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Fluid Mechanics / Pump Sizing

NPSH Available Calculator

Enter suction-side conditions to get NPSH Available. Compare against your pump's rated NPSH Required (from its datasheet) — NPSHa must exceed NPSHr, typically with a 0.5–1 m margin.

NPSH Available
— m

How this is calculated

NPSHa = (P_atm − P_vapor)/(ρg) + H_s − H_f
Enter values above to see the worked calculation.

When to use this calculator

NPSH Available describes how much suction pressure margin exists above the fluid's vapor pressure at the pump inlet. If NPSHa drops below the pump manufacturer's NPSH Required, the fluid flashes to vapor inside the pump — cavitation — which damages impellers and kills performance. Static suction head is positive when the source is above the pump (flooded suction) and negative when the pump has to lift fluid (suction lift).

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