Net Positive Suction Head Available (NPSHA)

Available suction head at the pump inlet - must exceed NPSH required (from the pump curve) with a ≥ 0.5 m margin to avoid cavitation.

PumpsCavitation

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

\text{NPSHA} = \frac{P_\text{atm} - P_\text{vap}}{\rho g} + z_\text{static} - h_f

Symbol	Meaning	Unit
$P_\text{atm}$	Atmospheric pressure above reservoir	Pa (from bar)
$P_\text{vap}$	Vapour pressure of the liquid	Pa
$z_\text{static}$	Elevation of reservoir above pump (positive down)	m
$h_f$	Friction losses in suction piping	m

Source: HI - Hydraulic Institute ANSI/HI 9.6.1

Available suction head at the pump inlet - must exceed NPSH required (from the pump curve) with a \u2265 0.