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Thread: Problems with System Curve in H2OMap Water

  1. #1

    Problems with System Curve in H2OMap Water


    I'm trying to get a system curve for the below system using H2OMap Water. The system consists of the following:
    • Raw water intake modelled as fixed head res
    • Single design point pump
    • Parallel mains, one with a PRV
    • WTP modelled as fixed head res

    The results of the system curve simulation, at least for the static head (0 flow), seem to be incorrect. The system consists of an intake at 12 m and a pump delivering to a WTP at 19.9 m. The static head should be 7.9 m, but the system curve is suggesting 3.807 m (see below). When the intake is modelled at 14 m the correct static head of 5.9 m is provided by the model.

    Does anyone know what could be causing this problem? Or have I missed something and made an error when modelling the system?



    H2OMAP Water System Curve Error.jpg

  2. #2
    Forum Moderator

    Innovyze Employee

    Innovyze Employee

    Join Date
    May 2015
    Hi Patrick,

    When a system curve is run in the software it basically places a positive demand on the suction of the pump and a negative demand on the discharge of the pump and makes the pump inactive. It then runs a series of runs (the number depends on how many points are selected in the system curve options) from zero to a maximum flow that is associated with where the pump selected would be expected to have a zero head gain. At the zero point the supply and demand are zero. But according to what you are describing the model results should have given the results you noted. The only thing I can think of was to double check the head values. Perhaps the intake was accidentally set at 16 m instead of 12 or that the receiving tank was set to 14.9 instead of 19.9 m as the results for headloss through the system appear fairly consistent except for the head difference.

    But given that, without looking at the model directly, it is not directly clear as to what could be causing your issue. Can you send this over to and we can take a more detailed look?

    Innovyze Support
    Patrick Moore
    Last edited by Patrick Moore; August 28, 2015 at 12:47 PM.

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