Net Positive Suction Head
It is possible to ensure that cavitation is
avoided during pump operation by monitoring the net positive
suction head of the pump. Net positive suction head (NPSH)
for a pump is thedifference
between the suction pressure and the saturation pressure of
the fluid being pumped.NPSH
is used to measure how close a fluid is to saturated
conditions. Equation 3-19 can be usedto
calculate the net positive suction head available for a pump.
The units of NPSH are feet of water.
NPSH = Psuction - Psaturation
NPSH = Net Positive Suction Head (m, in)
= suction pressure of the pump
saturation pressure for the fluid
By maintaining the available NPSH at a level
greater than the NPSH required by the pump manufacturer,
cavitation can be avoided.