NPSHa Calculator

Estimate available Net Positive Suction Head and compare it with pump NPSHr.

Calculator

Water / condensate property helper

For water and clean condensate, select temperature and the calculator will estimate density and vapor pressure from an internal table. For other liquids, keep manual input.

Estimated properties Manual
NPSHa —
NPSH margin —

Formula

Available NPSH is estimated as:

NPSHa = Psurface head + Hstatic − Pvapor head − hf

Where:

  • Psurface head = absolute pressure above liquid converted to head [m]
  • Hstatic = static suction head [m]
  • Pvapor head = vapor pressure converted to head [m]
  • hf = suction line losses [m]

Engineering note

The built-in table is intended for water and clean condensate only. For chemicals, hydrocarbons, mixtures, dirty liquids or process media, enter vapor pressure and density manually from a reliable datasheet or process specification.