Pump - NPSH Available (NPSHa)

Net Positive Suction Head Available (NPSHa) at pump inlet - must exceed NPSHr to avoid cavitation. Classical hydraulics check for cargo / ballast pumps.

NPSHPumpCavitation

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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{NPSH}_a = \frac{p_s}{\rho g} + h_s - h_f - \frac{p_v}{\rho g}

Symbol	Meaning	Unit
$p_s$	Suction-source pressure (absolute)	Pa
$h_s$	Static head	m
$h_f$	Friction loss suction line	m
$p_v$	Vapour pressure	Pa

Source: API 610 / ISO 13709

In short

Net Positive Suction Head Available (NPSHa) at pump inlet - must exceed NPSHr to avoid cavitation.

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