Pump — Power & NPSH

Head, hydraulic and electrical power, and the available NPSH with a cavitation check.

Unit system

Inputs

State of the fluidFlow rate

Pressure in the suction vessel (absolute)

A vented condensate tank sits at 1.013 bar a. For a pressurised vessel, its own pressure.Fluid temperature

Ignored when saturated condensate is selected — the temperature follows from the vessel pressure.Pressure rise required

Suction static head

How far the liquid level sits ABOVE the pump centreline. Enter a negative value if the pump is above the liquid.Suction line friction loss

NPSH required by the pump (NPSHr)

Read from the pump curve and it changes with flow. No selection is possible without the catalogue figure.Pump efficiency

Motor efficiency

NPSH available (NPSHa)

1,200mm

Cavitation check

CAVITATION — the available NPSH is BELOW what the pump needs. It will run, and it will eat its impeller.

NPSHr is read from the pump curve and RISES WITH FLOW. This check is for one operating point; look again at the top of the range.
With saturated condensate the pressure term is zero; only the static head holds NPSHa up. Every elbow in the suction line eats straight into the margin.

A PDF carrying the inputs, results, assumptions and the source. A one-time code is sent to your address.

Results are for engineering pre-assessment and are not a product selection commitment. Final responsibility rests with the user.