The NPSH (Net Positive Suction Head) is related to the problem of cavitation; besides head, capacity, and power demand,it represents one of the most important operational factors of a pump. There must be distinguished between NPSH of the plant (NPSHavailable) and NPSH of the pump unit (NPSHrequired). By simple comparison between NPSHav. and NPSHreq. one can judge whether the operational safety of any pump selected for the respective system is ensured or not. The condition for operation without cavitation is:
NPSHav.> NPSHreq.
The above requirement must be met over the entire permissible operating range of a pumping system.
