NPSH value of a pump, minimum pre-pressure
A calculation of the pump pre-pressure "H" is recommended:
- at high media temperatures
- if the flow rate is significantly higher than the nominal flow rate of the pump
- when the fluid is pumped from great depth
- when feeding the pumped medium over long pipes
- in poor feed conditions. To avoid cavitation, make sure that there is always a minimum pressure on the suction side of the pump
The maximum suction height "H" in m can be calculated as follows:
H = (Pb x 10,2) - NPSH - Hf - Hv - Hs
If a positive value is determined for "H", the pump can be operated at a suction height of at most "H" m.
If a negative value is determined for "H", an inlet pressure of at least "H" m is required.
Note: To prevent cavitation from occurring, never select a pump whose operating point is too far to the right of the NPSH characteristic.
The NPSH value of the pump must always be determined for the highest possible delivery rate.