving reservoir

Note:

You can create nodes and link them together automatically using the Add Pipe button. Just click the location where you want the first node, move the cursor, click again and repeat the procedure until done. The majority of nodes in the system can be entered in this way.

7. Add a pipe connecting Res1 to PJ1, and PJ1 to PMP1. a. Click Add Pipe. b. Then, click Res1. c. Then, click PJ1. d. Then, click PMP1. e. Right-click to finish adding pipe. 8. Complete the schematic of the entire transmission pipeline by adding all the nodes and pipes shown in “Table 3-1: Nodes and Elevations”on page 3-84 and “Table 32: Link (Pipe) Properties and Steady State HGL”on page 3-86.

HAMMER User's Guide

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Lesson 1: Pipeline Protection Note:

If the steady-state HGL was not provided, you could calculate it manually using the Hazen-Williams or Darcy-Weisbach formula or obtain it by running a steady-state model such as WaterCAD/ WaterGEMS, EPANET, or PIPE2000. If you have trouble entering decimals for any values (for example, if the value is automatically rounded), then use Tools > FlexUnits to set the precision for the attribute in question.

Table 3-2: Link (Pipe) Properties and Steady State HGL Pipe ID

Node From

Node To

Length (m)

Diameter (mm)

F. Node Hd (m)

T. Node Hd (m)

DarcyWeisbach Friction Factor (f)

PS1

Res1

PJ1

50

600

383.00

382.78

0.0191

PMP1S

PJ1

PMP1

40

600

382.78

382.78

0.0191

PMP1D

PMP1

PJ2

10

600

464.23

464.23

0.0191

P1

PJ2

J1

20

600

464.23

464.14

0.0191

P2

J1

J2

380

600

464.14

462.46

0.0191

P3

J2

J3

300

600

462.46

461.13

0.0191

P4

J3

J4

250

600

461.13

460.02

0.0191

P5

J4

J5

400

600

460.02

458.24

0.0191

P6

J5

J6

250

600

458.24

457.14

0.0191

P7

J6

Res2

175

600

457.14

456.36

0.0191

9. Set the Init. Flow for all pipes (Q) to 467.996 L/s. 10. Set the Wave Speed for all pipes to 1,200 m/s. Once you have finished adding these hydraulic elements to the system, your schematic should look like the following figure.

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HAMMER User's Guide

Quick Start Lessons

Add pipe Add node Specify units for this project

a. Select individual nodes from the drawing pane and set their names and elevations as shown in “Table 3-1: Nodes and Elevations”on page 3-84. Alternatively, you can select All Nodes from the drop-down menu at the top of the element selector in the Properties tab, as shown below, to display them. Again, you must set the name and provide the correct elevation for each node.

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Lesson 1: Pipeline Protection

Select element type

Use shortcut menu for FlexUnits

Click to open the FlexUnit menu

b. Similarly, select each pipe and set its label and other properties as shown in “Table 3-2: Link (Pipe) Properties and Steady State HGL”on page 3-86. Transient Tip: Elevations are extremely important in hydraulic transient modeling. This is because slopes determine how fast water columns will slow own (or speed up) as their momentum changes during a transient event. Therefore, defining the profile of a pipeline is a key requirement prior to undertaking any hydraulic transient analysis using HAMMER.

11. Click File > Save As to select a directory and save your file with a name such as Lesson1.hif (HAMMER file names are not case sensitive).

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HAMMER User's Guide

Quick Start Lessons

Wave speed for this pipe Steady-state flow Steady-state head at node J3 Steady-state head at node J4

Results display after a run

Importing a Steady-State Model from EPANET Note:

The results of the imported EPANET model will not match those of the model for which you entered data manually unless you change the lengths of pipes PMP1S and PMP1D as shown in “Table 3-2: Link (Pipe) Properties and Steady State HGL”on page 386.

For a detailed description of the procedure to import a steady-state model into HAMMER from EPANET, see “Importing from EPANET” on page 3-114. You can do this and return to Part 2 afterwards, or continue directly to Part 2 now.

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Lesson 1: Pipeline Protection

3.1.2

Part 2—Selecting the Transient Events to Model Any change in flow or pressure, at any point in the system, can trigger hydraulic transients. If the change is gradual, the resulting transient pressures may not be severe. However, if the change of flow is rapid or sudden, the resulting transient pressure can cause surges or water hammer (see “HAMMER Theory and Practice” on page B-235). Since each system has a different characteristic time, the qualitative adjectives gradual and rapid correspond to different quantitative time intervals for each system. There are many possible causes for rapid or sudden changes in a pipe system, including power failures, pipe breaks, or a rapid valve opening or closure. These can result from natural causes, equipment malfunction, or even operator error. It is therefore important to consider the several ways in which hydraulic transients can occur in a system and to model them using HAMMER. Transient Tip: If identifying, modeling, and protecting against several possible hydraulic transient events seems to take a lot of time and resources, remember that it is far safer and less expensive to learn about your system’s vulnerabilities by “breaking pipes” in a computer model—and far easier to clean up—than from expensive service interruptions and field repairs.

In this lesson, you will simulate the impact of a power failure lasting several minutes. It is assumed that power was interrupted suddenly and without warning (i.e., you did not have time to start any diesel generators or pumps, if any, prior to the power failure). The purpose of this type of transient analysis is to ensure the system and its components can withstand the resulting transient pressures and determine how long you must wait for the transient energy to dissipate. For many systems, starting backup pumps before the transient energy has decayed sufficiently can cause worse surge pressures than those caused by the initial power failure. Conversely, relying on rapid backup systems to prevent transient pressures may not be realistic given that most transient events occur within seconds of the power failure while isolating the electrical load, bringing the generator on-line, and restarting pumps (if they have not timed out) can take several minutes.

3.1.3

Part 3—Configuring the HAMMER Project Before running the HAMMER model you have created, you need to set certain runtime parameters such as the fluid properties, piping system properties, run duration, and output requirements. 1. Click Tools > Project Options or click the Project Options icon in the toolbar. 2. Select the Summary (default) tab and set the following parameters:

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HAMMER User's Guide

Quick Start Lessons –

Run Duration = 140

–

Time = Seconds

–

Pressure Wave Speed = 1250 m/s

–

Vapor Pressure = –10 m-Hd (default value).

Specify run duration in seconds or steps

Global wave speed Default vapor pressure

Transient Tip: Wave speed is a key parameter in transient analysis. Entering a pressure wave speed as a global parameter in the System tab overrides all wave speeds assigned to individual pipes. This is fine if all pipes in the system are made of the same material, otherwise it is preferable to leave the global wave speed field blank (not zero).

3. Click the Report Points tab and click Specific Points from the Report drop-down list. 4. Select the following points to report on: PMP1D:PMP1, P1:J1, and P2:J1 to output the transient history (or temporal variation of flow, head, and air or vapor volumes) at the pump and nearby nodes (you can also add other points of interest, such as P7:Res2).

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Lesson 1: Pipeline Protection

Specify selection type for report points

Nodes added for reporting

Remaining points (nodes) in the system

Note:

Click to add or remove report points

Ctrl+click and Shift+click only work for removing elements from the Report list; you cannot use Ctrl+click and Shift+Click to select multiple pipes in the System list.

5. Click the Report Paths tab and then click Add Path to create a new path, then name it Main. 6. Select the pipes PMP1D, P1, P2, P3, P4, P5, P6 and P7 in the System pane and add them to the Main path by clicking the > button. 7. Click OK to close the window.

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Quick Start Lessons

Click to add more paths Click to show path in the drawing pane Pipes in the path: Main

Click to add or remove pipes

8. Save the file with the same name (Lesson1.hif) using File > Save. You are now ready to run your HAMMER model.

3.1.4

Part 4—Performing a Transient Analysis In this section, you will first simulate transient pressures in the system due to an emergency power failure without any protective equipment in service. After a careful examination of your results, you will select protective equipment and simulate the system again using HAMMER to assess the effectiveness of the devices you selected to control transient pressures.

Analysis Without Surge Protection Equipment To perform a hydraulic transient analysis of the system after a sudden power failure without surge protection (other than the pump’s check valve): 1. Right-click the pump node (PMP1) and select Convert Type > Rotating Equipment > Shut After Time Delay, between 2 Pipes. You can also change this pump’s type from the toolbar by selecting it from the Rotating Equipment menu on the toolbar.

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Lesson 1: Pipeline Protection

Time delay before shutdown

Time to close check valve (no delay)

Note:

Do not set the X- and Y-coordinate values.

2. Set the pump parameters: a. Time Delay: Set this to 5 seconds. For convenience, it is assumed that the power failure occurs after 5 seconds, so that point histories will show the initial steady state during this period. b. Time to Close: Set this to 0 seconds. The power failure is assumed to be instantaneous and the check valve is allowed to close without any delay (zero) to protect the pump from damage. c. Diameter: Set the inside diameter of the pump’s intake flange to 600 mm. d. Specific Speed: Set this to U.S. 1280 - metric 25, based on the pump’s rotation speed (1760 rpm). See Appendix B for an explanation of how to determine a pump’s specific speed. e. Reverse Spin: Set this to Not Allowed. Not allowing reverse spin assumes there is a check valve on the discharge side of the pump or that the pump has a nonreverse ratchet mechanism. f.

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Percent Eff.: Set this to 85 percent.

HAMMER User's Guide

Quick Start Lessons g. Inertia of Pump: This is the combined pump, shaft, and motor inertia: set it to 169 nm2. This can be obtained from the manufacturer or estimated from its power rating (see “HAMMER Theory and Practice” on page B-235). h. Rotational Speed: Set this to 1760.0. 3. Save your changes. 4. Click GO (on the HAMMER toolbar) to display the Run Control dialog box. 5. Select the Generate Animation Data check box. (For more information on pump properties, see “Hydraulic Element Reference” on page 6-161.)

Note:

If you do not have Microsoft Access®, or if its path is undefined, you will not be able to click Generate Output Database to get formatted reports. You can set the executable path for Microsoft Access using Tools > Global HAMMER Options, selecting the File I/O tab, and clicking Browse to locate the MSACCESS.EXE file on your computer.

6. Click Run; a HAMMER run status window opens and displays the progress of the elapsed run. If you suspect that a data-entry error may have occurred, you can select Data Check before clicking Run, to perform a short run that detects errors before a (much longer) full run. 7. When the run is completed, the HAMMER Viewer opens automatically to let you view graphs and animate the hydraulic transient heads and flows.

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Click to plot profile Select parameter to plot Select point to plot

Select parameter to plot

Select path to plot

Reviewing your Results By default, HAMMER does not generate output for every location or every time step, since this would result in very large file sizes (tens or hundreds of megabytes). For the specific points or paths (e.g., profiles) you specified prior to the run, you can generate several types of graphs or animations to visualize the results: 1. HGL Profile: HAMMER can plot the steady-state hydraulic grade line (HGL) as well as the maximum and minimum transient head envelopes along the Main path. 2. Time History: HAMMER can plot the time-dependent changes in transient flow, and head and display the volume of vapor or air at any point of interest. 3. Animations: You can click Animate to visualize how system variables change over time after the power failure. Every path and history on the screen is synchronized and animated simultaneously. Note how transient pressures stabilize after a while. It is important to take the time to carefully review the results of each HAMMER run to check for errors and, if none are found, learn something about the dynamic nature of the water system (either experiment or see “Part 5—Animating Transient Results at Points and along Profiles” on page 3-100 for instructions on how to do the following). •

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The graph for the Main path shows that a significant vapor cavity forms at the local high point at the knee of the pipeline (i.e., the location where the steep pipe section leaving the pumps turns about 90 degrees to the horizontal in the pump station).

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Viewing the animation a few times shows that a vapor pocket grows at node J1 (as the water column separates) and subsequently collapses due to return flow from the receiving reservoir Res2. The resulting transient pressures are very sudden and they propagate away from this impact zone, sending a shock wave throughout the pipeline.

•

The time history at the pump shows that the check valve closes before these pressure waves reach the pump (zero flow), effectively isolating it from the system and protecting it against damage.

Vapor pocket at high point

Max. transient head

Steady-state head

Min. transient head

Pipe elevation

Analysis with Surge-Protection Equipment Certain protective equipment such as a gas vessel (also known as a hydropneumatic tank or air chamber), combination air valve CAV; also known as a vacuum-breaker and air-release valve, or a one-way surge tank can be installed at local high points to control hydraulic transients.

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Lesson 1: Pipeline Protection Note:

Adding surge-control equipment or modifying the operating procedures may significantly change the dynamic behavior of the water system, possibly even its characteristic time. Selecting appropriate protection equipment requires a good understanding of its effect, for which HAMMER is a great tool, as well as the good judgment and experience you supply.

It is clear that high pressures are caused by the sudden collapse of a vapor pocket at node J1. You could install a Gas Vessel at junction J1 to supply flow into the pipeline upon the power failure, keeping the upstream water column moving and minimizing the size of the vapor pocket at the high point (or even preventing it from forming). You can test this theory by simulating the system again using HAMMER and comparing the results with those of the unprotected run: 1. Right-click node J1 and select Convert Type > Protective Equipment > Gas Vessel.

2. Click Yes when prompted to reset the computed results. 3. Set the Gas Vessel properties: a. Set the Elevation to 408.000 m. b. Set the Diam. of Ori./Thrt. to 300 m. c. Set the Ratio of Loss to 2.5.

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Quick Start Lessons d. Set the Head Loss Coefficient to 1.0. e. Set the Bladder to Yes. f.

Set the Tank Vol. to 20.0,

g. Set the Preset Press. to 0.0. h. Do not change the X- and Y- coordinate values. 4. Select File > Save As and save the file with a new name: Lesson1_Protection.hif. 5. Click GO, check Generate Animation Data and click Run to run this model. 6. If you have done everything correctly, the maximum transient head envelopes with gas vessel protection should look as follows.

No significant air pocket

Max. transient head Steady-state head Min. transient head Pipe elevation

Installing a Gas Vessel at node J1 has significantly reduced transient pressures in the entire pipeline system. Due to this protection equipment, no significant vapor pocket forms at the local high point. However, it is possible that a smaller Gas Vessel could provide similar protection.

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Lesson 1: Pipeline Protection It is also possible that other protection equipment could control transient heads and perhaps be more cost-effective as well. Before undertaking additional HAMMER simulations, it is worthwhile to compare and contrast the results with or without the Gas Vessel. In “Part 6—Adding Comments to Generate Report-Ready Graphs” on page 3-103, you will learn how to change the appearance of HAMMER graphs. In “Lesson 3: Network Risk Reduction” on page 3-115, you will learn how to add your organization’s logo and many other useful presentation skills.

3.1.5

Part 5—Animating Transient Results at Points and along Profiles HAMMER provides many ways to visualize the simulated results using a variety of graphs and animation layouts. You must specify which points and paths (profiles) are of interest, as well as the frequency to output prior to a run, or HAMMER will not generate this output to avoid creating excessively large output files (.HOF). For small systems, you can specify each point and every time step, but this is not advisable for large water networks. For the same reason, HAMMER only generates the Animation Data (for on-screen animations) or Output Database (for tabular reports in Access) if you select this option in the Run dialog box.

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Quick Start Lessons Note:

To achieve shorter run times and conserve disk space, try to avoid generating voluminous output, such as Animation Data or Output Databases, at an early stage of your hydraulic transient analysis. Fast turnaround makes your evaluation of different alternatives more interactive and challenges you to apply good judgement as you compare your mental model of the system with HAMMER’s results—a good habit which is like estimating an answer in your head when using a calculator.

While you are still evaluating many different types or sizes of surge-protection equipment, you can often compare their effectiveness just by plotting the maximum transient head envelopes for most of your HAMMER runs. At any time, or once you feel you are close to a definitive surge-control solution, you can generate animation data in one of two ways: •

Use HAMMER to generate the animation data files before you run the program by clicking Generate Animation Data in the run dialog box (as you have already done this for the two previous runs). After the run, HAMMER automatically starts the HAMMER Viewer.

•

Immediately after a run (i.e., prior to the next run), you can generate animation data using Tools > Generate Animations. You will need to load this animation data using Tools > Viewer > Graphics and selecting the correct HAMMER output file (.HOF) prior to animating the results on screen.

Once you have generated the animation data files, you will be able to display animations without running HAMMER again. This saves a lot of time when comparing the results of several surge-control alternatives. You can load the animation data files using the HAMMER Viewer: 1. Click Tools > Viewer > Graphics. 2. Select the .HOF file you created previously. 3. In the HAMMER Viewer, select: –

Path: Main

–

Graph Type: Path & Volume

4. Click the Animate button. This loads the animation data and Animation Control.

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Select path to animate

Select parameter to animate

Click to animate

5. On the Animation Controller, click the play button to start the animation. At a certain time (19.5000 s), the animation window should look similar to the following figure.

Max. vapor pocket Animated vapor pocket

Max. transient head

Animated profile

Pipe elevation Min. transient head

6. Right-click on the graph and click Save as to save the result displayed on screen as a HAMMER graph (.GRP) or Windows bitmap (.BMP). You can reload HAMMER graphs later.

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Save the animated results in a HAMMER .GRP file

3.1.6

Part 6—Adding Comments to Generate Report-Ready Graphs 1. Using the HAMMER Viewer, you can plot a transient history at any point in the system to display the temporal variation of selected parameters (such as pressures and flow). You can also plot a profile of selected variables along a particular path to display the spatial extent of transient phenomena. Finally you can compare the results of two similar graphs generated with or without protection, for example. Let’s start with the simulated results without protection. 2. Select Tools > Viewer> Graphics and load Lesson1.hof file to start the HAMMER Viewer. 3. Select: –

History: P1:J1

–

Graph Type: Flow & Head

4. Click Plot to display this transient history. 5. Select: –

Path: Main

–

Graph Type: Path

6. Click Plot to display it. 7. To format a graph: a. Click the graph’s frame to select it (this will display square handles on the frame outline) b. Right-click the frame to open the graph’s shortcut menu.

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Lesson 2: Working with Data from External Sources c. Select a shortcut menu item, such as Draw Symbol. d. In the shortcut menu, you can select Format Graph to open the Format Graph dialog box and set the graph’s properties. 8. To change the figure number, title, date, and project number, double-click them and make the changes.

Change axis settings

Add hydraulic elements on the pipeline

Double-click to change the plot title

3.2

Lesson 2: Working with Data from External Sources Transient Tip: It is good engineering practice to run a HAMMER model without modifying any of its parameters after importing it from another steady-state model (i.e., EPANET). Since no transient event has been selected, HAMMER’s results should show no change in head and flow for any time and at any point in the system. If so, the initial steadystate can be considered correct. Otherwise, input parameters or solution tolerances need to be checked and likely corrected in the steady-state model.

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Quick Start Lessons HAMMER makes it easy to import hydraulic model data from other hydraulic models or database-enabled application software such as GIS (or to export HAMMER results to such software). In this Lesson, you will learn how to •

Import steady-state hydraulic model results from WaterCAD or WaterGEMS, EPANET, or PIPE2000/Surge2000 into HAMMER.

•

Export and import database files (in Microsoft Access .MDB format) for data sharing, result postprocessing, and interfacing with external data sources such as AutoCAD or GIS.

Importing a model saves time and reduces transcription errors because HAMMER automatically converts the majority of the data, but you still need to check the model and enter information specific to hydraulic transient analysis.

3.2.1

Part 1—Exporting an Input or Output File to a HAMMER Datastore A HAMMER datastore is a special database format (see “Starting a HAMMER Project” on page 4-137) that can be used to obtain input data or create output tables. This section discusses techniques to create, modify, and use the HAMMER datastore to run HAMMER.

Creating a HAMMER Input Datastore From any HAMMER input file (.HIF), you can create a HAMMER input datastore as follows: 1. Double-click the HAMMER desktop icon, or select HAMMER from the Windows Start menu: Start > All Programs > Haestad Methods > HAMMER > HAMMER to start HAMMER. Note:

You can use the Zoom Full Extent and Reset Zoom buttons to scale the network in the HAMMER window.

2. Click File > Open, and open Lesson2.hif (in the \HAMR\Tutorials\Lesson2 folder). 3. Click File > Export > Database > Input to create the HAMMER input datastore in .MDB format. 4. Name the file, Lesson2_Input.mdb. 5. HAMMER will create database tables and display the a message that the tables were successfully created. Click OK to continue. 6. A control window opens, letting you Create ASCII File, open the Database Window, or Exit Access.

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Lesson 2: Working with Data from External Sources Click Database Window and an Access database window opens.

Note:

You can make changes directly to the HAMMER input datastore or you can import data from external sources to any of its tables. Following this, you can import the modified HAMMER input datastore to perform another transient analysis.

7. Double-click an individual table, for example Pipes, to view and edit an element. For your hydraulic system, the Pipes Table should appear as follows.

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8. Experiment with other database tables (such as nodes, system, or path), make any changes you need, and save the file with the same name.

Creating an Output Datastore 1. You must run a HAMMER model prior to creating a HAMMER output datastore. a. Click GO in HAMMER Modeler. b. Select Generate Output Database. c. Click Run. Even if you did not select Generate Output Database, you can click File > Export > Database > Output to create a HAMMER output datastore. HAMMER creates an output database using the same name as the HAMMER input file (in this case Lesson2.mdb) and opens a control window:

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Note:

By default, HAMMER creates an output database template file (.MDB) and saves it with the same name as the HAMMER input file (.HIF) during each run. When you create the output datastore using the exporter, HAMMER populates that database template.

2. Select Extremes and click Display… to view the tabulated results in Access. The table should look appear as shown below. You can also view reports for vapor pockets, nodes, pipes, or the system summary.

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3.2.2

Part 2—Importing a HAMMER Datastore HAMMER cannot currently import a HAMMER input datastore directly using File > Import. However, you can import an input datastore into HAMMER using the following procedure: 1. From Windows Explorer or your favorite Windows file manager, locate the file Lesson2-input.mdb and double-click it to open Access and automatically load the input datastore you have just created. 2. Click Database Window to display the list of tables for this pipe system. 3. Make any changes to the datastore; for example, connect two pipes to node J2 and modify the Access database tables for Pipes, Nodes, and NodeDataSmall as the highlighted rows in the following figures show:

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Newly added pipes

Newly added nodes

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Newly added nodes

4. Save the database file with the same or a new name (same name is the default) and close the database. 5. Open Lesson2-input.mdb in Access. 6. When prompted, click Create ASCII File to create a HAMMER input file in a temporary .INP format. 7. Save this file with the name Lesson2-InputFromDatabase.INP and click OK. HAMMER displays the status of the creation of the file. 8. In HAMMER Modeler, click File > Open and select the HAMMER input file you have just created. You will see the modified pipe network with the two new pipes you just added to the HAMMER datastore’s database tables. 9. HAMMER automatically converts .INP files to the HAMMER input file format (.HIF). If a file with the same name exists, HAMMER prompts you to overwrite it or provide a different file name.

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New pipes added in the datastore

Using this technique, you can also modify an existing HAMMER input database by linking it to other pipe-system database files from external sources, such as Access databases created by AutoCAD or GIS software.

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3.2.3

Part 3—Importing Haestad Methods Models Using WaterObjects You can import system data from Haestad Methods’ WaterCAD or WaterGEMS hydraulic models directly into HAMMER using WaterObjects technology. 1. Select File > Import > Network > WaterCAD/WaterGEMS to open the WaterCAD/WaterGEMS Import dialog box.

Select units for exported model Select timestep to export (for extended period simulation)

Click to generate steady-state results to export

2. Use File > Open or the Ellipsis (…) button to select a WaterCAD or WaterGEMS file. The path of the file is listed in the project field. 3. Select a Scenario, Units, and Calculation Options (Steady-State or ExtendedPeriod Simulation time step). 4. Click Run Simulation to generate steady-state hydraulic results. 5. Click Create HAMMER Input File to generate an .HIF file (HAMMER will prompt you for the file name). After the input file is created, a message box will display any notes about the creation.

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3.2.4

Part 4—Importing from Other Models Importing from other models includes: •

“Importing from EPANET” on page 3-114

•

“Importing from PIPE2000 or Surge2000” on page 3-115

Importing from EPANET You can compare the model you are about to import from EPANET with the one you assembled in Part 1 of Lesson 1. To import data and steady-state results from the EPANET 2.0 hydraulic model: 1. Click File > Import > Network > Epanet 2.0. The Import EPANET File dialog box opens.

2. Click the EPANET Report File Browse button to select the EPANET Report File, Lesson2_Epanet.rpt, from the \Haestad \HAMR\Tutorials\Lesson2\EPANET folder. 3. Select the EPANET Network File Browse button to select Lesson2_Epanet.inp from the same folder. 4. Click the Output HAMMER File Browse button, and name the HAMMER input file Lesson2.hif. 5. Leaving the import Mode setting set to New. 6. Click Import. A dialog box will indicate the status of the import process.

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Quick Start Lessons 7. Select File > Open to load the HAMMER input file, Lesson2.hif, from the folder you specified during the import operation. 8. Compare this imported pipeline with the one you created using the HAMMER Modeler interface (see “Part 1—Creating or Importing a Steady-State Model” on page 3-82).

Importing from PIPE2000 or Surge2000 The procedure and interface for importing from PIPE2000 or Surge2000 is similar to that for EPANET. The import dialog for PIPE2000/Surge2000 is shown below.

3.3

Lesson 3: Network Risk Reduction In Lesson 1, you learned how to create and run a simple pipeline model and explored its different characteristics using HAMMER Modeler and HAMMER Viewer. In Lesson 2, you imported this same pipeline from EPANET into HAMMER. In Lesson 3, you will import a simple water-distribution network connected to the same pipeline introduced in Lesson 1, using WaterObject technology. You will then perform a more advanced hydraulic transient analysis, again in three steps: 1. Import the steady-state WaterCAD model into HAMMER and verify it. 2. Select a transient event to analyze and run the HAMMER model. 3. Annotate and color-code the resulting map, profiles, and histories using HAMMER’s powerful, built-in visualization capabilities.

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3.3.1

Part 1—Importing and Verifying the Initial Steady-States Follow these steps to import model data and steady-state results from WaterCAD or WaterGEMS into HAMMER (see “Part 3—Importing Haestad Methods Models Using WaterObjects” on page 3-113): 1. Start HAMMER from the Windows Start menu using Start > All Programs > Haestad Methods > HAMMER > HAMMER or double-click the HAMMER desktop icon (if any). 2. Click File > Import > Network > WaterCAD/WaterGEMS to open the WaterObject importer. 3. Browse your system to locate and open the file Lesson3-WtrGems.mdb from the folder Haestad\HAMR\Tutorials\Lesson3\WaterGEMS. 4. Click Steady-state, then click Run Simulation. Select cms, m in the Units dropdown list. Click Create HAMMER Input File and save the HAMMER input file as Lesson3.hif. Note:

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Set the Control Status of valve VLV1 to Throttled or Wide Open. Click Operating Rule and set the Relative Closure to 0 at 0 s and 0 at 1000 s (for example), so that the valve will remain fully open throughout the simulation.

HAMMER User's Guide

Quick Start Lessons Inspecting the steady-state model results using HAMMER Modeler reveals that the water transmission main now carries only 207 L/s of water from the pumping station to reservoir Res2 at elevation 456 m. A local main takes water from the transmission main at a tee located about 400 m from the pumping station, distributing 265 L/s to a nearby subdivision. The part of the subdivision close to the pumping station has lower ground (and therefore water main) elevations, while the far end has higher ground elevations. Your goal is to identify transient issues for this system and recommend surge protection alternatives. 5. By default, HAMMER selects a Constant speed pump (with no pump curve) to represent the imported pump. Prior to running the HAMMER model of this system, you need to select some profiles and points of interest. 6. Click Tools > Project Options and select the Report Points tab. Add nodes PMP1D:PMP1, P1:J1, P2:J1, P2:J2, P8:J2, P27:J19, P28:J19, P47:J34, and P50:J37 to the report points (you learned how to do this in Lesson 1). Note:

HAMMER plots time histories at a pipe’s end points, defined as the point on a pipe closest to a node and labeled Pipe_End_Point:Node. To obtain a complete picture of what is occurring at any given node, you must inspect every end point connected to that node (e.g., in this example, plot histories at end points P1:J1 and P2:J1 for node J1).

7. Click the Report Paths tab and create three paths as follows: –

Create Path1 and add pipes PMP1D, P1, P2, P3, P4, P5, P6, and P7 to it.

–

Create Path2 and add pipes PMP1D, P1, P2, P8, VLV1U, VLV1D, P9, P10, P14, P48, P49, and P50 to it.

–

Create Path3 and add pipes PMP1D, P1, P2, P8, VLV1U, VLV1D, P9, P15, P22, P24, P28, P30, P46, and P47 to it.

8. Click VLV1 and set the Disch. Coeff. to 0.9. 9. Click the Summary and set Run Duration = 160 s, Time = seconds, Wave Speed = 1250 m/s, and Vapor Pressure = -10 m-Hd (default value). 10. Click File > Save to save this HAMMER input file with the same name, Lesson3.hif. 11. Click File > Run and click Run to run the HAMMER model. 12. The HAMMER Viewer will open automatically after the run completes. Click Plot to generate a plot of the maximum and minimum head envelopes along Path1, Path2, and Path 3. The envelopes along Path1 should look like the following figure.

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13. Click Plot to generate a plot of the hydraulic transient history of Flow & Head at the pumping station. There should be no significant change in the steady-state conditions with time. Transient Tip: When you import a steady-state model using WaterObject, the Friction Coef. and Wave Vel. fields of individual pipes are left empty (not zero). This does not affect the results, since HAMMER calculates the friction factor prior to every run and because it uses the global Wave Velocity (in the System tab of the Model Settings dialog). If the pressure wave speed differs for individual pipes, you must enter a Wave Vel. value for each pipe in your system.

Results from the HAMMER run you have just completed do not show any change in the steady-state heads and flows throughout the water network as time passes. This indicates the imported steady-state model can be considered as correct. You are now ready to proceed with the hydraulic transient analysis for this network. If the solution tolerance of a steady-state model is too coarse, HAMMER’s highly accurate model engine may report transients at time zero in the .OUT file. This can usually be handled by running the steady-state model again with a much smaller error tolerance.

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3.3.2

Part 2—Selecting the Key Transient Events to Model In Lesson 1, you simulated the transient pressures resulting from a sudden power failure. In this lesson you will learn how to simulate transient pressures in a water distribution network triggered by an emergency pump shutdown and restart. Although a power failure often results in the worst-case conditions, restarting before friction has dissipated the transient energy can cause higher extreme pressures than the initial power failure.

3.3.3

Part 3—Performing a Transient Analysis In order to generate transient events for a rapid but controlled emergency pump shutdown and restart, you need to set appropriate pump characteristics to control the speed at which this pump can shut down and restart. One of the ways to do this is to install a variable-frequency drive (VFD), also known as a variable-speed pump.

Analysis without Surge Protection 1. Right-click node PMP1 and select Convert Type > Rotating Equipment > Variable Speed, between 2 Pipes. You can also select a different pump type in the Element Property pane. Note:

You will be prompted to reset the computed results. Click Yes.

2. You can use either Speed or Torque to control the VFD pump ramp times. In this lesson, you will learn how to control the pump using Speed. The property window for Variable Speed, between 2 Pipes appears as follows.

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Note:

HAMMER saves your data automatically when you exit a dialog box by clicking Close.

3. Click the drop-down list next to the Operating Rule. A data table for the pump’s Speed and operating Time appears. Fill the table as indicated and click Close to leave the table.

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Quick Start Lessons 4. Click Go to open the Run dialog box. Check Generate Animation Data and click Run to start the simulation. You will need the animation data later to animate the results on screen. When the run completes, it automatically loads the HAMMER Viewer, from which you can plot and animate your results. 5. Plot the transient history at end point PMP1D:PMP1 (i.e., the discharge side of the pump). It should look like the following figure and have these characteristics: –

After the emergency pump shutdown, pressure and flow drop rapidly, followed by a large upsurge pressure (at about 15 s) after flow returning to the pumping station collapses the vapor pockets at the high points. The check valve on the discharge side of the pump keeps the flow at zero during the initial and subsequent pressure oscillations (until the pump restarts).

–

The maximum transient head resulting from the pump restart does not exceed the maximum head reached about ten seconds after the initial power failure. This is because flow supplied by the pump prevents vapor pockets from reforming and collapsing again.

–

The system approaches a new steady state after 50 seconds and it has essentially stabilized to a new steady state by 90 seconds.

–

As expected, the final steady state is similar to the initial steady state.

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6. Plot the maximum and minimum transient head envelopes along the Paths Path1, Path2, and Path3. The Path3 envelopes should look like the following figure:

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In these figures, –

Subatmospheric transient pressures occur in almost half of the pipeline. Full vacuum pressure (–10 m) occurs at the knee of the pipeline (near the pump station) and at the local high point in the distribution network.

–

Maximum transient pressure heads are of the order of 100% above steadystate pressures along the majority of Path3. This is likely very significant compared to the pipes’ surge-tolerance limit, especially if the network contains older pipes. It would be useful to show the pipe’s working pressure and surge-tolerance limit on the paths to assess whether it can withstand these high pressures.

7. Experiment to learn the sensitivity of this system to an automatic, emergency shutdown and restart: –

Set different shutdown and restart ramp times for the pump. For example, try 10 s ramp times for the pump. How fast does the flow decrease to zero? Why?

–

Select different time delays between the pump shutdown and restart. What happens if you try to restart the pump when pressure is at its lowest, rising, or highest?

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Lesson 3: Network Risk Reduction 8. Identify the fastest ramp times and shortest time delay which do not result in unacceptable transient pressures anywhere in the system. Since the maximum transient envelopes depend on these two variables, several valid solutions are possible. You can document your solution in the operations manuals for the pumping station and verify its accuracy upon commissioning. Note:

The volume of vapor or air reported at a node is the sum of the volumes at every end point of all connected nodes. Since a pipe may have volumes elsewhere than at its end point, node and pipe volumes may not match. If more than two pipes connect to a node, the volume reported on a path (or profile) plot may not match the volume reported for that node’s history, or in the Drawing Pane, because a path can only include two of the pipes connecting to that node.

9. The results indicate that significant pressures occur in the system. After viewing the animations, it becomes even more clear that: –

High pressures result from the collapse of significant vapor pockets at local high points. Inspection of the transient histories at end-points P2:J1 and P27:J19 confirms that vapor pockets collapse at around these times.

–

The pump restarts at 25 s or 20 s after the start of the emergency pump shutdown, just as the high-pressure pulse from the collapse of a vapor pocket at node J1 is reaching the pump station. This pulse closes the check valve against the pump for a while, until it reaches its full speed and power at around 30 s.

–

Transient pressure waves travel throughout the system, reflecting at reservoirs, dead-ends, and tanks. This results in complex but essentially periodic disturbances to the pump as it attempts to re-establish a steady state.

–

As expected, the final steady-state head and flow are similar to the initial steady state.

Analysis with Surge-Protection Equipment You can select from an array of protective equipment to control high and low transient pressures in the pipeline (Path1) and distribution network (Path2 and Path3). Using HAMMER, you can assess the efficiency of alternative protection equipment, noting how protection for the pipeline affects conditions in the network and vice versa. In this example you will try to protect this entire system with two surge-control devices:

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A gas vessel or air chamber at node J1 similar to the protection used in Lesson 1. Due to the connected pipe network, transient pressure pulses fragment and attenuate more rapidly and there is much less flow in the pipeline; therefore a 5 m3 gas vessel is adequate. This is a significant reduction compared with the 20 m3 gas vessel in Lesson 1.

•

A simple flow-through surge tank or standpipe at the node J19. A combination air valve could also be considered for this location if freezing or land-acquisition costs are a concern.

To protect the system: 1. Right-click node J1 and select Convert Type > Protective Equipment > Gas Vessel. 2. Enter the following Gas Vessel parameters:

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Lesson 3: Network Risk Reduction 3. Right-click node J19 and select Convert Type > Protective Equipment > Surge Tank (Simple). 4. Enter the following simple surge tank’s parameters:

5. Select File > Save As to save the file with the name Lesson3-Protection.hif. 6. Click Go to run the model (check the option Generate Animation Data). 7. Once the run completes and HAMMER Viewer opens, select Path1, Path2, and Path3 in sequence and click Plot to generate graphs of their transient head envelopes. The envelope along Path3 with surge protection should look like the following figure:

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–

No subatmospheric pressures occur anywhere in the distribution network (along Path3).

–

High transient pressures are comparable to the steady-state pressures for the downstream half of Path3. Keeping transient water pressures within a narrow band reduces complaints and it could be important for certain industries.

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8. Compare the transient head envelopes and transient histories for HAMMER runs with different parameters, without and with protection: –

You may be able to reduce the size (and cost) of the Gas Vessel and Surge Tank (Simple) by changing their parameters until surge pressures are unacceptable.

–

Instead of the Gas Vessel and Surge Tank, you can also try installing a twoway or “combination” Air Valve at nodes J1 and J19.

9. Before recommending a surge-protection strategy for this system, you need to perform a transient analysis of an emergency power failure and other possible transient events. 10. Use HAMMER’s animation capabilities to prepare a presentation explaining the pros and cons of each protection alternative, as you did in Part 5 of Lesson 1. You will learn more advanced techniques in the next parts of this lesson.

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Lesson 3: Network Risk Reduction

3.3.4

Part 4—Color-Coding Maps, Profiles, and Point Histories In the design of a surge-control strategy for a water distribution network, the extreme states are usually of the greatest interest. HAMMER has built-in capabilities to visualize maximum and minimum simulated flows, heads, pressures, and volumes (vapor or air) throughout the pipe system. You can color-code nodes and pipes according to these different parameters. HAMMER Modeler also displays line thicknesses in proportion to the pipes’ diameter. In this part of the lesson, you will learn how to use HAMMER’s color-coding features to make your presentation more intuitive and compelling to your audiences. 1. In HAMMER Modeler, click File > Open and load the file Lesson3.hif. 2. Click the Go button on the HAMMER toolbar and click Run to generate output to be displayed with the color-coding. When the run is completed, you will see that the entire pipe network, including the nodes, is now shown in color. By default, HAMMER uses Maximum Head for both the pipes and nodes for color-coding. 3. Select any node on the map and set maximum and minimum pressures in the network to psi using FlexUnit. You can do this by clicking on the unit indicator in the Element Editor; for example, m-head or ft-head. 4. Use the Map Selection drop-down box on the HAMMER toolbar (left of the Globe icon) to select the parameters you want to display for pipes and nodes. The following screen prompts you for a selection. Keep Maximum Head (for pipes) and select Maximum Pressure (for the nodes).

5. Click on the Scales button at the bottom of the Map Selection choice list. The color settings correspond either to the Maximum Head or Maximum Pressure, if these are currently displayed in the Map Selection drop-down list. Select a Percentile scale.

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HAMMER’s Color Map Settings dialog for the variable Maximum Pressure (for nodes) shows the maximum and minimum values of this variable using the units you selected with the FlexUnits manager. The appearance of the resulting map depends on how skillfully you divide the total range into intervals and how you set colors corresponding to each of the interval boundaries: –

Select equal intervals by clicking on the Quartile, Quintile, Decile, and Percentile Scale Type. These correspond to upper and lower range limits of 25, 20, 10, and 1 percent, respectively.

–

You can also click Custom (Percent) to use the Low Percent and High Percent sliders or Custom (Value) to enter the limiting values directly.

Throughout this process, you can press Preview to update the map color and see the result of your changes as you make them. This saves a lot of time compared to repeatedly opening the Color Map Settings dialog, making a selection, and closing it again to view the resulting map. 6. In the Color Setting control, click the Add button to insert a new setpoint value, in percent, and its corresponding color using the Color Bar. Set the values and colors shown in the previous screen shot and click OK to return to HAMMER Modeler. 7. Similarly, set the values and colors for pipes as indicated in the next screen capture and click OK to return to HAMMER Modeler.

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Lesson 3: Network Risk Reduction

8. The resulting color-coded map for Maximum Head (for pipes) and Maximum Pressure (for nodes) should look like the following figure:

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Quick Start Lessons 9. Another way to obtain the above map using the Map Color Settings dialog is to click Presets and select Lesson3-Pipes (for pipes) and Lesson3-Nodes (for nodes) from the drop-down box. This will result in the same color map displayed above. 10. Try different ways to set the Scale Type and Color Setting values for different variables at pipes and nodes to try to make your presentation more descriptive. For example, you could try the following: –

In the Map Color Settings dialog, select the Color Setting preset System: Max. Head. Since suction line pressures are much lower than those in the pipeline and distribution network, you can alter the Minimum Value by clicking on Custom (Value) and entering 400 m. More of the pipes are now colored green, indicating normal to high heads in this system.

–

For pipes, set the percentage corresponding to the dark blue color so that subatmospheric pressures are displayed in this color, alerting you to potential pathogen intrusion and heavy pipe or joint pressure cycling.

–

For nodes, experiment with the percentages corresponding to yellow and orange until they correspond to the pipe’s working pressure or surge-tolerance limit.

Color-coding a map for selected variables provides an overview of extreme conditions in the entire system. This map can be compared with profiles and histories (or their corresponding animations). Some parts in the subdivision also experience high pressures. For example, the colorcoded map and the Results section of the Element Editor indicate that the point with the highest elevation in the subdivision, node J34, experiences the lowest minimum transient pressure, while the lowest point in the network, node J37, experiences the largest maximum transient pressure.

3.3.5

Part 5—Adding Comments to Generate Report-Ready Graphs In Lesson 1 you learned how to add comments and change the graph’s title and figure number using HAMMER Viewer. In this part of the lesson, you will learn more advanced graphing features, such as FlexUnits, and how to add your organization’s name and logo to the figures.

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Lesson 3: Network Risk Reduction You will also learn how to add lines showing pipes’ working pressure or surgetolerance limits, to check which parts of your pipe system are more vulnerable to surges and to help decide whether or not you need surge-protection equipment. Let’s start with your results for the transient analysis without surge protection and follow these steps: 1. In HAMMER Modeler, click Tools > Viewer > Graphics to start the HAMMER Viewer and load Lesson3.hof. 2. You can insert your company’s name and logo using the Tools > Set Logo and Tools > Set Company Name menu commands in the HAMMER Viewer. 3. Select the Time History PMP1D:PMP1 and Graph Type Flow & Head and click on Plot to generate the transient history at the pumping station. The head will be plotted in m and the flow will be plotted in cms (SI units). 4. Right-click anywhere outside the graph to open the menu. Click FlexUnits to open the FlexUnit Manager.

Note:

HAMMER’s FlexUnits Manager allows you to select and plot your results in different units, such as pressure head in U.S. units and flow in SI units. You can select the display precision and use scientific notation. Choices you make in the FlexUnits Manager will not affect the accuracy of the solution or the underlying data stored by HAMMER.

5. For plotting purposes, you can change the units for some variables using the FlexUnits Manager by:

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Quick Start Lessons –

Click SI for the Attribute Type row Elevation or Head under the column System. This drop-down menu allows you to convert this variable to U.S. units. As in other Haestad Methods software, FlexUnits automatically selects a corresponding unit with a similar size: m in SI units converts to ft. in U.S. units, in this case.

–

If your results were either very large or small, you could also change the unit to in., yd., mile, etc.

–

Similarly, change the unit for Flow from cms to l/s by clicking on the Attribute Type row Flow under the column Units. Change Display Precision to zero for Flow.

6. Click OK to save these settings and leave the FlexUnits Manager. From now on, Head will be displayed in ft. and Flow will be displayed in l/s, as shown in the figure below.

7. To help interpret the maximum transient head envelope along the profiles, you can add lines corresponding to the pipes’ working pressure or surge-tolerance limit. In HAMMER Viewer, select Path (Profile) Path1 and Graph Type Path and click Plot to view the graph.

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Lesson 3: Network Risk Reduction 8. Let’s assume that the working pressure of pipes in your network is 142 psi (100 m). Click on the graph frame and then right-click to display the menu. Click Format Data to open the following dialog box:

9. Select Current Line: Lesson3: Path1: Elevation and click on the Add Segment. A new segment is added parallel to the pipe. The offset is zero by default. Enter 100 in the Set Offset field and make sure there is a check in the Show box. You can add another line segment with an offset of about 140 m to represent a typical surge tolerance limit. This incorporates a safety factor for older pipes. You can also change the line segments’ type, thickness, and color. Note:

If your current FlexUnits settings for pressure are psi or kPa, you must convert the pipe’s working pressure and surge-tolerance limits to their equivalent heads and draw a line this distance above, and parallel to, your pipeline.

10. Click on the graph frame and then right-click to display the shortcut menu. Select Format Graph > Draw > Text to add the labels “Maximum Transient Head”, “Minimum Transient Head”, “Steady-state Head”, and “Pipe Elevation” to your graphs. Double-click the text to select a font and size for this text. The graph should now look like the following screen capture.:

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11. Plot transient pressures envelopes along Path2 and Path3 and add the working pressures in a similar way as you did for Path1 to check which part of your network may need additional surge protection. 12. To visualize the system interactively, do the following: a. Click Animate for Path3 and again for histories at end-points P27:J19 and P2:J1 (only P27:J19 is shown in the next figure). b. Rearrange the graphs on your desktop to look like the next figure. After adding suitable annotations and titles, right-click each one and select Save As > HAMMER Graph to save the to HAMMER graph files (.GRP) for subsequent recall. c. You can right-click any graph and turn its title bar off to maximize the proportion of area available for graphs. d. In the Animation Controller, click File > Save Animation As to save this layout in a HAMMER animation layout file (.ANI).

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Lesson 3: Network Risk Reduction

You can use the HAMMER Viewer to open a HAMMER output file (.HOF), then open its animation files (.ANI) to re-create your screen layout automatically. This simplifies the preparations required for later discussions.

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Chapter

4

Starting a HAMMER Project In this section, you will learn how HAMMER manages files and project data and the ways in which you can import model data from other models or databases. You will also learn how to enter project-specific information, including fundamental fluid and pipe properties. Finally, you will learn how to use the powerful FlexUnits feature to select a global unit system or change the display settings for any variable.

4.1

•

“File Management and Formats” on page 4-137

•

“Import and Export Commands” on page 4-139

•

“Project Management and Options” on page 4-142

File Management and Formats HAMMER lets you use several file formats.

4.1.1

HAMMER Input and Output Files HAMMER uses binary files with the extension .HIF to store model-specific information, including project option settings, color-coding, and annotations. Using the File > New menu command creates a HAMMER input file in .HIF format. HAMMER results are saved to an output file which uses the .HOF extension. Using the File > Run menu command creates a HAMMER output file in .HOF format (after the run is completed). Clicking Generate Animation Data adds animation data to the .HOF file for each selected point and profile.

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File Management and Formats

4.1.2

HAMMER Datastore and Access Connections In addition to the .HIF file format, network information and output results can also be stored in (or retrieved from) the HAMMER datastore. A HAMMER datastore is saved as a Microsoft Access .MDB file. Export your work to apply changes to a HAMMER datastore using File > Export > Database > Input or File > Export > Database > Output. For an example of how to do this, see “Part 1—Exporting an Input or Output File to a HAMMER Datastore” on page 3-105. Note:

A HAMMER output datastore (.MDB) file contains most of the input data you specified prior to running HAMMER, as well as the output data. Consequently, this file can be very large.

The HAMMER datastore consists of several tables whose entries can be edited using Access. You can create new entries in the datastore to add new hydraulic elements to a model. The first step to import this data into HAMMER is to click Create ASCII File (.INP) in the HAMMER database Control Window. This Control Window starts automatically when you export a HAMMER input file to a datastore using File > Export > Database > Input. Then, use File > Open to import the temporary ASCII .INP file into a standard binary HAMMER input file (.HIF). For an example of how to do this, see “Part 2—Importing a HAMMER Datastore” on page 3-109.

4.1.3

WaterObjects Connections For an example of how to use WaterObjects connections, see “Part 3—Importing Haestad Methods Models Using WaterObjects” on page 3-113.

4.1.4

Additional Files Note:

Use a separate folder for every HAMMER project to facilitate project management and backup. At this time, each HAMMER project requires a separate input file name.

HAMMER output graphs are saved in .GRP files and HAMMER animation layouts are saved in .ANI files. For typical users and projects, it can take anywhere from a few minutes to a half hour to create graph annotations and animation layouts. It is highly recommended that you backup all .GRP and .ANI files in your project folder. HAMMER also creates an empty output database template whether or not this option is selected in the Run dialog. HAMMER does not need this .MDB to function but Access scripts provided with HAMMER require it to generate tables and custom reports. You can delete any .MDB file created by HAMMER, if you no longer require it, or compress it using a third-party utility program.

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Starting a HAMMER Project Note:

Haestad Methods software such as WaterCAD or WaterGEMS can also store data in .MDB files. If you are saving files from these programs to the same folder as your HAMMER project files, be careful to give them different names to prevent loss of data.

HAMMER creates additional files in the same directory as your .HOF file to save the calculation results (.RPT, .OUT, .MDB). Since recomputing the input file can regenerate these results, these files do not necessarily need to be included when backing up your important model data. However, if you are unsure, back up all files present in your project directory.

4.1.5

Multiple Sessions and Submodels Note:

If your computer has sufficient RAM, it is possible to open more than one instance of HAMMER to copy and paste results between similar projects, but this is not recommended, as it may result in data loss. It is more efficient to copy and paste results between the .GRP files generated by each project.

HAMMER does not support either multiple sessions or submodels. HAMMER uses a single-document model. To compare results between different HAMMER project files, you can save each one as a separate HAMMER graph file in .GRP format, then cut and paste the results between graphs using the HAMMER Viewer. Memory requirements vary with project size, but .GRP files are quite compact.

4.2

Import and Export Commands The File > Import > Network menu command lets you import model data and steady-state results from EPANET version 2.0, WaterCAD/WaterGEMS using WaterObject technology or PIPE2000/Surge2000. You will then be able to save these data as a HAMMER project. Data can be imported into a new project or an existing project, for example to update the steady-state heads at the beginning of a transient analysis. PIPE2000/SURGE2000 data can only be imported into a new HAMMER project file.

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Import and Export Commands Note:

We have made every effort to prevent the loss of data during imports. However, all imported data should be checked for accuracy. WaterCAD or WaterGEMS projects should open and run in HAMMER after using the Import command, but additional data is usually required before a hydraulic transient analysis (e.g., pump and motor inertia). Once you save the project in HAMMER file format, either .HIF or .MDB (datastore), the HAMMER project files can no longer be opened in WaterCAD or WaterGEMS, but the original WaterCAD and WaterGEMS files are not lost.

You can also use the File > Export menu command to export HAMMER output to EPANET version 2.0 or to a Microsoft Access database in HAMMER datastore format. If you intend to run an EPANET file exported from HAMMER, make sure the HAMMER output represents a final steady state.

4.2.1

Importing/Exporting EPANET v.2.0 Note:

In Global HAMMER Options, Epanet EXE must display the path to your EPANET directory before you can import or export EPANET files (see “File I/O” on page 2-70).

In EPANET version 2.0, you will need to save the steady-state results to an EPANET report (.RPT) file prior to importing them into HAMMER. For an extended-period simulation (EPS), you must first select which time step you want to export from EPANET. Importing steady-state results from EPANET saves time and eliminates transcription errors, but additional information is required prior to running a HAMMER model. After importing your data into HAMMER, you will need to add data specific to hydraulic transients. To import EPANET model data and steady-state results into HAMMER, use the menu command File > Import > Network > Epanet 2.0 and either import it into a new HAMMER project file (set the import Mode to New) or use it to update an existing HAMMER project file (set the import Mode to Update). For more information, see “Importing from EPANET” on page 3-114. After the transient energy has attenuated and a new steady state has been achieved or if you created a steady-state model using HAMMER, you can also export some HAMMER results to EPANET 2.0 using the menu command File > Export > Network > Epanet 2.0.

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4.2.2

Importing/Exporting to a GIS or Database Using the HAMMER Datastore By default, HAMMER uses its own input and output file formats. The HAMMER datastore is an alternative method for creating and using input and output files to analyze any pipe system whose data can be output to a Microsoft Access .MDB file. HAMMER datastores can be used to create HAMMER input files from information contained in your GIS (i.e., network data) or other databases (e.g., water demands from meters). For example, you can obtain system data and topology from a GIS and export it to an .MDB connection file (e.g., HAMMER datastore). The process is described in “Part 2—Importing a HAMMER Datastore” on page 3-109. After importing a HAMMER datastore, you will typically need to add data specific to hydraulic transients, such as a pressure wave speed for each pipe, then save this input file as a HAMMER .HIF. After running HAMMER, the results can be exported to an .MDB connection file if you want to transfer data back to the GIS for postprocessing or visualization. Use the command File > Export > Database > Output. When new water-demand forecasts become available, you can export a new .MDB connection file from your database or GIS, copy it to the HAMMER datastore and import it. To do this, select Export ASCII from within Access and open the resulting file in HAMMER (see “Part 2—Importing a HAMMER Datastore” on page 3-109).

4.2.3

Importing from WaterGEMS/WaterCAD Using WaterObjects Note:

If you are saving a HAMMER file or database and are prompted that the file already exists, save using a different name than the one you have chosen, or make sure you are not overwriting an existing WaterGEMS/WaterCAD file that you need. If you import a file from WaterGEMS or WaterCAD, and then save the HAMMER database (*.mdb) file the same as your WaterGEMS/WaterCAD file, you will overwrite your WaterGEMS/ WaterCAD file.

You will need to select the scenario and alternative prior to using WaterObject technology to export model data and steady-state results from WaterCAD/WaterGEMS to HAMMER. For an extended-period simulation (EPS) file, you must first select which time step to export from WaterCAD or WaterGEMS to HAMMER.

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Project Management and Options To import WaterCAD or WaterGEMS model data and its steady-state results into HAMMER, use the menu command File > Import > Network > WaterCAD/ WaterGEMS. For more information, see “Part 3—Importing Haestad Methods Models Using WaterObjects” on page 3-113. Importing steady-state results using WaterObject technology saves time and eliminates transcription errors, but additional information is required prior to running a HAMMER model.

4.2.4

Importing PIPE2000 or Surge2000 You can import model data and steady-state results for a single time step into HAMMER. If you are working from an extended-period simulation (EPS) file, you must first select which time step to use. To import PIPE2000 or Surge2000 model data and its steady-state results into HAMMER, use the menu command File > Import > Network > Surge2000 and import it into a new HAMMER project file. For more information, see “Importing from PIPE2000 or Surge2000” on page 3-115. Importing steady state results saves time and eliminates transcription errors, but additional information is required prior to running a HAMMER model.

4.3

Project Management and Options At the beginning of a project, you need to set some parameters using the Global HAMMER Options and Project Options windows. You can specify the units, the friction formulas to be used, and whether you want to use tooltips. Note:

Options can be viewed or edited using the Tools > Global HAMMER Options or Tools > Project Options menu commands.

You can also access the FlexUnit Manager using the Tools > FlexUnits menu command (see “FlexUnits” on page 4-149) in order to globally specify the units and number of decimal places for displaying each model parameter.

4.3.1

Global HAMMER Options Colors Tab:

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You can specify the background and foreground colors of the Main Window and Drawing Pane in HAMMER Modeler. You can specify individual foreground colors for handles, lines, text, rubber band, and highlighted elements.

HAMMER User's Guide

Starting a HAMMER Project These color settings do not apply to the HAMMER Viewer, Profile, or History windows. Tooltips Tab:

Tooltips are short messages which pop up automatically whenever you pause over a HAMMER feature or icon. You can set a convenient time delay (in milliseconds) to prevent them from appearing most of the time or you can turn them off altogether. Don’t confuse tooltips with Sticky Tools.

File I/O Tab:

This tab allows you to specify default directories and the location of useful tools, such as:

Sticky Tools:

•

The default text editor (to open ASCII .RPT or .OUT files)

•

The location of the Microsoft Access database (to open tabular reports generated by HAMMER)

•

The location of the EPANET version 2.0 executable file (if available)

The Sticky Tools option is not part of the Global HAMMER Options dialog box. Sticky Tools can be turned on or off in HAMMER Modeler mode using the Push Pin button. With Sticky Tools disabled, the drawing pane cursor returns to the Select tool after a hydraulic element is inserted onto the Drawing Pane or a pipe run is finished. With Sticky Tools enabled, the tool does not reset to the Select tool, allowing you to continue dropping new elements into the drawing without reselecting the same hydraulic element from the toolbar menu.

4.3.2

Project Setup Set the following essential information about your HAMMER project: •

“Project Summary” on page 4-144

•

“Unit System” on page 4-145

•

“Liquid Properties” on page 4-146

•

“Selecting the Friction Method” on page 4-147

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Project Management and Options

Project Summary In the Summary tab of the Project Options window (Tools > Project Options), you can enter the Project Title and describe the source of your model data. If the HAMMER data were imported from another model, you can enter information such as the Source File, scenario and Alternative, and Time Step (if it came from an EPS run). You can change any of this information at any time. This tab is also where you specify the default wave speed, specific gravity, and run duration for the project. Determining Pressure Wave Speed HAMMER uses a default pressure wave speed of 1,000 m/s (3,280 ft./sec.). If your system includes pipes with different materials, you can specify a default pressure wave speed corresponding to the majority of pipes. To enter a different pressure wave speed for each pipe, select that pipe and use the Element Editor to enter a specific value. For more information, see “Celerity and Pipe Elasticity” on page B-257. Determining the Run Duration Run duration is measured either in seconds or as a number of time steps. HAMMER determines the length of each time step automatically. Time steps typically range from a few hundredths of a second to a few seconds, depending on the system and the pressure wave speeds. The run duration has a direct effect on the modeling computation time. For simple systems or if the time required to compute the HAMMER model is not a concern, it is ideal (but not always necessary) to set run durations long enough to allow a final steady state to be achieved once all transient energy attenuates. This is quite manageable in many cases, such as for the sample file Hamsam02.HIF, which requires about 30 to 40 seconds to reach a final steady state. Each system requires a different amount of time to reach a final steady state. Transient Tip: Every pipe system has a characteristic time period, T = 2 L/a, where L is the longest possible path through the system and a is the pressure wave speed. This period is the time it takes for a pressure wave to travel the pipe system’s greatest length two times. It is recommended that the run duration equal or exceed T. Another factor to consider when determining run duration is to allow enough time for friction to significantly dampen the transient energy. If in doubt, run HAMMER for a longer duration and examine the resulting graphs and time histories.

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Starting a HAMMER Project For larger systems, you can use the following guidelines to decide on the most appropriate run duration: 1. First run HAMMER for only a few time steps to identify the sources of transients (remember to output every time step in the Report Times tab of the Project Options dialog box—see “Report Times” on page 2-40). You can also check for input errors by clicking GO and Data Check in the run window. Finally, click GO and Full to run the model, and then look for errors in the steady-state model or other initial transients in the comments at the end of the HAMMER output file (.OUT). 2. Run HAMMER again for a duration of T=4 L/a (or greater) to verify that your simulation includes the maximum and minimum transient heads. These normally occur within this time frame. A longer run duration may be required if air pockets form or if a gas vessel or surge tank is installed, due to the persistence of oscillations in the system. 3. Run HAMMER again for a duration of T=20 L/a or greater, whatever is enough to allow friction to attenuate the transient energy and, consequently, to let the system approach or achieve a final steady state. Use the following friction method: –

If the cause of transients is a sudden valve closure or pipe break, select the unsteady (transient) friction mode in the Preferences tab (see “Preferences” on page 2-42) of the Project Options window.

–

If the system includes a gas vessel, surge tank, or air pocket, the quasi-steady friction mode may be sufficient.

–

The most extreme transient pressures (typically the first maximum and minimum reached) are often of primary interest because of the need to check if pipes will break. In such cases, or for the early runs, steady-state friction is often sufficient.

The preceding procedure increases the likelihood that you will correctly simulate the key aspects of the hydraulic transient event for your system. However, remember that L is only a characteristic length which may not be directly applicable to branched or looped networks or plants. Always use sound engineering judgment in reviewing HAMMER results and interpreting the output.

Unit System Note:

If the file you are editing in HAMMER Modeler is already associated with a WaterCAD/WaterGEMS file, changing the unit system may make it difficult to compare results between models.

Although units for individual variables can be controlled throughout HAMMER, you may find it useful to change your entire unit system at once to either the Système International (SI) unit system or the U.S. customary (English) system. You can do this using Tools > FlexUnits, and click the System SI or System U.S. button.

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Project Management and Options

Liquid Properties You can specify the type of liquid in Tools > Project Options > Summary. By default, HAMMER assumes the liquid is water at 20 degrees Celsius (about 65 degrees Fahrenheit), with a specific gravity of 1.0 and one atmosphere of ambient pressure. If the liquid being conveyed is not water, you must specify its specific gravity. Note:

The kinematic viscosity for water may be used in determining the friction coefficient in the Darcy-Weisbach Friction Method (see “Darcy-Weisbach Equation” on page B-278). but it is a default for HAMMER (not entered here).

Vapor Pressure A liquid’s vapor pressure limit is defined as the absolute pressure below which it flashes into its gas phase (vapor or steam for water) for the fluid temperature at which the system is operating. Vapor pressure is a fundamental parameter for any hydraulic transient analysis. Low transient pressures can cause a liquid to vaporize and, once one or more of these vapor pockets collapse later on, result in very large transient pressures, which may break pipes or other system components. Transient Tip: For drinking-water systems at typical temperatures and pressures, HAMMER uses an approximate vapor pressure of –10.0 m or –14.2 psi (gauge) or –32.8 ft. by default, depending on the unit system in use. Typically, a liquid’s vapor pressure can be obtained from tables (steam tables for water) given its temperature and absolute (not gauge) pressure. You might consider adjusting the vapor pressure if the elevation of your system is significantly different from mean sea level.

The vapor pocket collapse process is analogous to the well-known tip-cavitation phenomenon, which causes pitting damage at pump impellers; however, vapor pockets can be orders of magnitude larger than cavitation bubbles and can result in system-wide transients. Transient Tip: To determine the impact of collapsing vapor pockets on your system, set the vapor pressure to a large negative value which you do not expect to occur, such as –1000 m, and run HAMMER with a different file name. Then reset the vapor pressure to its true value and run HAMMER again. The difference between these results is due to the effect of vapor pressure.

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Starting a HAMMER Project Heating or pressurizing a fluid increases its vapor pressure—an important consideration in industrial applications. Consider both operating temperature and pressure when determining a liquid’s vapor pressure limit. (For example, water boils at a lower temperature at high altitudes due to the lower atmospheric pressure and lower absolute vapor pressure. Similarly, water boils at a higher temperature in a pressure cooker and this increased steam temperature accelerates the cooking process.)

Selecting the Friction Method The Friction Method option enables you to select the methodology for determining flow resistance and friction losses during calculations. This can be accessed from the menu using Tools > Project Options > Preferences. Available methodologies include: •

Steady-State Friction, including: Darcy-Weisbach, Hazen-Williams, and Manning

•

Quasi-steady Friction

•

Transient Friction, also known as unsteady friction

For more information on the theory for each of these friction models, see “Friction and Minor Losses” on page B-277. Steady-State Friction Methods The most widely used steady-state friction-loss calculation methods include: •

The Hazen-Williams method, in which friction losses are proportional to relative pipe roughness but not to changes in flow.

•

The Manning’s equation, in which friction losses are proportional to relative pipe roughness but not to changes in flow.

•

The Darcy-Weisbach method, in which friction losses are proportional to relative pipe roughness and to changes in flow.

In HAMMER, a hydraulic transient analysis usually begins with an initial steady state for which the heads and flows are known for every pipe in the system. Prior to beginning the transient calculations, HAMMER automatically determines the friction factor based on this information: •

If a pipe has zero flow at the initial steady-state, HAMMER obtains a friction factor based on its diameter from the following default table:

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Hazen-Williams Friction Coefficient, C

Approximate DarcyWeisbach Friction Coefficient, f

70

0.050

100

0.025

140

0.015

•

If a pipe has a nonzero flow at the initial steady-state, HAMMER automatically calculates a Darcy-Weisbach friction factor, f, based on the heads at each end of the pipe, the pipe length and diameter, and the flow in the pipe.

•

HAMMER uses the Darcy-Weisbach friction method in performing the hydraulic transient calculations. If you enter an f value for a pipe in the Element Editor, HAMMER uses this value in the calculations instead of the calculated value. Note:

If your steady-state model used another method to calculate friction losses, the friction coefficients may be imported into HAMMER, but they will not be used directly. Instead, HAMMER automatically uses the steady-state flow and heads (resulting from the other method) to calculate an equivalent DarcyWeisbach friction factor, f.

Quasi-Steady Friction The quasi-steady friction method uses variable Darcy-Weisbach friction factors, f, at each point along the system, so that friction losses for an instantaneous velocity match the friction losses which would occur for fully developed steady flows with the same cross-sectional average velocity. For more information, see “Quasi-Steady Friction” on page B-283. Transient or Unsteady Friction Compared to a steady state, fluid friction increases during hydraulic transient events because rapid changes in transient pressure increase turbulent shear. HAMMER can track the effect of fluid accelerations to estimate the attenuation of transient energy more closely than would be possible with quasi-steady friction. Computational effort increases significantly if transient friction must be calculated for each time step. This can result in long model calculation times for large systems with hundreds of pipes or more. Typically, transient friction has little or no impact on the initial low and high pressures, and these are usually the largest ever reached in the system.

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Starting a HAMMER Project Transient Tip: The steady-state friction method yields conservative estimates of the extreme high and low pressures which usually govern the selection of pipe class and surgeprotection equipment. However, if cyclic loading is an important design consideration, the unsteady friction method can yield less-conservative but rigorous estimates of recurring and decaying extremes.

For more information on the implementation of the transient friction method in HAMMER, see “Unsteady or Transient Friction” on page B-285.

4.3.3

Drawing Setup Set up the graphical display of elements in the drawing pane, including:

4.4

Lock Drawing Pane:

Use View > Lock Drawing Pane to disable the dragand-drop components of the Drawing Pane, but still be able to enter or modify data in the Element Editor and to pan, zoom, and otherwise reconfigure your view of the model schematic.

Anti-Alias:

Use View > Anti-Alias to enhance the appearance of straight lines in the HAMMER Drawing Pane.

Normalize:

Use View > Normalize Symbol Size to resize all hydraulic element symbols to a convenient size at the current zoom level. This setting persists as the zoom changes. Experiment with zooming in, clicking Normalize Symbol Size, and zooming out again to see how this feature allows you to set any desired line thickness and symbol size.

Symbol Visibility:

Turn on or off the display of pipe or node labels in Tools > Project Options > Other Options.

Selection Set Options:

You can pick (but not name or recall) element sets in the Drawing Pane and copy/paste them.

FlexUnits FlexUnits (the ability to control units, display precision, and scientific notation) are available from almost anywhere within Haestad Methods’ software, including the Element Editor, most windows, and the FlexUnits Manager.

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FlexUnits Note:

The units and formatting used to display numeric values can be changed from several other areas in the program, and any changes are project wide. For example, if the unit for length is changed from feet to meters, all windows, tables, and graphs display length in meters. If you change the units in a window from meters to yards, the FlexUnits Manager indicates that length is displayed in yards.

Click Tools > FlexUnits to open the FlexUnits Manager. The FlexUnits Manager lets you set the parameters for all the units used. It consists of the following columns: •

Attribute Type—Model parameter measured by the unit.

•

Unit—Type of measurement displayed. To change the unit of an attribute type, click the unit and select an alternate from the drop-down menu. This option also allows you to mix U.S. customary and SI units in the same project.

•

System—Sets the units to be used in the current project for each variable. Click to select a unit in the system column for the desired Attribute Type (row), and a choice list appears. Click to set the unit system to U.S. or S.I. as required. Click the System: U.S. (or System: SI) button to change the unit of every Attribute Type in the current HAMMER project file.

•

•

4.4.1

Display Precision—Controls rounding of numeric values or the number of digits to be displayed after the decimal point. –

Enter a number from 0 to 15 to indicate the number of digits to be displayed after the decimal point.

–

Enter a negative number to specify rounding to the nearest power of 10: –1 rounds to 10, –2 rounds to 100, –3 rounds to 1000, and so on. This feature works the same whether scientific notation is on or off.

Scientific Notation—Displays numbers using scientific notation. Click the check box to turn scientific notation on or off. If it is turned on, a check mark appears in the box.

Units Units are the method of measurement for the attribute or numeric variable. To change units, right-click the unit displayed next to the field to bring up the choice list, then click the desired unit. The list includes both SI metric and U.S. customary units, so you can mix unit systems within the same project. FlexUnits are intelligent—when you change units, the displayed value is converted to the new unit so the underlying magnitude of the attribute or numeric value remains the same. For example, a length of 100.0 ft. is not converted to a length of 100.0 m or 100.0 in. It is correctly converted to 30.49 m or 1200.0 in.

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4.4.2

Display Precision Note:

Changing the display precision or rounding numbers only formats numeric values. It does not affect calculation accuracy.

The precision setting can be used to control: •

“Number of Digits Displayed After Decimal Point” on page 4-151

•

“Rounding” on page 4-151

Number of Digits Displayed After Decimal Point Enter 0 or a positive number to specify the number of digits to be displayed after the decimal point. For example, if the display precision is set to 3, a value of 123.456789 displays as 123.457.

Rounding Enter a negative number to specify rounding to the nearest power of 10. Entering –1 rounds to the nearest 10, –2 rounds to the nearest 100, and so on. For example, if the display precision is set to –3, a value of 1234567.89 displays as 1235000.

4.4.3

Scientific Notation Note:

Displaying numbers using scientific notation only formats numeric values. It does not affect calculation accuracy.

Scientific notation displays any numeric value as a real number beginning with an integer or real value, followed by the capital letter E and an integer (possibly preceded by a sign). In the FlexUnits Manager, click Scientific Notation to turn scientific notation on or off. A check appears in the corresponding box to indicate that this setting is turned on.

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FlexUnits

4.4.4

Minimum and Maximum Allowed Value Note:

Allowable or recommended minimums and maximums are only available for certain parameters.

Minimum and maximum values are used to control the allowable range for an attribute or numeric value and to validate input. For example, some coefficient values might typically range between 0.09 and 0.20. A frequent input error is to misplace the decimal point when entering a value. If you enter a number that is less than the minimum allowed value, a warning message is displayed. This helps reduce the number of input errors. You may override these values in cases where you find the default limits too restrictive. The default limits are stored internally in the program and cannot be modified. Some attributes do not have theoretical minimum or maximum values, and others may have an acceptable range governed by calculation restrictions or physical impossibilities. For these attributes, minimum and maximum allowable values may not be applicable.

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Chapter

5

Layout and Editing Tools The layout and editing tools allow you to select hydraulic elements in the Drawing Pane of the HAMMER Modeler to perform various graphical or editing operations, locate particular elements, review the network for potential problems, add labels, and review your input data and results.

5.1

HAMMER Modeler One of the most powerful features of the HAMMER Modeler is the ability to create, move, edit, and delete network elements graphically. With these capabilities, working with your model becomes a simple point-and-click exercise. For more information, see “Lesson 1: Pipeline Protection” on page 3-82 and “Lesson 3: Network Risk Reduction” on page 3-115. Note:

If you move the mouse over a feature or hydraulic element and then stop moving it for a little while, a tooltip will display useful information about that feature or element, including its label. This feature is useful when the element labels have been turned off or when the drawing view is zoomed out.

Most network editing tasks can be performed using the mouse: •

“Creating New Elements” on page 5-154

•

“Morphing Elements” on page 5-155

•

“Selecting Hydraulic Elements” on page 5-155

•

“Editing Hydraulic Elements” on page 5-156

•

“Moving Hydraulic Elements” on page 5-156

•

“Copying/Cutting/Pasting/Deleting Elements” on page 5-156

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5.1.1

Creating New Elements The hydraulic element toolbar buttons displayed to the extreme right of the screen contain all of the tools necessary for adding network elements to the Drawing Pane. From left to right, these tools include: •

Pressure Junction Tool—In WaterCAD or WaterGEMS, Junctions are nonstorage nodes where water can leave the network to satisfy consumer demands or enter the network as an inflow. These are called Consumption nodes in HAMMER and are categorized as a system boundary since flow can only enter or leave a system at a boundary.

•

Pipe Layout Tool—Pipes are link elements that connect junction nodes, boundaries, rotating equipment, flow controls, and protection equipment. You can lay out a series of connected elements without stopping (a pipe run) and morph some of them into other element types later.

•

Boundaries Tools—Boundaries are system end points such as tanks, reservoirs, or dead ends. The water surface elevation of a tank changes as water flows into or out of it. The water surface elevation of a reservoir never changes during a HAMMER simulation, because it is assumed that its surface area and volume are large compared to the net transient volume change.

•

Flow Control Tools—Flow-control elements include orifices and control valves. Valves can open, throttle, or close during a hydraulic transient simulation and a rapid or sudden valve operation may cause the transient to occur. A valve is represented as a node between two pipes, unless stated otherwise.

•

Protective Equipment Tools—Protective equipment includes gas vessels, surge tanks, surge-control valves of various types, and rupture disks. Protective equipment is represented as a node between two pipes, unless stated otherwise.

•

Rotating Equipment Tools—Rotating equipment includes various types of pumps and turbines, which are represented as nodes in HAMMER. A pump adds head to the fluid as it passes through, whereas a turbine removes head from the fluid. Rotating equipment is represented as a node between two pipes, unless stated otherwise.

Although elements can be inserted individually, the most rapid method of network creation is through the Pipe Layout tool. You can use the Pipe Layout tool to connect existing nodes with new pipes and to create new nodes as you lay out the pipes. For example, when the Pipe Layout tool is active, clicking within the drawing pane inserts a node. Clicking again at another location inserts another node and connects the two with a pipe.

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5.1.2

Morphing Elements Occasionally, you may find that you need to replace a node with a different type of node. You can make this change through a process called morphing. With morphing, you change the type of a hydraulic element node without having to delete and recreate the node and its connecting links. Parameters that are common between the existing and new elements are copied into the new element (i.e., coordinates, elevations, etc.). To morph an existing hydraulic element into a different type of hydraulic element: 1. In the Drawing Pane, place the cursor over the element and right-click it. 2. Click Convert Type to open the submenu and display lists of available hydraulic elements. 3. Select the new hydraulic element from the available lists.

5.1.3

Selecting Hydraulic Elements You need to select one or more elements from the Drawing Pane before performing various operations, such as moving, deleting, and editing. When an element is selected in the Modeler Drawing Pane, it is displayed with a box around it. To select one or more hydraulic elements directly in the HAMMER Modeler Drawing Pane: •

Click on the Select tool (arrow icon), then move the cursor over the hydraulic element, and click once.

•

To select a group of hydraulic elements, click the Select tool, click anywhere in the Drawing Pane, and drag the mouse to form a selection box around the elements you want to select. All elements that are fully enclosed within the selection box are selected.

•

To select all elements in the system, select Edit > Select All or simply press Ctrl+A.

•

To toggle the selected status of one or more elements, you can click on each element while holding down Shift. You can also select a group of elements this way.

You can also use the Element Selector tool on the Properties pane: •

Select a single element by clicking one of the labels displayed in the list. This list can be resized horizontally or vertically if more space is required.

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HAMMER Modeler Note:

•

Limiting the type of elements displayed in the Element Selector does not hide any elements in the Drawing Pane.

You can filter the selection list by clicking the choice list at the top of the Element Selector and selecting one of the following: –

All Elements to display every type of hydraulic element (full listing)

–

All Pipes to limit the Element Selector display to pipes only

–

All Nodes to limit the display to nodes

–

Boundaries to limit the display to system boundaries. Note that this includes consumption nodes.

–

Flow Controls to limit the display to orifices and valves

–

Protective Equipment to limit the display to surge-control equipment

–

Rotating Equipment to display only pumps and turbines

Another way to select a hydraulic element is to locate it using the search command Edit > Find or F3, as described in “Finding Elements” on page 5-157. It will be selected automatically.

5.1.4

Editing Hydraulic Elements Click any element and the Element Editor displays its properties and lets you edit them.

5.1.5

Moving Hydraulic Elements You can change the location of elements easily. The first step is to select the elements to be moved. Next, click to drag the element and release the mouse button to drop the element at its new location. When a node is moved to a new location, all connected pipes remain attached, and the pipes’ data remains unchanged (except for z and y coordinates). A hydraulic element can also be moved by editing its coordinates in the Element Editor pane.

5.1.6

Copying/Cutting/Pasting/Deleting Elements HAMMER offers a full range of intuitive on-screen editing features to allow you to rapidly duplicate individual hydraulic elements or groups of elements:

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Layout and Editing Tools •

Copy—You can duplicate an element or a set of elements (with all data preserved) using the copy feature. Select the elements to duplicate and then select Edit > Copy from the menu or press Ctrl+C. You can also right-click any element and select Copy.

•

Cut—The cut feature is a combination of the copy and delete commands. It copies the selected elements to the Windows clipboard and deletes them from the Drawing Pane immediately. Select the elements to cut and then select Edit > Cut from the menu or press Ctrl+X. You can also right-click any element and select Cut. Note:

5.2

The integrity of the network is automatically maintained during deletions. This means that when a node is deleted, any connecting pipes are also deleted to prevent dangling pipes that would cause the network to be invalid.

•

Paste—Hydraulic elements previously copied or cut are retrieved from the Windows clipboard and placed on the Drawing Pane using the Edit > Paste menu command or by pressing Ctrl+V. You can also right-click anywhere in the Drawing Pane and select Paste.

•

Delete—To delete elements, select the elements to be deleted and then select Edit > Delete from the menu or press the Delete key. You can also right-click any element and select Delete.

Finding Elements This powerful feature allows you to quickly locate any element in the drawing by its label. It performs a case-insensitive search. To find an element: 1. Select Edit > Find or press: Ctrl+F or F3. 2. Choose the element type to search for: node or pipe. 3. Type the full label or substring of the label of the element you wish to find in the system. 4. If pipe is selected, you must define how this pipe should be located. Selecting by label will locate the pipe based on its label while selecting by node will locate the pipe by the label of the nodes attached to it. If both options are checked, both criteria will be used for the search. 5. Click Find to find the element. Selecting Edit > Find Next or pressing F3 repeats a search using the previous search criteria.

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View Menu

5.3

View Menu The View menu includes:

5.3.1

•

“Pan” on page 5-158

•

“Zoom” on page 5-158

•

“Drawing Pane” on page 5-158

Pan Using the pan feature, you can change your current view without changing the size, proportion, or zoom level of the current view. Select View > Pan and use the arrow keys, or click the Pan tool (hand icon), click and hold anywhere in the Drawing Pane, and drag the cursor to navigate around.

5.3.2

Zoom Zooming controls how large or small a drawing appears on the Drawing Pane. This is helpful when you want to enlarge the display to see local details or reduce it to see an entire system or network. Zooming does not change the actual size of the drawing, only the extent of the current view. From the View menu or the toolbars, you can perform the following zoom operations: Zoom In—Enlarge the level of detail shown on the Drawing Pane by clicking at the desired location. Using the mouse, you can use the same tool to define a selection box to zoom in to this area (called Zoom Window in WaterCAD or WaterGEMS). Zoom Out—Decrease the level of detail displayed in the Drawing Pane. Normalize Symbol Size—Adjust the size of all elements in the current zoom with respect to 100% zoom. Zoom Extents—Bring all elements in the drawing into view.

5.3.3

Drawing Pane Select View > Lock Drawing Pane to turn the Drawing Pane lock on and off. When the Drawing Pane is locked, you can select hydraulic elements to modify their parameters or inspect their results, but you cannot change their coordinates using the mouse. This avoids accidentally moving or deleting hydraulic elements. Select View > Anti-alias to improve the appearance of lines in the Drawing Pane.

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5.4

Screen Layout (Format Display) Menu These menu commands are only available from within the HAMMER Viewer. They can be invoked by right-clicking anywhere except a graph pane. Show Frame—Toggles the display of the frames which convert an on-screen plot to a report-ready figure, complete with your organization’s logo, project number, date, and a title block. For more information, see “Using Your Organization’s Name and Logo” on page 8-206. Page View—Toggles the display of the page outline to help you visualize how it will look after printing. With HAMMER figures, what you see is what you get (WYSIWYG), so there is no need for a print preview command. Lock Aspect Ratio—Toggles the display of the frames between figure format, in which the length and width are scaled to the paper size, and on-screen format for which you can set the length and width by dragging the corner of the graph window. Show Title Bar—Toggles the display of the graph window’s title bar. Turn title bars off to maximize the use of your display area when, for example, showing animations.

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6

Hydraulic Element Reference This reference provides a detailed description of the purpose, parameters, and proper use of the various hydraulic elements available in HAMMER. Using these hydraulic elements, virtually any system and surge-protection strategy can be modeled.

6.1

Overview of Hydraulic Element Properties Element Editor:

The primary component of a HAMMER project is the system model displayed in the Drawing Pane. Using the Select tool (arrow toolbar icon) and clicking on any hydraulic element in the Drawing Pane, or clicking on its label in the Element Selector list, automatically displays the element’s properties and results (if applicable) in the Element Editor. Results are displayed after each HAMMER run and they cannot be modified.

Element Type:

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You will learn about the input data requirements for each element and the way results are displayed in the Modeler and Viewer interfaces. Hydraulic elements are grouped into two general categories: pipes and nodes. Nodes are further classified into four types: •

Boundaries of the system—Includes consumption at a node, dead ends, reservoirs, maintenance hole with user-defined inflow hydrograph, and custom (periodic) head or flow at a system boundary.

•

Flow-control equipment—Includes valves of various types, orifices, and custom (rating curve) head-discharge relationships.

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Overview of Hydraulic Element Properties •

Surge-control equipment—Includes orifices, rupture disks, check valves, pressure-relief valves, surge-anticipator valves, vacuum breakers, combination air valves, surge tanks of various types, and gas vessels (standard or bladder type).

•

Rotating equipment—Includes pumps of various types and turbines.

Each of these element types and their members are described separately in the following sections. The fields describing each particular hydraulic element are also discussed, except for fields common to all, which are discussed in the next section. General Properties:

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Every hydraulic element has several general properties and these are listed at the top of the Element Editor: •

Type—Displays the type of each element such as pump, reservoir, and junction, when the particular element is selected.

•

Label—All elements inserted into HAMMER Drawing Pane have unit labels. HAMMER automatically assigns labels to the elements and you can change or edit labels at any time.

•

Coordinates—Except for pipes, every hydraulic element displayed on the HAMMER Drawing Pane has x and y coordinates.

•

Elevation—Except for pipes, every element has an elevation with respect to a certain datum, such as mean sea level. The elevations of the nodes at each end of a pipe determine the elevations along the top of the pipe, also known as obvert or crown. HAMMER assumes that all pipes are straight.

•

Report Period—The number of time steps between successive output data; overridden by the Report Times tab of the Project Options window. By default this printout is suppressed unless a report period is defined.

•

Description—A place to enter additional information about the element. By default, HAMMER leaves this field blank.

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6.2

Pipes Pipes link two nodes together and convey fluid between them. In HAMMER, all pipes flow full unless stated otherwise. Pipes have the following characteristics: •

Length—The length of the pipe is used in HAMMER calculations regardless of the x, y and elevation coordinates of the two nodes it connects.

•

Diameter—Inside diameter of the pipe (often abbreviated as I.D.). The pipe material and pressure rating class can significantly affect the actual inside diameter. Transient Tip: Entering an I.D. that is 5% too big increases the pipe’s area (and velocity) by about 10% and reduces friction loss predictions by about 20%, since losses are proportional to V2/2g. The effect may be even greater with a quasi-steady or unsteady friction method. Always consult manufacturer’s tables to enter the correct I.D. or, for older pipe, try to verify its I.D. in the field (it may have been reduced due to deposits or tuberculation).

•

Check Valve—When this box is checked, flow can only travel in the same direction as the flow at the initial time step (i.e., time zero).

•

From Node—The first of two nodes bounding a pipe, as displayed in the Element Selector.

•

To Node—The second of two nodes bounding a pipe, as displayed in the Element Selector.

•

Friction Coefficient—Pipe roughness coefficient or value associated with the roughness method selected during the project setup for the selected material, either a Hazen-Williams C or a Darcy-Weisbach f. If blank, HAMMER automatically calculates a value of f based on the flow, diameter, and heads at the start of transient simulations.

•

Wave Speed—The pressure wave speed for the liquid being conveyed, the pipe material selected, the working pressure rating (determined by its dimension ratio or DR), the bedding, and other factors. Pipe manufacturers often provide this parameter for water, assuming standard bedding and construction techniques.

•

Initial Flow—The flow in the pipe at time zero. If positive, the flow direction is towards the To Node.

•

From Node Head—The head at From Node at time zero.

•

To Node Head—The head at To Node at time zero.

After a HAMMER run completes successfully, the following results will be displayed: •

Max and Min Head—The maximum and minimum transient head experienced at any point in the pipe throughout the simulation period.

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Nodes

6.3

•

Max and Min Flow—The maximum and minimum transient flow experienced at any point in the pipe throughout the simulation period. Please note that the initial flow direction is taken as positive.

•

Max Vapor Volume—The maximum vapor volume, if any, that occurred at all locations in the pipe at any time during the simulation period.

•

Max Air Volume—The maximum air volume, if any, that occurred at all locations in the pipe at any time during the simulation period.

Nodes All nodes are pressurized in HAMMER, unless otherwise stated. Nodes are further classified into Boundaries, Flow Controls, Surge Protection, and Rotating Equipment. The simplest and most widely used node is called a junction. Junction—the meeting point of two or more pipes in the system. A junction does not open to atmosphere and it does not satisfy any water demand. The general properties of all hydraulic elements describe it completely. After a HAMMER run completes successfully, the following results are displayed:

6.4

•

Max and Min Head—The maximum and minimum transient head experienced throughout the simulation period. This value is the same as the endpoint of every pipe that connects to this node.

•

Max and Min Pressure—The maximum and minimum transient pressure experienced throughout the simulation period.

•

Max Vapor Volume—The maximum vapor volume, if any, that occurred at all locations in the pipe at any time during the simulation period.

•

Max Air Volume—The maximum air volume, if any, that occurred at all locations in the pipe at any time during the simulation period.

System Boundaries System boundaries are nodes at which transient pressure waves are typically reflected back to the system and where inflows or outflows may occur. HAMMER incorporates a rigorous mathematical formulation of each of these boundary conditions based on physics. Each of these hydraulic elements and their parameters are described below. •

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Consumption—represents an opening to atmosphere at the junction of two or more pipes or the end of a single pipe. Water demands from many houses or users are typically aggregated and represented as a Consumption node, consequently there can be no inflow of air from this node into the system. A Consumption node has the following parameters:

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Hydraulic Element Reference

•

–

Pressure required to deliver the Initial / Typical Flow from the system.

–

Initial/ Typical Flow is either the initial steady-state flow under a certain Pressure or the typical flow when the Pressure is zero.

Dead End—the end point of a closed pipe. A pipe with a Dead End should not have any flow, therefore the steady-state HGL should be the same at both ends of the pipe at time zero. A cavity can form at a Dead End, which has the following parameter: –

•

•

Initial Vapor Volume is the volume of vapor at the Dead End at the beginning of the simulation (i.e., time zero). The default value is zero.

Periodic Head/Flow—used to prescribe a boundary condition at a hydraulic element where flow can either enter or leave the system as a function of time. It can be defined either in terms of Head (for example, the water level of a clear well or process tank) or Flow (for example, a timevarying industrial demand). The periodic nature of variation of head/flow can be of sinusoidal or of any other shape that can be approximated as a series of straight lines. It has the following four attributes: –

Prescribed Quantity is either flow or head, with either a known periodicity or according to a user-defined repeatable pattern.

–

Mean Value is required only if the variation of flow or head is sinusoidal.

–

Amplitude is the maximum value of head or flow above the mean value.

–

Period is the oscillation period.

–

Phase in radians, ranging from zero to a maximum value of 2Π.

Maintenance Hole—represents a system boundary initially at atmospheric pressure, which can accept user-defined inflow patterns or hydrographs. The pipe connecting the system to the maintenance hole (MH) is assumed to be flowing full (i.e., pressurized). The parameters required to describe a MH are as follows: –

Diameter of the MH itself (default 48 in.).

–

Orifice Diameter controlling flow from the MH to the exit pipe connected to the system. This can be equal to but not greater than Diameter.

–

Cover Opening Diameter has a default value of 1.5 in. (38.1 mm), such as lift holes. If the MH is sealed, then the value of this parameter should be zero. For values greater than or equal to the diameter of the manhole, the air above the water surface is considered to be at atmospheric pressure.

–

Threshold Pressure has a default value of 300 lb. (136.1 kg) for any cover not fastened to the manhole. If the cover is firmly bolted or welded to the manhole, then enter a larger value, such as 100,000 lb. (45,367 kg), which HAMMER treats as infinite.

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Control Equipment

•

6.5

–

Ratio of Losses is the ratio of inflow head loss to outflow loss (for the same flow). The default value is 2.5.

–

Head Loss Coefficient is a dimensionless quantity.

–

Ground Elevation has a default value of 9,999 ft. (3,048 m).

–

Operating Rule defines the functional relationship between flow and time, if any.

Reservoir—a source of water that maintains a constant water level throughout the simulation.

Control Equipment Consider the following control equipment information:

6.5.1

•

“Flow-Control Valve Fundamentals” on page 6-166

•

“Flow-Control Valves as Sources of Hydraulic Transients” on page 6-167

•

“Flow-Control Valve Reference” on page 6-168

•

“Orifice Reference” on page 6-170

Flow-Control Valve Fundamentals A valve is an element that opens, throttles, or closes to satisfy a condition you specify. Like WaterCAD, HAMMER can model several different types of valves. The behavior of a valve is determined by the upstream and downstream conditions. Supported valve types include:

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•

Pressure-Reducer Valve (PRV)—PRVs throttle to prevent the downstream hydraulic grade from exceeding a set value. If the downstream grade rises above the set value, the PRV closes. If the head upstream is lower than the valve setting, the valve opens fully.

•

Pressure-Sustaining Valve (PSV)—PSVs throttle to prevent the upstream hydraulic grade from dropping below a set value. If the upstream grade is lower than the set grade, the valve closes completely.

•

Pressure-Breaker Valve (PBV)—PBVs are used to force a specified pressure (head) drop across the valve. These valves do not automatically check flow and actually boost the pressure in the direction of reverse flow to achieve a downstream grade that is lower than the upstream grade by a set amount.

•

Flow-Control Valve (FCV)—FCVs are used to limit the maximum flow rate through the valve from upstream to downstream. FCVs do not limit the minimum flow rate or negative flow rate.

HAMMER User's Guide

Hydraulic Element Reference •

Throttle-Control Valve (TCV)—TCVs are used as controlled minor losses. A TCV is a valve that has an associated minor loss that can change in magnitude according to the controls that are implemented for the valve.

•

General-Purpose Valve (GPV)—GPVs are used to model situations and devices for which the flow-to-headloss relationship is specified by you rather than using the standard hydraulic formulas. GPVs represent reduced-pressure backflowprevention (RPBP) valves or well draw-down behavior. Note:

You can change a valve from one type to another by a process called morphing. Just click the new valve-type button on the toolbar and drag the new valve on top of the old one.

Because the reaction time of the above valve types is too slow to react to fast and often cyclical hydraulic transient pressure wave fronts, HAMMER converts these to an equivalent orifice that remains fixed throughout the simulation.

6.5.2

Flow-Control Valves as Sources of Hydraulic Transients Flow-control stations typically include a flow meter, flow-control valve, and valves to isolate the station during maintenance activities. Flow-control stations are sometimes equipped with a remote terminal unit (RTU), which communicates with a Supervisory Control and Data Acquisition (SCADA) system, to monitor and control the station remotely. For more information about SCADA systems, see Advanced Water Distribution Modeling and Management, by Haestad Press. The transient pressures that result from the operation of flow-control valves depend on the design of the flow-control station, particularly the following parameters: •

The time period of the valve position change

•

The valve type and its hydraulic characteristics

•

The system hydraulic characteristics (for example, head loss in the piping relative to head loss through the valve)

When considering valve position change, it is important to consider that the reduction in flow due to valve closure is not proportional to the valve travel distance (stroke). In fact, with most valves (including hydrants), most of the change in velocity occurs when the valve is barely open. It is at this time that a quick turn of the valve can lead to a significant water hammer event. For example, if it takes 20 turns to close a valve and the initial velocity through the valve is 16 ft./sec. (5 m/s), the velocity may change to 6.6 ft./sec. (2 m/s) over the first 19 turns. The velocity is then reduced from 6.6 ft./sec. to zero over the last turn (known as the “effective stroke” of the valve). The change of velocity over the last interval having a duration equal to the characteristic time (2L/a) determines the magnitude of the transient.

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Control Equipment One of the most important considerations when selecting the flow-control valve type is cavitation. Cavitation occurs when the minimum pressure at critical points within the valve reaches the vapor pressure of the liquid, so that vapor bubbles form. If the differential pressure across the valve is excessive or if the pressure downstream of the valve is minimal, cavitation can occur during steady-state flow. Cavitation can damage the valve and cause excessive noise, especially if an inappropriate valve is selected. Control valves specifically designed to minimize the potential for cavitation should be selected for these cases. Depending on its severity, cavitation can also affect the hydraulic capacity of the valve. When the flow stream expands immediately downstream of the valve, the pressure increases, causing the vapor bubbles to collapse. This dynamic vaporization and collapse phenomenon causes noise and vibration and can erode the interior of the valve. This type of local cavitation should not be confused with large-scale vapor pocket formation and collapse due to system-wide hydraulic transients, such as a power failure.

6.5.3

Flow-Control Valve Reference Each type of flow-control valve is described separately below. •

•

Valve to Atmosphere—discharges water from the system at a pipe end open to atmospheric pressure. It has the following parameters: –

Initial Typical Flow is either the initial steady-state flow at a certain pressure or the typical flow when the pressure is zero.

–

Time Delay before the valve begins to open or close.

–

Time of Operation is a period of time required to open or close the valve.

–

Corresponding Pressures refers to the pressure at the initial or typical flow through the valve.

Valve of Check Type between 2 Pipes—a check valve between two pipes that closes instantaneously upon flow reversal. This assumes that no dampers or electrical controls modify the check valve’s closure time. When the pressure differential required to reopen the valve is exceeded, the valve opens again instantaneously. This valve can be closed initially. It has the following parameters: –

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Initial Flow should be zero if the valve is initially closed. If the valve is open, then enter the flow initially passing through the valve.

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Hydraulic Element Reference

•

•

–

Upstream Pipe whose end point denotes the upstream side of the valve and indirectly defines the direction of flow through the valve.

–

Threshold Pressure is the pressure difference between upstream and downstream sides of the valve required to open or reopen the valve. If a zero value is entered, the valve opens when the upstream pressure exceeds the downstream pressure.

Valve of Check Type at Wye Branch—this is similar to the Valve of Check Type between 2 Pipes, except that it is located on one of the three pipe branches connecting to a single junction node. When the pressure differential required to reopen the valve is exceeded, the valve opens instantaneously. This valve can be initially closed. It has following parameters: –

Initial Flow should be zero if the valve is initially closed. If the valve is open, then enter the initial value of flow through the valve.

–

Pipe denotes the location of the valve (e.g., in which of three branches?). When the valve is closed, this pipe acts as a dead end.

–

Flow Direction represents either the flow towards the wye branch or the flow away from the wye branch.

–

Threshold Pressure is the pressure differential between the upstream and downstream sides of the valve required to open or reopen the valve. If a zero value is entered, the valve opens when the upstream pressure exceeds the downstream pressure.

Valve of Various Types between 2 Pipes—an extremely versatile hydraulic element able to model six or more different types of valves. For the first five types of valves, the characteristics for fractional openings are hard-coded in HAMMER; however, you can enter a customized curve in the userspecified valve. It has the following parameters: –

Diameter is the size of the opening that can pass flow through the valve.

–

Discharge Coefficient is usually calculated from the relation between flow through the valve and the corresponding pressure drop across the valve at time zero. If there is no initial flow, the discharge coefficient can be obtained from the manufacturer or calculated.

–

Type of Valve can be one of several possible types: User-Specified, Needle, Circular Gate, Globe, Ball, or Butterfly. Any of these can function as a PRV, PSV, or FCV, depending on the Control Type.

–

Operating Rule defines the time-dependent opening (partial or full stroke) and closure (partial or full stroke) of the valve in a tabular form. The valve can be opened, paused, or closed partially or fully several times during the numerical simulation.

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Control Equipment

•

6.5.4

–

Control Type defines the four possible ways of operating modes of the valve: PRV (pressure-reducing valve), PSV (pressure-sustaining valve), FCV (flowcontrol valve), and none.

–

PRV/SRV Head option is necessary only for a PRV and PSV. It denotes the head to be maintained by the PRV or SRV at the downstream side of the valve. When the Control Type is set to FCV, enter the flow intended to pass through the FCV.

–

Control Status represents the state of the valve at time zero: Throttled, Wide Open, or Closed.

Valve with Linear Area Change between 2 Pipes—functions either as a check valve that closes instantaneously and remains closed when reverse flow occurs, or as a positive-acting leaf valve closing linearly over the prescribed time. Its parameters are: –

Time to Close is the operation time required to shut the valve. It is either instantaneous (if the time is set to zero, it will operate as a check valve) or gradual and linear whenever the Time to Close is greater than zero.

–

Diameter is the size of the opening allowing flow to pass through the valve.

Orifice Reference Orifices are a fixed or passive type of flow-control element. Each is described below. •

•

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Orifice to Atmosphere—represents an opening to atmosphere at a junction of two or more pipes or the end of a single pipe. The initial pressure is typically positive and there is usually an outflow from the system at time zero. It has the following parameters: –

Pressure refers to the pressure drop across the orifice corresponding to the initial steady-state or typical flow.

–

Initial/Typical Flow is either the initial steady-state flow at a specific pressure or the typical flow when the pressure is zero.

–

Initial Volume of Gas is the accumulated air at the orifice at the beginning of the simulation (the default value is zero).

Orifice at Branch End—a convenient way to add a length of pipe leading to a discharge point without having to enter the pipe explicitly. Results are identical to those obtained by entering an equivalent pipe ending at an orifice to atmosphere. –

Pressure drop across the orifice corresponding to the initial or typical flow.

–

Initial/ Typical Flow is either the initial steady-state flow under certain pressure or the typical flow when the pressure is zero.

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Hydraulic Element Reference

•

•

–

Pipe Length is automatically assigned a small value based on the average wave speed of the two adjacent pipes, but you can specify any convenient length.

–

Elevation of Orifice is equal to the elevation (by default) of the junction of the main pipe and branch pipe, but you can specify an elevation for sprinklers, for example.

Orifice between 2 Pipes—is an inline orifice characterized by a pressure drop across the orifice for a given flow. –

Pressure drop across the orifice corresponding to the initial or typical flow.

–

Initial Typical Flow is either the initial steady-state flow under certain pressure or the typical flow when the pressure is zero.

Rating Curve—is a boundary element which releases water from the system to atmosphere based on a customizable rating curve relating head and flow. –

6.6

Rating Curve is a functional relationship between time and flow and head entered in a table, enabling you to achieve a high degree of customization.

Rotating Equipment Pumps and turbines are classified as Rotating Equipment as a reminder that these turbomachines can reverse their spin direction during a hydraulic transient event, unless this is prevented by a nonreverse ratchet or check valve. Since both spin and flow can be in a positive or negative direction, four operating cases are possible for pumps and turbines. Four-quadrant curves are used to describe a pump’s hydraulic performance for each case. The common pump curve provided by vendors provides head and flow in the first quadrant only, for which spin and flow are both positive, at constant speed.

6.6.1

Pump Fundamentals A pump is a type of rotating equipment designed to add energy to a fluid. For a given flow rate, pumps add a specific amount of energy, or total dynamic head (TDH), to the fluid’s energy head at the pump’s suction flange. HAMMER automatically imports pump information from WaterCAD or WaterGEMS using WaterObjects technology. You may need to enter additional data to model dynamic effects. HAMMER can represent virtually any pump using one of these five hydraulic elements: •

Constant Speed between 2 Pipes—no pump curve

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Rotating Equipment •

Constant Speed between 2 Pipes—pump curve

•

Constant Speed at Reservoir—pump curve (a special case without a suction line)

•

Variable Speed, Between Two Pipes—four-quadrant pump curve built in

•

Shut after Time Delay, Between Two Pipes—four-quadrant pump curve built in

Only the last two allow you to change the speed of the pump during a simulation. The information needed to describe a pump’s hydraulic characteristics depends on the type selected, but the following are common parameters:

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•

Duty or Design Point—Point at which the pump was designed to operate, defined as its Nominal Flow and Nominal Head (1, 1 in the Pump Curve table). It is typically at or near the best efficiency point (BEP). For flows above or below this point, the pump may not be operating under optimum hydraulic conditions. Other points on the pump curve are entered as a ratio of the nominal head and flow (e.g., 0.1 to 1.2 times these values). If a pump curve is not available, see “First-Quadrant and Four-Quadrant Representations” on page 6-175.

•

Shutoff and Runout—Shutoff is the maximum head a pump can develop at zero flow. Runout is an operating point at the other extreme of the pump curve, where the pump is discharging at a high rate but is no longer able to add any energy (i.e., head) to the flow. HAMMER will not automatically shut down a pump if it reaches shutoff head or runout flow; therefore, this information is not required for a HAMMER run.

•

Elevation—The pump elevation is required to calculate suction or discharge pressures and to display the pump at the correct location on profile plots.

•

Efficiency—Efficiency is defined as the ratio of the hydraulic energy transferred to the water divided by the total electrical energy delivered to the motor. This parameter is only required for pumps whose speed changes during a simulation. It is used to determine the accelerating or decelerating torque, where required.

•

Speed—Rotational speed in revolutions per minute (rpm) of the impeller. This is commonly the same as the motor’s rotational speed, unless a transmission is installed. It is fixed for constant-speed pumps but can vary for variable-frequency drives. This parameter is only required for pumps whose speed changes during a simulation.

•

Inertia—Pump inertia is the resistance of the pump assembly to acceleration or deceleration. HAMMER uses inertia and efficiency to track the rate at which a pump spins up or down when power is added or removed, respectively. It is a constant for a particular pump and motor combination. For more information, see “Pump Inertia” on page 6-173.

•

Specific Speed—A pump’s specific speed is a function of its rotational speed, Nominal Flow, and Nominal Head. For more information, see “Specific Speed” on page 6-174.

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Hydraulic Element Reference

Pump Inertia If a pump’s speed will be controlled (i.e., ramped up or down, started or shut down during the simulation period) you need to enter the pump’s rotational inertia. Inertia is the product of the rotating weight with the square of its radius of gyration. Pumps with more rotating mass have more inertia and take longer to stop spinning after power fails or the pump is shut off. The trend has been towards lighter pumps with less inertia. Transient Tip: Pumps with higher inertias can help to control transients because they continue to move water through the pump for a longer time as they slowly decelerate. You can sometimes add a flywheel to increase the total inertia and reduce the rate at which flow slows down after a power failure or emergency shut down: this is more effective for short systems than for long systems.

The value of inertia you enter in HAMMER must be the sum of all components of the particular pump which continue to rotate and are directly connected to the impeller, as follows: •

Motor inertia—typically available from motor manufacturers directly, since this parameter is used to design the motor. The pump vendor can also provide this information.

•

Pump impeller inertia—typically available from the pump manufacturers’ sales or engineering group, since inertia is used to design the pump.

•

Shaft inertia—the shaft’s inertia is sometimes provided as a combined figure with the impeller. If not, it can either be calculated directly or ignored. Entering a lower figure for the total inertia yields conservative results because flow in the model changes faster than in the real system; therefore, transients will likely be overestimated.

•

Flywheel inertia—some pumps are equipped with a flywheel to add inertia and slow the rate of change of their rotational speed (and the corresponding change in fluid flow) when power is added or removed suddenly.

•

Transmission inertia—some pumps are equipped with a transmission, which allows operators to control the amount of torque transmitted from the motor to the pump impeller. Depending on the type of transmission, it may have a significant inertia from the friction plates and the mechanism used to connect or separate them.

While this may seem like a long list, it is often enough to enter only the pump and motor inertia and neglect the other factors. For design purposes, this tends to yield conservative results, because the simulated pump will stop more rapidly than the real pump would. Surge-protection designed to control the somewhat larger simulated transients should be adequate.

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Rotating Equipment If the motor and pump inertia are not available, they can be estimated separately and then summed (if they remain coupled after a power failure) using an empirical relation developed by Thorley:

I

I

pump = 1.5 ×10

7

×( P / N 3 )

0.9956

(P / N )

1.48

motor = 118 ×

where:

kgm 2 (6.1)

kgm 2

(6.2)

P is the brake horsepower in kilowatts at the BEP N is the rotational speed in rpm

If uncertainty in this parameter is a concern, several simulations should be run to assess the sensitivity of the results to changes in inertia.

Specific Speed If reverse spin is possible, a four-quadrant curve representation can be selected based on your pump’s specific speed. According to affinity laws, impellers with similar geometry and streamlines tends to have similar specific speeds. Transient Tip: To simulate a pump for which no pump curve is available or whenever there is a possibility of reverse flow or spin, selecting the built-in four-quadrant curve corresponding to the correct pump type is essential. Despite some approximation, HAMMER will output physically meaningful results provided you select the correct fourquadrant curve based on your pump’s specific speed. The results can help you decide whether or not additional detail is critical or even required.

To select an appropriate four-quadrant pump curve in HAMMER, simply calculate the specific speed and select the closest available setting in the Specific Speed field of the pump’s Element Editor. You can calculate your pump’s specific speed, Ns, using the following equation: 1 2 N S = NQ

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3

H4

(6.3)

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where:

N

=

Rotational Speed (rpm)

Q

=

Flow (m3/s or gpm). For double-suction units, flow is per suction.

H

=

Head (m or ft) at flow Q. For multi-stage units, head is per stage (e.g., total head divided by total stages).

“Table 6-1: Specific Speeds for Typical Pump Categories in both Unit Systems”on page 6-175 shows typical values of specific speed for which an exact four-quadrant representation is built into HAMMER. Centrifugal pumps tend to have lower specific speeds than axial-flow or multi-stage pumps. Few four-quadrant characteristic curves are available because they require painstaking laboratory work. The results of hydraulic transient simulations are not as sensitive to the specific speed selected, provided that a check valve is installed. You do not need to add a check valve because every pump in HAMMER has a built-in check valve immediately downstream of the pump. Note:

If you need a four-quadrant pump curve but your pump’s specific speed does not match one of the available options, select the closest one available or request it from the manufacturer. The prediction error cannot be linearly interpolated using specific speed, but you could run a different curve to bracket the solution domain.

Table 6-1: Specific Speeds for Typical Pump Categories in both Unit Systems Unit System

Specific Speed, Ns Centrifugal pumps (radial-vane or flange-screw types)

U.S. Customary SI Metric

Axial-Flow Pumps (mixed-flow or flange-screw types)

Multistage pumps (axial or mixed-flow)

1280

4850

7500

25

94

145

First-Quadrant and Four-Quadrant Representations Most pumps used in water and wastewater systems are equipped with check valves to preclude reverse flow and/or nonreverse or ratchet mechanisms that prevent the pump impeller from reversing its spin direction. This usually restricts the pump’s operation to the first quadrant. Provided such a pump will operate continuously at constant speed throughout the numerical simulation and never allow reverse flow or spin, a standard multipoint pump curve provides a rigorous and sufficient representation. Two hydraulic elements enable you to represent this common pump configuration:

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Rotating Equipment •

Constant Speed at Reservoir—Pump Curve

•

Constant Speed between 2 Pipes—Pump Curve

If you have the multipoint pump curve, you can enter it directly in HAMMER or import it using WaterObject technology. The pump curve is used by HAMMER to adjust the flow produced by the pump in response to changing system heads at its suction and discharge flanges throughout the simulation period. Note:

Entering name-plate values into HAMMER may result in significant prediction errors. These rated values may differ significantly from the pump’s actual operating performance.

If a pump curve is not available, but you can obtain the rated head and flow from the SCADA system or other measurements, enter these as the Nominal Flow and Nominal Head, and select the four-quadrant curves whose Specific Speed is closest to your pump: centrifugal, axial-flow (single and double-suction) and multistage (including vertical turbines), as shown in “Table 6-1: Specific Speeds for Typical Pump Categories in both Unit Systems”on page 6-175. You can also use one of these four-quadrant characteristic curves if reverse spin is possible, but you do not have these data for your pump. This will yield a physically meaningful answer, even if the parameters are inexact.

Variable-Speed Pumps (VSP or VFD) A variable-speed pump (VSP) is typically powered by a variable-frequency drive (VFD) motor controller or sometimes by a variable-torque transmission mechanism. Variable-frequency motor controllers and soft-starters modify the voltage phase angle using silicon controlled rectifiers to achieve speed variations in pumps. Variabletorque transmissions allow a differential between the motor and driven ends of a pump using special mechanical, magnetic, or hydraulic couplings. In practice, automatic start and stop sequences can be controlled to achieve any ramp time using a programmable logic controller (PLC). However, there may be limits to the minimum speed or torque which can be achieved. The period of time over which soft-starters can control the motor may be limited. Finally, operational reasons may require that startup, shifting and shutdown sequences be shortened as much as possible—but safely. HAMMER helps you estimate safe ramp times to make the most of your pump’s capabilities. In HAMMER, a variable pump is a prescribed boundary condition which is controlled by setting a time-dependent pattern for its rotational speed or torque. You can enter any speed or torque pattern, including delays, multiple ramps, and periods of continuous pumping.

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Hydraulic Element Reference HAMMER does not currently model loop-back controllers, which can modify the VFD’s speed or torque to achieve a specific head or flow at some location in the system. This is because the pump may stabilize to a new steady state within a few seconds, including during a power failure or a normal stop or start, for a typical transient event and the loop-back controller is likely not engaged during such operations.

6.6.2

Pump Element Reference The various types of pumps are described separately below. •

•

•

Constant Speed between 2 Pipes - No Pump Curve—A pump that operates at constant speed throughout the simulation using a built-in fourquadrant characteristic curve selected according to specific speed. This pump requires the following parameters: –

Initial /Typical Flow is the Nominal Flow the pump delivers under normal operating conditions. If it is not known, you could assume it is the steady-state flow.

–

Nominal Head is the head required to deliver the Nominal Flow at steady state. It is the difference between the heads at the suction and discharge sides of the pump or total dynamic head (TDH).

–

Specific Speed enables you to compare pumps from different manufacturers and models in a rigorous manner. HAMMER provides three built-in fourquadrant characteristic pump curves corresponding to the specific speeds of 1280, 4850, or 7500 (U.S. customary units) and 25, 94, or 145 (metric units).

Constant Speed, between 2 Pipes - Pump Curve—A pump that operates at constant speed throughout the simulation according to a pump curve. This pump requires the following parameters: –

Nominal Flow is the flow the pump delivers at the Nominal Head under normal steady-state operating conditions. Sometimes assumed to be the initial steady-state flow.

–

Nominal Head is the head required to deliver the Nominal Flow at steady state. It is the difference between the heads at the suction and discharge sides of the pump.

–

Pump Curve represents the head-discharge relationship of the pump at its rated speed. Values are entered relative to Nominal Head and Nominal Flow.

Constant Speed at Reservoir - Pump Curve—A pump that operates at constant speed throughout the simulation using a pump curve and assuming there is no suction system. Useful for sewage forcemains. This pump requires the following parameters:

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Rotating Equipment

•

–

Reservoir Head denotes the constant hydraulic grade line available at the reservoir.

–

Nominal Flow is the flow the pump delivers at the Nominal Head under normal steady-state operating conditions. Sometimes assumed to be the initial steady-state flow.

–

Nominal Head is the head required to deliver the Nominal Flow at steady state. It is the difference between the heads at the suction and discharge sides of the pump.

–

Pump Curve represents the head-discharge relationship of the pump at its rated speed. Values are entered relative to Nominal Head and Nominal Flow.

Shut after Time Delay, between 2 Pipes—A pump running at full speed prior to time zero that can be shut down, either at time zero or after a time delay, to represent a power failure or other emergency shutdown. This pump requires the following parameters: –

Time Delay is the time that must elapse before the pump shuts down. This time can also be set to zero (the default value) to simulate a shutdown at time zero.

–

Time to Close is the time required to close the discharge control or check valve after reverse flow is sensed at the pump. Unless the check valve is equipped with hydraulic piloting, dashpot damping, or electrical controls that modify its closure time, enter a value of zero and HAMMER will close it the instant flow drops to zero. If the discharge-control valve closes in a specific amount of time after the power failure, enter that closure time.

Transient Tip: HAMMER automatically simulates a check valve at the discharge flange of each pump. If no check valve is installed in your system, enter a number of “Time to Close” large enough to keep the check valve open throughout the simulation period. To close the check valve as soon as flow stops, enter zero.

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–

Diameter refers to the valve at full opening, typically equal to the internal diameter of the discharge flange.

–

Specific Speed provides four-quadrant characteristic curves to represent typical pumps for each of the three most common types: 1280, 4850, or 7500 (U.S. customary units) and 25, 94, or 145 (SI metric units).

–

Reverse Spin indicates whether the pump is equipped with a ratchet or other device to prevent the pump impeller from spinning in reverse. Set Reverse Spin either to Allowed or Not Allowed.

–

Percent Efficiency represents the efficiency of the pump as a percentage. This is typically shown on the pump curves provided by the manufacturer. A typical range is 85 to 95%, but values outside this range are possible.

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Hydraulic Element Reference

•

–

Inertia of Pump is proportional to the amount of stored rotational energy available to keep the pump rotating (and transferring energy to the fluid), even after the power is switched off. You can obtain this parameter from manufacturer’s catalogs, or from pump curves, or estimate it by correlating it to horsepower (see the empirical equations in “Pump Inertia” on page 6-173).

–

Rotational Speed denotes the rotation of the pump impeller in revolutions per minute or rpm. This is typically shown prominently on pump curves and stamped on the name plate on the pump itself.

Variable Speed, between 2 Pipes—A pump whose speed or torque can be controlled during the simulation period with an operating-rule table. HAMMER will use the correct head-discharge relationship at any speed. This pump requires the following parameters: –

Nominal Flow is the flow the pump delivers at the Nominal Head under normal steady-state operating conditions. Sometimes assumed as the initial steady-state flow.

–

Nominal Head is the head required to deliver the Nominal Flow at steadystate. It is the difference between the heads at the suction and discharge sides of the pump.

–

Time to Close is the time required to close the discharge control or check valve after reverse flow is sensed at the pump. Unless the check valve is equipped with hydraulic piloting, dashpot damping, or electrical controls that modify its closure time, enter a value of zero and HAMMER will close it the instant flow drops to zero. If the check valve and/or a discharge-control valve closes in a specific amount of time after the power failure, enter the closure time.

–

Diameter refers to the valve at opening, typically equal to the internal diameter of the discharge flange.

–

Specific Speed provides four-quadrant characteristic curves to represent typical pumps for each of the three most common types: 1280, 4850, or 7500 (U.S. customary units) and 25, 94, or 145 (SI metric units).

–

Control Variable allows you to select either Speed or Torque to control changes in the performance of this type of pump. Consult your motor controller or transmission documentation for the correct range and time limits that apply.

–

Percent Efficiency represents the efficiency of the pump as a percentage. This is typically shown on the pump curves provided by the manufacturer. A typical range is 80 to 95%, but values outside this range are possible.

–

Inertia of Pump is proportional to the amount of stored rotational energy used to keep the pump rotating (and transferring energy to the fluid), even after the power is switched off. You can obtain this parameter from manufacturer’s catalogs, or from pump curves, or estimate it by correlating it to horsepower (see “Pump Inertia” on page 6-173).

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Rotating Equipment

6.6.3

–

Nominal Speed denotes the rotation of the pump impeller per unit time, typically as rotations per minute or rpm. The head and flow delivered by the pump depend on it.

–

Operating Rule describes the set Speed or Torque with time. You can use this feature to simulate a rapid (or even instantaneous) pump shutdown and restart.

Turbine Element Reference A turbine is a type of rotating equipment designed to remove energy from a fluid. For a given flow rate, turbines remove a specific amount of energy from the fluid’s energy head at the turbine’s inlet. HAMMER provides a single turbine representation: •

6-180

Turbine between 2 Pipes—A turbine that undergoes electrical load rejection at time zero, requiring it to be shut down rapidly. The four-quadrant characteristics of generic units with certain specific speeds are built into HAMMER. The turbine element allows nonlinear closure of the wicket gates and is equipped with a spherical valve that can be closed after a time lag. It has the following parameters: –

Spherical Valve Time Delay is a period of time that must elapse before the spherical valve of the turbine activates.

–

Spherical Valve Operation Time is the time required to operate the spherical valve. By default, it is set equal to one time step.

–

Spherical Valve Diameter is the diameter of the spherical valve.

–

Specific Speed provides four-quadrant characteristic curves to represent typical turbines for three common types: 30, 45, or 60 (U.S. customary units) and 115, 170, or 230 (SI metric units).

–

Percent Efficiency represents the efficiency of the turbine as a percentage. This is typically shown on the curves provided by the manufacturer. A typical range is 85 to 95%, but values outside this range are possible.

–

Moment of Inertia The moment of inertia must account for the turbine, generator, and entrained water.

–

Rotational Speed denotes the rotation of the turbine blades per unit time, typically as rotations per minute or rpm. The power generated by the turbine depends on it.

–

Operational Rule describes the percentage of gate opening with time.

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Hydraulic Element Reference

6.7

Protection Equipment HAMMER lets you consider several aspects of protection equipment.

6.7.1

Check Valves There are several types of check valves available for the prevention of reverse flow in a hydraulic system. The simplest and often most reliable are the ubiquitous swing check valves, which should be carefully selected to ensure that their operational characteristics (such as closing time) are sufficient for the transient flow reversals that can occur in the system. Some transient flow reversal conditions can occur very rapidly; thus, if a check valve cannot respond quickly enough, it may slam closed and cause the valve or piping to fail. Check valves that have moving discs and parts of significant mass have a higher inertia and therefore tend to close more slowly upon flow reversal. Check valves with lighter checking mechanisms have less inertia and therefore close more quickly. External counterweights present on some check valves (such as swing check valves) assist the valve closing following stoppage of flow. However, for systems that experience very rapid transient flow reversal, the additional inertia of the counterweight can slow the closing time of the valve. Spring-loaded check valves can be used to reduce closing time, but these valves have higher head loss characteristics and can induce an oscillatory phenomenon during some flow conditions. It is important that the modeler understand the closing characteristics of the check valves being used. For example, ball check valves tend to close slowly, swing check valves close somewhat faster (unless they are adjusted otherwise), and nozzle check valves have the shortest closing times. Modeling the transient event with closing times corresponding to different types of check valves can indicate if a more expensive nozzle-type valve is worthwhile.

6.7.2

Pressure Relief and Other Regulating Valves Typically, if the decrease in pressure caused by a transient is insufficient to cause vacuum conditions in the system, the resulting positive transient may not be excessive and additional high-pressure protection devices might not be required. In some cases, however, pressure-relief valves must open quickly if the system pressure reaches a pre-established maximum pressure setting. The relief valve opens to discharge water, thus controlling the maximum system pressure. After the high pressure is relieved, the valve closes slowly to avoid creating a transient condition. If a storage facility exists on the suction side of the pumps, water is usually discharged to the tank, though it could also be discharged into the pump suction line or even to the atmosphere in systems without a tank. The pressure to which the valve is discharging should usually be modeled.

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Protection Equipment A surge-anticipator relief valve can be used instead of a pressure relief valve to control high-pressure transients, as seen in the following figure. This type of relief valve starts to open during the low-pressure period following an emergency pump shutdown in anticipation of a high-pressure transient. Since the anticipator valve is already open when the high-pressure transient reaches the valve, it is not required to sense the high pressure. This type of valve is more effective when high-pressure transients occur quickly and the limited opening time of a relief valve is not adequate. Set the lowpressure activation point carefully to avoid premature opening before the pump has spun down, which can cause a very steep negative transient wave. HIGH HGL

10 m HGL (A) START

HGL (B) MATURE

(C) REJOIN

Transient Tip: HAMMER assumes that any air admitted into the pipe system will be released back to atmosphere at the same location, or node. This is typically acceptable due to the rapidity of hydraulic transient phenomena and the tendency of water columns to rejoin at or near this location. For this reason, valves that only release air are not modeled.

Air-inlet valves or vacuum breakers can be installed at high points along the pipeline system to limit subatmospheric pressures locally and to inject air into the pipe system at locations vulnerable to water column separation. When pressure drops rapidly due to a power failure, for example, air is able to rapidly enter the system. Following the low-pressure transient, the air should be expelled slowly to avoid creating another transient condition. This process can repeat several times for some systems as transient cycles attenuate. Careful modeling of the air intake and release rates will indicate the amount of time required for the air to be expelled and the transient energy to be dissipated by friction, before the pumps are restarted. Transient Tip: HAMMER calculates the air flow velocity at the inlet or outlet orifices based on the ambient (atmospheric) and system pressures (which may be subatmospheric). If this velocity reaches the sonic limit, HAMMER will throttle air flow accordingly.

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Hydraulic Element Reference A wide variety of valves enable air to enter and/or leave the system, including air-inlet valves, air-release valves (ARV), vacuum-relief valves, vacuum-breaker valves, airvacuum valves (AVV), and combination air valves (CAV). You need to review the manufacturer’s technical information carefully when selecting an appropriate air valve for transient control. Do not rely only on the name and opening sizes of the valve; obtain diagrams and air-flow charts and input the correct information into HAMMER based on the physics of the valve.

6.7.3

Protective Equipment Reference •

•

Combination Air Valve (CAV)—is installed at local high points to allow air to come into the system during periods when the head drops below the pipe elevation and expels air from the system when water columns begin to rejoin. The presence of air in the line limits subatmospheric pressures in the vicinity of the valve and for some distance to either side, as shown on HAMMER profile graphs. Air can also reduce high transient pressures if it is compressed enough to slow the water columns prior to impact. This valve requires the following parameters: –

Initial Air Volume near the valve at the start of the simulation. The default value is zero. If there is an initial air volume, pressure at the valve must be equal to zero at the start of the simulation.

–

Small Outflow Diameter is the size of the opening that releases air from the system when the volume of air is less than the Transition Volume. This diameter is typically small enough to throttle air flow, compressing any air remaining in the system.

–

Transitional Volume is the threshold volume of air at which the outflow diameter changes between the smaller and bigger size. The default value of this parameter is zero.

–

Outflow Diameter is the size of the opening that releases air from the system when the volume of air is greater than, or equal to, the Transition Volume. This diameter is typically larger than the Small Outflow Diameter. Because it is rare for this to throttle, the default value of this diameter is considered to be infinite.

–

Inflow Diameter is the size of the opening that lets air enter the system. This diameter is typically large to allow the free entry of air without throttling. By default, this diameter is considered infinite in HAMMER.

Air Valve (Slow-Closing) between 2 Pipes—allows air into the system freely when the head drops to below the pipe elevation and releases air and/or fluid from the pipe when head increases again. Also known as a downsurge relief valve. Unlike a CAV, the large outlet closes over a preset time period. This valve requires the following parameters:

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•

–

Time to close the valve. Valve starts to close only when air begins to exit the pipe. If air reenters, then the valve opens fully again.

–

Diameter is the size of the valve opening for inflow and outflow.

SAV/SRV at End of 1 Pipe—represents a surge-anticipator valve (SAV), a surge relief valve (SRV), or both of them combined. A SAV opens on low pressure in anticipation of a subsequent high pressure. A SRV opens when pressure exceeds a threshold value. These valves require the following parameters: –

Type of Valve(s) provides three possible valve types: SAV, SRV, and SAV+SRV.

–

Diameter of Orifice/ Throat for the liquid discharged by the valve.

–

Parameters for SRV

–

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Diameter is the opening available to release fluid from the system.

-

Threshold Pressure is the critical pressure at which the SRV opens. This may be controlled by a spring, piloting, or other mechanism.

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Spring Constant represents the restoring force of the return spring per unit lift off the valve seat. A typical value of this constant is 150 lb/in (26.27 N/mm).

Parameters for SAV: -

Diameter is not used by HAMMER but useful for display. Flow through the valve is determined based on the Cv at Full Opening and valve type. It is assumed that the percent of open-area curve for each valve type corresponds to its Cv curve.

-

Threshold Pressure is the critical pressure below which the SAV opens.

-

Type of SAV provides five options: Needle, Circular Gate, Globe, Ball, and Butterfly.

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Time to Open is the time required to open the SAV fully upon activation.

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Open Time is the time the SAV remains fully open (i.e., the time between the valve’s opening and closing phases).

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Time to Close is the time required to close the SAV fully. SAV must be closed as soon as pressures are relieved to avoid developing too high a return-flow velocity. SAV may not be able to close against extremely high reverse-flow velocities for certain pilot configurations.

-

CV at Full Opening refers to the valve coefficient, which is a function of flow through the valve and the corresponding pressure drop across it.

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Hydraulic Element Reference •

6.7.4

SAV/SRV between 2 Pipes—operates in the same way and requires the same parameters as the SAV/SRV at End of 1 Pipe hydraulic element described previously.

Gas Vessels and Surge Tanks Flow-supplement protective devices work by allowing water to enter the system during low transient pressures and accepting flow from the system during high transient pressures. There are two common types of flow-supplement protective devices: •

A gas vessel (also known as an air chamber or hydro-pneumatic tank) is a pressure vessel that contains water and a volume of air that is maintained by an air compressor. When pumps are shut down and the flow and pressure decrease at the pump discharge, the air in the chamber expands as a result of the pressure drop, and water enters the system from the chamber. Redundant compressors are required to inject air at the correct pressure into the gas vessel because the pressurized air will dissolve into the water as time passes. Since the gas vessel operates at line pressure, a sight gauge or other method is required to detect the liquid level in the pressure vessel.

•

A surge tank (also known as a stand pipe) typically has a relatively small volume and is located such that its normal water level is equal to the hydraulic grade line at steady state. When low transient pressures occur, the tank feeds water into the system by gravity to avoid subatmospheric pressure at the tank connection and vicinity.

The piping connection between the gas vessel or surge tank and the system is sized to provide adequate flow capacity when these are supplying water to the system and to cause significant head loss when refilling from the system to dissipate transient energy. Decision makers need to compare the life-cycle costs of the alternate routes and transient protection prior to selecting one surge-control strategy over another. Using gas vessels and surge tanks to protect drinking water systems can result in water-quality deterioration and a loss of disinfectant residual. These devices should be equipped with a mechanism for circulating the water. A further complication occurs when the tanks are located in cold climates, where the water can freeze. •

Surge Tank (Simple)—controls pressure surges generated by rapid changes in flow at a pump station or turbine. The surge tank supplies water into the system during rapid drops in head to avoid subatmospheric pressures and water column separation. This alleviates both low and high pressures in

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Protection Equipment the system. Its size should be sufficient to prevent it from draining completely (to prevent air intrusion into the system) and to prevent it from overflowing when pressures increase again and the tank refills during the transient. It has the following properties:

•

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Initial Water Level is the water level at the beginning of the simulation. By default, the Initial Water Level is equal to the steady-state head of the adjacent pipe, provided a check valve is not installed.

–

Diameter is used to determine the cross-sectional area of the tank under the assumption that it is circular (if not, enter an equivalent diameter for the tank.)

–

Diameter of Orifice refers to the size of the opening to release water into the system during low pressures and to accept water from the system during high pressures.

–

Elevation of Top of Tank is selected by default in such a way that there will not be any overflow from the tank. If a value is entered, an overflow from the tank to atmospheric pressure is possible.

–

Check Valve Installed denotes whether the check valve is installed. The default option is NO. If a check valve is installed, this device is referred to as a one-way surge tank.

–

Ratio of Losses represents the ratio of the head losses for inflow to outflow. The default value of this parameter is 2.5. Differential orifices can create different head losses depending on the direction of flow.

–

Head Loss Coefficient is a dimensionless quantity that can be determined from the flow through the orifice and corresponding pressure drop.

–

Weir Coefficient represents a value equal to the weir discharge coefficient times the width of the weir. It can be calculated from the standard weir equations, provided that the flow and head over the weir are know. By default, it is the large positive number 99999, which assumes that the liquid level does not significantly exceed the elevation of the top of tank during an overflow.

Surge Tank (Differential) between 2 Pipes—is similar to the Surge Tank (Simple), but with the following additional parameters to reflect the internal riser: –

Diameter is the internal diameter of the surge tank.

–

Diameter of Orifice is the opening in the internal riser to allow flow from the riser to the surge tank or from the surge tank into the riser.

–

Diameter of External Riser refers to the diameter of the lower riser between the hemispherical base of the surge tank and the pipe conveying water.

–

Diameter of Internal Riser denotes the diameter of the upper riser inside the surge tank.

–

Elevation of Junction of Risers is the elevation at which the external and internal risers meet.

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•

–

Elevation of Orifice refers to the elevation of the orifice in the internal riser.

–

Elevation of Top of Base denotes the elevation of the top of the hemispherical base of the tank. For a cylindrical tank, this is equal to the pipe elevation.

–

Elevation of Top of Riser refers to the top elevation of the internal riser.

–

Elevation of Top of Tank represents the elevation of the top of the surge tank which generally higher than the top of the riser.

–

Head Loss Coefficient applies to flow from the tank to the riser. It must be a positive number.

Surge Tank (Variable Area)—Similar to a simple surge tank, but with a cross-sectional area that varies with elevation. It has the following parameters: –

Diameter of Orifice refers to the size of the opening to release water into the system during low pressures and to accept water from the system during high pressures.

–

Ratio of Losses represents the ratio of the head losses for inflow to outflow. The default value of this parameter is 2.5. Differential orifices can create different head losses depending on the direction of flow.

–

Head Loss Coefficient is a dimensionless quantity that can be determined from the flow through the valve and corresponding pressure drop.

–

Tank Geometry refers to the pairs of equivalent diameters and elevations which describe the geometry of the surge tank.

Gas Vessel—A gas vessel is typically a cylindrical or spherical pressure vessel containing fluid at the bottom and an entrapped gas (usually air or nitrogen) overlying the liquid. The entrapped gas undergoes compression and expansion in accordance with the gas law. If the gas vessel contains enough gas to prevent water columns from separating, it can be an extremely effective way to avoid or reduce pressure surges. A differential orifice can also be installed at the connection to the system to dissipate the transient energy more rapidly. A gas vessel has the following parameters: –

Initial Volume of Gas is the initial volume of gas in the pressure vessel at the start of the simulation. During the transient event, this gas volume expands or compresses, depending on the transient pressures in the system.

–

Diameter of Orifice/ Throat is the size of the opening between the gas vessel and the main pipe line. It is typically smaller than the main pipe size.

–

Ratio of Losses refers to the ratio of inflow head loss to outflow loss (for the same inflow and outflow rate.) The default value is 2.5.

–

Head Loss Coefficient is a dimensionless quantity that can be computed from the flow and head across the connecting pipe, differential orifice, and isolation valve (if any).

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Exponent in Gas Law refers to the exponent to be used in the gas law equation. The usual range of this exponent is 1.0 to 1.4. The default value used by HAMMER is 1.2.

–

Bladder denotes whether the gas is contained within a bladder. The default setting for this option is NO. If it is set to YES, HAMMER automatically assumes that the bladder occupied the full-tank volume at the preset pressure at some time and that the air volume was compressed to a smaller size by the steady-state pressure in the system.

Rupture Disk between 2 Pipes—A rupture disk node is located between two pipes. It is designed to fail when a specified threshold pressure is reached. This creates an opening in the pipe through which flow can exit the system, either to atmosphere or to another pressurized pipe system, such as a suction line. It has the following parameters: –

Typical Pressure refers to a pressure drop across the (failed) rupture disk at the Typical Flow.

–

Typical Flow refers to any typical positive flow through the (failed) orifice that corresponds to the Typical Pressure.

–

Threshold Pressure refers to the pressure beyond which the rupture disk breaks and allows flow to exit the system.

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Chapter

7

Modeling Capabilities

HAMMER’s unmatched capabilities can model and optimize practically any distribution system.

7.1

Hydraulic Transient Analysis Use HAMMER to simulate short-lived but often extreme hydraulic transient pressures and flows, as well as to predict the formation and collapse of air or vapor pockets in your system. HAMMER has the following capabilities: •

Automatically import model data from widely used steady-state models, such as EPANET, WaterCAD/WaterGEMS, PIPE2000, and others via GIS or database systems.

•

Perform a hydraulic transient analysis to see how the system behaves over time after a power failure, pipe break, pump or valve operation, equipment failure or operator error. You can specify the following options: –

Choose a rigorous Method of Characteristics (MOC) solution based on elastic theory. The MOC simulates wave propagation in a frictionless and slightly compressible liquid, as described in “Method of Characteristics (MOC)” on page B-250.

–

Use common steady-state friction methods, such as Hazen-Williams or Darcy-Weisbach, or more accurate quasi-steady or unsteady (transient) friction methods.

–

Use simple pump representations or multipoint head-discharge curves, complete with four-quadrant characteristics automatically selected based on specific speed.

–

Use simple valve representations or multipoint head-discharge (Cv) curves.

–

The vaporous cavitation model invoked when pressure reaches full vacuum is described separately in “Water Column Separation and Vapor Pockets” on page 7-193.

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Hydraulic Transient Analysis •

Specify surge-control equipment based on your results, including surge tanks, surge-anticipator valves, combination air valves, gas vessels (air chambers), and rupture disks.

•

Visualize extremely high and low transient heads and flows using color-coded maps, animated profiles, and histories at every point of interest—before they can break pipes, fatigue joints, and cause leaks throughout your system.

Steady-state hydraulic models, such as WaterCAD, simulate systems in which a dynamic equilibrium has been achieved and where changes in head or flow take minutes to hours. In contrast, HAMMER simulates hydraulic systems whose balance has been upset by rapid control-valve operation or other emergencies—all occurring in seconds or fractions of a second. With HAMMER’s added simulation power comes a higher computation cost, since many time steps must be calculated, using more complex equations to track dynamic changes systemwide. Fortunately, HAMMER automatically adjusts its solution method to minimize execution time, while delivering detailed and accurate solutions. HAMMER uses one or both of these algorithms: •

Method of Characteristics (MOC) solution of the full continuity and momentum equations for a Newtonian fluid (i.e., elastic theory), which account for the fact that liquids are compressible and that pipe walls can expand under high pressures.

•

Differential equation solution to the momentum and continuity equations based on rigid-column theory, which assumes that liquids are incompressible and pipes are rigid.

HAMMER uses MOC systemwide for virtually every simulation. The simpler, faster rigid-column algorithm is also applied in specific reaches for a few special applications. Although MOC is preferred, due to its greater accuracy, both methods are described separately below.

7.1.1

Rigid-Column Simulation Rigid-column theory is suitable for simulating changes in hydraulic transient flow or head that are gradual in terms of the system’s characteristic time, T = 2 L/a (Appendix B). This type of hydraulic transient is often referred to as a mass-oscillation phenomenon, where gradual changes in momentum occur without significant or sharp pressure wave fronts propagating through the system. For example, mass oscillations can occur when a vacuum-breaker or combination air valve lets air into the system at a local high point (to limit subatmospheric pressures). The water columns separate and move away from the high point as air rushes in to fill the space between them. Eventually, flow reverses towards the high point, where the air may be compressed as it is expelled. This back-and-forth motion of the water columns may repeat many times until friction dissipates the transient energy.

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Modeling Capabilities From the HAMMER Tools > Project Options menu, click the Other Options tab and set Extended CAV (combination air valve) to True. HAMMER will track the extent of the air pocket and the resulting mass-oscillation and water column accelerations. HAMMER still calculates the system-wide solution using MOC and elastic theory; it uses rigid-column theory only for the pipes nearest the high point. This results in more accurate solutions, without increasing execution times.

7.1.2

Elastic Simulation Elastic theory is suitable for simulating changes in hydraulic transient flow or head of all types, whether gradual, rapid, or sudden in terms of the system’s characteristic time. A popular and proven way to implement an elastic theory solver is the Method of Characteristics (MOC). The MOC is an algebraic technique to compute fluid pressures and flows in a pressurized pipe system. Two partial differential equations for the conservation of momentum and mass are transformed to ordinary differential equations that can be solved in space-time along straight lines, called characteristics. Frictional losses are assumed to be concentrated at the many solution points. HAMMER’s power derives from its advanced implementation of elastic theory using the MOC, which results in several advantages: •

Rigorous solution of the Navier-Stokes equation, including higher-order minor terms and complex boundary conditions, whose physics can be described with mathematical rigor.

•

Robust and stable results minimizing numerical artifacts and achieving maximum accuracy. Convergence is virtually assured for most systems and tolerances.

•

Research and field-proven method based on numerous laboratory and field experiments, where transient data were measured and used to validate numerical simulation results.

Numerical methods for solving hydraulic transient systems or describing their boundary conditions are continuously evolving. The ideal model should have the right balance of proven algorithms and leading-edge methodologies. HAMMER is such a model. It is the result of decades of experience and innovation by Environmental Hydraulics Group’s senior staff combined with Haestad Methods’ software expertise and track record in bringing leading-edge technologies into widespread use.

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7.1.3

Data Requirements and Boundary Conditions The data requirements of hydraulic models increase with the complexity of the phenomena being simulated. A steady-state model’s simple dataset and system representation are sufficient to determine whether the network can supply enough water to meet a certain average demand. An extended-period simulation (EPS) model requires additional data, but it can indicate whether the system can provide an acceptable level of service over a period of minutes, hours, or days. EPS models can also be used for energy-consumption studies and water-quality modeling. Data requirements for hydraulic transient simulations are greater than for EPS or steady-state runs. In addition to the information required by a steady-state model, you also need to determine the following: •

Pipe elasticity (i.e., pressure wave speed)

•

The fluid’s vaporization limit (i.e., vapor pressure)

•

The pumps’ combined pump and motor inertia and controlled ramp times, if any.

•

Pump or pump-turbine characteristics for hydropower systems.

•

The valves’ controlled operating times and their stroke to discharge coefficient (or open area) relationship.

•

The characteristics of surge-protection equipment.

For more information, see “Hydraulic Element Reference” on page 6-161.

7.2

Infrastructure and Risk Management HAMMER provides input to operation procedures to increase infrastructure life and reduce the risk of service interruptions in the following ways:

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•

Reduce wear and tear from pressure cycling due to rapid industrial demand changes, incorrect control-valve operations, or water-column separation.

•

Reduce the risk of pipe breaks, leaks, and unaccounted-for water (UFW) by optimizing normal and emergency procedures to minimize transient pressure shock waves.

•

Predict overflows at outfalls or spills to the environment more accurately.

•

Manage the risk of contamination during subatmospheric transient pressures, which can suck air, dirt, and contaminants into your system.

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Modeling Capabilities

7.3

Water Column Separation and Vapor Pockets During a hydraulic transient event, the hydraulic-grade line (HGL), or head, at some locations may drop low enough to reach the pipe’s elevation, resulting in sub-atmospheric pressures or even full-vacuum pressures. Some of the water may flash from liquid to vapor while vacuum pressures persist, resulting in a temporary water-column separation. When system pressures increase again, the vapor condenses to liquid as the water columns accelerate toward each other (with nothing to slow them down unless air entered the system at a vacuum breaker valve) until they collapse the vapor pocket; this is the most violent and damaging water hammer phenomenon possible. HAMMER makes a number of assumptions with respect to the formation of air or vapor pockets and the resulting water column separation: •

HAMMER models volumes as occupying the entire cross section of the pipe. This may not be realistic for small volumes, since they could overlie the liquid and not create column separation, as in the case of air bubbles, but this does not result in significant errors.

•

HAMMER models air or vapor volumes as concentrated at specific points along a pipe. Volume at a node is the sum of the end points (a special case of a point) for all pipes connected to it. However, HAMMER can simulate an extended air volume if it enters the system at a local high point (via a combination air valve or CAV) and if it remains within the pipes connected to it.

•

HAMMER ignores the reduction in pressure-wave speed that can result from the presence of finely dispersed air or vapor bubbles in the fluid. Air injection using diffusers or spargers can be difficult to achieve consistently in practice and the effect of air bubbles (at low pressures) on wave speed is still the subject of laboratory investigations.

In each case, the assumptions are made so that HAMMER’s results provide conservative predictions of extreme transient pressures.

7.3.1

Global Adjustment to Vapor Pressure If system pressure drops to the fluid’s vapor pressure, the fluid flashes into vapor, resulting in a separation of the liquid columns. Consequently, vapor pressure is a fundamental parameter for hydraulic transient modeling. Vapor pressure changes significantly at high temperature, operating pressure, or altitude. Fortunately, it remains close to HAMMER’s default value for a wide range of these variables for typical water pipelines and networks.

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Water Column Separation and Vapor Pockets If your system is at high altitude or if it is an industrial system operating at high temperatures or pressures, consult a steam table or vapor-pressure curve for the liquid. Consider a few extra model runs to assess the sensitivity of the hydraulic transient simulation results to global changes in vapor pressure—you can change it on the System tab of the Project Options window (Tools > Project Options).

7.3.2

Global Adjustment to Pipe Elevations HAMMER calculates the elevation along the top of any pipe (also known as its obvert or crown) from a straight line joining the elevations of the two nodes it connects to. Because differences can occur between as-constructed pipe elevations (or surveys) and the design drawings that hydraulic models are typically based on, it is prudent to assess the sensitivity of the hydraulic transient simulation results to changes in elevation. If the transient HGL drops below the pipe elevation, vapor pockets can form and collapse. HAMMER speeds this process by allowing you to make a global adjustment to pipe elevations from the Tools > Project Options menu command; click the Preferences tab and type in the amount to increase the pipe elevations. After running HAMMER, you can save the resulting profile as a HAMMER graph (.GRP) and copy data from several such graphs onto a common graph showing the sensitivity to elevation errors.

7.3.3

Global Adjustment to Wave Speed The pressure-wave speed is a fundamental parameter for hydraulic transient modeling, since it determines how quickly disturbances propagate throughout the system. This affects whether or not different pulses may superpose or cancel each other as they meet at different times and locations. Wave speed is affected by pipe material and bedding, as well as by the presence of fine air bubbles in the fluid. The default value of 1,000 m/s (3,280 ft./sec.) is for metal or concrete pipe. Although higher wave speeds are conservative for typical systems composed of a single pipe material, such as pipelines, consider a few extra model runs to assess the sensitivity of the hydraulic transient simulation results to global changes in wave speed; you can change it on the Summary tab of the Project Options window (Tools > Project Options).

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Modeling Capabilities

7.3.4

Automatic Selection of the Time Step HAMMER selects the time step used in its calculations automatically, based on the wave speed and the length of each pipe in the system, so that a sharp pressure-wave front can travel the length of one of the pipe’s interior segments in one time step. Encoding long pipeline systems with very short pipes, such as discharge-header piping inside the pump station, may significantly decrease the time step and increase the time required to complete a run. Warning!

Using very short pipes (in a pump station) and very long pipes (transmission lines) in the same HAMMER model could require excessive adjustments to the wave speed. If this happens, HAMMER prompts you to subdivide longer pipes to avoid resulting inaccuracies.

A smaller time step may cause HAMMER to track the formation and collapse of very fine vapor pockets, each of which may result in pressure spikes with low magnitudes but high frequencies.

7.4

Check Run This feature allows you to validate your model against typical data entry errors, hard to detect topology problems, and modeling problems. When the Data Check button is selected, in the Run dialog box, the model is automatically validated before detailed calculations are begun. The process produces either a dialog box stating No Problems Found or a status log (see “Status Log” on page 12-539) with a list of messages. The data check algorithm performs the following validations: •

Network Topology—Checks that the network contains at least one boundary node, one pipe, and one junction, the minimum network requirements. It also checks for fully connected pumps and valves and that every node is reachable from a boundary node through open links.

•

Element Validation—Checks that every element in the network is valid for the calculation. For example, this validation ensures that all pipes have nonzero length, nonzero diameter, etc. Each type of element has its own checklist. This same validation is performed when you edit an element in a dialog box.

The validation process generates two types of messages. A warning message means that a particular part of the model (e.g., a pipe’s roughness) does not conform to the expected value or is not within the expected range of values. This type of warning is useful but not fatal. Therefore, no corrective action is required to proceed with a calculation. Warning messages are often generated as a result of a topographical or data-entry error and should be corrected.

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Orifice Demand and Intrusion Potential Note:

If your model will not run due to error messages and you do not know how to proceed, please contact Haestad Methods’ support staff (see “Contacting Haestad Methods” on page 1-13).

An error message, on the other hand, is a fatal error and the calculation cannot proceed before it is corrected. Typically, error messages are related to problems in the network topology, such as a pump or valves not being connected on both its intake and discharge sides.

7.5

Orifice Demand and Intrusion Potential In WaterCAD and WaterGEMS, flow emitters are devices associated with junctions that model the flow through a nozzle or orifice (i.e., orifice demand). The demand or flow rate through the emitter varies in proportion to the pressure at the junction raised to some power. The constant of proportionality is termed the discharge coefficient. For nozzles and sprinkler heads, the exponent on pressure is 0.5 and the manufacturer usually states the value of the discharge coefficient as the flow rate in gpm through the device at a 1 psi pressure drop (or L/s at a 1 m pressure drop). Emitters are used to model flow through sprinkler systems and irrigation networks. They can also simulate leakage in a pipe connected to the junction (if a discharge coefficient and pressure exponent for the leaking crack or joint can be estimated) or to compute a fire flow at the junction. In HAMMER, any demand at a node is called a consumption node and is treated as an orifice discharging to atmosphere that cannot allow air back into the system during periods of subatmospheric pressure. This is because the majority of water demands entered into hydraulic models are really the sum of several houses or demand points, each located at a significant distance from the point where their aggregate demand is being modeled. By default, HAMMER assumes that any air allowed into the system at the individual demand points cannot reach the aggregate demand location. If this is not the case, use one of the following hydraulic elements:

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•

Orifice to Atmosphere—Models a demand point located a hydraulically short distance from its node coordinates (based on the wave speeds of the pipes connected to it). The initial pressure and flow are used to automatically calculate a flow emitter coefficient, which will be used during the simulation to calculate transient outflows. If pressure in the system becomes subatmospheric during the simulation, this element allows air into the system. You can also specify a volume of air at time zero to use this element to simulate an inrush transient.

•

Orifice at Branch End—Models a demand point in a manner similar to the element Orifice to Atmosphere. You can enter the orifice’s elevation and distance away from the node’s coordinates to simulate fire hoses or sprinkler systems.

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Modeling Capabilities Table 7-1: HAMMER Consumption Node Table

7.6

Hydraulic Elements

System Pressure Positive

Negative

Consumption

Pressure dependent

No flow

Orifice to Atmosphere

Pressure dependent

Air intrusion

Orifice at Branch End

Pressure dependent

Water intrusion

Numerical Model Calibration and Validation As part of its expert witness and break-investigation service, EHG has calibrated and validated HAMMER’s numerical simulations for different fluids and systems for clients in the civil (water and wastewater), mining (slurry), and hydropower sectors. Comparisons between computer models and validation data can be grouped into the following three categories: •

Cases for which closed-form analytical solutions exist given certain assumptions. If the model can directly reproduce the solution, is considered valid for this case. The example file Hamsam01.HIF is a validation case against the Joukowski equation.

•

Laboratory experiments with flow and pressure data records. The model is calibrated using one set of data and, without changing parameter values, it is used to match a different set of results. If successful, it is considered valid for these cases.

•

Field tests on actual systems with flow and pressure data records. These comparisons require threshold and span calibration of all sensor groups, multiple simultaneous datum and time base checks and careful test planning and interpretation. Sound calibrations match multiple sensor records and reproduce both peak timing and secondary signals—all measured every second or fraction of a second.

It is extremely difficult to develop a theoretical model that accurately simulates every physical phenomenon that can occur in a hydraulic system. Therefore, every hydraulic transient model involves some approximations and simplifications of the real problem. For designers trying to specify safe surge-control systems, conservative results are sufficient. The differences between computer model results and actual system measurements are caused by several factors, including the following difficulties:

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Numerical Model Calibration and Validation •

Precise determination of the pressure-wave speed for the piping system is difficult, if not impossible. This is especially true for buried pipelines, whose wave speeds are influenced by bedding conditions and the compaction of the surrounding soil.

•

Precise modeling of dynamic system elements (such as valves, pumps, and protection devices) is difficult because they are subject to deterioration with age and adjustments made during maintenance activities. Measurement equipment may also be inaccurate.

•

Unsteady or transient friction coefficients and losses depend on fluid velocities and accelerations. These are difficult to predict and calibrate even in laboratory conditions.

•

Prediction of the presence of free gases in the system liquid is sometimes impossible. These gases can significantly affect the pressure-wave speed. In addition, the exact timing of vapor-pocket formation and column separation are difficult to simulate.

Calibrating model parameters based on field data can minimize the first source of error listed above. Conversations with operators and a careful review of maintenance records can help obtain accurate operational characteristics of dynamic hydraulic elements. Unsteady or transient friction coefficients and the effects of free gases are more challenging to account for. Fortunately, friction effects are usually minor in most water systems and vaporization can be avoided by specifying protection devices and/or stronger pipes and fittings able to withstand subatmospheric or vacuum conditions, which are usually short-lived. For systems with free gas and the potential for water-column separation, the numerical simulation of hydraulic transients is more complex and the computed results are more uncertain. Small pressure spikes caused by the type of tiny vapor pockets that are difficult to simulate accurately seldom result in a significant change to the transient envelopes. Larger vapor-pocket collapse events resulting in significant upsurge pressures are simulated with enough accuracy to support definitive conclusions. Consequently, HAMMER is a powerful and essential tool to design and operate hydraulic systems provided the results are interpreted carefully and scrutinized as follows:

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•

Perform what-if analyses to consider many more events and locations than can be tested, including events that would require destructive testing.

•

Determine the sensitivity of the results to different operating times, system configurations, and operating- and protective-equipment combinations.

•

Based on a calibrated or uncalibrated model, predict the effects of proposed system capacity and surge-protection upgrades by comparing them against each other.

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Modeling Capabilities These are facilitated if transient pressure or flow measurements are available for your system, but valid conclusions and recommendations can usually be obtained using HAMMER alone.

7.6.1

Gathering Field Measurements Rather than conventional pressure gages and SCADA systems, high-speed sensors and data logging equipment are needed to accurately track transient events. The pressure transducer should be very sensitive, have a high resolution, and be connected to a high-speed data acquisition unit. It should be connected to the system pipeline with a device to release air, because air can distort the pressure signal transmitted during the transient. Recording should not begin until all air is released from the pipeline connection and the pressure measurement interval is defined. Typically, at least two measuring locations should be established in the system and the flow-control operation should be closely monitored. The timings of all recording equipment must be synchronized. For valves, the movement of the position indicator is recorded as a function of time. For pumps, rotation or speed is measured over time. For protection devices such as oneway and two-way surge tanks and hydro-pneumatic tanks, the level is measured over time.

7.6.2

Timing and Shape of Transient Pressure Pulses With respect to timing, there should be close agreement between the computed and measured periods of the system, regardless of what flow-control operation initiated the transient. With a well-calibrated model of the system, it is possible to use the model in the operational control of the system and anticipate the effects of specific flow-control operations. This requires field measurements to quantify your system’s pressure-wave speed and friction, with the following considerations: •

Field measurements can clearly indicate the evolution of the transient. The pressure-wave speed for a pipe with typical material and bedding can be determined if the period of the transient (4 L/a) and the length (L) between measurement locations is known. If there is air in the system, the measured wave speed may be much lower than the theoretical speed.

•

If friction is significant in a system, real-world transients attenuate faster than the numerical simulation, particularly during longer time periods (t > 2 L/a). Poor friction representation does not explain lack of agreement with an initial transient pulse.

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Numerical Model Calibration and Validation In general, if model peaks arrive at the wrong time, the wave speed must be adjusted. If model peaks have the wrong shape, the description of the control event (pump shutdown or valve closure) should be adjusted. If the transient dies off too quickly or slowly in the model, the friction losses must be adjusted. If there are secondary peaks, important loops and diversions may need to be included in the model.

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Chapter

8

Presenting Your Results This section covers the various methods provided for viewing, annotating, graphing, animating, and reporting your data. It also presents the tools available for generating maps, profiles, and time-history plots, which can be color-coded based on the simulation results. HAMMER makes it easy to review and present your results quickly and efficiently with the following options: •

Color-coded Map—HAMMER can color-code the pipes and nodes in a model according to the calculated results, including maximum or minimum head or pressure, maximum or minimum flow, and maximum volume of air or vapor.

•

HGL Profile—HAMMER can plot or animate the steady-state hydraulic grade line (HGL) and all profiles show the maximum and minimum transient head envelopes along any path. The envelopes provide a visual summary of extreme conditions simulated for the pipe system.

•

Time History—HAMMER can plot or animate the time-dependent changes in the simulated transient flow, head, and volume of vapor or air at any point of interest.

•

Synchronized Animation—You can visualize how system variables change over time and space, since every path and history is synchronized and animated simultaneously.

•

Tabulated Reports—You can create an output database in Access and click your way to professional reports and tables. These reports and queries can also be customized.

It is important to take the time to carefully review the results of each HAMMER simulation to check for data-input errors and learn about the dynamic nature of the pipe system. HAMMER’s powerful visualization and reporting capabilities make this easier.

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Reports

8.1

Reports You can enter your organization’s name using Tools > Viewer > Graphics to open the HAMMER Viewer, then Tools > Set Company Name.

8.1.1

Using Time or Head to Trigger Output Using Tools > Project Options or the toolbar button and clicking the Preferences tab allows you to trigger output to start only after the following occur: •

You can request HAMMER to show only the extreme heads that occur during the hydraulic transient simulation—even if these are less severe than the initial steady state—by opting to show heads after the First Maximum or Minimum has been reached in the Show Extreme Heads After field. The default is to show all heads from time zero.

•

You can set a particular time upon which HAMMER will start time-dependent output by entering a value (in seconds) in the Report History after Time field.

These features allow you to significantly reduce the size of output files whenever one or more transient events must take place prior to the transient you want to display in the final output. This is especially useful when Generate Animation Data is selected (in the Run Control window that appears after pressing either the GO or COMPUTE buttons) for several profiles and points. This feature also applies to reports and tables you can obtain from Access by selecting Generate Output Database before a HAMMER run.

8.1.2

Text Output File Options You can choose whether or not to generate ASCII text files, which contain tabulated output, by selecting the Tools > Project Options menu command and clicking on the Other Options tab. Setting both the Enable Text Reports and Print Standard Output Log to True generates the following text files after each successful HAMMER simulation: •

Tabulated Report (.RPT)—includes the following information and tables: –

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Snapshot tables for selected points and for every time step selected for output.

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Presenting Your Results –

History table for every selected end point and every time step selected for output.

–

Extreme heads table for each path, including a row for each end point (and the interior calculation points HAMMER adds automatically); each with column entries for Distance along the path, Elevation, Initial Head, Maximum Head, Maximum Volume, and Vapor Pressure (which can be ignored in water and wastewater systems).

•

Output log file (.OUT)—includes summary information in formatted tables showing key simulation parameters, system information, connectivity, pipe data, initial conditions, and hydraulic element details, such as valve closure or pump curves. HAMMER outputs text messages to this file while it is running. If a run terminates abnormally, the log becomes an error summary that is automatically displayed by the HAMMER Modeler GUI.

•

Standard Output Log (.OUT)—provides detailed information about the first, second, and last time steps in the detailed output log (.OUT). This is done to report any initial surges at time zero, such as may result from an unbalanced initial steady state (perhaps imported from another program) or a sudden valve or pump operation specified in HAMMER. The last time step is useful to check whether a final steady state has been reached or, for example, all air or vapor has been expelled from the system.

•

Print Opening/Closing Pockets in Log (.OUT)—Includes the opening and closing times or vapor pockets if this option was set to True before the run.

While the formatted ASCII text files described in this section are useful for postprocessing, it is usually more efficient to generate the Access .MDB file and to use the predefined and customizable reports it provides instead.

8.1.3

Predefined Report Formats in Access After a successful simulation, HAMMER can generate a Microsoft Access database (.MDB), complete with predefined queries and reports, in one of two ways: •

Select Generate Output Database before clicking File > Run and then Run in the Run Control window.

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Reports

•

Select File > Export > Database > Output after a successful simulation (and before any other simulation is begun).

The HAMMER output database provides a Control Window from which you can select one of the following reporting options: Summary:

Extremes:

The summary report provides the following information at a glance: •

Date and time the model was run

•

Number of pipes and nodes in the model

•

Maximum and minimum heads and pressures for the most extreme locations

•

Maximum volumes of air or vapor for the most extreme locations

The extremes report provides the following information as a detailed, sorted table in which each line is a different point simulated in the HAMMER model: •

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Maximum and minimum heads and pressures for each point

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Presenting Your Results

Pockets:

Nodes:

Pipes:

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•

Upsurge ratio, or the maximum transient head divided by the steady-state head

•

Date and time the report was generated (in the table footer)

The pockets report provides the maximum volume of vapor or air pockets ever reached at every location in the pipe system during the simulation. Interior points are listed for some pipes using the following nomenclature: p#:##%, where p# is the pipe’s ID and the ##% after the colon is the location expressed as a percent of the pipe length, beginning at that pipe’s From-Node end. The following information is listed: •

Type of volume (air or vapor)

•

Maximum volume reached during the simulation

•

Current volume at the end of the simulation period

•

Number of collapses (i.e., number of times the water columns rejoined to close successive pockets at this same location)

•

Date and time the report was generated (in the table footer)

The nodes report provides a list of all nodes in the model grouped by category: •

Label and elevation

•

Number of pipes or branch pipes connected to each node

•

Date and time the report was generated (in the table footer)

The pipes report provides the following information as a detailed, sorted table in which each line is a different pipe simulated in the HAMMER model: •

Pipe label

•

Length

•

Diameter

•

Hazen-Williams coefficient

•

Velocity

•

Date and time the report was generated (in the table footer)

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Hydraulic Element Labels and Colors This feature makes generating a report a simple point-and-click exercise. You can select from one of these predefined reports and print some of them for an appendix. Note:

8.2

If you are familiar with Access, you can also customize the report formats and/or the queries with which they populate the tables.

Hydraulic Element Labels and Colors You can customize HAMMER for your particular situation.

8.2.1

•

“Using Your Organization’s Name and Logo” on page 8-206

•

“System Colors and Display Options” on page 8-206

•

“Hydraulic Element Labels” on page 8-207

•

“Hydraulic Element Colors” on page 8-207

Using Your Organization’s Name and Logo You can enter your organization’s name and logo using Tools > Viewer > Graphics to open the HAMMER Viewer and then Tools > Set Company Name and Tools > Set Company Logo. Your logo must supplied in .GIF format. Your company’s name will be displayed as text next to the logo, if available. You can also display only a logo or only text if you prefer.

8.2.2

System Colors and Display Options You can change the color and fonts used to display hydraulic element labels, including the background color of the Drawing Pane, using Tools > Global HAMMER Options, selecting the Colors tab, and clicking the color (the numbers represent a color; click to edit them). In the Other Options tab, you can set the default font and toggle the anti-alias feature, for sharper lines and symbols, on or off. Click Tools > Global HAMMER Options, select Other Options, and set the field Optimized Animation Performance to True if you want to minimize the wait time between clicking Animate and the start of animation. However, setting this option to True uses more RAM than setting it to False; so, setting the field Optimized Animation Performance to False may reduce the use of virtual memory and be more appropriate for large systems.

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Presenting Your Results You can use the Capture Screen (camera) toolbar icon to save the contents of the current Drawing Pane view to a .JPEG or .GIF graphic file. You can paste this graphic in reports and figures.

8.2.3

Hydraulic Element Labels Depending on the level of detail shown on the screen, you can display or hide hydraulic element labels using Tools > Project Options and selecting the Other Options tab to toggle the following display options:

8.2.4

•

Show Node Labels—toggle on (True) or off (False) to display node labels.

•

Show Pipe Labels—toggle on (True) or off (False) to display pipe labels.

•

Short Label Display—toggle on (True) or off (False). Short Labels are useful when importing from large GIS or CAD files, where much of the hydraulic element labels may not be very informative from a hydraulic perspective. This feature abbreviates the labels to the first and last characters only, separated by a tilde (~) character. You can choose the number of characters to display using Short Labels in the Max. Char Output field.

Hydraulic Element Colors The Map Selection color coding choice lets you assign colors and sizes to hydraulic pipe and node elements in the Drawing Pane based on a variety of input and output attributes. For any attribute, you can supply a color scale or have HAMMER generate one for you. For example, you can supply a color scale to display all pipes whose maximum transient heads are between 20 and 40 m in green, those between 40 and 110 m in blue, and those above 110 m in red. For more information, see “Generating Color Maps” on page 8-208. Once simulation results have been calculated, HAMMER automatically stores them in the .HIF so you can display results in the Element Editor and Drawing Pane without running HAMMER again. It also sets the line thickness of each pipe in proportion to its diameter. You can assign one of several transient results to pipes or nodes in the Map Selection toolbar as shown in “Table 8-1: Transient Result Display Options using the Map Selector”on page 8-208.

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Generating Color Maps

8.3

Generating Color Maps In designing a surge control strategy for a water-distribution network or pipeline, the extreme states are usually of the greatest interest. HAMMER has built-in capabilities to visualize maximum and minimum simulated flows, heads, pressures, and volumes (vapor or air) throughout the pipe system. You can color-code nodes and pipes according to these different parameters. HAMMER Modeler also displays line thicknesses in proportion to the pipes’ diameter. HAMMER makes it easy to color-code pipes and nodes in the Drawing Pane of the HAMMER Modeler based on calculated results, such as the transient heads, pressures, flows, and volumes. A Map Selector toolbar icon gives immediate access to the color-coding options available for pipes and nodes, as shown in the following table. Table 8-1: Transient Result Display Options using the Map Selector Pipes

Nodes

Maximum Head

Maximum Head

Minimum Head

Minimum Head

Maximum Flow

Maximum Pressure

Minimum Flow

Minimum Pressure

Maximum Vapor Volume

Maximum Vapor Volume

Maximum Air Volume

Maximum Air Volume

At the bottom of the options listed for Pipes and Nodes, you can click Legend (then click the Drawing Pane) to display a scale bar, or you can click Scales to open the Color Map Settings window for the currently selected output variable. Simply select the Color Ramp, Scale Intervals, and Scale Limits and click Apply to visualize the resulting map. For an example of how to select a color map scale, see “Part 4—Color-Coding Maps, Profiles, and Point Histories” on page 3-128. HAMMER’s Color Map Settings dialog for the chosen calculated result, such as Node Maximum Pressure, shows the maximum and minimum values of this output variable using the units you selected with the FlexUnits manager (or the default units). The appearance of the resulting map depends on how skillfully you divide this total output range into intervals and set colors corresponding to each of the interval boundaries, as follows:

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Presenting Your Results •

Select equal intervals by clicking on the Quartile, Quintile, Decile, or Percentile Scale Type. These correspond to upper and lower range limits of 25, 20, 10, and 1 percent, respectively.

•

You can also click Custom (Percent) to use the Low Percent and High Percent sliders or Custom (Value) to enter the limiting values directly.

The procedure for selecting a color map scale has the following four steps: 1. Color Setting—Each scale is defined as a number of continuous color ramps interpolated between the specific colors shown in the middle column. You can click any of these colors to display a color selector window. You can pick a color by clicking anywhere on the color swatch displayed; or you can click either the RGB or the HSB tab to enter specific numeric values to define a color more exactly. 2. Scale Type—HAMMER lets you select equal intervals ranging from quartiles to percentiles or specify custom percentages using the sliders provided. Alternatively, you can enter custom values for the Minimum Value and Maximum Value of your scale inside or outside the simulated range. Clicking Apply updates the color ramp table and scale display automatically. Within the output-variable range bounded by the Minimum Value and Maximum Value, you can click Add or Delete to change the number of intervals of the color ramp. Note:

If you want to display a categorical scale, for which the boundaries between different classes are sharp, add two “%” rows to the color ramp with very close numbers, such as 15% and 16%, and select significantly different colors for these boundary points.

3. Scale Limits—The scale limits determine the portion of the output variable range for which the continuous color variation you selected is used. Whether you select it based on percentages or enter it directly, all locations with a value equal to or lower than the Minimum Value are displayed with the color corresponding to this lower limit. All locations with a value equal to or greater than the Maximum Value are displayed with the color corresponding to this upper limit. Transient Tip: Set the limits of your scale presets according to the limits of your actual system. For example, enter the surge-tolerance limit as the Maximum Value of pressure. Similarly, enter zero flow or zero pressure for the Minimum Value of the flow and pressure scales, respectively.

4. Once you have defined a scale that is suitable for your system and the selected output variable, you can save it for future use by clicking Save Preset. In any HAMMER project, you can select presets saved previously using the Presets choice list. You can also delete presets you no longer need by clicking Delete Preset, making a selection from the deletion choice list and clicking OK.

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Profile Plots along a Path (or Walk)

8.4

Profile Plots along a Path (or Walk) A profile is a graph that plots a particular attribute across a distance, such as ground elevation and HGL along a series of connected pipes. As well as these side or sectional views of the ground elevation, profiles can be used to show the pipeline, hydraulic grade, transient head, vapor or air volume. Although profiles in general are not limited to a specific alignment, piping-network models are usually concerned with a specific profile alignment called a network walk or path (for more information, see “Walking the Path (or Profile Setup)” on page 8210).

8.4.1

Walking the Path (or Profile Setup) Setting up a profile is a matter of selecting the path or walk for which variables such as elevation and calculated results will be plotted. Use Tools > Project Options and click the Report Paths tab to display HAMMER’s profile-selection tool. Note:

A path or walk is a nonbranching path through the network that can only be extended at either end. Pipes cannot be added along the midsection of the path or walk. Likewise, elements in the midsection of the path or walk cannot be deselected without first deselecting all of the elements between one end and the undesired element.

The Path tool includes four main areas:

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•

Point Histories—Specifies whether the results calculated at interior points need to be output only along the paths or throughout the entire network (not necessary).

•

Path List—Lists the paths that are currently defined and lets you Add Path, Remove Path, Rename Path, or Show Path (in the Drawing Pane). If pipe colors are currently Off in the Map Selector toolbar icon in HAMMER Modeler, clicking Show Path selects all pipes belonging to the current path, colors them red, and resets the zoom window to zoom into the area traversed by the path (or walk).

•

System Pipes—Initially, this box lists all pipes currently in the model and it continues to do so if the Show All option is selected (at the bottom of the box). Otherwise, this box only shows pipes connected to the previously selected pipe to simplify the profile selection (after the first pipe in the path is selected). It is recommended that you use the default and not Show All pipes.

•

Report Pipes—Shows the pipes currently included in the path profile in order. Double-click any pipe to display the cumulative length from the beginning of the first pipe. A green light and message appears at the bottom of the box as long as the path is valid (i.e., a path cannot have branches or gaps).

HAMMER User's Guide

Presenting Your Results When everything is set up to your satisfaction, close the Project Options window to return to HAMMER Modeler.

8.4.2

Path or Profile Plot The HAMMER Viewer can be started from the HAMMER Modeler using Tools > Viewer > Graphics. You can select the Path or Profile as well as the variables to plot from this window and display the result either as a graph (click Plot) or an animation (click Animate). The default is to plot or animate all variables for the first path listed. Clicking Animate displays the graph and the Animation Controller (see “Animating Maps, Profiles and Point Histories” on page 8-215). Whether they were created as plots or animations, all HAMMER graphs can be modified and printed as follows:

8.5

Output:

Any HAMMER plot can be copied to a Windows .BMP file or printed out directly.

Graph Formatting:

Click any graph frame and then right-click to display the menu and select Format Graph. Select either the X-Axis or Y-Axis tabs and then select the following tabs to display standard graph formatting options, including: Scales (including FlexUnits), Titles, Labels, Ticks, and Grids. For more information, see “Graph Formatting and Annotation” on page 8-212.

Time History Graphs at a Point Using the HAMMER Viewer, you can plot a transient history at any point in the system to display the temporal variation of selected parameters (such as heads and flows). You can also plot a profile of selected variables along a particular path to display the spatial extent of transient phenomena. Finally, you can compare the results of two similar graphs.

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Graph Formatting and Annotation To generate a time history, follow these simple steps: 1. In HAMMER Modeler, select Tools > Viewer > Graphics to display the HAMMER Viewer, then load the .HOF file containing your results. You can also load a .GRP if you previously created a graph and saved it for this project. 2. Select the end point you want to plot a history for P??:J??, where ?? represents the pipe and node used in the end point’s name. Select a Graph Type such as Head & Flow and click Plot to display the transient history. 3. To format a graph, click its frame to select it (this will display square handles on the frame outline), and right-click this frame to open the graph’s context menu. Move the cursor and click to select a context menu command, such as Draw Symbol. You can also click Format Graph as described in “Graph Formatting and Annotation” on page 8-212. Right-click anywhere on the graph to display a menu to toggle the display of the Show Page View and Show Frame on or off. To change the figure number, title, date, and project number, double-click on these areas and make the required changes. The graph-formatting options available for Time History plots are identical to those described in “Graph Formatting and Annotation” on page 8-212.

8.6

Graph Formatting and Annotation These features customize the way a graph looks and add explanatory symbols and text labels. You can also add a figure title, date, and number to generate report-ready output.

8.6.1

Graph Formatting Click any graph frame and then right-click to display the menu and select Format Graph. Select either the X-Axis or Y-Axis tabs and then select the following tabs to display standard Haestad graph formatting options, including Scales (with FlexUnits), Titles, Labels, Ticks, and Grids: Transient Tip: The high and low limits of the axes should be selected based on the minimum and maximum attribute values for the entire simulation period and for all locations in the current project—or even for several alternative HAMMER surge-control projects. This will make direct comparison of different locations and surge-protection alternatives easier.

•

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Titles—Every graph has three titles: Graph title, X-Axis title, and Y-Axis title. You can select the font and size of each title.

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8.6.2

•

Automatic Scaling—By default, HAMMER uses Automatic Scaling to set the X- and Y-axis minimum, maximum, and increment values. To customize an axis, turn the check mark off and enter the desired values for the minimum, maximum, and increment. You can customize a single axis while leaving the other in the Automatic Scaling mode.

•

Ticks —You can specify whether tick marks should be displayed inside, outside, or across the axis.

•

Grid —You can specify grid lines for one or both axes. You can also specify the line type, thickness, and color of each grid.

Output Variable Formatting These options allow you to format graphs to compare the results of different HAMMER surge-control projects. •

Line Formatting—Click any graph frame, right-click to display the menu, and select Format Data. Select one of the lines displayed on the profile, such as the pipe elevation, maximum or minimum transient envelope, or steady-state HGL. You can change the line type, color, and thickness of any line. You can also define a new line segment, parallel to any line, by specifying the segment’s line properties, the X-coordinates at its beginning and end, and the distance away from the original line, or Y-offset. Transient Tip: Convert the pipes’ working pressures and surgetolerance limits to equivalent heads in m or ft. Use the Add Segment button to display these as lines parallel to the pipe profile. You can then readily interpret the maximum and minimum transient envelopes in terms of the pipe’s fatigue or rupture limits.

•

Shade Formatting—Click any graph frame, right-click to display the menu, and select Format Shades. Select any two of the lines displayed on the profile, such as the pipe elevation and minimum transient head, and define a shade color and opacity to use whenever the Top Line falls below the Bottom Line. You can also swap the Top Line and Bottom Line.

•

Copy and Paste Settings—Click any graph frame, right-click to display the menu, and select Copy Settings / Paste Settings. You can copy the settings of one HAMMER graph and apply them to any other similar HAMMER graph.

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Graph Formatting and Annotation

8.6.3

•

Copy and Paste Symbols—Click any graph frame, right-click to display the menu, and select Copy Symbols / Paste Symbols. You can copy the symbols of one HAMMER graph and apply them to any other similar HAMMER graph. Symbols include hydraulic element symbols, text, lines, and other annotations.

•

Copy and Paste Data—Click any graph frame, right-click to display the menu, and select Copy Data / Paste Data (+) / Paste Data (-). You can copy the data and lines displayed on one HAMMER graph and paste them to any other similar HAMMER graph. Selecting Paste Data (-) deletes the contents of the target graph prior to the paste operation. Selecting Paste Data (+) adds the lines to the existing graph content.

Adding Annotations Whenever a graph pane is selected, HAMMER Viewer provides several graphical annotation tools for enhancing the appearance of your plots. Graphical annotations can be manipulated like any other element in the graph pane; you can add, move, and delete them. To add graphical annotation to a graph, right-click its frame and select from the available tools:

8.6.4

•

Draw Lines—Adds horizontal, vertical, or diagonal lines to the graph pane. Double-click any line to select its line type, color, and thickness.

•

Draw Text—Adds horizontal or vertical text. Click on text to change its location in the graph pane. Double-click any text to select its font, size, and color.

•

Draw Symbol—Adds predefined symbols such as valves, pumps, and other hydraulic elements to the graph pane. Click on the symbol to change its location in the graph pane. Double-click any symbol to select its size, line pattern, line thickness, and line color.

No Need for Print Previews The HAMMER Modeler’s Drawing Pane, as well as every graph and animation generated by HAMMER, is “What You See is What You Get” or WYSIWIG—it will print as displayed on the screen. Consequently, there is no need for a print-preview feature in HAMMER. Right-click anywhere on the graph (except the graph pane) and toggle the Page View option ON to get a sense of the proportions imposed by the page size and margins.

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Presenting Your Results

8.7

Animating Maps, Profiles and Point Histories HAMMER provides many ways to visualize the simulated results using a variety of graphs and animation layouts. For small systems, you can specify each point and every time step for output, but this is not advisable for larger networks. Usually, you specify which points and paths (profiles) are of interest and the frequency to output results prior to a run. This avoids creating excessively large output files (.HOF). For the same reason, HAMMER only generates the Animation Data (for on-screen animations) or Output Database (for tabular reports in Access) if you select this option in the Run dialog box. Transient Tip: To achieve shorter completion times and conserve disk space, try to avoid generating voluminous output, such as Animation Data or Output Databases early in your hydraulic transient analysis. Fast turnaround makes your evaluation of different alternatives more interactive and challenges you to apply good judgment as you compare your mental model of the system with HAMMER’s results—a good habit which is like estimating an answer in your head when using a calculator.

Early in a HAMMER project, you evaluate many different types or sizes of surge protection equipment with many different HAMMER input and graph files. You can often compare the effectiveness of different protection by plotting the maximum transient head envelopes with the same y-axis limits. At any time, or once you feel you are close to a definitive surge-control solution, you can generate animation data in one of two ways: •

Tell HAMMER to generate the animation data files before you run the program by clicking Generate Animation Data in the run dialog box. If you generated animation data during the run, HAMMER automatically starts the HAMMER Viewer after a successful run.

•

Immediately after a run (i.e., prior to the next run), you can generate animation data using Tools > Generate Animations. You will need to load this animation data using Tools > Viewer > Graphics and selecting the correct HAMMER output file (.HOF) prior to animating the results on screen.

Once you have generated the animation data files, you can display animations without running HAMMER again. This saves a lot of time when comparing the results of several surge-control alternatives. You can load the animation data files using the HAMMER Viewer (Tools > Viewer > Graphics in Modeler):

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Animating Maps, Profiles and Point Histories In the HAMMER Viewer, select one of the available Paths from the choice list. Usually, you will select the Graph Type Path & Volume and then click the Animate button. This automatically loads the animation data and starts the Animation Controller, as follows: 1. On the Animation Controller, click the play button (second from the left) to start the animation. 2. Right-click on the graph and click Save as to save the result displayed on screen as a HAMMER graph (.GRP) or Windows bitmap (.BMP). You can reload HAMMER graphs later. 3. Open as many histories and paths (also known as profiles or walks) as you want and position them on the screen. Again, annotate and save each one as a HAMMER graph (.GRP). 4. When the on-screen layout and graph annotations are ready for a presentation, select File > Save Animation As and type in a name to save the entire animation layout as an .ANI file for rapid recall later. 5. Once you are done for this session and close the Animation Controller, you are prompted to close all graphs. Click Yes. 6. In the future, you can use the HAMMER Viewer to open the animation layout directly by clicking File > Open and selecting the .ANI file. This automatically starts the Animation Controller, opens the .HOF and .GRP files, positions the graphs on the screen, and returns control to you so you can begin your presentation—all in a matter of seconds! 7. You can also display a color-coded map by repositioning and sizing the HAMMER Modeler window. Click Show Tabs to toggle the display of the tabs off to maximize the available display area. Note:

You can generate the maximum and minimum transient maps by clicking the Capture Screen button on the HAMMER Modeler toolbar. These need to be added as the last two frames of an .AVI file to be accessible using the HAMMER Animation Controller.

8. During an animation, you can use the Animation Controller to change the frame rate or frame position interactively with the sliders provided. You can stop the animation at any time and then, for example, step through a vapor-pocket collapse frame by frame. You can also jump to a specific time by selecting it from the choice list. Practice using these tools to prepare a polished and powerful presentation. 9. Carefully select the key locations at which to show histories and the key profiles to illustrate topography. This keeps the number of graphs to be animated to a minimum. An animated map is often as effective as several animated profiles.

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Presenting Your Results 10. For large networks, multiple displays increase the amount of screen area available for animating graphs; however, keep in mind that most people find it difficult to track many graphs at once, unless the frame rate is very slow and many explanations are provided. This can detract from the overall visual impact of the presentation. 11. You can also use a computer projector to magnify the size of each graph. This is highly recommended if you will be presenting the results to more than about three people.

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Appendix

A

Frequently Asked Questions A.1

Overview: “How Do I” “How Do I” tips are available in the following categories: •

“Import/Export Tips” on page A-219

•

“Modeling Tips” on page A-224

•

“How Do I Access the Knowledge Base?” on page A-231

•

“Display Tips” on page A-231

•

“Editing Tips” on page A-233

Extensive, up-to-date tips are available by clicking the Globe on the toolbar, which will take you to the ClientCare area of the Haestad Methods Web site. There, you can consult Frequently Asked Questions (FAQs), modeling tips, and other useful information in our KnowledgeBase or do a search on any keyword. This area of the Web site is only available if you are participating in the ClientCare program. If the information you need is not available in this section, click the Search tab at the top of the Help window for an index. To make your work easier, HAMMER and the Help system are designed to be used together. If you have a high-resolution display monitor, you will probably find it helpful to size the frames of both the program and the Help windows so that they fit side by side. Then, while using the program, you can use the right mouse button or click on the Help tab to update the Help window with context-sensitive Help.

A.2

Import/Export Tips Note:

You can import data from virtually any database capable of exporting to a Microsoft Access file.

The following tips are covered in this section: •

“Transitioning from Steady-State Models to HAMMER” on page A-220

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Import/Export Tips

A.2.1

•

“Importing Data from WaterCAD/WaterGEMS Models” on page A-223

•

“Importing EPANET Files” on page A-223

•

“Importing Surge2000 and PIPE2000 Data” on page A-223

•

“Importing from a Database Using the HAMMER Datastore” on page A-223

•

“Additional Considerations When Working with Large Model Files” on page A224

Transitioning from Steady-State Models to HAMMER The following sections cover the key aspects of importing data from WaterCAD/ WaterGEMS using WaterObject technology, from EPANET, or from other steady-state hydraulic models.

Scenario Management Alternatives are collections of data, such as junction demands or pump and valve operational settings. A scenario references a certain combination of these alternatives to reduce the chance of alternative data sets being mishandled. Typically, water-supply scenarios are managed in the steady-state model, such as WaterCAD or WaterGEMS, and the selected design is subsequently imported to HAMMER as an initial steady state, where it is analyzed for hydraulic transients to specify suitable surge-protection equipment. HAMMER does not support scenario management directly, but it can store the name of the original WaterCAD or WaterGEMS file, the name of the scenario, and the time step you imported in the Summary tab of the Project Options dialog. Each HAMMER model generates its own set of input and output files, which can be very large, consequently, you should be aware of the following:

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•

HAMMER does not store multiple scenarios in a single file at this time, in part to limit file size and also to avoid decreasing performance when generating tabular reports or viewing animations. Each scenario must be saved as a separate set of input and output files.

•

You cannot open multiple files at once within a HAMMER session. If you need to compare the results of different output files, you can save each file’s results to a HAMMER graph file (.GRP) and copy and paste data between these .GRP files. This uses less computer resources than opening each in a separate instance of HAMMER from the START menu.

HAMMER User's Guide

Frequently Asked Questions •

It is highly recommended that you create a new folder for each alternative to store the many files HAMMER may create (.HIF, .HOF, .ANI, .GRP, .MDB, .RPT, .OUT, and others)

•

As your understanding of the pipe system’s response to transients improves with each HAMMER run, you may want to archive or compress certain folders to save disk space. Be sure to keep the .HIF and any .GRP or .MDB you generated yourself from the FILE menu. Animations are stored in the .HOF (output data) and .ANI (layout).

Demand Alternatives Steady-state models consider many demand alternatives (Avg. Day, Max Day, Peak Hr.) and development conditions (Year 2018, Year 2033). Transient Tip: For each development condition, two demand alternatives are typically critical in terms of their potential for significant hydraulic transients: peak hour and minimum hour. Results should be scrutinized at each location with a major facility (e.g., reservoir or booster pump) and for pipeline profiles/paths along the largest pipes connecting pumping and storage elements.

Control Valves Transient Tip: Hydraulic transients of interest to designers usually result in pressure wave fronts which travel so quickly throughout a water system that the most severe high and low pressure cycles occur before control valves have sufficient time to significantly respond to these changes. Since pressure-relief and other valves may not react quickly enough during a transient event, HAMMER maintains their initial settings throughout the simulation period. It is safer to neglect the pressure relief such valves may provide during transients and to rely solely on surgecontrol valves or other equipment specially designed to control transients. If valves are controlled according to pressure or flow at a given node, complete the transient analysis (which lasts a few seconds or minutes), then set up the final steady state in WaterCAD and restart your EPS simulation to model these modulating valves.

Based on hydraulic conditions in the system at steady state (i.e., time zero) HAMMER will convert the following valve types to valves with a fixed opening (acting as an inline orifice), which results in an equivalent head loss:

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Import/Export Tips •

Pressure-Regulating Valves (PRVs) that open to allow liquid to escape when pressure equals or exceeds a set point.

•

Flow-Control Valves (FCVs) that throttle open or closed to maintain a set flow rate.

•

Pressure-Sustaining Valves (PSVs) that throttle open or closed to maintain a set pressure.

•

Pressure-Breaker Valves (PBVs) that create a constant headloss across the valve.

•

Throttle-Control Valves (TCVs) that allow you to adjust minor loss coefficients based on system pressures, HGLs, or time.

•

Any open or partially open isolation valve.

Pumps and Pump Curves HAMMER supports multipoint pump curves to describe the relationship between flow and head for the overwhelming majority of applications for which both are positive. This is because pumps are typically equipped with a check valve to prevent flow from reversing through the pump. In fact, HAMMER also provides four-quadrant characteristic curves in terms of relative flow, Q, and speed, N, to describe every possible mode of operation for a turbomachine, be it a pump or turbine: •

First quadrant (Q>0, N>0)—the majority of pumps in water systems.

•

Second quadrant (Q<0, N>0)—flow reverses through the pump even though the pump’s spin direction is unchanged (assuming no check valve or nonreturn ratchet).

•

Third quadrant (Q<0, N<0)—flow and spin reverse and the turbomachine performs like a turbine, removing some energy from the fluid.

•

Fourth quadrant (Q>0, N<0)—flow is exiting as per the pump design, but spin reverses and power is dissipated, while the turbomachine is removing energy from the liquid. For more information, see “Pump Theory” on page B-267.

In Summary HAMMER can accurately represent many more features and behaviors than steadystate models. The following are two very important points that we emphasize as you prepare to use HAMMER for the first time:

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•

Context-sensitive online help is available from anywhere in the program by pressing the F1 key or by clicking the Help toolbar button.

•

Don’t be afraid to explore. Some of the most-intuitive features can be easy to overlook, but are great time-savers once you discover them. Play with the model and discover the satisfaction that comes from mastering such a powerful tool.

HAMMER User's Guide

Frequently Asked Questions

A.2.2

Importing Data from WaterCAD/WaterGEMS Models You can use WaterObjects technology to import data from a WaterCAD or WaterGEMS model into HAMMER. Start WaterObjects using File > Import > Network > WaterCAD/WaterGEMS on the HAMMER menu. The import procedure is described in detail in “Part 3—Importing Haestad Methods Models Using WaterObjects” on page 3-113.

A.2.3

Importing EPANET Files Note:

In EPANET, pumps and valves are modeled as links. In HAMMER, they are modeled as node elements. Hence, during an import, each EPANET valve and pump link is replaced by two pipes and one pump or valve element. This will not affect the behavior of these elements in your system.

Select File > Import > Network and choose EPANET. Then, from the File > Open window, select the EPANET file to import. For more information, see “Part 1— Creating or Importing a Steady-State Model” on page 3-82.

A.2.4

Importing Surge2000 and PIPE2000 Data This program supports the import of most hydraulic elements from PIPE2000 data sets. Alternatively, you may be able to open these and resave them as EPANET version 2.0 format, which can be imported into HAMMER. HAMMER imports pipes and most nodes from Surge2000 models. You need to insert certain pump, valve, tank data, and additional information into the current project. For more information, see “Part 4—Importing from Other Models” on page 3-114.

A.2.5

Importing from a Database Using the HAMMER Datastore HAMMER’s ability to read and write Access database files means that your hydraulic model can easily be linked to virtually any major database, spreadsheet, or GIS product currently in use today. HAMMER’s support for FlexUnits ensures you are not limited to a specific unit system. For more information, see “Part 1—Exporting an Input or Output File to a HAMMER Datastore” on page 3-105.

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Modeling Tips

A.2.6

Additional Considerations When Working with Large Model Files It is possible to run out of RAM while running or animating very large networks with thousands of pipes or by running HAMMER for thousands of seconds. Due to inherent memory-management default in Windows, it is possible for performance to decrease drastically if your system is forced to create virtual memory on the hard disk. To avoid this, it is recommended you use the following memory-management procedure:

A.3

•

Don’t use Generate Animation Data or Generate Output Database unless you need to actually view the animations or use the Access database or reports, respectively. This will decrease execution time and memory use.

•

Always output the minimum number of time steps possible, relying on the maximum transient envelopes for the extreme high and low heads. In Project Options, click the Report Times tab and use the periodically option, with a period of 10 or 20. Only for the final run or when smooth animations are required should you ever output every time step (and even then, only if required).

•

Close animation data files (.ANI or .HOF), the HAMMER Viewer, and the Animation Controller when they are not in use. This frees up valuable memory and resources during a large system run.

•

If you have been editing large model files for a few hours in HAMMER Modeler, consider closing it and reopening it and your .HIF file prior to a large model run. This closes the Java VM and creates a new one, which may free memory in some cases.

Modeling Tips These FAQs are related to modeling water-distribution networks with HAMMER. Also, please keep in mind that Haestad Methods offers workshops in North America and abroad throughout the year. These workshops cover these and many more modeling topics in depth.

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Frequently Asked Questions

A.3.1

How Do I Set Up a HAMMER Project? How do I calculate the pressure wave speed for different materials, fluids, and anchorage conditions? The pressure-wave speed or acoustic wave speed of a liquid is the speed at which a disturbance propagates through a closed-conduit, pressurized piping system. See “Liquid Properties” on page 4-146 for values and ranges for water and typical (buried) pipe materials. The pressure-wave speed depends on the liquid's wave celerity and the pipe and bedding or anchorage as described in detail in “Celerity and Pipe Elasticity” on page B-257. How do I choose the most appropriate four-quadrant pump curve and what are the errors involved? If you need a four-quadrant pump curve but your pump's specific speed does not match one of the available options, select the closest one available or request it from the manufacturer. The prediction error cannot be linearly interpolated using specific speed, but you could run a different curve to bracket the solution domain. For more information, see “First-Quadrant and Four-Quadrant Representations” on page 6-175 and “Specific Speed” on page 6-174. What is the effect of using the various friction models and when is it appropriate to use each one? The most widely used steady-state friction loss calculation methods include the Hazen-Williams and Manning’s equations—in which friction losses are proportional to relative pipe roughness but not to changes in flow. HAMMER uses the more rigorous Darcy-Weisbach method, in which friction losses are proportional to relative pipe roughness and to changes in flow. In HAMMER, a hydraulic transient analysis usually begins with an initial steady state in which the heads and flows are known for every pipe in the system. Prior to beginning the transient calculations, HAMMER automatically determines the friction factor based on this information. HAMMER can also use advanced quasi-steady or transient friction models. For more information, see “Selecting the Friction Method” on page 4147. How do I determine the need for a transient analysis? It is always a good idea to run HAMMER to check extreme transient pressures for any system with large changes in elevation, long pipelines with large diameters (i.e., mass of water), and initial (e.g., steady-state) velocities in excess of 1 m/s. In some cases, hydraulic transient forces can result in cracks or breaks, even with low steady-state

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Modeling Tips velocities. For more information, see “Design of Protective Equipment” on page B244. The effect of system topology, fluid characteristics, and most likely causes of transients are discussed in terms of the possible effects of transients in “Overview of Hydraulic Transients” on page B-236. Compared with steady-state models, what additional data or considerations are required for a transient model? Data requirements for hydraulic transient simulations are greater than for EPS or steady-state runs. In addition to data required by a steady-state model, you also need to determine the following: •

Pipe elasticity (pressure-wave speed)

•

The fluid’s vaporization limit (vapor pressure)

•

Pumps’ combined pump and motor inertia and controlled ramp times, if any

•

Pumps or pump-turbine characteristics for hydropower systems

•

Valves’ controlled operating times and their stroke-to-discharge coefficient (or open-area) relationship

•

The characteristics of surge-protection equipment

See the HAMMER help resources and “Hydraulic Element Reference” on page 6-161 to ensure that the correct data and parameters are entered in the model. For more information, see: “Data Requirements and Boundary Conditions” on page 7-192. How does HAMMER determine the time step? Note:

The time step cannot be directly modified in HAMMER. This is to avoid excessively long runs and large memory requirements on the one hand, or inaccurate answers due to coarse time steps on the other hand.

HAMMER selects a suitable time step automatically, using an advanced optimization algorithm that considers the lengths and pressure-wave speeds of pipes, network complexity, and heuristics. How does HAMMER model water-column separation and the movement of air? Air and/or vapor can fill a pipe when the water it carries separates into two columns due to rapidly changing momentum and hydraulic transient pressures. HAMMER has an advanced vaporous-cavitation model and it is even able to model the position of the air/liquid interface at high points. For more information, see “Water Column Separation and Vapor Pockets” on page 7-193.

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Frequently Asked Questions

A.3.2

Modeling a Hydropneumatic Tank Hydropneumatic tanks, also known as air chambers, are modeled using a gas vessel element in HAMMER as a reminder that these are pressure vessels, which must be specified with care and in accordance with local codes (e.g., ASME code). Consider a few key concepts: •

The gas and liquid in the pressure vessel are at the same pressure, typically equal to the discharge header pressure. Gas vessel pressure has no relationship to the liquid level, which must be determined based on level probes and, ideally, a sight glass as a backup.

•

The volume of gas required depends on the hydraulic transient dynamics of the system; there must be enough gas to avoid a partial vacuum in the vessel when the gas expands.

•

The volumes of gas and liquid required are proportional to the volume of vapor predicted by HAMMER for an unprotected run.

•

Try several HAMMER runs, changing the initial volume of gas until the liquid outflow is sufficient to limit extreme transient heads, and/or to dampen transient energy quickly enough. A differential orifice will generally attenuate transients faster.

For more information, see “Gas Vessel or Air Chamber” on page B-294.

A.3.3

Modeling a Pumped Groundwater Well A groundwater well is modeled using a combination of a reservoir and a pump. Set the hydraulic grade line of the reservoir at the static groundwater elevation. The hydraulic profile of a groundwater well pump’s vertical suction and, often, horizontal discharge line results in a “knee” at the turn to the horizontal. For pumps installed near or below ground level, it is possible to achieve vapor pressure and water-column separation at the knee, because the water in the vertical riser slows more rapidly than the water in the horizontal section after a power failure. This can result in very significant and sudden high pressures when the water columns subsequently rejoin. Unless well heads are capped and surrounding soils are not contaminated, it is possible to suck air and/or groundwater into the horizontal pipeline during the resulting subatmospheric or vacuum-pressure conditions. Such short-lived transients can potentially contaminate the water supply.

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Modeling Tips

A.3.4

Modeling Parallel Pipes Warning!

Different profiles will result in different changes in momentum, and potentially very different transient pressures, during a transient event. Hydraulic transient equivalency is not the same as steady-state equivalency.

HAMMER allows you to create parallel pipes by drawing pipes with the same end nodes. If you plan to combine two parallel pipes into one equivalent pipe with a larger diameter, check that they both have the same vertical profile.

A.3.5

Modeling Pumps in Parallel and Series Note:

With pumps in series, it is often possible to use a single composite pump rather than multiple pumps. When pumps are shut off, it is easier to control a single pump.

Pumps in parallel can be modeled by inserting a pump on different pipes that have the same suction and discharge nodes or by modeling the suction and discharge headers explicitly. However, short pipes in suction and discharge headers are extremely close together from a hydraulic transient perspective. Based on wave speeds of, typically, 1,000 m/s, an entire header will usually behave as a single node, so consider modeling it that way.

A.3.6

Modeling Hydraulically Close Tanks If tanks are hydraulically close, as in the case of several tanks adjacent to each other, it is convenient to model these tanks as one composite tank with the equivalent total surface area of the individual tanks. This process hides fluctuations that may occur if the tanks are modeled individually. Such fluctuations can be caused by small differences in flow rates to or from the adjacent tanks, which may offset the water surface elevations over time enough to become significant.

A.3.7

Top-Feed/Bottom Gravity Discharge Tank A tank element in HAMMER is modeled as a bottom-feed tank. Some tanks, however, are fed from the top, which is different hydraulically and should be modeled as such.

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Frequently Asked Questions

Elevated tank

To distribution system Pump

Reservoir

Figure A-1: Top Feed/Bottom Gravity Tank To model a top-feed tank at steady state, start by connecting an orifice to atmosphere to the end of the pipe feeding the tank, but do not connect the orifice to the tank. Run HAMMER. If transient inflows are small compared to the tank volume, you can model the tank as a reservoir. Otherwise, take the simulated transient orifice outflows and enter them as a time-varying inflow hydrograph for the MH element. The outlet of the reservoir or MH tank can then proceed to the distribution system.

Orifice to atmosphere

Tank represented as a reservoir or as a MH with a time-varying inflow

P-2

P-3 P-7

Reservoir

P-6

Pump

P-4

J1

J2

Figure A-2: Example Layout

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Modeling Tips

A.3.8

Estimating Hydrant Discharge Using Flow Emitters In HAMMER, hydrants are modeled using the hydraulic element orifice at branch end. You can enter the length of the connecting pipe or “Fire Hose” and the elevation of the discharge point or nozzle. HAMMER models the outflow as an orifice demand (i.e., as a function of head) in a manner analogous to a flow emitter in WaterCAD. HAMMER automatically calculates the emitter coefficient based on the typical flow and pressure you specify. In order to accurately model a hydrant, you can find an overall head loss for the hydrant and the conversion of pressure head to velocity head (K value) from AWWA Standards C502 and C503. For example, the standards state that a 2.5 in. (63 mm) outlet must have a pressure drop less than 2.0 psi (1.46 m) when passing 500 gpm (31.5 l/s). You can enter these pressure drops and flows directly in HAMMER. A typical hydrant lateral in North America is 6 in. (150 mm) and typical outlet sizes are 2.5 in. (63 mm) and 4.5 in. (115 mm). Values for k vary from minimum values, which can be back calculated from AWWA standards, to much higher values actually delivered by hydrants. Values for K for a range of k values for 6 in. (150 mm) pipes are given in the following table. Table A-1: Emitter K Values for Hydrants Outlet Nominal (in.)

k gpm, psi

k l/s, m

K gpm, psi

K l/s, m

2.5

250-600

18-45

150-180

11-14

2-2.5

350-700

26-52

167-185

13-15

4.5

447-720

33-54

380-510

30-40

The listed coefficients given are based on a 5 ft. (1.5 m) burial depth and a 5.5 in. (140 mm) hydrant barrel. A range is given because each manufacturer has a different configuration for hydrant barrels and valving. The lowest value is the minimum AWWA standard.

A.3.9

Modeling Variable-Speed Pumps HAMMER can model the behavior of variable-speed pumps (VSP), whether they are controlled by variable-frequency drives, hydraulic transmissions, or other couplings between the motor and impeller ends. You can specify speed or torque ramps directly and let HAMMER keep track of the rate at which flow will ramp up or down as a function of efficiency and inertia, just as the motor controllers or soft-starters do in actual systems. No work-around is required.

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Frequently Asked Questions •

One parameter that can be used to adjust pump performance is its speed. For any speed less than the motor’s full rated speed, HAMMER automatically uses the pump affinity laws to adjust the pump-head characteristic curve.

•

You can specify a variation in torque, typically to model pumps whose motor input is constant but where a variable-torque transmission is used to transfer it to the impeller. These mechanisms are common in industrial applications and for some older pumps.

Motor start and stop sequences are usually predetermined, being merely activated by a Start or Stop command on the motor control center panel or SCADA system. During the ensuing pump operation, it is often not possible to control the pump based on the system conditions. Steady-state pumping must first be achieved. HAMMER does not support feedback-loop pump controls (based on the pressure or flow at a node). For this behavior, model the transient event with a duration long enough to return the system to a final steady state. Then transfer this steady state back to WaterCAD and continue your analysis of the system as an extended-period simulation.

A.4

How Do I Access the Knowledge Base? You can access hundreds of commonly asked questions at our online Knowledge Base. The quickest way to access the Knowledge Base is to click the Globe Icon in the product toolbars. This will automatically log you on to our Web site. Simply click the Knowledge Base icon next to the Haestad product of interest. If the computer you are using does not have internet access, you can log on to Knowledge Base at an alternate computer by going to http://www.haestad.com and entering the ClientCare portion of the Web site. You can then log on with the Product ID located in the back of the user’s manual or your PID number.

A.5

Display Tips This section discusses the following tips: •

“How Do I Display my Organization’s Name and Logo?” on page A-232

•

“How Do I Control Element and Label Display?” on page A-232

•

“How Do I Color-Code Elements?” on page A-232

•

“How Do I Reuse Sets of Hydraulic Elements?” on page A-233

•

“How Do I Copy a Path from One HAMMER Project to Another?” on page A233

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Display Tips

A.5.1

How Do I Display my Organization’s Name and Logo? Note:

Entering an organization name will affect graphs and tables generated by HAMMER.

In HAMMER Modeler, select Tools > Viewer > Graphics to start the HAMMER Viewer, and do the following:

A.5.2

•

Click Tools > Set Logo to enter your organization’s logo. It must be a .GIF file. Text you enter as your organization’s name will only display in the space left over by the icon.

•

Click Tools > Set Company Name to enter your organization’s name. If you do not enter a logo, the name will occupy all of the available space on graphs. The organization name also appears in the footers of predefined tables.

How Do I Control Element and Label Display? To change the appearance of element symbols and labels: •

Select Tools > Global HAMMER Options and select the Other Options tab. You can select the default font and turn on anti-alias display for sharper lines and curves. You can also set the background and foreground Drawing Pane colors in the Colors tab.

•

Select Tools > Project Options and then the Other Options tab. You can select the default font here as well and turn on the display of pipes or node labels. You can also toggle the display of short labels or full-length labels. These options can help clean up the display of a large system in the Drawing Pane.

These changes have no effect on pipe lengths or other model parameters.

A.5.3

How Do I Color-Code Elements? To color-code hydraulic elements shown on the Drawing Pane, do the following: 1. Select the Map Selector choice list on the HAMMER Modeler toolbar. 2. Select the variables to use for color-coding nodes and pipes. You can choose from maximum or minimum heads, pressures, or flows and maximum vapor or air volume. 3. Click Scales at the bottom of the Pipe or Node portion of the choice list to display the Color Map Settings window.

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Frequently Asked Questions 4. Select a color ramp and the values for its upper and lower limits. You can also set intermediate limits and colors and HAMMER will automatically interpolate between these values. 5. Click Legend at the bottom of the Pipe or Node portion of the Map Selection list, then click a location in the Drawing Pane to display the legend and color-scale bar.

A.5.4

How Do I Reuse Sets of Hydraulic Elements? HAMMER makes it easy to select and reuse sets of hydraulic elements to quickly assemble repetitive models of pump suction and discharge lines, for example: 1. Click the Select (arrow) icon on the toolbar and select the hydraulic elements you want to reuse, then select Edit > Copy. 2. Do not click elsewhere in the drawing. Select Edit > Paste to reproduce this set of hydraulic elements as many times as you like. HAMMER will automatically assign different labels to each node and pipe you add to the Drawing Pane in this way. Inserted sets are automatically selected to allow you to move them around easily.

A.5.5

How Do I Copy a Path from One HAMMER Project to Another? If each of the pipes in a valid path exists in another HAMMER project file, you can copy the path using Tools > Copy Paths. Click Browse to select the file that already has the path, click to check the paths to copy, and click Browse to select the project file to which you want to copy the paths. Click Copy to complete the task.

A.6

Editing Tips The right mouse button can be used to: •

Select units and precision for displaying data.

•

Get help for dialog boxes and data entry fields.

•

Open a shortcut menu of command options for an element.

HAMMER User's Guide

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Editing Tips

A-234

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Appendix

B

HAMMER Theory and Practice HAMMER is an advanced numerical simulator of hydraulic transient phenomena (water hammer) in water, wastewater, industrial, and mining systems. Built with busy engineers in mind, it simplifies data entry and allows you to focus on visualizing, improving, and delivering your results quickly and professionally. HAMMER can handle any fluid or system that a typical steady-state hydraulic model like WaterCAD can, but it can also solve a broader range of problems, as shown in the table below. Table B-1: HAMMER Capabilities WaterCAD

HAMMER*

Steady or gradually varying turbulent flow

Rapidly varying or transient flow

Incompressible, Newtonian, singlephase fluids

Slightly compressible, two-phase fluids (vapor and liquid) and two-fluid systems (air and liquid)

Full pipes

Closed-conduit pressurized systems with air intake and release at discrete points

• * HAMMER capabilities are in addition to WaterCAD’s capabilities

With HAMMER, you can analyze drinking water systems, sewage forcemains, fire protection systems, well pumps, and raw-water transmission lines. You can change the specific gravity of the fluid to model oil or slurries, for example. HAMMER assumes that changes in other fluid properties, such as temperature, are negligible. It does not currently model fluids with significant thermal variations, such as can occur in cogeneration or industrial systems. The HAMMER algorithms will grow and evolve to keep pace with the state of the practice in water distribution and wastewater collection modeling. Because the mathematical solution methods are continually extended, this manual deals primarily with the fundamental principles underlying these algorithms and focuses less on the details of their implementation.

HAMMER User's Guide

B-235

Acknowledgements This appendix introduces the principles of hydraulic transients in piping systems, reviews current analytical approaches and engineering practices, discusses the potential sources and impacts of water hammer, and presents a proven approach to help you select and size surge-control equipment. Several transient simulations are integrated into the discussion to provide context.

B.1

Acknowledgements HAMMER is based on technology originally created by Environmental Hydraulics Group (EHG), led by Dr. Alan Fok, P.Eng., a designated Hydraulic Specialist, and assisted by Dr. Sheldon Zemell. Haestad Methods and EHG have forged a long-term collaboration to support and improve HAMMER. The software is intended to represent the latest technology in water hammer analysis and design. Some of the text in this section is adapted from Chapter 13 of Haestad Press’ Advanced Water Distribution Modeling and Management (AWDM), written by Dr. Edmundo Koelle, Dr. Thomas Walski, P.E., and the Haestad staff, or extracted from Alan Fok’s past technical publications and Ph. D. thesis.

B.2

Overview of Hydraulic Transients A transient is a temporary flow and pressure condition that occurs in a hydraulic system between an initial steady-state condition and a final steady-state condition. When velocity changes rapidly in response to the operation of a flow-control device (for instance, a valve closure or pump start), the compressibility of the liquid and the elasticity of the pipeline cause a transient pressure wave to propagate throughout the system. If the magnitude of this transient pressure wave and the resulting transient flow variation is great enough and adequate transient-control measures are not in place, a transient can cause system hydraulic components to fail (for instance, a pipe burst). Transient Tip: In general, transients resulting from relatively slow changes in flow rate are referred to as surges, and those resulting from more rapid changes in flow rate are referred to as water hammer events. Surges in pressurized systems are different than tidal or storm surges, flood waves, or dam breaks, which can occur in open-water bodies. A water hammer wave travels much faster in a pressurized system and it can burst even the strongest pipes. In general engineering practice, the terms surge, transient, hammer, and water hammer are synonymous.

Transients can occur in pressurized systems conveying any fluid, including the following:

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HAMMER User's Guide

HAMMER Theory and Practice •

Water (raw or treated) systems—transmission lines including booster stations, low-head pumps and piping in water treatment plants, or high-lift pump stations and connected networks or distribution systems with branching and looping pipes.

•

Wastewater (sewage) systems—pressurized sewage forcemains, surcharged sewers flowing by gravity, and sewers that are partially pressurized and partially open channel.

•

Combined sewers and tunnels—combined sewers under surcharge with deepwell pump stations, time-varying inflows from surface sewer systems to drop shafts, and large storage chambers or deep tunnel conveyance or storage systems.

•

Hydro power—penstocks, turbines, and tailraces, including spherical valves.

•

Slurry or oil pumping—mining slurries and tailings reclaim lines, oil transmission pipelines, airport refueling systems, and liquefied natural gas (LNG) pumping.

•

Industrial fluid systems—closed loops, heaters, coolers, boilers, steam, and other water-conveyance or cogeneration systems. This requires a special version of HAMMER to track the heat of the fluid. A transient analysis is critical for operator safety.

HAMMER has been used extensively to analyze and design water and wastewater systems, as well as slurry and oil systems. EHG has analyzed steam, industrial, and cogeneration systems with custom versions and has calculated transient forces on above-ground anchors.

B.2.1

History of Solution Methods The study of hydraulic transients is generally considered to have begun with the works of Joukowsky (1898) and Allievi (1902). The historical development of this subject makes for good reading (Wood F., 1970). A number of pioneers made breakthrough contributions to the field, including R. Angus and John Parmakian (1963), who popularized and refined the graphical calculation method. Benjamin Wylie and Victor Streeter (1993) combined the method of characteristics with computer modeling. The field of fluid transients is still rapidly evolving worldwide (Brunone et al., 2000; Koelle and Luvizotto, 1996; Filion and Karney, 2002; Hamam and McCorquodale, 1982; Savic and Walters, 1995; Walski and Lutes, 1994; Wu and Simpson, 2000). Various methods have been developed to solve transient flow in pipes. These range from approximate equations to numerical solutions of the nonlinear Navier-Stokes equations: •

Arithmetic method—Assumes that flow stops instantaneously (in less than the characteristic time, 2 L/a), cannot handle water column separation directly, and neglects friction (Joukowski, 1898; Allievi, 1902).

HAMMER User's Guide

B-237

Overview of Hydraulic Transients •

Graphical method—Neglects friction in its theoretical development but includes a means of accounting for it through a correction (Parmakian, 1963). It is timeconsuming and not suited to solving networks or pipelines with complex profiles.

•

Design charts—Provides basic design information for simple topologies at a few specific points (valve closure, pump and pipeline with no protection, surge tank, or air chamber protection). This method has been replaced by computer programs (Fok, 1978; Fok, 1980; Fok et al., 1982) based on the transient energy concept and backed by field and laboratory work (Fok, 1987).

•

Wave-plan method—Represents initial transient disturbances as a series of pulses and tracks reflections at boundaries (Wood et al., 1966).

•

Method of Characteristics (MOC)—Most widely used and tested approach, with support for complex boundary conditions and friction and vaporous cavitation models. HAMMER uses the MOC. It converts the partial differential equations (PDEs) of continuity and momentum (e.g., Navier-Stokes) into ordinary differential equations that are solved algebraicially along lines called characteristics. An MOC solution is exact along characteristics, but friction, vaporous cavitation, and some boundary representations introduce errors in the results (Gray, 1953; Streeter and Lai, 1962; Elansary, Silva, and Chaudhry, 1994).

Haestad Press’ 2002 Advanced Water Distribution Modeling and Management documents other less-common methods. Transients have also been studied using: •

Laboratory Models—A scale model can be built to reproduce transients observed in a prototype (real) system, typically for forensic or steam system investigations. As a design method, this approach is limited by model scale effects and by very high costs. However, models have provided invaluable basic research data on vaporous cavitation and vortex shedding (St. Anthony Falls) and transient friction (Perugia, Italy).

•

Field Tests—Field tests can provide key modeling parameters such as the pressure-wave speed or pump inertia. Advanced flow and pressure sensors equipped with high-speed data loggers make it possible to capture fast transients, down to 5 milliseconds. Methods such as inverse transient calibration and leak detection use such data. Like all tests, however, data are obtained at a finite number of locations and generalizing the findings requires assumptions, with uncertainties spread across the system. At best, tests provide local data and a feel for the systemwide response. At worst, tests can lead to physically doubtful conclusions limited by the scope of the test program.

Neither laboratory models nor field testing can substitute for the careful and correct application of a proven hydraulic transient computer model, such as HAMMER.

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HAMMER Theory and Practice The extended-period simulation (EPS) capability of models such as WaterCAD or WaterGEMS does not consider momentum, and is therefore incapable of analyzing hydraulic transients. Such simulations are sufficient to analyze hydraulic systems that undergo velocity and pressure changes slowly enough that inertial forces are insignificant. If a system undergoes large changes in velocity and pressure in short time periods, then transient analysis is required.

B.2.2

Causes of Transient Initiation The cause of a hydraulic transient is any sudden change in the fluid itself or any sudden change at the pressurized system’s boundaries, including: •

Changes in fluid properties—such as depressurization due to the sudden opening of a relief valve, a propagating pressure pulse, heating or cooling in cogeneration or industrial systems, mixing with solids or other liquids (may affect fluid density, specific gravity, and viscosity), formation and collapse of vapor bubbles (cavitation), and air entrainment or release from the system (at air vents and/or due to pressure waves).

•

Changes at system boundaries—such as rapidly opening or closing a valve, pipe burst (due to high pressure) or pipe collapse (due to low pressure), pump start/ shift/stop, air intake at a vacuum breaker, water intake at a valve, mass outflow at a pressure-relief valve or fire hose, breakage of a rupture disk, and hunting and/or resonance at a control valve.

Sudden changes such as these create a transient pressure pulse that rapidly propagates away from the disturbance, in every possible direction, and throughout the entire pressurized system. If no other transient event is triggered by the pressure wave fronts, unsteady-flow conditions continue until the transient energy is completely damped and dissipated by friction. The majority of transients in water and wastewater systems are the result of changes at system boundaries, typically at the upstream and downstream ends of the system or at local high points. Consequently, you can reduce the risk of system damage or failure with proper analysis to determine the system’s default dynamic response, design protection equipment to control transient energy, and specify operational procedures to avoid transients. Analysis, design, and operational procedures all benefit from computer simulations with HAMMER. The three most common causes of transient initiation, or source devices, are all moving system boundaries.

HAMMER User's Guide

B-239

Overview of Hydraulic Transients

H.G .L.

Reservoir

Check Valve

Pump Sump

Pump

H.G.L.

H.G.L. Penstock Governor

Fl

ow

Generator F lo w Gate Turbine

Valve

Tailrace

Turbine

Valve

Figure B-1: Common Causes of Hydraulic Transients Pumps—A pump’s motor exerts a torque on a shaft that delivers energy to the pump’s impeller, forcing it to rotate and add energy to the fluid as it passes from the suction to the discharge side of the pump volute. Pumps convey fluid to the downstream end of a system whose profile can be either uphill or downhill, with irregularities such as local high or low points. When the pump starts, pressure can increase rapidly. Whenever power sags or fails, the pump slows or stops and a sudden drop in pressure propagates downstream (a rise in pressure also propagates upstream in the suction system). Turbines—Hydropower turbines are located at the downstream end of a conduit, or penstock, to absorb the moving water’s energy and convert it to electrical current. Conceptually, a turbine is the inverse of a pump, but very few pumps or turbines can operate in both directions without damage. If the electrical load generated by a turbine is rejected, a gate must rapidly stop flow, resulting in a large increase in pressure, which propagates upstream (in the penstock). Valves—A valve can start, change, or stop flow very suddenly. Energy conversions increase or decrease in proportion to a valve’s closing or opening rate and position, or stroke. Orifices can be used to throttle flow instead of a partially open valve. Valves can also allow air into a pipeline and/or expel it, typically at local high points. Suddenly closing a flow-control valve (with piping on both sides) generates transients on both sides of the valve, as follows:

B-240

•

Water initially coming towards the valve suddenly has nowhere to go. As water packs into a finite space upstream of the valve, it generates a high-pressure pulse that propagates upstream, away from the valve.

•

Water initially going away from the valve cannot suddenly stop, due to its inertia and, since no flow is coming through the valve to replace it, the area downstream of the valve may “pull a vacuum,” causing a low-pressure pulse to propagate downstream.

HAMMER User's Guide

HAMMER Theory and Practice The similarity of the transient conditions caused by different source devices provides the key to transient analysis in a wide range of different systems: understand the initial state of the system and the ways in which energy and mass are added or removed from it. This is best illustrated by an example for a typical pumping system (see “Figure B2: Typical Locations where Transient Pulses Initiate”on page B-242): 1. A pump (upstream source device) starts up from the static HGL and accelerates flow until its input energy reaches a dynamic equilibrium with friction at the steady HGL. 2. A power failure occurs and the pump stops supplying hydraulic energy; therefore, the HGL drops rapidly at the pump and a low-pressure pulse propagates downstream towards the reservoir. Subatmospheric pressures can occur at the high point (minimum transient head), but the reservoir maintains downstream pressure at its liquid level by accepting or supplying liquid as required, often several times during the transient event. Note:

As the HGL drops to the pipeline elevation, a vacuum breaker valve can be installed at the local high point to supply or expel air from the system in a manner analogous to the reservoir. This tends to maintain atmospheric pressure at the valve, minimizing subatmospheric pressures when air is admitted and often reducing high pressures when air is expelled.

3. The pressure pulse is reflected toward the pump, but it encounters a closed check valve (designed to protect the pump against high pressures) that reflects the pulse as a high pressure toward the reservoir again (maximum transient head). 4. Friction eventually attenuates the transient energy and the system reaches a final steady state: static HGL, in this case, since pumping has stopped and flow at the reservoir is zero. The foregoing discussion illustrates the typical concepts to consider when analyzing hydraulic transients. Computer models are an ideal tool for tracking momentum, inertia, and friction as the transient evolves, and for correctly accounting for changes in mass and energy at boundaries. Note that transients propagate throughout the entire pressurized system.

HAMMER User's Guide

B-241

Overview of Hydraulic Transients

Maximum Transient Head Friction ( hf )

Reservoir

Steady HGL Static HGL

High Point Devices

Pipeline

m imu Min

ad t He n e i ns Tra

Downstream Source Devices

Upstream Source Devices Reservoir

Figure B-2: Typical Locations where Transient Pulses Initiate Note:

B.2.3

Devices can be a pump, valve, or other operable equipment.

Impacts of Transients Hydraulic transients can result in the following physical phenomena: High or low transient pressures—These can be applied to piping and joints in a fraction of a second and they often alternate from high to low and vice versa. High pressures resulting from the collapse of vapor pockets are analogous to cavitation in a pump: they primarily accelerate wear and tear, but they can burst a pipe by overcoming its surge-tolerance limit. Subatmospheric or even full-vacuum pressures can combine with overburden and groundwater pressures to collapse pipes by buckling failure. Groundwater can also be sucked into the piping. High transient flows—These can result in significant degradation of water quality as deposits and rust are loosened and entrained at high velocities. This is aggravated whenever flows reverse direction during a transient event. High-velocity flows also exert forces at pipe bends. Transient forces—Rapidly moving pressure pulses result in temporary, but very significant, transient forces at bends and other fittings, which can cause joints to move. Even for buried pipe, repeated deflections combined with pressure cycling can wear out joints and result in leakage or outright failure. Thrust blocks are typically sized for steady-state forces plus a safety factor—not transient forces—and typically

B-242

HAMMER User's Guide

HAMMER Theory and Practice resist thrust in only one direction. In pump stations, low pressures on the downstream side of a slow-closing check valve may result in a very fast closure known as valve slam. A 10 psi (69 kPa) pressure differential across the face of a 16 in. (400 mm) valve can result in impact forces in excess of 2,000 lb. (8,900 N). Column separation—Water columns typically separate at abrupt changes in profile or local high points due to subatmospheric pressure. The space between the water columns is filled either by the formation of vapor (e.g., steam at ambient temperature) or air, if it is admitted to the pipeline through a valve. With vaporous cavitation, a vapor pocket forms and then collapses when the pipeline pressure increases as more flow enters the region than leaves it. Collapse of the vapor pocket can cause a dramatic high-pressure transient if the water column rejoins very rapidly, which can, in turn, cause the pipeline to rupture. Vaporous cavitation can also result in pipe flexure that damages pipe linings. High pressures can also result when air is expelled rapidly from a pipeline, which tends to repeat more times than when a vapor pocket collapses. Vibrations—Rapid transient pressure fluctuations can result in vibrations or resonance that can cause even flanged pipes and fittings (bend and elbows) to dislodge, resulting in a leak or rupture. In fact, the cavitation that commonly occurs with water hammer can—as the phenomenon’s name implies—release energy that sounds like someone pounding on the pipe with a hammer. Hydraulic transient impacts can be expected at the following locations: •

Check valves at pumps as flow reverses from the downstream reservoir to the pump.

•

Reservoir inlet valves, altitude valves at elevated tanks, or isolation valves if they close rapidly.

•

Local high points where vapor or air pockets collapse.

•

Dead ends as they reflect incoming pulses with up to double the wave amplitude.

•

Pipe bursts, where flow leaving the system may exceed the steady-state flow (in systems with high static head compared to the dynamic head).

•

Surge-control devices if not properly designed or operated.

•

Changes in pipeline profile or alignment where transient forces may be significant.

Hydraulic transient impacts can be expected to occur at the following times: •

Pump startup before transient energy has decayed sufficiently or before all air has been removed from the line.

HAMMER User's Guide

B-243

Hydraulic Transient Theory •

Pump emergency shutdown which may result in water-column separation and severe transient pressures due to vapor or air pocket formation and collapse.

•

Pump shifting during normal operations, which may result in frequent pressure shocks.

Environmental concerns due to hydraulic transients include: •

Sewage spills or leaks to soils or groundwater during high transient pressures.

•

Drinking water contamination due to air, debris, or groundwater intrusion during subatmospheric pressures.

Hydraulic transients can result in the following infrastructure management issues and risks:

B.2.4

•

Premature aging and wear of valves, pipes, and pumps due to high magnitude and/ or frequent pressure shocks.

•

Pump cavitation due to low suction head and pipe lining damage due to vacuum conditions.

•

Rapid pump or valve operation by major water users (e.g., a food production factory) may accelerate the pipe material and anchor fatigue in their vicinity.

•

Service interruptions due to repair and maintenance of infrastructure.

Design of Protective Equipment For typical water-distribution main installation, transient analysis may be necessary even if velocities are low. System looping and service connections may amplify transient effects and need to be studied carefully. Transient analysis should be performed for large, high-value pipelines, especially those with pump stations. A complete transient analysis, in conjunction with other system design activities, should be performed during the initial design phases of a project. Normal flow-control operations and predicable emergency operations should, of course, be evaluated during the design. However, uncommon flow-control activities can occur once the system is in operation, making it important that all factors that could affect the integrity of the system be considered.

B.3

Hydraulic Transient Theory In pressurized networks, a steady-state condition or transient event at one point in the system can affect all other parts of the system. Consequently, computer models must consider every pipe that is directly connected to a pressurized system, regardless of administrative or political boundaries.

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HAMMER Theory and Practice While a systemwide approach increases the information an engineer must consider, the physical principles that govern the behavior of the network provide a unified conceptual basis for tackling the problem. Two fundamental laws apply to steadystate, EPS or transient models: •

Conservation of mass—also expressed as the continuity equation, which states that matter cannot be created or destroyed.

•

Conservation of energy—also expressed as the momentum equation, which states that energy cannot be created or destroyed.

The best way to arrive at sound, physically meaningful conclusions and recommendations is to keep these principles in mind whenever you interpret the results of a hydraulic model. HAMMER makes this easy by tracking the mass inflow or outflow of air or water at any location and by plotting or animating the resulting total energy at any point and time in the system.

B.3.1

Conservation of Energy The first law of thermodynamics states that for any given system and time interval, the change in total energy is equal to the difference between the heat transferred to the system and the work done by the system on its surroundings. In hydraulic terms, changes in the total energy of a fluid do not consider changes in its internal (molecular) forms of energy, such as electrical and chemical energy, because these are usually relatively small. In hydraulic terms, energy is often represented as energy per unit weight, resulting in units of length. At any point in a hydraulic system, the total energy of a fluid consists of three components that can be expressed as an equivalent elevation, or head: Pressure Head:

p/γ

Elevation Head:

z

Velocity Head:

V2/2g

Where

HAMMER User's Guide

p

=

pressure (N/m2, lb/ft2)

γ

=

specific weight (N/m3, lb/ft3)

z

=

elevation (m, ft)

V

=

velocity (m/s, ft/sec.)

g

=

gravitational acceleration constant (m/s2, ft/sec.2)

B-245

Hydraulic Transient Theory Converting the total energy to an equivalent head allows it to be plotted on the same scale as elevation for any point in the system, either on pipeline profiles or maps, allowing engineers to visualize changes as slopes or contour lines, respectively. This gives a better feel for the resulting behavior of the system, especially when reviewing the results of an EPS or transient analysis. Further, the difference between this energy level and the pipeline elevation is equal to the total gauge pressure.

B.3.2

Governing Equations for Steady-State Flow Steady-state models, such as WaterCAD or WaterGEMS, are capable of two modes of analysis: steady state and extended period simulation (EPS). EPS solves a series of consecutive steady states using a gradient algorithm and accounting for mass in reservoirs and tanks (e.g., net inflows and storage). Both methods assume the system contains an incompressible fluid, so the total volumetric or mass inflows at any node must equal the outflows, less the change in storage. In addition to pressure head, elevation head, and velocity head, there may also be head added to the system, for instance, by a pump, and head removed from the system by friction. These changes in head are referred to as head gains and head losses, respectively. Balancing the energy across two points in the system yields the energy or Bernoulli equation for steady-state flow:

P1 V2 P V2 + z1 + 1 + h p = 2 + z2 + 2 + hL γ 2g γ 2g

Where

(B.1)

p

=

pressure (N/m2, lb/ft2)

γ

=

specific weight (N/m3, lb/ft3)

z

=

elevation at the centroid (m, ft)

V

=

velocity (m/s, ft/sec.)

g

=

gravitational acceleration constant (m/s2, ft/sec.2)

hp

=

head gain from a pump (m, ft)

hL

=

combined headloss (m, ft)

The components of the energy equation can be combined to express two useful quantities, the hydraulic grade and the energy grade:

B-246

HAMMER User's Guide

HAMMER Theory and Practice •

Hydraulic grade—The hydraulic grade is the sum of the pressure head (p/γ ) and elevation head (z). The hydraulic head represents the height to which a water column would rise in a piezometer. The plot of the hydraulic grade in a profile is often referred to as the hydraulic grade line or HGL.

•

Energy grade—The energy grade is the sum of the hydraulic grade and the velocity head (V2/2g). This is the height to which a column of water would rise in a pitot tube. The plot of the hydraulic grade in a profile is often referred to as the energy grade line or EGL. At a lake or reservoir, where the velocity is essentially zero, the EGL is equal to the HGL, as can be seen in the following figure.

Figure B-3: EGL and HGL

Conservation of Mass at Steady State At any node in a system containing incompressible fluid, the total volumetric or mass flows in must equal the flows out, less the change in storage. Separating these into flows from connecting pipes, demands, and storage, gives the continuity equation:

∑ QIN ∆t = ∑ QOUT ∆t + ∆Vs Where

HAMMER User's Guide

QIN

=

total flow into the node (m3/s, cfs)

QOUT

=

total demand at the node (m3/s, cfs)

∆VS

=

change in storage volume (m3, ft3)

∆t

=

change in time (sec.)

(B.2)

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Hydraulic Transient Theory

Conservation of Energy at Steady State The conservation of energy principle states that the head losses through the system must balance at each point. For pressure networks, this means that the total head loss between any two nodes in the system must be the same regardless of what path is taken between the two points. The sign of the head loss must be consistent with the assumed flow direction (i.e., gain head when proceeding opposite the flow direction and lose head when proceeding in the flow direction). The same basic principle can be applied to any path between two points. The combined head loss around a loop must be zero to achieve the same hydraulic grade as at the beginning.

B.3.3

Governing Equations for Unsteady (or Transient) Flow Hydraulic transient flow is also known as unsteady fluid flow. During a transient analysis, the fluid and system boundaries can be either elastic or inelastic: •

Elastic theory describes unsteady flow of a compressible liquid in an elastic system (e.g., where pipes can expand and contract). HAMMER uses the Method of Characteristics (MOC) to solve virtually any hydraulic transient problems.

•

Rigid-column theory describes unsteady flow of an incompressible liquid in a rigid system. It is only applicable to slower transient phenomena.

Both branches of transient theory stem from the same governing equations. HAMMER uses the more advanced elastic theory systemwide for virtually every simulation, but it can also switch to the faster rigid-column theory (in specific reaches and for special applications) to reduce execution time, as discussed in “Rigid-Column Simulation” on page 7-190. The continuity equation and the momentum equation are needed to determine V and p in a one-dimensional flow system. Solving these two equations produces a theoretical result that usually corresponds quite closely to actual system measurements if the data and assumptions used to build the numerical model are valid. Transient analysis results that are not comparable with actual system measurements are generally caused by inappropriate system data (especially boundary conditions) and inappropriate assumptions.

Continuity Equation for Unsteady Flow The continuity equation for a fluid is based on the principle of conservation of mass. The general form of the continuity equation for unsteady fluid flow is as follows:

B-248

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HAMMER Theory and Practice

∂H dH a 2 ∂V +V + =0 ∂t ∂x g ∂x Where

(B.3)

a

=

pressure wave speed

V

=

average velocity in the pipe, parallel to the x-axis

H

=

hydraulic grade line or HGL

The second term on the left-hand side of the preceding equation is small relative to other terms and is typically neglected, yielding the following simplified continuity equation, as used in the majority of unsteady models:

∂H a 2 ∂V + =0 g ∂x ∂t

(B.4)

Momentum Equation for Unsteady Flow The equations of motion for a fluid can be derived from the consideration of the forces acting on a small element, or control volume, including the shear stresses generated by the fluid motion and viscosity. The three-dimensional momentum equations of a real fluid system are known as the Navier-Stokes equations. Since flow perpendicular to pipe walls is approximately zero, flow in a pipe can be considered one-dimensional, for which the continuity equation reduces to:

fV V ∂V ∂V ∂H +V +g + =0 ∂x 2D ∂t ∂x Where

f

=

Darcy-Weisbach friction coefficient

=

inside diameter of the pipe (or equivalent dimension)

V

=

velocity of fluid

γ

=

specific weight of the fluid

D

(B.5)

The last term on the left-hand side represents friction losses in the direction of flow:

HAMMER User's Guide

B-249

Hydraulic Transient Theory

fV V 2D The first term on the left-hand side is the local acceleration term, while the second term represents the convective acceleration, proportional to the spatial change of velocity at a point in the fluid, which is often neglected to yield the following simplified equation:

fV V ∂V ∂H +g + =0 ∂t ∂x 2D

(B.6)

Equations B.4 and B.6, though rigorous and explicit, incorporate the following assumptions, which are often not strictly valid in real water systems: •

Fluid is homogeneous—water typically incorporates a small amount of dissolved and/or entrained air whose exact percentage changes along the system.

•

Fluid and pipe wall are linearly elastic—in aging water pipes whose shape has become noncircular and whose integrity may be compromised by cracks (virtually every water system leaks), fluid may escape the system rather than being compressed and deformations imposed on piping may not be entirely recovered.

•

Flow is one-dimensional—this assumption has been shown to be inaccurate at tees in suction lines. Minor losses result from three-dimensional vorticity.

•

Pipe flows full—even in pressurized systems, air or vapor can accumulate at local high points, forcing the water to accelerate and pass underneath it. In extreme cases, this phenomenon can significantly diminish pumping efficiency (e.g., vapor lock).

•

Average velocity is used—experiments show that the velocity distribution changes across a cross section during transient events, even for flow in straight pipes.

•

Viscous losses similar to steady state—emerging research in transient or unsteady friction is challenging this assumption.

Nevertheless, these assumptions are essentially valid for the majority of the time in the majority of water systems. Solving these equations yields accurate numerical simulation results in most cases.

Method of Characteristics (MOC) HAMMER uses the most widely used and tested method, known as the Method of Characteristic (MOC), to solve governing equations B.4 and B.6 for unsteady pipe flow. Using the MOC, the two partial differential equations can be transformed to the following two pairs of equations:

B-250

HAMMER User's Guide

HAMMER Theory and Practice

⎫ ⎪ fV V g dH dV + + = 0⎪ ⎪ ⎪ a dt dt 2D ⎪ ⎬ ⎪ dx ⎪ = +a ⎪ ⎪ dt ⎪ ⎭

⎫ ⎪ fV V g dH dV + + = 0⎪ ⎪ ⎪ a dt dt 2D ⎪ ⎬ ⎪ dx ⎪ = −a ⎪ ⎪ dt ⎪ ⎭

−

C+ (B.7)

C− (B.8)

Equations B.7 and B.8 cannot be solved analytically, but they can be expressed graphically in space-time as characteristic lines (or curves), called characteristics, that represent signals propagating to the right (C+) and to the left (C-) simultaneously and from each location in the system. At each interior solution point, signals arrive from the two adjacent points simultaneously. A linear combination of H and V is invariant along each characteristic if friction losses are neglected; therefore, H and V can be obtained exactly at solution points. With head losses concentrated at solution points and the assumption that friction is small, an iterative procedure is used in conjunction with MOC to advance the solution in time. Transient modeling essentially consists of solving these equations, for every solution point and time step, for a wide variety of boundary conditions and system topologies. To obtain a general computer model like HAMMER, the following additional capabilities are required: •

Boundary conditions must also be expressed as algebraic and/or differential equations based on their physical properties. This must be done for every hydraulic element in the model and solved along with the characteristic equations.

•

Equations of state are incorporated to model vaporous cavitation, whereby the fluid can flash into vapor at low pressures, for example. The assumptions incorporated into HAMMER are described in “Water Column Separation and Vapor Pockets” on page 7-193.

•

The length of computational reaches must be set to achieve sufficient accuracy without resulting in too small a time step and an excessively long execution time. HAMMER automatically sets an optimal time step based on pipe lengths, wave speeds, and overall system size, so you can get your model results faster.

•

Friction losses are assumed to be concentrated at solution points. Different models can be implemented, ranging from steady-state to quasi-steady to unsteady (transient) friction.

HAMMER User's Guide

B-251

Hydraulic Transient Theory HAMMER has been used for over 15 years on a large number of water and wastewater projects, evolving during this time to add new boundary conditions while preserving ease of use and accuracy. Thus, it is a proven model with many “electron miles” and a solid track record of matching field observations (when available). It has also been used to model other fluids and tackle problems in other industry sectors, adding to its generality and confirming its robust algorithms. A derivation of the complete equations for transient analysis (using elastic theory) is beyond the scope of this manual, but it can be found in other references, such as Almeida and Koelle (1992) and Wylie and Streeter (1993). The derivation for incompressible flow and rigid pipe walls is provided in the next section. The derivation of the wave celerity and pressure-wave speed for compressible flow and elastic system boundaries is provided next.

B.3.4

Rigid Column Theory The rigid model assumes that the pipeline is not deformable and the liquid is incompressible; therefore, system flow-control operations affect only the inertial and frictional aspects of transient flow. Given these considerations, it can be demonstrated using the continuity equation that any system flow-control operations results in instantaneous flow changes throughout the system, and that the liquid travels as a single mass inside the pipeline, causing a mass oscillation. If liquid density and pipe cross section are constant, the instantaneous velocity is the same in all sections. These rigidity assumptions result in an easy-to-solve ordinary differential equation; however, its application is limited to the analysis of surge. Newton’s second law of motion is sufficient to determine the dynamic hydraulic of a rigid water body during the mass oscillation: dH = f (L/D)(V|V|/2g) + (L/g) (dV/dt) Where

dH

=

(B.9)

change in head (m, ft)

If a steady-state flow condition is established—that is, if dV/dt = 0—then this equation simplifies to the Darcy-Weisbach formula for computation of head loss over the length of the pipeline. However, if a steady-state flow condition is not established because of flow control operations, then three unknowns need to be determined: H1(t) (the lefthand head), H2(t) (the right-hand head), and V(t) (the instantaneous flow velocity in the conduit). To determine these unknowns, the engineer must know the boundary conditions at both ends of the pipeline.

B-252

HAMMER User's Guide

HAMMER Theory and Practice Using the fundamental rigid-model equation, the hydraulic grade line can be established for each instant. The slope of this line indicates the head loss between the two ends of the pipeline, which is also the head necessary to overcome frictional losses and inertial forces in the pipeline. For the case of flow reduction caused by a valve closure (dQ/dt < 0), the slope is reduced. If a valve is opened, the slope increases, potentially allowing vacuum conditions to occur. The change in slope is directly proportional to the flow change. Generally, the maximum transient head envelope calculated by rigid water column theory (RWCT) is a straight line, as shown in the following figure. Maximum Transient Head Envelope (Elastic) Maximum Head (Rigid) Reservoir Steady-State HGL id) Head (Rig Minimum

Minimum Transient Head Envelope (Elastic)

Pipeline Pump Station Reservoir

+

Transient Energy Calculated by Elastic Water Column Theory (EWCT) Transient Energy Calculated by Rigid Water Column Theory (RWCT)

Figure B-4: Static and Steady HGL versus Rigid and Elastic Transient Head Envelopes The rigid model has limited applications in hydraulic transient analysis because the resulting equations do not accurately model pressure waves caused by rapid flowcontrol operations. The rigid model applies to slower surge or mass oscillation transients, as defined in “Wave Propagation and Characteristic Time” on page B-261. During mass oscillations, moderate changes in head occur slowly, allowing changes of the liquid density and/or elastic deformation of the pipeline to be neglected. Mass oscillations routinely occur while deep sewers or tunnel systems are filling. Based on simulations for an actual project, “Figure B-5: Mass Oscillations during Deep Tunnel Filling”on page B-254 shows: •

Liquid levels in the large transmission (sewer or tunnel) and storage (large vertical chamber) elements typically rise gradually as the system fills.

•

The different flow rates contributed by surface sewers, and conveyance in the deep system, causes each storage chamber (A, B, and C) to fill at a different rate.

HAMMER User's Guide

B-253

Hydraulic Transient Theory •

Liquid levels in smaller inflow drop shafts can fluctuate significantly at a much higher frequency than the large storage chambers, possibly resulting in a spill to surface sewers or even to ground level. Resonance and amplification are possible in these shafts and elastic theory may be required to correctly model the faster changes in liquid level.

•

As the entire system becomes full, levels in the large chambers may significantly exceed the ground elevation as excess energy is required to accelerate water (in the submerged outfall pipes) from zero to a steady-state velocity. Overflows may occur at the chambers unless adequate provision is made for this temporary condition. 85 Initial spill

80

Start of spill to ground

Start of overflow to Lake at large storage chambers via three submerged pipes

Lake Level 75.2 m

75

Rapid and large level fluctuations in small shafts by Elastic Water Column Theory (EWCT)

Water Level Elevation (m)

70

65

60

55 Water levels rise slowly in large chambers as mass oscillations take place. Solvable using Rigid Water Column Theory (RWCT.)

50

45

Legend

40

Storage Chamber A Inflow Shaft

35

Storage Chamber B Storage Chamber C

30

25

0

5

10

Time (minutes)

15

(from EHG project)

Figure B-5: Mass Oscillations during Deep Tunnel Filling This example illustrates the importance of using HAMMER to identify the spill potential of a deep sewer or storage system prior to detailed design and commissioning.

B-254

HAMMER User's Guide

HAMMER Theory and Practice

B.3.5

Rigid Column versus Elastic Theory Prior to the widespread use of computers, the subject of rigid water column-theory was very popular. Substantial effort was devoted by numerous researchers and engineers to improve its accuracy and to determine the range of its application. “Figure B6: When to Use Elastic versus Rigid Column Theory for a Valve Closure”on page B256 is a dimensionless plot of valve closure time (divided by half the characteristic time, L/a) versus the ratio of initial head to transient head in a frictionless (or very low friction) system. The graph shows that different researchers, beginning in 1933, proposed various criteria to determine when an elastic solution is necessary and when a rigid-column solution is sufficiently accurate. The thick black lines were obtained from computer simulations using both methods and showing the level of error resulting from using RWCT instead of EWCT (Fok, 1987). The error resulting from RWCT instead of EWCT is shown graphically in “Figure B-6: When to Use Elastic versus Rigid Column Theory for a Valve Closure”on page B-256. EWCT correctly accounts for fluid compressibility, resulting in a significantly higher estimate of the maximum transient head than RWCT. HAMMER solves every problem using elastic theory and the MOC for maximum accuracy.

HAMMER User's Guide

B-255

Hydraulic Transient Theory

Fok’s boundary (1987) between EWCT and RWCT using HAMMER

5 2.5 % of ERROR

VALVE HEAD,

Ho = (gho/avo)

20 10

Symbols g = gravitational acceleration (m/s) ho = head loss across valve (m) a = pressure wave speed (m/s) Vo= initial flow velocity through valve (m/s) tq = time of valve closure (s) l = pipe length (m)

Wo

’s od

RW

( CT

) ,74 73 19

TIME of VALVE CLOSURE T q = (tq/l/a) (from Dr. Fok’s 1987 Thesis)

Figure B-6: When to Use Elastic versus Rigid Column Theory for a Valve Closure

B.3.6

Elastic Theory The elastic model assumes that changing the momentum of the liquid causes expansion or compression of the pipeline and liquid, both assumed to be linear-elastic. Since the liquid is not completely incompressible, its density can change slightly during the propagation of a transient pressure wave. The transient pressure wave will have a finite velocity that depends on the elasticity of the pipeline and of the liquid as described in “Celerity and Pipe Elasticity” on page B-257.

B-256

HAMMER User's Guide

HAMMER Theory and Practice In 1898, Joukowski established a theoretical relationship between pressure and velocity change during a transient flow condition. In 1902, Allievi independently developed a similar elastic relation and applied it to a uniform valve closure. The elastic theory developed by these two pioneers is fundamental to the field of hydraulic transients. The combined elasticity of both the water and the pipe walls is characterized by the pressure wave speed, a. This relation is a simplified form of the equation (see equation B.7) applicable to an instantaneous stoppage of velocity. (H – Ho) = –a / g (V – Vo) Where

o

=

(B.10) denotes initial conditions.

For an instantaneous valve closure or stoppage of flow, the upsurge pressure (H–Ho) is known as the “Joukowski head.” Given that a is roughly 100 times as large as g, a 1 ft./sec. (0.3 m/s) change in velocity can result in a 100 ft. (30 m) change in head. Because changes in velocity of several feet or meters per second can occur when a pump shuts off or a hydrant or valve is closed, it is easy to see how large transients can occur readily in water systems. The mass of fluid that enters the part of the system located upstream of the valve immediately after its sudden closure is accommodated through the expansion of the pipeline due to its elasticity and through slight changes in fluid density due to its compressibility. This equation does not strictly apply to the drop in pressure downstream of the valve, if the valve discharges flow to the atmosphere.

B.4

Water System Characteristics Haestad Press’ Advanced Water Distribution Modeling and Management describes many of the topics in this section in greater detail.

B.4.1

Celerity and Pipe Elasticity The elasticity of any medium is characterized by the deformation of the medium due to the application of a force. If the medium is a liquid, this force is a pressure force. The elasticity coefficient (also called the elasticity index, constant, or modulus) is a physical property of the medium that describes the relationship between force and deformation. Thus, if a given liquid mass in a given volume (V) is subjected to a static pressure rise (dp), a corresponding reduction (dV < 0) in the fluid volume occurs. The relationship between cause (pressure increase) and effect (volume reduction) is expressed as the bulk modulus of elasticity (Eν) of the fluid, as given by:

HAMMER User's Guide

B-257

Water System Characteristics

Ev = −

Where

dp dp = dV dρ V ρ

(B.11)

Ev

=

bulk modulus of elasticity

dp

=

static pressure rise

=

incremental change in liquid volume with respect to initial volume

=

incremental change in liquid density with respect to initial density

dV dρ/ρ

A relationship between a liquid’s modulus of elasticity and density yields its characteristic wave celerity:

a=

Where

Ev dp = ρ dρ

a

(B.12) =

characteristic wave celerity of the liquid

The characteristic wave celerity (a) is the speed with which a disturbance moves through a fluid. Its value is approximately 4,716 ft./sec. (1,438 m/s) for water and approximately 1,115 ft./sec. (340 m/s) for air. Injecting a small percentage of small air bubbles can lower the effective wave speed of the fluid/air mixture, provided it remains well mixed. This is difficult to achieve in practice, because diffusers may malfunction and air bubbles may come out of suspension and coalesce or even buoy to the top of pipes and accumulate at elbows, for example. In 1848, Helmholtz demonstrated that wave celerity in a pipeline varies with the elasticity of the pipeline walls. Thirty years later, Korteweg developed an equation to determine wave celerity as a function of pipeline elasticity and liquid compressibility. HAMMER uses an elastic model formulation that requires the wave celerity to be corrected to account for pipeline elasticity.

B-258

HAMMER User's Guide

HAMMER Theory and Practice

Ev a=

ρ Ev ∆A 1+ A∆p

(B.13)

Equation B.13 is valid for thin walled pipelines (D/e > 40). The factor ψ depends on pipeline support characteristics and Poisson’s ratio. ψ depends on the following: •

Pipe is anchored throughout against axial movement: ψ = 1 – µ2, where µ is Poisson’s ratio

•

Pipe is equipped with functioning expansion joints throughout: ψ = 1 – µ/2

•

Pipe is supported only at one end and allowed to undergo stress and strain both laterally and longitudinally: ψ = 5/4 – µ (ASCE, 1975)

For thick-walled pipelines, various theoretical equations have been proposed to compute celerity; however, field investigations are needed to verify these equations. Tables “Table B-2: Physical Properties of Some Common Pipe Materials”on page B259 and “Table B-3: Physical Properties of Some Common Liquids”on page B-260 provide values for various pipeline materials and liquids that are useful to calculate celerity during transient analysis. “Figure B-7: Celerity versus Pipe Wall Elasticity for Various D/e Ratios”on page B-261 provides a graphical solution for celerity given pipe-wall elasticity and various diameter/thickness ratios. Table B-2: Physical Properties of Some Common Pipe Materials Material

Young’s Modulus

Poisson’s Ratio, µ

(10 lbf/ft )

(GPa)

Steel

4.32

207

0.30

Cast Iron

1.88

90

0.25

Ductile Iron

3.59

172

0.28

Concrete

0.42 to 0.63

20 to 30

0.15

Reinforced Concrete

0.63 to 1.25

30 to 60

0.25

Asbestos Cement

0.50

24

0.30

PVC (20oC)

0.069

3.3

0.45

9

HAMMER User's Guide

2

B-259

Water System Characteristics Table B-2: Physical Properties of Some Common Pipe Materials (Cont’d) Material

Young’s Modulus

Poisson’s Ratio, µ

(10 lbf/ft )

(GPa)

Polyethylene

0.017

0.8

0.46

Polystyrene

0.10

5.0

0.40

Fiberglass

1.04

50.0

0.35

Granite (rock)

1.0

50

0.28

9

2

Table B-3: Physical Properties of Some Common Liquids Liquid

B-260

Temperature (oC)

Bulk Modulus of Elasticity

Density

(106 lbf/ft2)

(GPa)

(slugs/ ft3)

(kg/m3)

Fresh Water

20

45.7

2.19

1.94

998

Salt Water

15

47.4

2.27

1.99

1,025

Mineral Oils

25

31.0 to 40.0

1.5 to 1.9

1.67 to 1.73

860 to 890

Kerosene

20

27.0

1.3

1.55

800

Methanol

20

21.0

1.0

1.53

790

HAMMER User's Guide

HAMMER Theory and Practice

Figure B-7: Celerity versus Pipe Wall Elasticity for Various D/e Ratios For pipes that exhibit significant viscoelastic effects (for example, plastics such as PVC and polyethylene), Covas et al. (2002) showed that these effects, including creep, can affect wave speed in pipes and must be accounted for if highly accurate results are desired. They proposed methods that account for such effects in both the continuity and momentum equations.

B.4.2

Wave Propagation and Characteristic Time Note:

The representative system length, L, can be approximated for a network by taking the longest path connecting a pump to a storage element, such as a tank or reservoir.

The pressure wave generated by a flow-control operation propagates with speed a, reaching the other end of the pipeline in a time interval equal to L/a seconds. The same time interval is necessary for the reflected wave to travel back to its origin, for a total of 2 L/a seconds. The quantity 2 L/a is termed the characteristic time for the pipeline. It is used to classify the relative speed of a maneuver that causes a hydraulic transient. If a flow-control operation produces a velocity change in a time interval less than or equal to a pipeline’s characteristic time, the operation is considered “rapid.” Flowcontrol operations that occur over an interval longer than the characteristic time are designated “gradual” or “slow.” The classifications and associated nomenclature are summarized in the following table for different operation time, Tm.

HAMMER User's Guide

B-261

Water System Characteristics .

Table B-4: Classification of Flow Control Operations Based on System Characteristic Time Time of Maneuver

Operation Classification

TM = 0

Instantaneous

T M ≤ 2L ⁄ a

Rapid

T M > 2L ⁄ a

Gradual

T M » 2L ⁄ a

Slow

The characteristic time is significant in transient flow analysis because it dictates which method is applicable for evaluating a particular flow-control operation in a given system. The rigid model provides accurate results only for surge transients generated by slow flow-control operations that do not cause significant liquid compression or pipe deformation. Instantaneous, rapid, and gradual changes must be analyzed with the elastic model. HAMMER uses the elastic model by default to ensure an accurate solution, regardless of the system’s characteristic time.

B.4.3

Wave Reflection and Transmission Pipelines In addition to the equations describing transient flow, it is important to know about the effect of boundaries—such as tanks, dead ends, and pipe branches—that modify the effects of hydraulic transient phenomena. Transient Tip: Hydraulic systems commonly have interconnected pipelines with differing characteristics, such as material and diameter. These pipeline segments and connection points (nodes) define a system’s topology.

When a wave traveling in a pipe and defined by a head pulse Ho comes to a node, it is transmitted with a head value Hs to all other connected pipes and reflects back to the initial pipe with a head value Hr. The wave reflection occurring at a node changes the head and flow conditions in each of the pipes connected to the node. If the distances between the pipe connections are small, the head at all connections can be assumed to be the same (that is, the head loss through the node is negligible), and the transmission factor (s) can be defined as

B-262

HAMMER User's Guide

HAMMER Theory and Practice

Ao ∆H s a s= = n o ∆H o A ∑ ai i =0 i 2

Where

(B.14)

s

=

transmission factor (dimensionless)

Hs

=

head of transmitted wave (ft, m)

Ho

=

incident head pulse (ft, m)

Ao

=

incoming pipe area (ft2, m2)

ao

=

incoming wave speed (ft/sec., m/s)

Ai

=

area of i-th pipe (ft2, m2)

ai

=

wave speed of i-th pipe (ft/sec., m/s)

n

=

number of outgoing pipes

i

=

pipe number index

In a closed system without friction to dampen transients, transients would persist indefinitely. However, viscous and friction effects typically cause transients to attenuate within seconds to minutes. HAMMER is an essential tool to keep track of the transient pressure-wave reflections and the friction and elastic effects during the simulation, as follows: •

Because friction does exist in an actual system, the potential head change calculated using the Joukowsky equation underestimates the actual head rise. This underestimation is due to packing—an additional increase in head occurring at the valve as the pressure wave travels upstream.

•

The small velocity behind the wave front means that the velocity difference across the wave front is less than Vo, so the pressure change is progressively less than the potential surge as the wave travels upstream. This effect, which is concurrent with line packing, is called attenuation or reduction.

•

Transient pressure waves are partially transmitted and simultaneously reflected back at every junction with other pipes, depending on their wave speed and diameter.

Although HAMMER calculates the proportion of an incoming transient energy pulse that is transmitted and reflected at each junction node, it is useful to consider how this phenomenon takes place in a typical hydraulic system using the relation for the reflection factor:

HAMMER User's Guide

B-263

Water System Characteristics

r=

Where

∆H r = s −1 ∆H o

(B.15)

r

=

reflection factor

Hr

=

head of reflected wave (ft, m)

Several special cases can be considered, including:

B.4.4

•

Pipe connected to a reservoir—In this case, n = 1, s = 0, and r = –1. In other words, a wave reaching a reservoir reflects with the opposite sign.

•

Pipe connected to a dead-end or closed valve—In this case, n = 1, and, through the derivation of an equation for r similar to Equation B.14, it can be shown that r = 1. In other words, a wave reflects at a closed extremity of a pipe with the same sign and, therefore, head amplification occurs at that extremity. If a flow-control operation causes a negative pressure wave that reaches a closed valve, the wave’s reflection causes a further reduction in pressure. This transient flow condition can cause liquid column separation and, in low-head systems, potential pipeline collapse. At a dead end, the wave is reflected with twice the pressure head of the incident wave.

•

Pipe diameter reduced (celerity increase)—In this case, A1 < A0, and s > 1, so the head that is transmitted is amplified. For example, if A1 = A0/4 (or D1 = D0/2), then s = 8/5=1.6 and r = s – 1 = 0.6, and the head transmitted to the smaller pipeline is 60 percent greater than the incoming head. The larger pipeline is also subjected to this head change after the wave partially reflects at the node. If the diameter is reduced to zero, the junction becomes a dead end.

•

Pipe diameter increased (celerity decrease)—In this case, an attenuation of the incident head occurs at a pipeline diameter increase. The smaller pressure wave is transmitted to the larger pipeline and, after the reflection, the smaller pipeline is subjected to the lower final head. At an expansion, the reflected wave has the opposite sign of the incident wave. In the limit, as the diameter increases indefinitely, the reservoir case is obtained.

Type of Networks and Pumping Systems Although an infinite number of network topologies are possible, the possibilities can be reduced to the following key characteristics:

B-264

HAMMER User's Guide

HAMMER Theory and Practice •

Network characteristics—A water system usually consists of several main transmission pipelines (from pumping stations to reservoirs, elevated tanks, or booster stations) and many branches and loops to distribute water to local water-demand points.

•

Piping characteristics—These include pipeline length (L), diameter (D), roughness (C or f), elevations or profile (based on topography), water levels at suction and receiving water bodies, flow (Q), pressure head (H) at nodes, and pressure wave speed (a).

•

Pressure wave speed—This varies from as low as 340 m/s to as high as 1,438 m/ s for water in thin-walled plastic pipes to thick steel pipes, respectively. Pressure wave speed is also affected by pipe installation due to bedding, anchorage, and soil conditions.

•

Modeling complexity—In the past, networks were usually reduced to a few key water mains, taking the flow distribution, pipeline profiles, and kinetic energy of the system into consideration. This usually provided conservative results for these main lines, but the transient energy transmitted from the main lines to the distribution network (or vice versa) was overlooked. Modern computer models, such as HAMMER, can simulate networks with thousands of pipes and dozens or hundreds of boundary conditions.

For the purpose of transient analysis, pumping systems can be grouped as follows: •

Open pumping system—An open-water system consists of upstream reservoirs, pump stations, and downstream reservoirs or elevated tanks. Transient pressurewave travel is confined to a single system and transient energy cannot be transmitted to another system. With a favorable pipeline profile (e.g., concave upward), no significant vapor cavity occurs and the water columns do not separate. The maximum upsurge pressure seldom rises 50% higher than the steady pressure head. However, an irregular pipeline profile can result in a large watercolumn separation and severe transient pressures. Vapor or air pockets will eventually collapse due to flow reversing from the upstream reservoir or tank.

•

Closed system—In a closed system, the pump supplies water and maintains adequate pressure for the whole system. There is neither a reservoir nor a standpipe in the system. Closed systems usually service a small water supply zone. Pumps employed in a closed system often have flat pump curves that are undesirable from a transient perspective because rapid flow alterations can occur. After a power failure, the downsurge likely results in more vapor cavities than in an open system, while the upsurge is relatively small in comparison. Upon pump startup, higher transient pressures can be expected due in part to the greater number of air cavities that are trapped and remain in the system, and in part due to inherently rapid flow acceleration. The air trapped at local high points should always be released.

HAMMER User's Guide

B-265

Water System Characteristics •

Boosted system—For some water systems, water may be delivered directly to a booster pumping station that resupplies water to another system on its discharge side. Normally, no reservoir or suction well is installed upstream of the booster pumping station; consequently, the hydraulic performance of one side of the booster pumping system can be significantly affected by the transient conditions of the other side. From a hydraulic point of view, all possible combinations of power failure should be considered, including: –

All the pump stations fail while the booster continues to operate.

–

Only the booster fails while all others continue to operate.

–

A global power failure occurs at all pumping stations for both systems.

Because of flow continuity, the booster pump stops soon after a power failure in the upstream system and the resulting transients may be similar to a power failure at both pumping stations. In cases where the booster pump fails while the upstream pump continues to operate, a worse transient may result in part of the water system.

B.4.5

Putting It All Together Prior to performing the calculations of transient flow and head, HAMMER surveys the system’s characteristics, considers the various pipe and fluid properties, and automatically determines an optimal time step. By default, HAMMER uses the method of characteristics and short time steps to ensure that simulation results will be accurate enough to support firm conclusions about the effects of transients in the system. HAMMER takes hours of guesswork about time steps and methodology out of your day, allowing you to focus on interpreting and communicating the results to stakeholders. As a modeler, you need to focus on the following factors for a successful HAMMER run:

B-266

•

Pick the run duration following the guidelines in “Project Management and Options” on page 4-142.

•

Enter the correct liquid properties as described in “Liquid Properties” on page 4146.

•

Select an advanced friction model if the effects of repeated transient cycling is a concern, as described in “Selecting the Friction Method” on page 4-147.

•

Describe the boundary conditions and other hydraulic elements correctly using the information provided in “Hydraulic Element Reference” on page 6-161.

HAMMER User's Guide

HAMMER Theory and Practice After a successful run, you need to interpret the results as described in “Reviewing your Results” on page 3-96. Perhaps you need a few runs to assess the sensitivity of your results to vapor pressure, elevations, and wave speed if the model predicts “Water Column Separation and Vapor Pockets” on page 7-193. Finally, even the most thorough analysis has little value if its conclusions and recommendations are not communicated clearly and powerfully; review the quick start lessons and the tips provided in “Presenting Your Results” on page 8-201.

B.5

Pump Theory This section supplements the discussion of “Rotating Equipment” on page 6-171, covering the following topics: •

“Pump Fundamentals” on page 6-171

•

“Pump Inertia” on page 6-173

•

“Specific Speed” on page 6-174

•

“First-Quadrant and Four-Quadrant Representations” on page 6-175

•

“Variable-Speed Pumps (VSP or VFD)” on page 6-176

The above topics introduced the subject as a means of selecting the correct pump representation for a particular HAMMER run. The following sections focus on theoretical and practical aspects:

B.5.1

•

“Pump Characteristics and Behavior” on page B-267

•

“Variable-Speed Pumps” on page B-269

•

“Constant-Horsepower Pumps” on page B-270

Pump Characteristics and Behavior Pumps are an integral part of many pressurized systems. Pumps add energy, or head gains, to the flow to counteract head losses within the system. A pump is defined by its curve, which relates the pump head, or the head added to the system, to the flow rate. This curve indicates the ability of the pump to add head at different flow rates. To model the behavior of the pump system, additional information is needed to find the actual point at which the pump will operate. The system operating point is based on the point at which the pump curve crosses the system curve representing the static lift and head losses due to friction and minor losses (for more information, see “Minor Losses” on page B-282). When these curves are superimposed, the operating point is found at their intersection. This is shown in the following figure:

HAMMER User's Guide

B-267

Pump Theory

Figure B-8: System Operating Point As water-surface elevations and demands throughout the system change, the static head (Hs) and headlosses (HL) vary. This changes the location of the system curve, while the pump characteristic curve remains constant. These shifts in the system curve result in a shifting operating point over time periods ranging from minutes to hours. At steady state, a pump can be described using a simple curve relating the total dynamic head (TDH) added to the fluid at every possible flow rate within the pump’s operating range. Additional curves describe the pump’s suction energy (e.g., its required net positive suction head or NPSHR) and power requirements at each flow rate. From a hydraulic transient perspective, these dynamic variables must be considered, including power input; rotational speed; and the moment of inertia of the pump, motor, and shaft (including couplings). Each of these properties can have a pronounced effect on the behavior of the pump during a surge or after a power failure: 1. Pump inertia—Pumps with a lighter impeller and motor have a small moment of inertia; they can be accelerated and stopped faster because there is less stored kinetic energy. The trend has been towards lighter pumps. After a power failure, low-inertia pumps maintain forward flow for a shorter time and stop sooner. This results in more-sudden changes in flow and pressures than would occur with heavier pumps, and consequently in more-severe water hammer. 2. Pump curve shape—Flat pump curves are undesirable from a hydraulic transient perspective because they can result in a large change in flow rate for a moderate change in head. This can result in a very rapid decrease in flow during an emergency shutdown. 3. Dynamic change to the system curve—After a large pipe break or uncontrolled valve opening, the system head curve can suddenly drop far below its usual head requirement, so the pump no longer needs to add much (if any) energy to supply the required flow. In cases such as these, the pump’s run-out head can become

B-268

HAMMER User's Guide

HAMMER Theory and Practice higher than the required static lift. Very large losses in the suction system may result in cavitation and overspeed conditions, both of which can cause pump wear and damage. This can be avoided by proper pump selection (steady state) and controls to shut the pump down and reduce or stop flow during such transients. 4. Dynamic change to the operating point—A shut-off head too close to the highhead end of the operating range could result in nuisance interruptions of power to the pump, each of which results in a hydraulic transient due to the emergency pump shut down (similar to a power failure). 5. Change in NPSHR due to wear or impeller trimming—NPSHR is different for each turbomachine in a pump station, but manufacturers typically provide this information. The NPSHR of neighboring pumps can be different from each other. Further, the manufacturer’s NPSHR curve can become invalid after decades of wear, poor maintenance, or actual modifications to the impeller. Fortunately, NPSH can be obtained from field tests. The available NPSHA is determined based on the reservoir head and losses in the suction system. Pump cavitation occurs if the NPSH margin, NPSHA – NPSHR is insufficient. Even at incipient cavitation, an inadequate margin can result in less efficient pumping or even in a breakdown of the pump curve, whereby a pump may be running but contributing very little head above a limiting flow. Consult Hydraulic Institute (http://www.pumps.org) publications for more information on this important issue. Whenever a pump is forced outside its normal operating range during a hydraulic transient, vibrations and cavitation may result—even if it does not reach shut-off or runout conditions. Reverse spin can force the pump motor (if it is not disconnected) to generate electricity, rapidly increasing its temperature and possibly damaging the motor-control circuitry. For these reasons, it is wise to protect pumps against transient damage by providing suitable discharge-side check valves.

B.5.2

Variable-Speed Pumps A pump’s characteristic curve is fixed for a given motor speed and impeller diameter, but can be determined for any speed and any diameter by applying the affinity laws. For variable speed pumps, these affinity laws are presented as:

Q1 n1 = Q2 n2

(B.16)

and 2 h1 ⎛⎜ n1 ⎞⎟ =⎜ ⎟ h2 ⎜⎝ n2 ⎟⎟⎠

HAMMER User's Guide

(B.17)

B-269

Pump Theory

Where

Q

=

pump flow rate (m3/s, cfs)

h

=

pump head (m, ft)

n

=

pump speed (rpm)

Figure B-9: Effect of Relative Speed on Pump Curve

B.5.3

Constant-Horsepower Pumps WaterCAD and WaterGEMS provide many ways to enter pump curves, as described in “Pump Fundamentals” on page 6-171. HAMMER allows any pump curve to be represented as pairs of heads and corresponding flows, interpolating linearly between these values when required during the simulations. It is therefore desirable to enter as many line segments as is practical to accurately describe the pump’s operating range. Fortunately, HAMMER automatically imports pump curves. If a multiple point rating curve was entered in WaterCAD, WaterGEMS, or produced using the LevenbergMarquardt Method, as shown in the following equation, an equivalent multiple-point rating curve is imported automatically into HAMMER.

Y = A − ( B ×QC )

Where

B-270

(B.18)

Y

=

head (m, ft)

Q

=

discharge (m3/s, cfs)

A, B, C

=

pump curve coefficients

HAMMER User's Guide

HAMMER Theory and Practice

B.6

Valve Theory Several types of valves are in use at any one time in a pressurized system. These valves have different behaviors due to their different purposes, but all valves are used for controlling flow. They can be opened, closed, or throttled to achieve the desired result. In terms of hydraulic transient analysis and design, valves can be classified as flow control or surge control valves. Flow control valve types are discussed in “FlowControl Valve Fundamentals” on page 6-166:

B.6.1

•

Pressure-reducing valves (PRVs)

•

Pressure-sustaining valves (PSVs)

•

Pressure-breaker valves (PBVs)

•

Flow-control valves (FCVs)

•

Throttle-control valves (TCVs)

•

General-purpose valves (GPVs)

Valve Selection and Sizing Considerations HAMMER is the most versatile design tool for valve sizing because it allows you to simulate the operating conditions a valve is likely to encounter during steady-state or transient events. HAMMER models valves differently depending on their response time. The principal difference between flow-control and surge-control valves is their response or activation time: Flow control valves—The majority of valves in a water system are intended for on/ off operation (i.e., they either allow or block flow). In addition to this, flow-control valves throttle flow using various methods that depend on the valve body, piston or pinch mechanism, and actuator. Although special trim is available to deal with sustained high-velocity or high-pressure differentials, most flow-control valves are not designed to react to or handle transient conditions for any length of time. They are typically actuated to ensure a slow opening or closure. Actuators are typically hydraulic, electric, or (less often for water systems) compressed air: •

Hydraulic actuators—Small-diameter tubes called pilots are connected upstream and downstream of the valve and the difference in pressure between these points is used to open or close it. The type of valve depends on how the upstream and downstream pilots are connected to the valve body and/or drained out of it to ambient, or atmospheric, pressure. The term piloting is often used to describe the hydraulic (and sometimes electrical) circuitry and connecting tubes.

•

Electric actuators—These are motors coupled to gear works to ensure a gradual opening or closure. In water systems, electric actuators are most often used to operate large isolation valves, only some of which may be connected to backup or emergency power (for use during a power failure). Typically, a manual over-ride

HAMMER User's Guide

B-271

Valve Theory and hand wheel is also provided for each valve. The gear ratios are set so that a large number of turns is required on the wheel to fully open or close the valve. Even for the fittest operator, this ensures that the valve cannot be closed too quickly, to prevent water hammer. •

Compressed-air actuators—Compressed- or instrument-air actuators are far more common in industrial settings, where valves and flows are typically smaller than in water or wastewater systems (e.g., typically m3/hr. instead of m3/s, respectively). The compressed air is typically maintained at a set pressure and some reserve capacity is usually stored to allow operations to continue after a power failure. Since compressors are required to maintain pressure in a gas vessel, it is possible to use such actuators nearby, but this is rarely done.

Surge-control valves—The majority of surge-control valves are sized and actuated to respond very quickly to hydraulic transient conditions and to handle far greater flows and pressure drops than flow-control valves (albeit for shorter times). Small tanks containing compressed nitrogen or other special gases are sometimes provided to help valves open more quickly. The piloting is typically designed to respond to sudden or gradual changes in pressure or even to the rate of change of pressure. Hydraulic or compressed-air actuators are preferred because these valves are typically installed to protect against a power failure or sag, during which electrical actuators may fail to operate. Because hydraulic transients occur so quickly in most systems, the time required to bring backup power on line is often too long to be of use during transients. Any valve can initiate a hydraulic transient if it is opened or closed too quickly with respect to the system’s characteristic time, or if it is operated in an uncontrolled manner. Uncontrolled operation can occur due to a failure of hydraulic piloting to react during very high reverse-flow velocities, for example. This illustrates the importance of sizing a valve to handle the full range of flows it will encounter during its service life. Another example is that instrument-air pressure can fail to reach a valve at the correct flow rate or pressure, due to clogged filters or worn orifices, incapacitating its compressed-air actuator. Transient Tip: It is essential to follow the valve manufacturer’s selection, sizing, and maintenance schedules to avoid specifying a valve that is unsuitable for a specific application. A critical first step in the process of sizing surge-control valves is to perform a thorough hydraulic transient analysis using HAMMER to determine the normal and transient conditions the valve will encounter during its entire service life (e.g., for current, interim, and ultimate water-supply conditions and surge-control scenarios). Improper selection or sizing of surge-control valves can result in worse transients than if no protection were installed.

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HAMMER Theory and Practice

B.6.2

Typical Valve Bodies and Pistons Every flow- or surge-control valve consists of a valve body to convey (and sometimes redirect) flow and a piston to open, restrict, or block flow. Since all valves can cause a sudden stoppage of flow, resulting in hydraulic transients if closed too quickly, it is important to know how each type operates. The following paragraphs summarize key characteristics for each type: Butterfly valves are very common in water systems, primarily for on-off and throttling service. A circular disc or vane pivots around an axis at right angles to the direction of flow in the pipe. Typically, a quarter-turn is sufficient to open or close this valve. Actuators are often installed to require a large number of turns to prevent rapid closure, sudden stoppage of flow, and the resulting hydraulic transients. Gate valves are a general-service valve used primarily for on-off, nonthrottling service. A flat face, vertical disc, or gate slides down through the valve to block flow. These valves can be found on very large suction or discharge piping inside most water pumping stations, often equipped with actuators with very large gear ratios to allow manual operation. They may be operated only yearly or less frequently. Globe valves are used for on-off service and throttling applications. A plug with a flat or convex bottom is lowered onto a matching horizontal seat located at the center of the valve. Raising the plug opens the valve, allowing flow. Many different types of materials and pistons are available, including anticavitation or multi-orifice cages. Globe valves are typically available with a straight-through body or with an angle body that simultaneously turns flow through 90 degrees. Plug valves are used primarily for on-off service and some throttling. They control flow by means of a cylindrical or tapered plug with a hole in the center that either lines up with the flow path or blocks it with a quarter-turn in either direction. Actuators are often installed to require a large number of turns to prevent rapid closure, sudden stoppage of flow, and the resulting hydraulic transients. Plug valves are common in process or industrial applications. Ball valves are used primarily for on-off service and some throttling. They are similar to the plug valve but use a rotating ball with a hole through it. Many garden hose attachments are ball valves, requiring a quarter-turn to open or close, but many faucets are also ball valves that require many turns. Large ball valves are used to throttle flow in pump-discharge lines. Diaphragm valves handle corrosive, erosive, and dirty service. They close by means of a flexible diaphragm attached to a piston, sometimes called a compressor, that can be lowered by the valve stem onto a weir to seal and cut off flow. Diaphragm valves are used for waste water, industrial fluids, and for mining applications, such as pumping light slurries or tailings-reclaim water.

HAMMER User's Guide

B-273

Valve Theory Pinch valves are particularly suited for slurries or liquids with large amounts of suspended solids. They seal by means of one or more flexible elements, such as a rubber tube, that can be pinched to shut off flow. The flexible element can vary widely from food-grade to special natural and synthetic rubbers to handle corrosive and/or abrasive fluids and mixtures. Needle valves are volume-control valves that restrict flow in small lines. Needle valves are commonly used for speed control in piloting by allowing operators to set the time required for fluid to move to or from the valve piston chamber. The fluid going through the valve turns 90 degrees and passes through an orifice that is the seat for a rod with a cone-shaped tip. Positioning the cone in relation to the seat changes the size of the orifice.

B.6.3

Closing Characteristics of Valves Depending on the body and piston for a type of valve, closing it by moving the piston at a constant rate results in a different rate of decrease in the area open to flow. Near the end of the closure, some types decrease this area faster while others slow down. HAMMER has built-in area-closure characteristics for various types of valves to ensure this important factor is represented adequately. You can select the correct valve type and know that the decrease in flow will be modeled in a realistic manner as the valve closes. Note:

For most manufacturers, the rate at which area decreases as the valve closes is a close approximation to the rate at which flow decreases, often reported as a Cv curve. If either curve is available for your valve, you can enter it as an area-closure curve in HAMMER.

For ease of interpretation, valve closing can be represented numerically by the shape of closure (S) parameter that represents the rate of opening area deceleration during the time of a complete closure (Tc), or stroke time, if the stroke varies linearly with time. If a partial closure, opening, or full opening is specified, HAMMER correctly tracks the area open to flow. The following equations are used to relate area to stroke: •

Increasing deceleration—If the rate of change of the area open to flow (with respect to a constant stroke speed) increases at the end of the closure period, the valve closing pattern can be expressed as: A/A0 = 1 - (T/Tc )-S

B-274

(B.19)

HAMMER User's Guide

HAMMER Theory and Practice

Where

A/A0 T/Tc S

•

=

the fraction of the full valve-opening area

=

the fraction of time required to completely close the valve

=

the shape of valve closure, which is greater than 1 for increasing deceleration

Decreasing deceleration—If the rate of change of the area open to flow (with respect to a constant stroke speed) decreases at the end of the closure period, the exponent S should be less than 1 and the valve-closing pattern can be expressed as A/A0 = (1 - T/Tc )-S

(B.20)

For valves commonly used in engineering practice, the following values of S are used by HAMMER according to the valve type: Valve

S

Butterfly valve

-1.85

Ball valve

-1.35

Globe valve

1.00

Circular gate valve

1.35

Needle valve

2.00

User-defined (enter curve)

n/a

The relationship between the fraction of area open to flow (A/A0) and the stroke (T/Tc) is shown in the following figure.

HAMMER User's Guide

B-275

Valve Theory

10

Accelerating Uniform Decelerating

9

Needle Valve

8

Opening Area A/Ao

Decrease in Open Area near end of Closure

Circular Gate Valve (Accelerated Closure)

Circular Gate Valve

7 6 5

Globe Valve

4 Ball Valve

3 2

A/Ao = 1-(T/Tc)-S Needle S = 2 Circular Gate S = 1.35 Where S > 1 Globe S = ± 1, linear

A/Ao = (1-T/Tc)- S Ball S = -1.35 Butterfly S = -1.85 Where S < -1

Butterfly Valve

1 0

1

2

3

4

5

6

7

8

9

10

T/Tc

Figure B-10: Relationship between Fraction of Area Open to Flow and Stroke

B.6.4

Flow-Decreasing Characteristics Normally, the flow rate decreases much slower than that of the opening area during the early stage of the valve closing. However, this pattern inverts toward the end of the valve-closing period. As shown in the figure below for most common valves, the majority of flow drops to zero quickly near the end of the valve-closing stroke (or time).

B-276

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HAMMER Theory and Practice

10 9

Circular Gate Valve (Accelerating Closure)

Flow Decrease Q/Qo

8 7 6

Butterfly Valve

5 4 3 2 1 0

1

2

3

4

5

6

7

8

9

10

T/Tc

Figure B-11: Flow Patterns for Common Valves

B.7

Friction and Minor Losses Friction loss methods include:

B.7.1

•

“Hazen-Williams Equation” on page B-277

•

“Darcy-Weisbach Equation” on page B-278

•

“Manning’s Equation” on page B-280

•

“Quasi-Steady Friction” on page B-283

•

“Unsteady or Transient Friction” on page B-285

Hazen-Williams Equation The Hazen-Williams formula is frequently used in the analysis of pressure-pipe systems (such as water distribution networks and sewer force mains). The equation is:

Q = k ⋅ C ⋅ A ⋅ R 0.63 ⋅ S 0.54

HAMMER User's Guide

(B.21)

B-277

Friction and Minor Losses

Where

B.7.2

Q

=

discharge in the section (m3/s, cfs)

C

=

Hazen-Williams roughness coefficient (unitless)

A

=

flow area (m2, ft2)

R

=

hydraulic radius (m, ft)

S

=

friction slope (m/m, ft/ft)

k

=

constant (0.85 for SI units, 1.32 for U.S. units).

Darcy-Weisbach Equation Because of its nonempirical origins, the Darcy-Weisbach equation is viewed by many engineers as the most accurate method for modeling friction losses. It most commonly takes the following form:

hL = f ⋅

Where

L V2 D 2g

(B.22)

hL

=

headloss (m, ft)

f

=

Darcy-Weisbach friction factor (unitless)

D

=

pipe diameter (m, ft)

L

=

pipe length (m, ft)

V

=

flow velocity (m/s, ft/sec.)

g

=

gravitational acceleration constant (m/s2, ft/sec.2)

For section geometries that are not circular, this equation is adapted by relating a circular section’s full-flow hydraulic radius to its diameter as: D = 4R Where

R

=

hydraulic radius (m, ft)

D

=

diameter (m, ft)

This can then be rearranged to the form:

B-278

HAMMER User's Guide

HAMMER Theory and Practice

Q = A ⋅ 8g ⋅

Where

R⋅S f

(B.23)

Q

=

discharge (m3/s, cfs)

A

=

flow area (m2, ft2)

R

=

hydraulic radius (m, ft)

S

=

friction slope (m/m, ft/ft)

f

=

Darcy-Weisbach friction factor (unitless)

g

=

gravitational acceleration constant (m/s2, ft/sec.2)

The Swamee and Jain equation can then be used to calculate the friction factor. For more information, see “Swamee and Jain Equation” on page B-279.

Swamee and Jain Equation Note:

The kinematic viscosity is used in determining the friction coefficient in the darcy-weisbach friction Method. The default units are initially set by Haestad Methods.

f =

Where

1.325 2 ⎡ ⎛ ⎞⎟⎤ ⎜ ε . 5 74 ⎢ln ⎜ + ⎟⎥ ⎢ ⎜⎝ 3.7 D Re0.9 ⎟⎠⎥⎦ ⎣

f

=

friction factor (unitless)

ε

=

roughness height (m, ft)

D

=

pipe diameter (m, ft)

Re

=

Reynolds number (unitless)

(B.24)

The friction factor is dependent on the Reynolds number of the flow, which is dependent on the flow velocity, which is dependent on the discharge. This process requires the iterative selection of a friction factor until the calculated discharge agrees with the chosen friction factor.

HAMMER User's Guide

B-279

Friction and Minor Losses

Colebrook-White Equation The Colebrook-White equation is used to iteratively calculate the Darcy-Weisbach friction factor. Its free-surface form is

⎛ k 1 2.51 = −2 log ⎜⎜⎜ + ⎜⎝12.0 R Re f f

⎞⎟ ⎟⎟ ⎟⎟⎠

(B.25)

Its full-flow (closed conduit) form is

⎛ k 1 2.51 = −2 log ⎜⎜⎜ + ⎜⎝ 3.7 D Re f f

Where

B.7.3

⎞⎟ ⎟⎟ ⎟⎟⎠

(B.26)

f

=

friction factor (unitless)

k

=

Darcy-Weisbach roughness height (m, ft)

Re

=

Reynolds Number (unitless)

R

=

hydraulic radius (m, ft)

D

=

pipe diameter (m, ft)

Manning’s Equation Note:

Manning’s roughness coefficients are the same as the roughness coefficients used in Kutter’s equation. This friction method is not used in HAMMER, but it is included here for completeness.

Manning’s equation, which is based on Chézy’s equation, is one of the most popular methods in use today for free-surface flow. For Manning’s equation, the roughness coefficient in Chézy’s equation is given by: 1

R 6 C=k⋅ n

B-280

(B.27)

HAMMER User's Guide

HAMMER Theory and Practice

Where

C

=

Chézy’s roughness coefficient (m1/2/s, ft1/2/sec.)

R

=

hydraulic radius (m, ft)

n

=

Manning’s roughness (s/m1/3)

k

=

constant (1.00 m1/3/m1/3, 1.49 ft1/3/ft1/3)

Substituting this roughness into Chézy’s equation gives you the well-known Manning’s equation:

Q=

Where

2 1 k ⋅ A⋅ R 3 ⋅ S 2 n

(B.28)

Q

=

discharge (m3/s, cfs)

k

=

constant (1.00 m1/3/s, 1.49 ft1/3/sec.)

n

=

Manning’s roughness (unitless)

A

=

flow area (m2, ft2)

R

=

hydraulic radius (m, ft)

S

=

friction slope (m/m, ft/ft)

Chézy’s Equation Chézy’s equation is rarely used directly, but it is the basis for several other methods, including Manning’s equation. Chézy’s equation is:

Q = C ⋅ A⋅ R ⋅ S

Where

HAMMER User's Guide

(B.29)

Q

=

discharge in the section (m3/s, cfs)

C

=

Chézy’s roughness coefficient (m1/2/s, ft1/2/sec.)

A

=

flow area (m2, ft2)

R

=

hydraulic radius (m, ft)

S

=

friction slope (m/m, ft/ft)

B-281

Friction and Minor Losses

B.7.4

Minor Losses Minor losses in pressure pipes are caused by localized areas of increased turbulence that create a drop in the energy and hydraulic grades at that point in the system. The magnitude of these losses is dependent primarily upon the shape of the fitting, which directly affects the flow lines in the pipe.

Figure B-12: Flow Lines at Entrance The equation most commonly used for determining the loss in a fitting, valve, meter, or other localized component is:

hm = K

Where

V2 2g

(B.30)

hm

=

loss due to the minor loss element (m, ft)

K

=

loss coefficient for the specific fitting

V

=

velocity (m/s, ft/sec.)

g

=

gravitational acceleration constant (m/s2, ft/sec. 2)

Typical values for fitting loss coefficients are included in the fittings table, see “Fitting Loss Coefficients” on page B-311. Generally speaking, more-gradual transitions create smoother flow lines and smaller head losses. For example, “Figure B-12: Flow Lines at Entrance”on page B-282 shows the effects of entrance configuration on typical pipe entrance flow lines.

B-282

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HAMMER Theory and Practice

B.7.5

Quasi-Steady Friction In HAMMER, a hydraulic transient analysis usually begins with an initial steady state for which the heads and flows are known for every pipe in the system. Prior to beginning the transient calculations, HAMMER automatically determines the friction factor based on the following information: 1. If a pipe has zero flow at the initial steady state, HAMMER obtains a friction factor from a default table based on its diameter: Table B-5: Default Friction Coefficient Equivalents Hazen-Williams Friction Coefficient, C

Approximate DarcyWeisbach Friction Coefficient, f

70

0.050

100

0.025

140

0.015

2. If a pipe has a nonzero flow at the initial steady state, HAMMER automatically calculates a Darcy-Weisbach friction factor, f, based on the heads at each end of the pipe, the pipe length and diameter, and the flow in the pipe. 3. HAMMER uses the Darcy-Weisbach friction method in performing either steadystate or transient friction calculations. If you enter an f value for a pipe in the Element Editor, HAMMER uses this value in the calculations instead of the default value. The Darcy-Weisbach method reflects the changes in total fluid and pipe friction as flow changes, as compared with the other methods shown in “Figure B-13: Comparison of Friction Coefficients in Various Methods”on page B-284.

HAMMER User's Guide

B-283

Friction and Minor Losses

Figure B-13: Comparison of Friction Coefficients in Various Methods

Note:

If your steady-state model used another method to calculate friction losses, the friction coefficients can be imported into HAMMER but they will not be used directly. Instead, HAMMER automatically uses the steady-state flow and heads (resulting from the other method) to calculate an equivalent DarcyWeisbach friction factor, f.

The quasi-steady friction method uses variable Darcy-Weisbach friction factors, f, at each point along the system. Thus, friction losses for an instantaneous velocity match the friction losses for fully developed steady flows with the same cross-sectional average velocity. This method is more computationally demanding than steady-state friction. Because it assumes that the friction factor does not vary with time, the steady-state friction method is a special case of the quasi-steady method. The quasi-steady friction method is virtually an unsteady method, although one based on steady-state friction factors.

B-284

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HAMMER Theory and Practice

B.7.6

Unsteady or Transient Friction Compared to a steady state, fluid friction increases during hydraulic transient events because rapid changes in transient pressure and flow increase turbulent shear. HAMMER can track the effect of fluid accelerations to estimate the attenuation of transient energy more closely than would be possible with quasi-steady or steady-state friction. Computational effort increases significantly if transient friction must be calculated for each time step. This can result in long model-calculation times for large systems with hundreds or pipes or more. Typically, transient friction has little or no effect on the initial low and high pressures, and these are usually the largest ever reached in the system. This is illustrated from the following HAMMER simulation results comparing steady, quasi-steady and transient friction methods.

250 Steady

Quasi-Steady

Transient

Steady 230

Head (m)

Quasisteady

210

Unsteady (Transient) 190 0

5

10

Time (s)

15

20

25

Figure B-14: HAMMER Results for Steady-State, Quasi-Steady, and Transient Friction Methods Transient Tip: The steady-state friction method yields conservative estimates of the extreme high and low pressures that usually govern the selection of pipe class and surgeprotection equipment. However, if cyclic loading is an important design consideration, the unsteady friction method can yield less-conservative estimates of recurring and decaying extremes.

HAMMER User's Guide

B-285

Developing a Surge-Control Strategy

B.8

Developing a Surge-Control Strategy Ideally, a system is designed and operated to minimize the likelihood of damaging transient events. However, in reality, transients still occur; thus, methods for controlling transients are necessary. This section has two goals: (1) to make the hydraulic engineer aware of the system conditions that lead to the development of undesirable transients, such as pump and valve operations, and (2) to present the protection methods and devices that should be used during design and construction of particular systems and discuss their practical limitations. There are two possible strategies for controlling transient pressures. The first is to focus on minimizing the possibility of transient conditions during project design by specifying appropriate flow-control operations and avoiding the occurrence of emergency and unusual system operations. The second is to install protection devices to control potential transients due to uncontrollable events, such as power and equipment failures. Systems protected by adequately designed surge tanks are generally not adversely affected by emergency or unusual flow-control operations, because operational failure of surge tanks is unlikely. In systems protected by gas vessels, however, an air outflow or air-compressor failure can lead to damage from transients. Consequently, potential emergency situations and failures should be evaluated and avoided to the extent possible through the use of alarms that detect device failures and control systems that act to prevent them. With most small, well-gridded water-distribution network piping, sufficient safety factors are built into the system, such as adequate pipe-wall thickness and sufficient reflections (tanks and dead ends) and withdrawals (water use). The effects of transients are most likely to result in pipe failures in long pipelines with long characteristic times (large values of 2 L/a), high velocities, and few branches. Filion and Karney (2002) found that water usage and leaks in a distribution system can result in a dramatic decay in the magnitude of transient pressure effects.

B.8.1

Piping System Design and Layout When designing water-distribution systems, the engineer needs to consider economic and technical factors, such as acquisition of property, construction costs, site topography, and geological conditions. In addition, emergency flow-control scenarios should be analyzed and tested during the design phase, since they affect the piping system design and the specification of surge-protection equipment.

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HAMMER Theory and Practice Pipeline layouts with undulating topographic profiles are common. For these systems, it may be desirable to change the route and/or profile of the pipeline to avoid high points that are prone to air accumulation or exposure to low pressures (or both), but this is seldom possible. If the minimum transient head is above the elevation of the piping system, then transient protection devices are most likely unnecessary, thus minimizing construction costs and operational risks. Low-head systems are more prone to experience transient vacuum conditions and liquid-column separation than are high-head systems. If the system designer does not account for the occurrence of low transient pressures in low-head systems, then a pipeline with inadequate wall thickness may be specified, potentially leading to pipeline collapse even if the pipeline is buried in a well-compacted trench. For example, low-head systems with buried steel pipelines and diameter/thickness ratios (D/e) more than 200 should be avoided because of the risk of structural collapse during a transient vacuum condition, particularly if the trench fill is poorly compacted. Steel, PVC, HDPE, and thin-wall ductile-iron pipes are susceptible to collapse due to vapor separation, but any pipe that has been weakened by repeated exposure to these events may experience fatigue failure. A pipe weakened by corrosion may also fail. Where very low pressures are possible during transient events, the engineer may choose to use a more expensive material to preclude the chance of collapse. For example, for large-diameter pipes under high pressures, steel is usually more economical than ductile iron or high-pressure concrete. However, the engineer may select high-pressure concrete or ductile iron because it is less susceptible to collapse and may eliminate the need for operational constraints. Piping systems constructed above ground are more susceptible to collapse than buried pipelines. With buried pipelines, the surrounding bedding material and soil provide additional resistance to pipeline deformations and help the pipeline resist structural collapse. Above-ground pipelines must be anchored securely against steady-state and transient forces. Using combination-air valves to avoid subatmospheric or vacuum conditions requires careful analysis of possible transient conditions to ensure that the air valve is adequately sized and designed. Several cases cited in the literature describe the collapse of piping systems due to the failure of an air inlet valve that was poorly sized, designed, or maintained. Combination-air valves can provide reliable surge control, but the potential for operational failures in air valves should not be ignored. Other factors that influence extreme transient heads are pressure wave speed and liquid velocity. Selecting larger diameters to obtain lower velocities with the purpose of minimizing transient heads is acceptable for short pipeline systems delivering relatively low flows. However, for long pipeline systems, the diameter should be selected to optimize construction and operating costs. Long piping systems almost always require transient protection devices.

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Developing a Surge-Control Strategy After considering these factors during the conceptual and preliminary designs, the project should move into the final design phase. Any changes to the system during final design should be analyzed with the transient model to verify that the previous results and specifications are still appropriate prior to commissioning.

B.8.2

Protection Devices Using a transient model, the engineer can try different valve operating speeds, pipe sizes, and pump controls to see if the transient effects can be controlled to acceptable levels. If transients cannot be prevented, specific devices to control transients may be needed. Some methods of transient prevention include: •

Slow opening and closing of valves—Generally, slower valve-operating times are required for longer pipeline systems. Operations personnel should be trained in proper valve operation to avoid causing transients.

•

Proper hydrant operation—Closing fire hydrants too quickly is the leading cause of transients in smaller distribution piping. Fire and water personnel need to be trained on proper hydrant operation.

•

Proper pump controls—Except for power failures, pump flow can be slowly controlled using various techniques. Ramping pump speeds up and down with soft-start or variable-speed drives can minimize transients, although slow opening and closing of pump-control valves downstream of the pumps can accomplish a similar effect, often at lower cost. The control valve should be opened slowly after the pump is started and closed slowly prior to shutting down the pump.

•

Lower pipeline velocity—Pipeline size and thus cost can be reduced by allowing higher velocities. However, the potential for serious transients increases with decreasing pipe size. It is usually not cost effective to significantly increase pipe size to minimize transients, but the effect of transients on pipe sizing should not be ignored in the design process.

•

Stronger pipe—For long-term reliability, pipes and joints should be strong enough to resist both high and subatmospheric, or even vacuum, pressures.

To control minimum pressures, the following can be adjusted or implemented:

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•

Pump inertia

•

Surge tanks

•

Air chambers

•

One-way tanks

•

Air inlet valves

•

Pump bypass valves

HAMMER User's Guide

HAMMER Theory and Practice To control maximum pressures, the following can be implemented: •

Relief valves

•

Anticipator relief valves

•

Surge tanks

•

Air chambers

•

Pump bypass valves

The items in the preceding lists are discussed in the sections that follow. These items can be used singly or in combination with other devices.

B.8.3

Approaches to Surge Protection A reliable surge-protection system must be in place before the occurrence of uncontrolled emergency conditions (e.g., power failure or load rejection in a pump or turbine). The most common tactics to control water hammer can be grouped into three categories, as shown in the following table. Table B-6: Comparison of Surge-Protection Approaches Approach

SystemImprovement Approach

FlowSupplement Approach

Surge-Relief Approach

Surge Control Measures/Impacts

•

•

Surge tank

•

•

Air chamber

•

Increase pump inertia

Various surgecontrol valves including SRV, CAV, and SAV

•

Rupture disk

Realign pipeline route

•

Recut or improve profile

•

Enlarge pipe size

•

Reduce flow

Reliability

+++++

+++

+

Cost

---

-

+++

Operation and Maintenance

+++++

+++

+

Complexity

+++

++

+

Flexibility

---

+

+++

• Legend: + Positive effect, - Negative effect

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Developing a Surge-Control Strategy Note:

Careful operational procedures and maintenance programs are very important to protect the water system from water hammer damage due to equipment malfunction.

These three approaches differ significantly in terms of the required civil and piping works, physical appearance, hydraulic characteristics, long-term reliability, operational complexity and flexibility, and cost of construction, operation, and maintenance. However, these measures have a common basis—all three attempt to protect the system from water hammer by reducing the rate of change of flow to minimize the effects of transients. Each approach modifies a different governing parameter, as described in the following sections. Table B-7: Governing Parameters for Hydraulic Transients A) Piping system characteristics (i) Static variables •

Pipe length (L)

•

Pipe size (D)

•

Pipe profile

•

Static lift (Ho)

•

Pipeline surface roughness (C or f)

•

Pressure wave speed (a)

•

Pipe flow (Q) or velocity (V)

•

Node pressure (P) or head (H)

•

Network connectivity (looping, branching, dead ends)

B) Pump-motor characteristics (turbine characteristics are similar) •

Power (Pw)

•

Rotating speed (N) or torque (M)

•

Pump total dynamic head (TDHo)

•

Pumping capacity (Qo)

•

Moment of inertia (WR2)

•

Net positive suction head required (NPSHr)

C) Valve characteristics

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HAMMER Theory and Practice Table B-7: Governing Parameters for Hydraulic Transients (Cont’d) •

Types (check valve, surge anticipator, vacuum breaker, air release ….)

•

Closure characteristics (butterfly, needle, …)

•

Operation procedures (time to open, close, operating curve ….)

D) Surge tank characteristics •

Diameter (Ds) or surface area (As)

•

Geometry and variation

•

Top (spilling) and bottom (dewatering) elevation

•

Orifice size and differential ratio

E) Air Chamber characteristics •

Diameter (Da) and length (La)

•

Orifice size and differential ratio

•

Orientation (vertical or horizontal)

F) Transient characteristics •

Upsurge head (Hup)

•

Downsurge head (Hdown)

•

Flow (Q) and direction

•

Vapor or air volume in line

•

Time for maximum transient to occur

•

Dampening rate

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Developing a Surge-Control Strategy

System-Improvement Method This method is the most reliable, with the least operation and maintenance requirement. However, it is very expensive and usually used only as a last resort. It consists of the following measures: 1. Reduce velocity—The smaller the pipe flow velocity, the less potential there is for a large rate of change in velocity (dV/dt). Normal velocities can be reduced by enlarging the pipe diameter or redistributing the flow to twin pipes. 2. Pipe material—The pressure wave speed a of a flexible pipe material is less than that for rigid pipe. For a very fast stoppage of flow (< 2 L/a), the transient effect of pressure-wave speed is prominent. Changing pipe material may improve the outcome, although the surge tolerance of a more flexible pipe may be less. 3. Pipeline improvement—Pipeline profiles with prominent local high points are susceptible to the occurrence of subatmospheric or even full vacuum pressure, resulting in water-column separation and vapor or air pockets in the pipeline. Very high upsurge pressures can result when water columns subsequently rejoin. Extra excavation or fill can reduce or eliminate local high points.

Flow-Supplement Approach This approach can be used to effectively control transients resulting from a pump shutdown or startup. Following a power failure, energy stored in hydraulic or mechanical devices can be converted into kinetic energy to force flow into the system and prevent vapor or air pockets from forming. Such energy conversions reduce the rate of change of flow and, consequently, the magnitude of the resulting hydraulic transients. Part of the flow enters the surge tank or air chamber at start-up or during the upsurge, thereby reducing the effects of an otherwise rapid increase in flow. Due to its relatively high cost, this very reliable method may not be feasible in small water systems. The following sections describe specific implementations of the flow-supplement approach.

Two-Way Surge Tank A two-way surge tank controls transients by converting stored potential energy in the elevated water body inside the tank into kinetic energy, which supplements flow in the piping system at critical times (or vise versa, for pipe flow into the tank) during periods of rapid flow variation. The tank is normally located at the pumping station or at a high point in the system.

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HAMMER Theory and Practice A differential orifice may be installed at the riser of the tank to throttle reverse flow from the system to the tank, but create very little loss for flow leaving the tank. If an overflow and drain is provided, the tank can also act as a foolproof overpressure device that can overflow in a controlled manner. One of the main concerns is the stability problem inside the tank. A rapid rise or drop in water level in the tank should be avoided. Usually, the surface area of the tank should be significantly larger than that of the pipeline. In a high-head water system or a sanitary forcemain, a two-way surge tank may not be economically feasible because of height or odor problems. A sample HAMMER run extracted from a case study is shown in the following figure.

Surge Tank

Figure B-15: Output of HAMMER Run for a Two-Way Surge Tank

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Developing a Surge-Control Strategy

One-Way Surge Tank A one-way surge tank is a relatively small conventional surge tank, with a check valve in the connecting pipe, or riser, that only allows flow out of the tank. The tank water level is maintained by an altitude valve bypassing the check valve. The tank is located at the high point to supply water and prevent water-column separation. However, oneway tanks provide no upsurge protection to the system because no flow is allowed back into the tank. Wherever there is a possibility of freezing, surge tanks may require insulation or heating. On sewerage forcemains, special consideration should be given to: •

The design of the check valve at the riser to protect against debris or jamming.

•

Careful pump restart procedures following a power failure.

•

Cost of refilling this tank with drinking water (to avoid odors).

•

A chamber may be required to enclose the tank.

•

A sanitary sewer may be required to drain liquid overtopping the tank.

Gas Vessel or Air Chamber This control device functions similarly to a surge tank but its potential energy is stored as compressed air. The air chamber is usually used in a high-head pumping system. It should be located close to the pumping station and inside an enclosed building. Auxiliary equipment such as compressors are also required. A differential orifice can be installed to minimize the chamber size by creating greater head losses for inflows to the vessel than to outflows entering the system. For a system with a high friction head, one should consider optimizing the chamber by installing several clusters of probes, each throttling and/or starting (or stopping) a specific number of operating pumps. “Figure B-16: Output of HAMMER Run for an Air Chamber”on page B-295 shows the effectiveness of a gas vessel in controlling hydraulic transients.

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HAMMER Theory and Practice

f

Figure B-16: Output of HAMMER Run for an Air Chamber Some manufacturers and engineers reduce the air chamber size by letting air into it during the downsurge period. There are a number of serious concerns in the practical application of this, as follows:

HAMMER User's Guide

B-295

Developing a Surge-Control Strategy •

If the downsurge head drops to or below the pump station elevation, part of the pipeline may already be subjected to subatmospheric pressures or even a fullvacuum condition. This may defeat the purpose of an air chamber installed to protect against the downsurge.

•

Normally, an air chamber requires a high static head to be practical. If the downsurge head drops to the pump station, a large upsurge head can also bounce back, considerably higher than the static head. This may also defeat the purpose of its upsurge protection.

•

Air inside a gas vessel (air chamber) is always contained by a thick metal shell and separated from atmospheric pressure by piping and a reservoir. With an airinlet valve mounted on the top, during the downsurge period a large quantity of air at atmospheric pressure can rush into the chamber. During the upsurge (or even possibly during normal operation) period, the huge pressure difference between the inside and outside of the chamber provides a high possibility that a large volume of air could escape through a leak in the inlet valve. Since an air chamber is a pressure vessel, pressure inside the chamber is many times greater than atmospheric pressure outside the chamber. The mechanical part of the air-inlet valve can leak or fail.

When a significant volume is required, two smaller gas vessels should be considered to provide redundancy whenever one unit has to be maintained, or in case one loses its gas volume and is ineffective during a transient. The following appurtenances require careful design: •

There should be two or more redundant air compressors, each equipped with a tank to store enough air at the required pressure to supply the gas vessel for short times after a power failure. Compressors should be capable of running from generators during an extended power failure if diesel fire pumps will be running.

•

Level-control probes should be set for high and low level, high and low alarm, and drain or fill. Compressors should be started and stopped according to these levels. Avoid setting high- and low-level probes too close to the normal operating range to avoid spurious warnings—this can cause operators to ignore more serious lowor high-level alarms.

Increase of Inertia Inertia increases when flywheels are added to a shaft to increase the kinetic energy stored in rotating parts, thereby buffering a rapid pump shutdown. Pumps have tended to get smaller and smaller (with less inertia) and lighter, multistage vertical pumps are used more frequently. This has tended to make this option far less common.

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B.8.4

Pump Protection Pump protection includes: •

“Check Valve” on page B-297

•

“Booster Pump Bypass” on page B-297

Check Valve A check valve on the discharge line of a pump should have a fast closing time to prevent flow reversal through the pump and the valve slam that can occur with delayed valve closure, or where surge tanks are incorporated into the pump station design. Valve slam can damage the valve, pump, or system piping. If it is not possible to have a check valve that closes before the surge tank responds and slams the valve, some type of dampening device, such as a dash pot, is necessary to control valve closure during the last 5 to 10 percent of the valve travel.

Booster Pump Bypass Another type of protection device is the pump bypass. The following figure shows a booster pumping system. When the booster pumps shut down, the resulting reduction in flow generates pressure waves on both sides of the pump. The wave traveling upstream is a positive transient and the wave traveling downstream is a negative transient.

Figure B-17: Booster Pumping System with Bypass

HAMMER User's Guide

B-297

Developing a Surge-Control Strategy Depending on the relative lengths of the upstream pipeline (LS) and the downstream pipeline (LR) and the magnitude of the velocity changes, a pump bypass connection can act as a transient protection element. Water continues past the booster station if the downstream pressure falls below the upstream pressure, thus limiting the pressure rise upstream of the booster station and the pressure drop downstream. The next figure shows the transient analysis results for such a system. These results show that the bypass opened to transfer water from the upstream pipeline to the downstream pipeline, which helped to attenuate or control the maximum and minimum pressure transients on the upstream and downstream sides of the station.

Figure B-18: Booster Pump Shutdown The effectiveness of a booster-station bypass depends on the specific booster pumping system and the relative lengths of the upstream and downstream pipelines. If the lowpressure surge generated on the discharge side of the pump is still greater than the high-pressure surge generated on the suction side of the pump (which tends to occur if LR < LS), the bypass will not open. For systems in which the bypass may not open, other transient protection devices are necessary. Each system should be individually analyzed to assess the occurrence of excessive high- and/or low-pressure transients and determine strategies to control potentially excessive pressures.

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B.8.5

Surge-Relief Valves There are many documented cases of poorly specified control valves. Some of these valves do not operate adequately because of excessive head loss or cavitation during steady-state flow conditions; others are inadequate to control hydraulic transients because of poor valve selection or poor operation. When specifying valves for flow control and/or pumping stations, the engineer must carefully evaluate the type, number, and size of valves to provide adequate steady and transient flow regulation. Note:

Even with a comprehensive understanding of the system equipment and operations, the engineer should realize that it may not be possible to precisely model the actual system and system components. Therefore, it is the engineer’s responsibility to recognize these modeling limitations, use appropriate safety factors, and apply good engineering judgement when performing transient analysis.

The advantage of surge-relief valves is that they are relatively inexpensive and easy to fit into a pumping system at the locations of interest. Generally, valves control surge conditions by opening and/or closing according to preset characteristics. This restricts hydraulic transients to more tolerable limits, but it can rarely eliminate cavitation or water-column separation. Moreover, if the valves are oversized or operated too rapidly, other types of water hammer problems may result (e.g., water bleeding, and excessive flow reversals), possibly resulting in worse transients than without valve protection. However, with careful HAMMER modeling and design, valves offer a versatile and powerful means to safely control water hammer. The following are different types of surge-relief valves: •

Check valve—mechanical or electrical control

•

Pressure-relief valve

•

Station-bypass line with check valve

•

Inline bypass with check valve

•

Air-inlet (vacuum breaker) valve

•

Air-release valve

•

Combined air valve

•

Hydraulically controlled slow-closing air valve

•

Surge-anticipator valve

•

Rupture disk

The following descriptions and figures show their geometry and schematics:

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Developing a Surge-Control Strategy Check valve—a check valve is commonly installed in a municipal pumping station to prevent flow from reversing through the pump. A dashpot may be provided to avoid check valve slam; however, surges still may occur in the piping system and other methods may also be required. A check valve equipped with an electronically controlled closure device is often used by engineers. The timing and rate of closure must be carefully set to protect both the pump and the discharge system.

Qo Flow

Flow at P.S.

Check With Valve Time

a) Check Valve

Rotential Reverse Flow

Pressure-relief valve—This valve is usually installed across the pumps and discharge headers or at critical points along the pipeline. It opens when a preset pressure is exceeded and closes immediately after pressure drops below this setting. A damped closure may be provided to allow for a longer closing time. One of the main concerns is the considerable time lag for the valve to open following a power failure. Transient pressure waves can come and go in a fraction of second. Very often, this valve is used as a redundant measure, to limit the pressure rise during normal pumping operations.

Pump station bypass with check valve—If the suction water level is high, a bypass line can slow the reduction in flow by supplying water to the pipeline during the downsurge period (following a power failure) using potential energy in the suction reservoir. However, it provides no upsurge protection to a pumping system because no back flow is allowed through the check valve. It can be effective in a downhill or flat pipeline. A smaller bypass line is sometimes provided (as shown by dotted lines) around the check valve in the primary bypass line.

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Inline bypass with check valve—The check valve is usually located downstream of the location of cavitation at a high point. The bypass line should be sized so that no high pressure is built up at the downstream section and no large reverse-flow velocity occurs in the upstream section of the check valve. Normally, an air valve needs to be installed at the crest to eliminate vapor pressure, and a surge-anticipator valve is located at the pump station to protect it and the pipe section between the pump and the high point.

Air-inlet (vacuum-breaker) valve—This valve consists of an orifice that can be opened or blocked based on system pressure, often by a float device. When pressure drops below the valve elevation, air is sucked in quickly through the inlet orifice to maintain atmospheric pressure. If the opening is too small, the incoming air velocity may reach the sonic limit, resulting in subatmospheric pressure inside the system. This valve does not allow air to escape the system; it must exit farther down the line. Air-release valve—This valve also consists of an orifice equipped with a mechanism to open or close it, often by a float device. When air accumulates inside the valve body, or reaches a preset residual volume, air is released from the valve in an orderly and gradual manner. Air is not allowed to enter the system. This valve is commonly installed at all local high points within the water system. Combination air valve—Combination air valves consist of at least two components: a) a large air inlet valve, b) a large outlet orifice (two-way), and possibly a restrictor of some kind to reduce the opening to a much smaller orifice (three-way) when air in the valve body is less than the residual volume. When pressure drops below the elevation of the valve, air enters quickly through the vacuum breaker to maintain the pressure near atmospheric. Upon the upsurge, air can be expelled quickly through the bigger

HAMMER User's Guide

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Developing a Surge-Control Strategy outlet, until the air in the system is almost totally removed and water starts to enter the valve body. The remaining air volume inside the valve is released in a controlled manner by the small outlet orifice, acting as an air cushion to reduce the transient pressure rise. This type of valve is popular both for water-distribution systems and sanitary forcemains. However, if the air volume allowed into the pipe system is big and, if it is released too quickly, excessively high transient pressures can occur when the two water columns accelerate towards each other during a prolonged period of air release. The static head can defeat the effectiveness of the air cushion due to the large buildup of momentum in these accelerating water columns.

Hydraulically controlled slow-closing air valves—This valve is located at high points of the piping system and acts like an air-inlet valve and surge-anticipator. When line pressure at the valve drops below atmospheric pressure, it admits air into the pipeline. Upon upsurge, air, water, or a mixture of air and water can bleed out to the atmosphere. One of the drawbacks of this installation is the need for a piping system to drain water away.

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HAMMER Theory and Practice Surge-anticipator valve—The surge anticipator is normally installed across the pump suction and discharge headers, with suitable connecting piping. It opens quickly at a specified time after power failure (or at a preset low-pressure limit) to allow flow to begin before the main upsurge returns to the pump station, then closes slowly at a preadjusted rate. During the valve-closing period, flow may decrease much more rapidly than the opening area of the valve. High flow velocities in the pipeline can prevent a hydraulically actuated SAV from closing, in extreme cases. Consult the valve manufacturer’s catalog to select the correct valve type, size, and piloting (if applicable) for your application. Time Delay

Fully Open

Valve Opening

Valve Operation

g) Surge Anticipator

(Automatic Control)

Fast Open

Slow Closing

Time

Rupture disk—A rupture disk is equipped with a membrane which can burst to discharge a large flow rate and relieve mass (pressure) from the system whenever transient pressures exceed a pre-set value. Such disks may rupture at a different pressure and both the upper and lower burst limit provided by the manufacturer should be modeled using HAMMER. Pressure-sustaining valve—This valve is usually installed at the downstream end of a pump-discharge line. It dissipates large amounts of energy just before flow drains to a lower-energy water system. The valve sustains a stable pressure to the upstream, higher-head system, by adjusting the opening area of the valve multi-orifices. However, during the transient period, this valve cannot physically tune the orifices fast enough to catch rapid pressure changes. A sample run based on a case study is presented in the following figure. As shown, the combination air valve does not help to control surge due to the big air pocket and the high head at the downstream reservoir, in this particular case.

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Developing a Surge-Control Strategy

Figure B-19: HAMMER Results for a Combined Air Valve

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B.8.6

Operation and Maintenance The following items can be considered when setting operation and maintenance procedures for a pumping system: •

Time delay—Following a power failure or emergency shutdown, pumps should be restarted only after transients have had sufficient time to decay and air has been removed from the piping as much as possible. A transient decay analysis can be simulated and a timer should be used to prevent a premature pump restart of: –

The diesel pump

–

The duty pump (if power resumed quickly)

–

The standby power grid

Transient Tip: Restart time delays required to allow transients to decay are typically short in terms of water supply (tens of seconds). However, transients caused by a power failure may already have come and gone (in a fraction of second) within the same restart period. Should significant air still remain in the water system, a fast restart of the above device may actually worsen hydraulic transients.

•

Slow change of pump operation—Flow in the water system will increase or decrease slowly if the following procedures are applied: –

Sequential pump shutdown or startup

–

Variable-speed pump ramps up and down gradually

–

Soft-start motor controllers for pump startup and shutdown

–

Slow and progressive operation of pump discharge control valves

–

Slow operation of isolation valves, drain valves, or reservoir/tank inlet valves

•

Air venting—The air trapped at local high points must always be released during both normal and emergency pumping operations. During line filling, air at local high points must be vented in the proper order and pump flow must be much smaller than its design capacity to avoid severe hydraulic transients and pipe breaks.

•

Suction system hydraulics—The size of the suction well and/or the suction lines should be designed and operated adequately to prevent spilling or dewatering. Whenever the capacity of the pump station increases, the suction system should be modeled and possibly upgraded to ensure that NPSHA is greater than NPSHR, while the upstream reservoir can freely fluctuate between designed high- and lowwater levels.

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Engineer’s Reference

B.9

•

Slow change of valve operation—Valve opening or closing times must be long enough. Alternatively, two or more stages can be used, with different stroke speeds for each.

•

Alarm setup—Alarm systems should be regularly tested and checked. If false alarms occur frequently, conduct an analysis to determine the causes and provide remedial measures. Otherwise, operators may shutdown the alarm system to eliminate annoyances.

•

Maintenance—It is essential to regularly inspect and clean the protection devices, particularly those located outside the pump station.

•

Staff training—A workshop can be presented to the engineers and operators, who often know their water system better than any expert. Very often, the system needs to be pushed beyond normal operating ranges to achieve the water-supply objectives. Training is particularly critical for existing pumping stations that have been upgraded many times. It is also possible that operators are not aware of transients occurring far from the pump station, where no one may be present to experience them.

Engineer’s Reference This section contains tables of commonly used roughness values and fitting loss coefficients. Roughness Values:

B-306

•

“Roughness Values—Manning’s Equation” on page B-307

•

“Roughness Values—Darcy-Weisbach Equation (Colebrook-White)” on page B308

•

“Roughness Values—Hazen-Williams Equation” on page B-309

•

“Typical Roughness Values for Pressure Pipes” on page B-310

•

“Fitting Loss Coefficients” on page B-311

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B.9.1

Roughness Values—Manning’s Equation Commonly used roughness values for different materials are: Table B-8: Manning’s Coefficient (n) for Closed Metal Conduits Flowing Partly Full Channel Type and Description

Minimum

Normal

Maximum

a. Brass, smooth

0.009

0.010

0.013

1. Lockbar and welded

0.010

0.012

0.014

2. Riveted and spiral

0.013

0.016

0.017

1. Coated

0.010

0.013

0.014

2. Uncoated

0.011

0.014

0.016

1. Black

0.012

0.014

0.015

2. Galvanized

0.013

0.016

0.017

1. Subdrain

0.017

0.019

0.021

2. Storm drain

0.021

0.024

0.030

b. Steel

c. Cast iron

d. Wrought iron

e. Corrugated metal

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Engineer’s Reference

B.9.2

Roughness Values—Darcy-Weisbach Equation (Colebrook-White) Commonly used roughness values for different materials are: Table B-9: Darcy-Weisbach Roughness Heights e for Closed Conduits

B-308

Pipe Material

ε (mm)

ε (ft.)

Glass, drawn brass, copper (new)

0.0015

0.000005

Seamless commercial steel (new)

0.004

0.000013

Commercial steel (enamel coated)

0.0048

0.000016

Commercial steel (new)

0.045

0.00015

Wrought iron (new)

0.045

0.00015

Asphalted cast iron (new)

0.12

0.0004

Galvanized iron

0.15

0.0005

Cast iron (new)

0.26

0.00085

Concrete (steel forms, smooth)

0.18

0.0006

Concrete (good joints, average)

0.36

0.0012

Concrete (rough, visible, form marks)

0.60

0.002

Riveted steel (new)

0.9 ~ 9.0

0.003 - 0.03

Corrugated metal

45

0.15

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B.9.3

Roughness Values—Hazen-Williams Equation Commonly used roughness values for different materials are: Table B-10: Hazen-Williams Roughness Coefficients (C) Pipe Material

C

Asbestos Cement

140

Brass

130-140

Brick sewer

100

Cast-iron New, unlined

130

10 yr. Old

107-113

20 yr. Old

89-100

30 yr. Old

75-90

40 yr. Old

64-83

Concrete or concrete lined Steel forms

140

Wooden forms

120

Centrifugally spun

135

Copper

130-140

Galvanized iron

120

Glass

140

Lead

130-140

Plastic

140-150

Steel Coal-tar enamel, lined

145-150

New unlined

140-150

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Engineer’s Reference Table B-10: Hazen-Williams Roughness Coefficients (C) (Cont’d) Pipe Material

C

Riveted

B.9.4

110

Tin

130

Vitrified clay (good condition)

110-140

Wood stave (average condition)

120

Typical Roughness Values for Pressure Pipes Typical pipe roughness values are shown below. These values vary according to the manufacturer, workmanship, age, and many other factors. Table B-11: Comparative Pipe Roughness Values Material

Manning’s HazenCoefficient Williams n C

Darcy-Weisbach Roughness Height k (mm)

k (0.001 ft)

Asbestos cement

0.011

140

0.0015

0.005

Brass

0.011

135

0.0015

0.005

Brick

0.015

100

0.6

2

Cast-iron, new

0.012

130

0.26

0.85

Steel forms

0.011

140

0.18

0.6

Wooden forms

0.015

120

0.6

2

Centrifugally spun

0.013

135

0.36

1.2

Copper

0.011

135

0.0015

0.005

Corrugated metal

0.022

—

45

150

Galvanized iron

0.016

120

0.15

0.5

Glass

0.011

140

0.0015

0.005

Lead

0.011

135

0.0015

0.005

Concrete:

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HAMMER Theory and Practice Table B-11: Comparative Pipe Roughness Values (Cont’d) Material

Manning’s HazenCoefficient Williams n C

Darcy-Weisbach Roughness Height

Plastic

0.009

150

0.0015

0.005

Coal-tar enamel

0.010

148

0.0048

0.016

New unlined

0.011

145

0.045

0.15

Riveted

0.019

110

0.9

3

Wood stave

0.012

120

0.18

0.6

Steel

B.9.5

Fitting Loss Coefficients For similar fittings, the K-value is highly dependent on such things as bend radius and contraction ratios. Table B-12: Typical Fitting K Coefficients Fitting

K Value

Pipe Entrance

Fitting

K Value

90° Smooth Bend

Bellmouth

0.03-0.05

Bend Radius / D = 4

0.16-0.18

Rounded

0.12-0.25

Bend Radius / D = 2

0.19-0.25

Sharp-Edged

0.50

Bend Radius / D = 1

0.35-0.40

Projecting

0.80

Contraction—Sudden

Mitered Bend θ = 15°

0.05

D2/D1 = 0.80

0.18

θ = 30°

0.10

D2/D1 = 0.50

0.37

θ = 45°

0.20

D2/D1 = 0.20

0.49

θ = 60°

0.35

θ = 90°

0.80

Contraction—Conical D2/D1 = 0.80

0.05

D2/D1 = 0.50

0.07

HAMMER User's Guide

Tee Line Flow

0.30-0.40

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References Table B-12: Typical Fitting K Coefficients (Cont’d) Fitting D2/D1 = 0.20

K Value 0.08

Expansion—Sudden

K Value

Branch Flow

0.75-1.80

Cross

D2/D1 = 0.80

0.16

Line Flow

0.50

D2/D1 = 0.50

0.57

Branch Flow

0.75

D2/D1 = 0.20

0.92

45° Wye

Expansion—Conical

B.10

Fitting

D2/D1 = 0.80

0.03

D2/D1 = 0.50

0.08

D2/D1 = 0.20

0.13

Line Flow

0.30

Branch Flow

0.50

References Allievi, L., “General Theory of Pressure Variation in Pipes”, Ann. D. Ing. Et Archit. Ital. Dec. 1902. English translation by Holmes, E., ASME, 1925 ASCE. (1975). Pressure Pipeline Design for Water and Wastewater. ASCE, New York, New York. Bergeron, L., “Waterhammer in Hydraulics and Wave Surge in Electricity”, John Wiley & Sons, Inc., N.Y., 1961 Brunone, B., Karney, B.W., Mecarelli, M., and Ferrante, M. “Velocity Profiles and Unsteady Pipe Friction in Transient Flow” Journal of Water Resources Planning and Management, ASCE, 126(4), 236-244, Jul. 2000. Chaudhry, M.H., “Applied Hydraulic Transients”, Van Nostrand Reinhold Co., N.Y., 1979 Chaudhry, M.H. and Yevjevich, V. (1981) “Closed Conduit Flow”, Water Resources Publication, USA Chaudhry, M. H. (1987). Applied Hydraulic Transients. Van Nostrand Reinhold, New York. Elansari, A. S., Silva, W., and Chaudhry, M. H. (1994). “Numerical and Experimental Investigation of Transient Pipe Flow.” Journal of Hydraulic Research, 32, 689.

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HAMMER Theory and Practice Filion, Y., and Karney, B. W. (2002). “A Numerical Exploration of Transient Decay Mechanisms in Water Distribution Systems.”, Proceedings of the ASCE Environmental Water Resources Institute Conference, American Society of Civil Engineers, Roanoke, Virginia Fok, A., “Design Charts for Air Chamber on Pump Pipelines”, J. of Hyd. Div., ASCE, Sept. 1978 Fok, A., Ashamalla, A., and Aldworth, G., “Considerations in Optimizing Air Chamber for Pumping Plants”, Symposium on Fluid Transients and Acoustics in the Power Industry, San Francisco, U.S.A. Dec. 1978 Fok, A., “Design Charts for Surge Tanks on Pump Discharge Lines”, BHRA 3rd Int. Conference on Pressure Surges, Bedford, England, Mar. 1980. Fok, A., “Waterhammer & Its Protection in Pumping Systems”, Hydrotechnical Conference, CSCE, Edmonton, May 1982 Fok, A., “A contribution to the Analysis of Energy Losses in Transient Pipe Flow”, Ph.D. Thesis, University of Ottawa, 1987 Fox, J.A., “Hydraulic Analysis of Unsteady Flow in Pipe Network”, Wiley, N.Y., 1977 Hamam, M.A. and McCorquodale, J.A., “Transient Conditions in the Transition from Gravity to Surcharged Sewer Flow”, Canadian J. of Civil Eng., Sep. 1982 Jaeger, C., “Fluid Transients in Hydro-Electric Engineering Practice”, Blackie & Son Ltd., 1977 Joukowski, N. Paper to Polytechnic Soc. Moscow, Spring of 1898, English translation by Miss O. Simin. Proc. AWWA, 1904 Koelle, E., Luvizotto, Jr., E., and Andrade, J.P.G. “Personality Investigation of Hydraulic Networks using MOC – Method of Characteristics” Proceedings of the 7th International Conference on Pressure Surges and Fluid Transients, Harrogate Durham, United Kingdom, 1996. Li, J. & McCorquodale, A. (1999) “Modelling Mixed Flow in Storm Sewers,” Journal of Hydraulic Engineering, ASCE, Vol. 125, No. 11, pp. 1170-1180. Moody, L. F., “Friction Factors for Pipe Flow”, Trans. ASME, Vol. 66, 1944 Parmakian, J., “Waterhammer Design Criteria”, J. of Power Div., ASCE, Sept. 1957 Parmakian, J. (1963). Waterhammer Analysis. Dover Publications, Inc., New York, New York.

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References Pickford, J., “Analysis of Surge”, Macmillian, London 1969 Quick, R.S., “Comparison & Limitations of Various Waterhammer Theories”, J. of Hyd. Div., ASME, May 1933 Rich, G.R., “Hydraulic Transients”, Dover, USA 1963 Savic, D.A., and Walters, G.A. (1995). “Genetic Algorithms Techniques for Calibrating Network Models”, Report No. 95/12, Centre for Systems and Control Engineering, School of Engineering, University of Exeter, Exeter, United Kingdom, 41. Sharp, B., “Waterhammer Problems & Solutions”, Edward Arnold Ltd., London 1981 Song, C.C. et al, “Transient Mixed-Flow Models for Storm Sewers”, J. of Hyd. Div., Vol. 109, Nov. 1983 Stephenson, D., “Pipe Flow Analysis”, Elsevier, Vol. 19, S.A. 1984 Streeter, V. L., Lai, C. (1962). “Waterhammer Analysis Including Fluid Friction.” Journal of Hydraulics Division, ASCE, 88, 79. Streeter V.L. and Wylie E.B., “Fluid Mechanics”, McGraw-Hill Ltd., USA 1981 Thorley, A.R.D., “Fluid Transients in Pipeline Systems”, D.&L. George, Herts, England, 1991. Tullis, J.P., “Control of Flow in Closed Conduits”, Fort Collins, Colorado, 1971 Vallentine, H.R., “Rigid Water Column Theory for Uniform Gate Closure”, J. of Hyd. Div. ASCE, July 1965 Watters, G.Z., “Modern Analysis and Control of Unsteady Flow in Pipelines”, Ann Arbor Sci., 2nd Ed., 1984. Walski, T.M. and Lutes, T.L. (1994) “Hydraulic Transients Cause Low-Pressure Problems.” Journal of the American Water Works Association, 75(2), 58. Wood, D. J., Dorsch, R. G., and Lightner, C. (1966). “Wave-Plan Analysis of Unsteady Flow in Closed Conduits.” Journal of Hydraulics Division, ASCE, 92, 83. Wood, F.M., “History of Waterhammer”, Civil Engineering Research Report, #65, Queens University, Canada, 1970. Wood, F.M., “Comparison of the Rigid Column and Elastic Theories for Waterhammer”, Can. Hydraulic Conference, U. of Alberta, Edmonton, May 1973.

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HAMMER Theory and Practice Wu, Z. Y., and Simpson, A.R. “Evaluation of Critical Transient Loading for Optimal Design of Water Distribution Systems.” Proceedings of the Hydroinformatics conference, Iowa, 2000. Wylie, E.B., “Rigid Water Column Theory”, Ch. 6. 7 in “Closed Conduit Flow”, edited by Chaudhry & Yeijevich, V., Water Resource Publications, USA, 1981 Wylie, E. B., and Streeter, V. L. (1993). Fluid Transients in Systems. Prentice-Hall, Englewood Cliffs, New Jersey. Zielke, W., “Frequency Dependent Friction in Transient Pipe Flow”, Ph. D. Thesis, U. of Michigan, 1966.

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References

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Appendix

C

About Haestad Methods Haestad Methods offers software solutions to civil engineers throughout the world for analyzing, modeling, and designing all sorts of hydrologic and hydraulic systems, from municipal water and sewer systems to stormwater ponds, open channels, and more. With point-and-click data entry, flexible units, and report-quality output, Haestad Methods is the ultimate source for your modeling needs. In addition to the ability to run in Stand-Alone mode with a CAD-like interface, three of our products—WaterCAD, StormCAD, and SewerCAD—can be totally integrated within AutoCAD. These three programs also share numerous powerful features, such as scenario management, unlimited undo/redo, customizable tables for editing and reporting, customizable GIS, database and spreadsheet connection, and annotation. Be sure to contact us or visit our Web site at http://www.haestad.com to find out about our latest software, books, training, and open houses.

C.1

Software Haestad Methods software includes: •

“WaterGEMS”

•

“WaterCAD”

•

“SewerCAD”

•

“StormCAD”

•

“PondPack”

•

“FlowMaster”

•

“CulvertMaster”

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Software

C.1.1

WaterGEMS WaterGEMS brings the concept of water modeling and GIS integration to the next level. It is the only water-distribution modeling software that provides full, completely seamless integration with GIS applications. Now the combined functionality of WaterCAD and GIS can be utilized simultaneously, synthesizing the distinct advantages of each application to create a modeling tool with an unprecedented level of freedom, power, efficiency, and usability. You can create, display, edit, run, map, and design water models from within the GIS environment, and view the results of the simulations as native GIS maps or with traditional Haestad Methods modeling tools. These abilities, in conjunction with the crossproduct functionality provided by the core Unified Data and Object Model architecture, provide a powerful cutting-edge solution for your modeling projects. WaterGEMS works within your choice of environments: ArcView, ArcEdit, ArcInfo, AutoCAD, or the standalone WaterGEMS Modeler interface.

C.1.2

WaterCAD WaterCAD is the definitive model for complex pressurized-pipe networks, such as municipal water-distribution systems. You can use WaterCAD to perform a variety of functions, including steady-state and extended-period simulations of pressure networks with pumps, tanks, control valves, and more. WaterCAD’s abilities also extend into public safety and long-term planning issues, with extensive water quality features, automated fire protection analyses, comprehensive scenario management, and enterprisewide datasharing faculties. WaterCAD is available with your choice of a stand-alone graphical user interface and an AutoCAD-integrated interface.

C.1.3

SewerCAD SewerCAD is a powerful design and analysis tool for modeling sanitary sewage collection and pumping systems. With SewerCAD, you can develop and compute sanitary loads, tracking and combining loads from dry-weather and wet-weather sources. You can also simulate the hydraulic response of the entire system (gravity collection and pressure force mains), observe the effects of overflows and diversions, and even automatically design selected portions of the system. Output covers everything from customizable tables and detailed reports to plan and profile sheets. SewerCAD can be run in a stand-alone graphical user interface, an AutoCAD-integrated interface, or an ArcView- or ArcInfo-integrated interface.

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About Haestad Methods

C.1.4

StormCAD StormCAD is a highly efficient model for the design and analysis of storm sewer collection systems. From graphical layout and intelligent network connectivity to flexible reports and profiles, StormCAD covers all aspects of storm-sewer modeling. Surface inlet networks are independent of pipe connectivity and inlet hydraulics conform to FHWA HEC-22 methodologies. Gradually varied flow algorithms and a variety of popular junction-loss methods are the foundation of StormCAD’s robust gravity piping computations, which handle everything from surcharged pipes and diversions to hydraulic jumps. StormCAD is available with your choice of a stand-alone graphical user interface, an AutoCAD-integrated interface, or an ArcView- or ArcInfo-integrated interface.

C.1.5

PondPack PondPack is a comprehensive, Windows-based hydrologic modeling program that analyzes a tremendous range of situations, from simple sites to complex networked watersheds. HAMMER analyzes pre- and postdeveloped watershed conditions and estimates required storage ponds. PondPack performs interconnected pond routing, and also computes outlet rating curves with tailwater effects, multiple outfalls, pond infiltration, and pond-detention times. PondPack builds customized reports organized by categories, automatically creating section and page numbers, tables of contents, and indexes. You can quickly create an executive summary for an entire watershed or build an elaborate drainage report showing any or all report items. Graphical displays, such as watershed diagrams, rainfall curves, and hydrographs, are fully compatible with other Windows software, such as AutoCAD.

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Haestad Press

C.1.6

FlowMaster FlowMaster is an efficient program for the design and analysis of a wide variety of hydraulic elements, such as pressure pipes, open channels, weirs, orifices, and inlets. FlowMaster’s Hydraulics Toolbox can create rating tables and performance curves for any variables, using popular friction methods. Inlet calculations follow the latest FHWA guidelines, and weighting of irregular section roughness can be based on any popular techniques.

C.1.7

CulvertMaster CulvertMaster helps engineers design new culverts and analyze existing culvert hydraulics, from single-barrel crossings to complex multibarrel culverts with roadway overtopping. CulvertMaster computations use HDS No. 5 methodologies, allowing you to solve for whatever hydraulic variables you don’t know, such as culvert size, peak discharge, and headwater elevation. Output capabilities include comprehensive detailed reports, rating tables, and performance curves.

C.2

Haestad Press Haestad Press provides civil engineering professionals with affordable, quality reference and textbooks dedicated to the practical application of engineering theory to hydraulics and hydrology. Haestad Press publications include:

C-320

References and Textbooks:

Authored by industryrecognized experts, Haestad Press offers a complete line of reference books for use in both academic and professional settings.

Technical Journals:

With an eye towards computer technology, journals like “Current Methods” address the latest innovations in water-resources modeling and practical modeling case studies, as well as offering credit towards certification.

Independent Papers:

Haestad Press also provides funding for engineers to write case studies of their projects, with potential publication in a variety of industry journals and magazines.

HAMMER User's Guide

About Haestad Methods

C.3

Training and Certification The Haestad Methods Continuing Education department has rightfully earned a reputation for excellence among hydraulic modelers, because of both the high quality of the educational experience and the friendly and professional environment that is provided at locations throughout the world. These training programs are famous for efficiently and effectively teaching engineers how to apply hydraulic theory and state-of-the-art software to real-world design situations. Modelers can become certified in a variety of water-related fields, through an assortment of teaching methods including •

JumpStart seminars

•

Comprehensive workshops

•

Publication-Based programs

To obtain more information about Haestad Methods certification programs or to see upcoming events in a city near you, visit http://www.haestad.com.

C.3.1

Accreditations Haestad Methods has achieved the highest levels of accreditation from both the International Association for Continuing Education and Training (IACET) and the Professional Development Registry for Engineers and Surveyors (PDRES). In addition to Haestad Methods’ own prestigious certifications, these endorsements enable modelers to earn Continuing Education Units (CEUs) and Professional Development Hours (PDHs) for their satisfactory participation in various training and educational programs.

C.4

Internet Resources In addition to modeling software, continuing education, and publications, Haestad Methods also provides Internet-based tools to help engineers manage their account information, manage their projects, and manage their sanity. Use the Globe button to access the Haestad Methods knowledge base and instant software updates for ClientCare subscribers. For more information, see “Upgrades and the Globe Button” on page 1-7.

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Internet Resources

C.4.1

Instant Account Management Now you can go on-line to manage your own account information, such as to conveniently maintain your products, customize your communication settings, or indicate your areas of interest. Just visit the accounts section at http://www.haestad.com.

C.4.2

CivilQuiz.com CivilQuiz.com is a great way to treat yourself to some fun with a quick on-line engineering challenge, and maybe win a laptop or other prizes along the way. You can even submit your own questions to stump future CivilQuiz players.

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Appendix

D

Environmental Hydraulics Group HAMMER is based on technology originally created by Environmental Hydraulics Group, Inc. (EHG), consulting engineers with a solid track record across Canada and four continents. For over 15 years, local and international firms and governments have relied on EHG’s stable team to solve their most difficult hydraulic problems: we are the Water Hammer Specialists. Our track record is proof of our ability to resolve complex challenges in the public, mining, industrial, and power sectors in dealing with environmental and hydraulic issues. HAMMER is owned and marketed worldwide by Haestad Methods, Inc., who have forged a long-term collaboration with EHG to support, improve and provide training for it. EHG hopes you will benefit from HAMMER’s powerful capabilities and, when you need it, we offer engineering services for expert reviews, build-operate-transfer models, teaming, and consulting (http://www.ehg-inc.com). EHG can measure transient flows and pressures in your system to calibrate HAMMER to explain breaks. EHG brings the right combination of experience, testing expertise and emerging talent to contribute to your project.

D.1

Water Networks and Transmission Lines Water systems are EHG’s core expertise. EHG has used HAMMER to model entire networks for the City of Thunder Bay, Ontario (150,000 population); Calgary, Alberta (900,000 population); Alliston and parts of the City of Toronto. Explosive growth in the City of Toronto and the surrounding Peel and York Regions (populations 2.5, 1.0, and 0.8 million, respectively) requires massive infrastructure investments. EHG was retained to ensure the resulting Peel-York water supply pipeline (dark line) and the area’s pump stations (PS) and distribution networks will be expanded and operated reliably: EHG’s hydraulic and water hammer models of the Peel-York pipeline guided route selection, conceptual and detailed design of 10 PS, 3 reservoirs and 40 km (18 miles) of 2100 and 1800 mm (82 and 70 in) pipe—all tied into existing water networks.

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Water Networks and Transmission Lines

EHG completed NPSH and pump tests (ANSI 1.6 standard) at the City of Toronto’s 800 MLD (211 MGD) Ellesmere pump station. The calibrated model supports a 40% increase in capacity with improved surge protection. EHG was retained to provide hydraulic input to a network-wide optimization and risk-reduction strategy for Toronto and York, Niagara, and Ottawa. Long-distance water transmission lines must be economical, reliable and expandable. EHG’s track record includes multi-booster pressurized lines with surge protection ranging from check valves to gas vessels. EHG has particular expertise designing pressurized and open-channel pipeline segments, using gravity flow where possible to reduce energy costs. EHG has ensured reliable water transmission for the Peel-York and City of Toronto systems described above and also:

D-324

•

225 MLD, 56 km, 1050 mm (60 MGD, 35 mi, 40 in) line for the capital City of Regina, Saskatchewan (200,000 population).

•

346 MLD, 50 km, 1200 mm (91 MGD, 31 mi, 47 in) line for the City of London, Ontario (340,000 population), including two large gas vessel installations.

•

60 MLD, 57 km, 600 mm (16 MGD, 35 mi, 24 in) line for Alliston, Ontario (30,000 population), with supply to a Honda plant and a 10 km line to Beeton.

•

Major pipelines in Tanzania, Nevada (USA), Argentina, and Vietnam.

HAMMER User's Guide

Environmental Hydraulics Group

D.2

Deep Sewers and Tunnels EHG's experience with hydraulic structures in large, complex systems has provided effective solutions to many problems using computer (numerical) or scale (physical) models for plant operations, combined sewer overflow (CSO) reduction and outfall dispersion studies. EHG used HAMMER to design a practical and economical solution to the City of Ottawa’s sanitary trunk system problems after power failures. Rapid surcharge and surge fronts had damaged infrastructure and caused spills to the local environment. Field checking and detailed modeling revealed City of Ottawa that a mass flow reversal and oscillation phenomenon could occur in this system. Reconfiguring the pump station with a high-tech “duck bill” check valve resulted in a longterm, reliable solution. EHG contributed input to environmental assessment (EA) for the City of Hamilton’s Greenhill drop shaft and CSO tank twinning project. This 44 m (144 ft.) drop shaft and 200 m (660 ft.) tunnel conveys flows ranging from 0.5 to 50 m3/s (18 to 1,800 cfs) under the environmentally-protected Niagara Escarpment. EHG designed, constructed and tested a 1:12 scale model to configure a vortex-inlet design for the new drop and tunnel using the existing system for air recirculation at low flows. EHG resolved constraints ranging from surges (due to attachment during surcharge) to moving hydraulic jumps and integrated the existing CSO tank in an end-to-end hydraulic conveyance analysis for the upgraded system, complete with a new 65 ML (17 million gallon) tank with flushing system. The project passed numerical and scale model proof-of-concept tests, following which more scale modeling was ordered to guide detailed design.

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Hydraulic Testing and Forensic Engineering

City of Hamilton

EHG has provided expert review of the City of Toronto’s 4 km long, 40 m deep, 85 ML Western Beaches tunnel and participated on a design-build team for the City of Ottawa’s 4.8 km, 57 ML Somerset tunnel—both complete with drop and overflow shafts. Key considerations include air handling, mass oscillations during filling and surcharge of the surface sewers and/or overflow handling. EHG offers the right combination of experience, expertise and tools to find solutions.

D.3

Hydraulic Testing and Forensic Engineering EHG offers on-site hydraulic test and training services including: Pump testing including head-efficiency-flow and NPSHR curves and a calibrated model of suction system losses and NPSHA—complete with discharge system and yard piping. Reservoir mixing using tracers complete with log-inactivation report and improvement tips. EHG also calibrates scale or computer models. Troubleshooting of all kinds to find and fix hydraulic bottlenecks, explain breaks, etc…. Operator and supervisor training in pump stations and industrial/mining plants for water hammer safety and maximum efficiency. City of Thunder Bay

D-326

Plant conveyance, fill/drain and transient reviews complete with dynamic models.

HAMMER User's Guide

Environmental Hydraulics Group

D.3.1

Pump Station Upgrades and NPHS Testing Pump tests are the best way to get reliable estimates of how an upgraded pump station will perform based on the proposed and existing pump curves. These may match (or not) at the operating point, significantly affecting the firm capacity. The published pump curves are often not enough because impeller trimming, cavitation and wear can all change a pump's head-flow performance. In addition, pump performance at the factory is never the same as its output at the pump station. Testing is a wise investment, given the high energy cost of running the wrong pump combinations or the expense involved with incorrectly installing or operating a new pump. EHG and CWS use a modified ANSI 1.6 (Hydraulic Institute standard) test procedure to obtain the NPSHR and head vs. flow curves for your pump. State-of-the-art Primayer pressure loggers (± 2%) and Quadrina insertable flow meters (± 5%) obtain data every 5 seconds. The procedure yields a calibrated suction system model in WaterCAD (and HAMMER if requested), complete with NSPHA at each pump location. Based on this, you can make important upgrade decisions (or defer them) with confidence.

D.3.2

Expert Witness and Break Investigations The professional engineers of Ontario (PEO) designated EHG’s founder and CEO, Dr. Alan Fok, P.Eng., a Hydraulic Specialist in 1983 for his contributions to hydraulics. EHG has performed pre-trial investigations, discovery and expert witness services for several high-profile legal cases ranging from a penstock burst on the Welland Canal to two urban flooding and erosion lawsuits (EHG acted for the plaintiff on one and the defense for the other). EHG’s objective field work, analysis and computer modeling helps the parties to settle the matter or find a mediated solution.

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Field and Lab Tests for Disinfection EHG performed five break investigations including computer modeling and reports in 2002-2003 alone. EHG identified the causes and provided practical solutions to difficult problems ranging from repeated pipe bursts, river crossing breaks, thrust restraint failure, pump casing bursts, shaft breaks, and premature impeller wear due to cavitation on the suction and discharge sides. In addition to ensuring worker and environmental safety, the cost of this service is typically repaid several times over within a few years by eliminating the need to repair breaks and lost production.

Sand sucked in, contamination

D.4

Field and Lab Tests for Disinfection EHG has provided field tests and scale models in the lab to ensure that water reservoirs deliver the required log-inactivation and disinfection performance: •

Scale model of the Ottawa South reservoir (4.6 ML capacity), with inflows ranging from 5 to 25 MLD and strict criteria for the chlorine residual in all areas of the reservoir. EHG ensured the turn over rate of the water volume was maximized and provided a chlorine diffuser design.

•

Scale model of the Glen Cairn reservoir (68 ML capacity), with inflows ranging from 5 to 30 MLD. This was modeled in the lab to identify dead zones (see photo) and resolve them using inexpensive diffuser and baffling designs.

•

Tracer Test of the Brantford Water Treatment Plant, whose contact chamber was upgraded with baffles to improve disinfection performance. EHG confirmed this by determining the current T10, T50, and T90 values in the upgraded contact chamber. This was used to predict seasonal log-inactivation performance. EHG has also performed sub-atmospheric leakage tests to ASTM standards. This was done to explain repeated pipe breaks but this work led to improved standards for gasket designs and installation techniques in the province of Ontario.Subatmospheric transient pressures can suck contaminants into the water system.

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Environmental Hydraulics Group

D.5

Hydropower and Cogeneration The use of small hydroelectric plants and/or cogeneration is prevalent in Ontario and their hydraulic components serve multiple uses. Their primary purpose is to provide power and/or to reuse energy (i.e., hot water) to heat the facility and sometimes the surrounding homes and businesses. EHG has modeled district cooling and heating water systems, hydro tailraces, and two different types of penstocks impacting a canal and generating station, respectively. EHG explained the cause of the penstock rupture in the Welland Canal on the St. Lawrence Seaway using advanced HAMMER technology and other tools. EHG has correctly predicted the operational behavior of hydro systems (penstock and tailrace) and helped explain a needle valve break.

D.6

Mining and Industrial EHG has a strong track record in resolving critical safety and production issues faced by the mining and industrial sectors. EHG's specialist hydraulic services are essential for safe, uninterrupted and efficient hydraulic conveyance of water, process fluids and slurries. EHG has provided pre-design and post-break project reviews to mining clients directly as well as in close partnership with leading firms. Our clients include Barrick Gold, Newmont, QIT Fer et Titane, Inco, and others. EHG has been consulted on several of Barrick Gold’s plant projects. EHG does not endorse products and its specialist practice extends to all sectors (power, public, legal), therefore, EHG is completely independent and objective when assessing facts or rendering opinions. EHG’s advanced hydraulic services include: •

Hydraulic conveyance—ensure your plant can perform at maximum efficiency by eliminating bottlenecks, such as under-sized pipes and launders or transitions.

•

Plant optimization—improve solids separation in thickeners or mix using gravity jets and tanks to minimize settlement, scale and power requirements.

•

Slurry and process pumping—keep operators and equipment safe from water hammer damage and reduce down-time due to unplanned emergency shut-downs.

•

Pre-start hydraulic review—identify key operational constraints for starting, ramping and stopping a plant or pipeline; including restarts after a break or planned maintenance.

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Mining and Industrial

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Index Symbols .ANI 26, 138 .GRP 138, 139, 212 .HIF 137, 138, 141 .HOF 26, 137 .MDB 138, 139, 141 .MDB import and export 105 .OUT 139, 203 .RPT 139, 140

A about HAMMER 1 Access 95, 105 acknowledgements 236 addresses 13 AdminTools 11 air chamber 294 air chambers 190 air release valve 183 air vacuum valves 183 air volume maximum 164 amplitude 165 animate 211 animation 201, 215 controller 26 generate 26 animation controller 216 animation data 215 animations 26 annotation 212 annotations adding 214 anti-alias 149 anticipator valves 190 ARV 183 ASCII text 203 attribute type 150 attribute value ranges 152 automatic scaling 213

HAMMER User's Guide

AVV 183 axes 211

B Bernoulli equation 246 bladder 188 booster pump bypass 297 bottom gravity discharge tank 228 boundaries 164 boundaries of the system 161 boundary conditions 192 buttons 75 online help topic navigation 36

C calibration 197 CAV 183 celerity 257 certification 321 characteristic time 261 check run 195 check valve 163 check valves 181, 297 check valves between two pipes 168 check valves installed 186 Chezy’s equation 281 CivilQuiz.com 322 ClientCare 7, 219 closed-form analytical solutions 197 coefficient head loss 166 Colebrook-White typical values 308 Colebrook-White equation 280 color coding line thickness 128 color map selector 232 color maps 208 color ramp 209 Index-331

D color-code 201 colors 206 colors tab 142 combination air valves 183, 190 company name 232 conservation of energy 245, 248 constant horsepower pumps 270 constraining input 152 consumption node 164, 196 contact 13 contacting Haestad Methods 13 contamination 192 continuity equation 247 continuity equation for unsteady flow 248 control status 170 control type 170 control valves 221 control variable 179 copy graph settings 213 copying elements 157 corresponding pressures 168 cover opening diameter 165 create ASCII file 138 creating new elements 154 CulvertMaster 320 curve pumps 177, 270 cutting elements 157

dead end 165 decimal point 151 deleting elements 157 demand alternatives 221 design point 172 determining run duration 144 diameter 163, 165, 184 maintenance hole cover 165 orifice 165 pumps 178 discharge coefficient 169 display options 206 display precision 151 display tips 231 draw lines 29 symbols 29 text 29 draw lines 214 draw symbol 214 draw text 214 drawing options 149 drawing pane 19 lock 149 locking 158 duty point 172

D

echoid 11 editing elements 156 efficiency pumps 172 EGL 247 EHG 2, 323 elastic simulation 191 elastic theory 248, 255, 256 elasticity 257 element display 232 element map WaterCAD to HAMMER 47 WaterGEMS to HAMMER 47 element selector control 19 elements color code 232 colors 206, 207 coordinates 162

Darcy-Weisbach 148 equation 278 roughness values 308 Darcy-Weisbach equation 278 data copy 28 paste 28 data check 195 data form add 30 set 30 swap 30 data logging 199 data requirements 192 database 26 datastore 138 import/export 141

Index-332

E

HAMMER User's Guide

F copying 157 cutting 157 data control 19 deleting 157 description 162 editing 156 editor 161 elevation 162 finding 157 general properties 162 label 162 labels 206, 207 moving 156 pasting 157 report period 162 selecting 155 type 161, 162 validation 195 elevation 166 of the top of base 187 of the top of tank 186 of top of riser 187 of top of tank 187 pumps 172 e-mail 13 emitter k values for hydrants 230 energy grade 247 engineer’s reference 306 English 145, 150 Environmental Hydraulics Group (EHG) 2, 323 EPANET 25, 105, 139, 223 export 140 import 114, 140 equations Bernoulli 246 Chezy’s 281 Colebrook-White 280 continuity 247 continuity for unsteady flow 248 Darcy-Weisbach 278 Hazen-Williams 277 Levenberg-Marquardt method 270 Manning’s 280 method of characteristics 250 momentum for unsteady flow 249 Swamee and Jain 279 transients 248 unsteady state 248 valve closing pattern 274 HAMMER User's Guide

estimating hydrant discharge 230 exponent in gas law 188 export 139 .MDB 105 database 141 EPANET 105, 140 GIS 141 tips 219 external tool manager 25 external-source data 105 extreme heads 203 extremes reports 204

F favorites 34 field measurements 199 file formats 137 file I/O tab 143 files input and output 137 finding elements 157 first law of thermodynamics 245 fitting loss coefficients 311 FlexUnits 26, 142, 145, 150 defined 149 manager 150 flow 164, 181, 187 maximum and minimum 164 flow control equipment 161 flow decreasing characteristics 276 flow emitters 196, 230 FlowMaster 320 format data 28 figure 28 graph 28 line 213 shade 213 format data 213 format display 159 format graph 211, 212 formatted reports 95 friction 285 friction coefficient 163 friction loss 277 quasi-steady 148 steady-state 147 Index-333

G transient 148 unsteady 148 friction method 147 friction methods 189

G gas vessel 294 definition 187 gas vessels 185, 190 generate animation data 137, 215 generate animations 26, 215 generate output database 95 getting started 81 global HAMMER options 142, 232 globe button 7 graph annotation 212 graph formatting 211, 212 graph settings 213 graph type 212 grid lines 213 grids 211 ground elevation 166 groundwater well 227

H Haestad Methods about us 317 accreditations 321 certification 321 continuing education 321 knowledge base 231 publications 320 software 317 training 321 Haestad Press 320 HAMMER about 1 capabilities 235 datastore 138 getting started 12, 81 installing 3 learning 12, 13 lessons 81 network installation 10 network license 8

Index-334

network registration 8 operating systems 5 preferences 26 registration 6 sales 13 suggestions to Haestad Methods 15 support 13 tutorials 81 upgrades 7 HAMMER main window 18 HAMMER viewer 20 Hazen-Williams 147 Hazen-Williams equation 277 coefficients 310 roughness values 309 head maximum and minimum 163, 164 head loss coefficient 166, 186, 187 head losses 186 Helmholtz 258 help using 30 See also online help. HGL 201, 247 HGL profile 201 hiding symbols 149 high-speed sensors 199 history 211 history table 203 hydrant discharge 230 hydraulic element reference 161 hydraulic elements reuse 233 hydraulic grade 247 hydraulic transient numerical simulation 190 See also transient. hydraulic transient analysis 189 hydraulic transients overview 236 hydraulically close tanks 228 hydropneumatic tanks 227

I import 139 .MDB 105 database 141

HAMMER User's Guide

J EPANET 105, 140, 223 GIS 141 PIPE2000 105, 142, 223 Surge2000 105, 223 tips 219 WaterCAD 105 WaterCAD/WaterGEMS 141 WaterGEMS 105 WaterGEMS/WaterCAD 223 import EPANET 114 import PIPE2000 115 import Surge2000 115 independent papers 320 index 32 inertia 173, 179, 296 pumps 172, 173 inflow diameter 183 infrastructure 192 initial air volume 183 initial flow 177 initial typical flow 168 initial volume of gas 187 initial water level 186 input files 137 installation 3, 5 network 10 troubleshooting 6 installing HAMMER 3 interior points 205 introduction 1

J

display 232 graph 211 node 207 pipe 207 short 207 large files 224 lessons 81 network risk reduction 115 one 82 pipeline protection 82 three 115 two 105 working with data from external sources 105 Levenberg-Marquardt method 270 license 6 network 7, 8 line thicknesses 128 line formatting 213 liquid 146 liquid properties 146 lock 158 lock aspect ratio 29, 159 lock drawing pain 24 lock drawing pane 149 log file 203 logo 206, 232 logs view 25 loss 277 losses 186, 282 minor 282 losses ratio 166

junction defined 164

M

K K coefficients 311 k values 230 kinematic viscosity 279 knowledge base 231

L labels 206

HAMMER User's Guide

magnify 158 main window 18 maintenance hole 165 maintenance procedures 305 manhole nodes maintenance hole 165 Manning’s equation 147, 280 roughness values 307 typical values 310 maps color 208 maximum value 152 Index-335

N mean value 165 measurements 199 menus 19, 21 edit 23 file 22 format display 29 format graph 27 help 27 tools 25 view 24 method of characteristic (MOC) 250 method of characteristics (MOC) 191 methods for solving transient flow 237 metric 145, 150 Microsoft Access 95, 105, 203 minimum value 152 minor losses 277, 282 fitting 311 modeling tips 224 moment of inertia 180 momentum equation 249 morphing elements 155 mouse button 233 moving elements 156 msaccess.exe 95 multiple pump curve 270

N Navier-Stokes 191 network 7, 8 license manager 11 network licensing 7 network topologies 264 network topology 195 new elements 154 node reports 205 nodes 164 at pipe ends 163 consumption 164, 196 dead end 165 periodic head or flow 165 to 163 nominal flow 177 nominal head 177 normalize 149 normalize symbol size 24

Index-336

numerical calibration 197 numerical simulation 190

O one-way surge tank 186 online book using 30 online help favorites tab 34 index tab 32 navigation buttons 36 previous/next buttons 36 related topics 32, 35 search tab 33 topics 35 using 30, 31 open HAMMER 17 operating point 267 operating rule 166, 169, 180 operating systems supported 5 operation classification 261 operation procedures 305 operation time 261 operational rule 180 options 206 orifice at branch end 170, 196 orifice between two pipes 171 orifice demand 196 orifice diameter 165 orifice to atmosphere 170, 196 orifices rating curve 171 reference 170 oscillation period 165 other options 232 outflow diameter 183 output 202 output database 26 output files 137 output manager 25 output variable 26 overflows 192 overview transients 236

HAMMER User's Guide

P

P page setup 29 page view 29, 159, 214 pan 24, 158 parallel pipes 228 parallel pumps 228 parameters 26 paste graph settings 213 paste symbols 28 pasting elements 157 path 210 definition 20 path list 210 PDF 30 percent efficiency 178 turbine

efficiency 180 performing calculations of transient flow and head 266 period 165 periodic flow 165 periodic head 165 phase 165 phone numbers 13 pipe bonding nodes 163 pipe breaks 192 pipe elasticity 257 pipe elasticity and celerity 259 pipe elevations adjustment 194 pipe materials 259 PIPE2000 105, 139, 223 import 115, 142 pipes 163 check valve 163 diameter 163 friction coefficient 163 length 163 pipes reports 205 piping design 286 piping layout 286 PLC 176 plot 210, 211 pocket reports 205 point design/duty 172

HAMMER User's Guide

point histories 210 Poisson’s ratio 259 precision 151 preferences 26 prescribed quantity 165 pressure 178 head 246 maximum and minimum 164 pressure relief valves 181 pressure wave 261 pressurized systems 236 previews 214 print previews 214 profile 210 profile plot 211 profile setup 210 programmable logic controller 176 project options 142, 232 protection devices 288 protection equipment 181, 244 pump curves 222 pump quadrants 222 pumping systems 264 pumps 222 behavior 267 bypass 297 characteristics 267 constant horsepower 270 constant speed at reservoir 172 constant speed between 2 pipes 171, 172 control variable 179 curve 177 diameter 178 efficiency 172, 178 element reference 177 elevation 172 flow 177 fundamentals 171 head 177 inertia 172, 173, 179 operating point 267, 268 operating rule 180 pressure 178 protection 297 quadrants 175 reverse spin 178 shut after time delay 172 specific speed 172, 174 speed 172, 177, 179 Index-337

Q theory 267 time delay 178 time to close 178, 179 variable speed 269 variable speed (VSP) 176 variable speed between two pipes 172

Q quadrant representations 175 quadrants 222 quasi-steady friction 283 quasi-steady friction loss 148 quick start 81

R RAM 224 rating curve 171 ratio of losses 166, 186, 187 reference 161 pumps 177 references 312 references and textbooks 320 registration 6, 8 network 8 related topics 32 defined 35 report printout suppressed 162 report history after time 202 report paths 210 report pipes 210 reports 201 extremes 204 formatted 95 nodes 205 pipes 205 pockets 205 summary 204 tabulated 202 view 25 requirements to run HAMMER 4 reservoir 166 reverse flow 181 reverse spin 178 Reynolds number 279

Index-338

rigid column simulation 190 rigid column theory 248, 252, 255 risk management 192 rotating equipment 162, 171 rotational speed 179, 180 roughness coefficient 307 roughness height 279, 280, 308 roughness values Colebrook-White 308 Darcy-Weisbach 308 Hazen-Williams 309 Manning’s 307 typical 310 rounding 151 rule 166 run duration 144 runout 172 rupture disk 188

S sales 13 SAV 184 save animation as 216 save preset 209 SCADA 199 scale intervals 209 scale limits 209 scenario management 220 scientific notation 151 screen layout 159 searching for elements 157 second law of motion 252 selecting elements 155 selection set options 149 Sentinel 7, 9 serial number 6, 8 series pumps 228 setting run duration 144 settings 26 model 26 system 26 SewerCAD 318 short label display 207 shortcut menu 233 show extreme heads after 202 show frame 29, 159

HAMMER User's Guide

T show title bar 29, 159 shutoff 172 SI 150 simulation elastic 191 rigid column 190 sizing text 76 slow closing air valve 183 small outflow diameter 183 snapshot tables 202 software suggestions 15 software network registration 8 software registration 6 specific speed 177, 180 equation 174 pumps 172, 174 speed pumps 172 spherical valve 180 spring constant 184 SRV 184 start EPANET 25 start HAMMER 17 status bar 19 defined 79 steady state flow 246 steady-state friction loss 147 sticky tools 143 StormCAD 319 suggestions 15 summary reports 204 summary tab 144 support 7, 13 surge anticipator 182 surge anticipator valve 184 surge control 286 surge control equipment 162 surge control strategy 286 surge protection 289 surge relief valve 184 surge relief valves 299 surge tank 292, 294 surge tanks 185, 190 Surge2000 105, 139, 223 import 115 Swamee and Jain equation 279 symbol size 24 HAMMER User's Guide

symbol visibility 149 symbols hiding 149 normalize 149 system boundaries 164 system pipes 210 system requirements 4 system settings 26

T tables WaterObjects to HAMMER conversion 47 tabulated report 202 tanks hydraulically close 228 top feed/bottom discharge 228 technical journals 320 technical support 13 telephone numbers 13 text 202 text sizing 76 thickness of a line 128 threshold pressure 165, 169, 184, 188 tick marks 213 ticks 211 time delay 178 time history 201 time of operation 168 time step selection 195 time to close 170, 178, 179, 184 time to open 184 tips display 231 import/export 219 modeling 224 title bar 18 titles 212 to node 163 toolbars 19, 75 tooltips tab 143 top feed tank 228 topics online help 35 training 321 transient flow equations 248 transient friction 285 Index-339

U transient friction loss 148 transient head 163, 164 transient heads 190 transient history 211 transient pressure 164 transient pressure pulses 199 transients causes 239 effects 242 initiation 239 overview 236 theory 244 transition volume 183 transmission pipelines 262 turbine 180 inertia 180 operational rule 180 rotational speed 180 specific speed 180 turbine element reference 180 tutorials 81 See also lessons. types of networks 264 types of pumping systems 264 types of valve 273 typical flow 177 typical pressure 188

U U.S. customary 145, 150 uninstallation 5 troubleshooting 6 unit system 145 units 26, 145, 150 unsteady friction 285 unsteady friction loss 148 unsteady state equations 248 upgrades 7 upstream pipe 169 URL 13 using help 30

V vacuum 193

Index-340

vacuum breakers 182 validation 195, 197 value ranges 152 valve spherical 180 valve closing pattern 274 valve of check type at wye branch 169 valve of various types between two pipes 169 valve to atmosphere 168 valve with linear area change between two pipes

170

valves 271 air inlet 182 air release 183 air vacuum 183 ball 169 bodies 273 butterfly 169 check 181 circular gate 169 closing characteristics 274 combination air 183 globe 169 needle 169 operating rule 169 pistons 273 pressure relief 181 regulating 181 selection 271 sizing 271 slow closing 183 surge anticipator 182, 184 surge relief 184, 299 theory 271 time to close 170 types 273 user-specified 169 vacuum breakers 182 vapor 193 vapor pockets 193 vapor pressure adjustment 193 vapor volume 164 vapor volume maximum 164 variable speed pumps 176, 230, 269 view logs 25 reports 25 view menu 158 HAMMER User's Guide

W VSP 176, 230

W walk 210 water column separation 193 WaterCAD 105, 139, 318 import 141, 223 WaterCAD to HAMMER elements 47 WaterGEMS 105, 139, 318 import 141, 223 WaterGEMS to HAMMER elements 47 WaterObject 141 WaterObjects 223 wave propagation 261 wave reflection 262 wave speed 144 adjustments 194 wave velocity 163 wear-and-tear 192 Web site 13 weir coefficient 186 what HAMMER is 1 workshops 13 WYSIWYG 214

Y Young’s modulus 259

Z zoom 24, 158

HAMMER User's Guide

Index-341

Z

Index-342

HAMMER User's Guide