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net positive suction head??

Discussion in 'Irrigation' started by turfman59, May 26, 2003.

  1. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    Hey all~ I"m studying for my test and I'm having trouble grasping the meaning behind
    "Net Positive Suction Head Required
    & Net Positive Suction Head Available"
    on a pump curve.

    Any help with the concept would be appreciated, THANKS!!:dizzy:
  2. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Messages: 1,712

    This formula best explains

    What the end result is you must have more suction "available" created by the pump design, than what is "required" to get the liquid into the pump.

    If we were on the outbound side of the pump we'd be talking about this as pressure loss. The pump must create enough suction to over come the elevation difference plus any flow restrictions in getting the liquid into the pump impeller.
  3. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    Now that makes sense.
    on a pump chart (curve) this makes little to no sense
    I see the curve start high and go down and then back up to the same height,, whats that all about
  4. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    of all the points on a pump chart, this is the only one that makes no sense. I guess I cant get my bearings on what it is telling me. Is it related to dynamic flow through the gallons per minute.

    I can understand the definition of the NPSH formula but I cant relate it to a curve

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