Centrifugal pumps starting NPSH requirement

The reason can be explained by referring to Fig. 1, Up to a certain critical flowrate, Qc, the net-positive-suction-head (NPSH) requirements of a centrifugal pump increase, approximately, as the square of the flowrate [2. Above Qc, however, the NPSH requirements start to increase at a much faster rate — shown schematically in Fig. 1. 

Starting NPSH The required liquid head needed to overcome the inertia of static liquid in the suction of a centrifugal pump. 

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