Troubleshooting EPS run warnings

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Info Water Pro offers many simulation types

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including standard simulation of hydraulics and water quality

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pipe break analyses,

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firef flow and multi fire flow analysis. SCADA data integration,

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hydrant capacity assessments

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and pump capacity analyses.

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You can perform these simulations in the run manager and all

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of them are based on the EPA A net engine.

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While using Info

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Water Pro,

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it can be useful to learn why your simulation

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ran successfully or failed to converge to a solution.

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There are settings messages and reports that can help

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you to fix errors and run better simulations.

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A good starting tip is to keep a design log of all your simulations.

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So you can refer back to it when similar issues occur.

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The more models you build the easier these errors are to resolve.

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The run manager provides a color coded stoplight as a

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visual reference to know the status of your run simulation

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depending on the color of the spotlight.

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There are different ways you can go about troubleshooting failed simulations.

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A green stoplight represents a good run of your simulation.

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You did not receive any warnings.

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A gray stoplight indicates that your simulation did not run at all.

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No output was produced.

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This usually occurs when info

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water pro is unable to create the EPA net input file due to bad or missing data.

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You can start troubleshooting by looking at any pop-up

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messages and reviewing the message board for errors,

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error messages indicate the key data ids of elements to fix.

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You may see the message missing input data which includes common error, 200 codes.

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If so you may have illegal or missing data.

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For example,

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pipe roughness length and diameter must be non zero.

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The tank initial level must be less than maximum level and more than minimum level.

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The valve pump tank or reservoir type field may not be specified

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if you see the message object refers to undefined element.

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This is often a pipe with an inactive node

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missing pattern or curve referenced means that you should change

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the curve or pattern used or create the missing one.

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If you see bad input data, then you should check your object data such as

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invalid pump curve. The curve values must decrease in head as flow increases

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missing tanker reservoir.

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The model must have at least one water source

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control on a check valve pipe.

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No controls or initial status should be found on a check valve

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orphan node.

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Make sure the node is connected to the system

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direction of pipes connected to pumps or valves.

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Make sure that both pipes are in the direction of flow.

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A red stoplight indicates that your simulation failed to converge to a solution.

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You need to reconfigure your simulation for it to run correctly.

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There are multiple possible reasons why the model did not solve.

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If you see input data issues,

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these issues may be similar to the missing or

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bad data errors that result in a gray stoplight.

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Review the message board to see the element ids. You need to fix

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model. Convergence issues may result in a max trial's exceeded warning.

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Convergence failure is often due to

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elements fighting for control of the hydraulic grade line H G L

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pressure reducing valves, prvs or other elements fighting

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switching check valves and unstable simple controls,

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changing convergent settings can help a model converge

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in the run manager on the standard tab click simulation options

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in the simulation options.

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Dialogue on the general tab, adjust the convergence criteria settings,

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maximum trials

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generally if no solution is found in 200 trials, it will not solve

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relative flow error. Epa net accuracy

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keep between 0.1 and 0.1.

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After max trials, epa net unbalanced

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choose stop to stop the run completely or continue to allow extended trials,

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extended run trials set as 10 to 50 max

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in the advanced tab.

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There are other settings that may help solve convergence issues.

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Relaxation factor.

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A value of 0.6 is better to use if you have convergence issues.

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As this is the EPA net default

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stamping limit

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set at 10 times the relative flow error setting

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status check and max status check,

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leaving these of their default values is recommended

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if these are changed, it can cause unexpected run issues

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allow a disconnected run

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check to see the results from connected elements

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to research and resolve simulation failures.

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It is also helpful to view the full hydraulic status report

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in the run manager on the standard tab. Click the report options, browse button

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in the simulation report,

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dialogue set the hydraulic status to full so that the status

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report includes information from each trial of each hydraulic analysis.

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This level of detail is useful for

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debugging networks that become hydraulically unbalanced.

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It is also useful to leave generate

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network summary table and generate warning messages selected

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after a successful or failed run.

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Click the report icon to open the full hydraulic status report.

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Here you can view the following

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a summary of the run settings.

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Details of each trial and relative flow change per trial

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element status changes

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a summary of supply demand and storage and a list of statuses at the end of a run

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to debug or troubleshoot failed simulations.

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Search for warning and caution in the report.

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Investigate each warning and caution message by the element id.

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Some common messages include maximum trials exceeded the

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program was unable to reach its convergence goal.

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Pump can't deliver head.

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A

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pump is at shut off

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pump can't deliver flow.

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A pump is past the last point of a multi point curve.

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Disconnected nodes

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it cannot satisfy the demand.

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As closed elements are cutting the nodes off from a known head.

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FCV can't deliver flow.

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There is not enough head to drive flow

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in the report,

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you can also look for repeated status changes of elements such as open to closed,

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closed to active and active to open.

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Depending on the elements that have been identified. You can investigate further

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valdes.

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This often indicates which elements are fighting for control.

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Pump I DS

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can indicate instability or pump curve issues.

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Make sure that the pump curve has a shut off head

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at zero flow or it may keep turning on and off.

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PRV I DS.

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Instability may only be seen at higher flows.

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Check the valve setting HGL for each valve

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check valve ids

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investigate why these are opening and closing

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other keywords to search for

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temporarily closed.

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This could be a tank that is switching between empty and full

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review the tank filling controls and investigate if there

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are zone interface elements that were accidentally opened,

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disconnected nodes,

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either demand cannot be met or there is no path to a known HGL.

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A yellow stoplight indicates your run did not

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meet the standards of a good simulation.

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You need to review and potentially fix the warning messages

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found on the warnings pop up or message board.

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In

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this case,

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you can troubleshoot using the partial output

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found in the full hydraulic status report.

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Look at the last hour and other key areas to diagnose why the run did not complete.

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A simple test is to add all tanks into a domain and use a tank group graph on the domain

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tanks going 0% or 100% full.

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Just before run failure indicate where the issue resides.

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Review the controls for the elements that are

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draining and filling those tanks for errors.