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NPSH module / example

Calculation of net positive suction head in suction lines

Task

A subcooled liquid flows from a vessel through a pipe. The liquid level is kept at a constant height by an inlet.

We need to determine the NPSH.

Operating data

Volume flow

V = 20 m3/h

Diameter (of pipe)

d = 50 mm

Total length (of pipe)

L = 15 m

Density

ρF = 720 kg/m3

Dyn. viscosity

η = 0,1 mPas

Vapour pressure

PSatt = 0,8 bar

Temperature

T = 80 °C

Input


Results

Condition for operating without cavitation: NPSH actual ≥   NPSH required

After having entered the pressure volume curve, the head of the plant and the pump curve can be presented graphically.

The system is shown in a sketch on the input mask.