NPSH Calculator – Net Positive Suction Head for Pump Systems

Calculate Net Positive Suction Head Available (NPSHa)

kg/m³
kPa
meters (enter negative if liquid below pump)
meters
kPa (at pumping temperature)

Quickly calculate Net Positive Suction Head available (NPSHa) to ensure optimal pump performance and prevent damaging cavitation. This tool helps engineers understand fluid system requirements for reliable pump operation and efficient fluid transfer.

Formula:

The Net Positive Suction Head available (NPSHa) is calculated using the following formula:

NPSHa = (Ps / ρg) + Z - (Pv / ρg) - Hfs

  • Ps: Absolute pressure at the liquid surface (e.g., atmospheric pressure for an open tank, or tank pressure for a closed tank)
  • ρ: Fluid density
  • g: Acceleration due to gravity (9.81 m/s2 or 32.2 ft/s2)
  • Z: Static elevation difference between the liquid surface and the pump inlet centerline (positive if liquid surface is above the pump, negative if below)
  • Pv: Vapor pressure of the liquid at the pumping temperature
  • Hfs: Total friction losses in the suction piping system from the liquid surface to the pump inlet

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