PlantLogica

University

Calculator

NPSH Calculator

Calculate Net Positive Suction Head available to determine whether a pump will cavitate — essential for safe pump installation design.

Interactive toolUpdated July 2026

Inputs

Vapour pressure 2.34 kPa

Positive for flooded suction, negative for lift.

Sea level 101.3; reduce for altitude.

Results

NPSH Available

11.61 m

NPSHr 3.00 m · margin 8.61 m

NPSHa
11.61 m
NPSHr
3.00 m

How It Works

NPSHa = (P_atm − P_vap)/ρg + h_static − h_friction

Rule: NPSHa must exceed NPSHr by at least 0.5–1.0 m. Hot liquids have higher vapour pressure, reducing NPSHa; increasing suction pipe diameter reduces friction and raises NPSHa.

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