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Thread: Pump curve NPSH

  1. #1
    Member
    Join Date
    Dec 2016
    Posts
    37

    Pump curve NPSH

    I have a pump curve (attachment). The curve that is supposed to show the NPSH shows Flow vs Horsepower.
    How can I input this curve? Do I use the curve type 4 (NPSH vs Flow)?
    Pump.jpg

  2. #2
    Forum Moderator

    Innovyze Employee



    Join Date
    May 2015
    Posts
    298
    Vladimir,

    An NPSH vs Flow curve should show Flow vs NPSH using your units for Flow and NPSH should show in your units for head. In InfoWater this is a curve type 4 in the curve editor. However you can also use a type ) which is a "General" curve. The only challenge to General curves is that they don't show units and are expected to be in the proper units. General curves always work because EPANET our hydraulic engine only has one type of curves. The other types are mostly to help users get the units correct.

    However on the curve you show it only shows the pump curve (on top) and the horsepower curve on the bottom with two curves for each depending on the impeller size, but it does not show the NPSH requirements.

    Here is a couple of links on how to read pump curves that may assist you:

    Article 1: http://www.nesc.wvu.edu/pdf/DW/publi...PumpCurves.pdf
    Article 2: https://www.pumpsandsystems.com/topi...and-npsh-tests

    For an actual pump curve you would use the one of the top curves in the pump curve and enter that as either a general curve or as as Type 2 Head vs. Flow curve using your Head and flow units used in the model. You just need to know which impeller diameter your pump will use so as to select the correct curve. I would recommend using at least 7 or more points if you do a multiple point pump curve though as it will linearly interpolate between the points provided. This will best reflect the true shape of the curve.

    Here are the two types of information shown on your pump curve:
    (click if need larger image)
    pump curve example.jpg

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