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Adding PRV, cant meet Demand flow gpm.

Hi. I am new to Watergems. I have added a PRV in a layout due to which I have met my requoired pressures. But I am unable to meet the demand flow. My PRV is at a lower Elevation than the junctions where demand is not met. Please suggest. Thanks.

  • Hello Shaher,

    Tank is full notification is seen which implies that tank is having sufficient water to supply demands. Also the flows arrows of pipes shows that demands are met. Since this is steady state analysis adjacent pipe is also not closes as it is one step analysis, so demands are not cut off.

    All all junctions demand not met or only few junctions? Please check demand in the results section of junction properties.

    Please check lesson 4, a sample model located at C:\Program Files (x86)\Bentley\WaterGEMS\Lessons as a reference. 

    Also here is learning resource guide, which shall help you to learn the software. 

    Learning Resource Guide for new users of Bentley WaterGEMS and WaterCAD

    If required please upload your model for our review. 

    Sharing model files.

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Hello Sushma, as you can see in the results table my demand is not met. Also, does the negative sign mean the direction is the opposite? Thanks.

  • Where are you seeing in the results table that the demands are not met? In your screenshot of the junction table, I can see that the calculated demand is 100 gpm at each junction and the hydraulic grade is above the physical elevation.

    A negative flow in a pipe means the flow is traveling opposite of the direction of the pipe (based on the start and stop node). See: What does it mean if a pipe's flow is negative?

    If you're referring to the pressure calculated at the nodes - the PRV will only reduce pressure on the immediate downstream side. There may be additional headloss in the pipes downstream of the PRV, and the elevations of the downstream nodes may be higher (pressure = hydraulic grade minus physical elevation). See: How does the Pressure Reducing Valve (PRV) work in WaterGEMS and WaterCAD?

    If you need further assistance, please provide a copy of the model using the link from Sushma's reply, along with the steps needed to observe the problem.


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: ShaherYaar Khan