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Pump and check valve

Sam81 Member Posts: 36
I’ve been on a job where they replace a floor mount pump with a smaller type inline pump of coarse the suction diffuser Andy triple duty valve was removed instead he installed a standard swing check that chatters like crazy, I know it should be certain amount of pip diameters in order to silent the turbulence just went to know the calculations or any other ideas


  • hot_rod
    hot_rod Member Posts: 14,786
    What type of flow rates?

    A swing check needs to be sized to the actual flow rate, not pipe size. That way the actual flow can push the gate fully open, out of the flow stream to help eliminate clatter. Orientation is important also some can be installed in horizontal and vertical position, other suggest horizontal mount only.

    The cv number assigned to a check valve is in the full open position.

    There are better checks to be used in hydronics, like a spring check with conical shape and soft seat. Watts, Conbraco and others have hydronic duty checks available in a wide range of sizes

    A typical swing check needs to have a pressure differential across it to shut and seal, think sump pump or sewer ejection pump.

    With closed loop hydronics, when the pump shuts down the pressure is the same on both sides of the check, it may not close, or seal completely. Variable speed pumps can complicate it further.

    One rule of thumb is 12 pipe diameters of straight pipe upstream of a check.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Sam81
    Sam81 Member Posts: 36
    THanks hot rod this is the exact info I needed
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