Analysis and Design of Distribution Systems for Potable Water using the EPANET model Part 2

Modern pipe network models Kypipes WaterCAD CyberNET EPANET www.epa.gov/ORD/NRMRL/wswrd/ epanet.html

EPANET performs extended period simulation of hydraulics and water quality within pressurized pipe networks. A network can consist of: pipes nodes (pipe junctions) pumps valves storage tanks reservoirs EPANET computes at each timestep flow in each pipe pressure at each node height of water in each tank or reservoir, water “age” (residence time) concentration of each water quality parameter

EPANET Applications Design to ensure adequate flow and pressure tank elevations and sizes pipe sizes size and location of pumps to ensure assessment and management use of alternative sources within multiple source system cost of various pumping schedules Schedule pipe cleaning and replacement

Hydraulic Modeling Capabilities Computes friction head loss using either Hazen-Williams, Darcy-Weisbach, or Chezy-Manning equations. Includes minor head losses for bends, fittings, etc. Models constant or variable speed pumps. Computes pumping energy and cost. Models various types of valves including shutoff, check, pressure regulating, and flow control valves

EPANET model components --links connected to nodes EPANET model components --links connected to nodes. Links: pipes, pumps, and control valves. Nodes: junctions, tanks, and reservoirs

Steps in Using EPANET Set program defaults (naming convention, pipe roughness, unit system, head loss formula) Draw the distribution system (Section 6.1 in manual) by inserting nodes and connecting with links; underlay a graphic if desired Edit the properties of the objects that make up the system (Section 6.4), eg, pipe length and diameters, nodal elevations Describe how the system is operated (Section 6.5) Select a set of analysis options (Section 8.1) – timestep, duration Run hydraulic/water quality analysis (Section 8.2) View results (Chapter 9) Change parameters and repeat as necessary

Program User Interface map toolbar browser (data and map tabs) property editor

Project Setup Project >> Defaults View >> Options

Creating Network using tools on map toolbar

Connect nodes with pipes, add pumps, valves and labels

Use the map tab of the browser to color-code nodes and pipes according to different properties

Set properties for nodes (junctions) and pipes. First, chose category of object from the data browser Then double click in list or on map to select Click “Add” icon to create a new object of current category

Set properties for nodes (junctions) and pipes For junctions, minimum required information is demand and elevation. These will be filled in after you run a simulation

Set properties for nodes (junctions) and pipes • For pipes, minimum required information is start and end nodes, lengths, diameters, and roughness. These will be filled in after you run a simulation

Set properties for tanks, reservoirs and pumps

Pump Curves

Set properties for tanks Minimum information is elevation, a diameter, a minimum, maximum and an initial water level.

Sign on flow indicates direction relative to flow arrow on the map.

This allows you to vary nodal demands throughout the day

View results on the map

Common errors/warnings “Network is disconnected” No connecting/open link to all nodes with demands. “Hydraulic equations unsolvable” Network is disconnected or unrealistic values specified for network properties. “Pumps cannot deliver flow or head” Pump asked to operate outside range of characteristic curve; turned off if asked to deliver head greater than shutoff head. “System unbalanced” EPANET cannot converge; can occur if pumps turn on/off or valves open/close from trial to trial.