Net Positivie Suction Head (NPSH)

• NPSHr = head required @ the eye of the pump’s impeller to prevent cavitation, a function of pump design.
• NPSHa = head available from the suction side of the system, must always equal or exceed the required (NPSHr) to prevent cavication

NPSHa Factors Table

Positive	Negative
1) Absolute pressure on liquid	1) Vapor pressure of the liquid, absolute
2) Static suction head	2) Friction & entrance losses
	3) Static suction lift