What is NPSH and how to prevent cavitation phenomenon

NPSH is an important parameter that measures the ability of a pump or other fluid machinery to prevent liquid vaporization under specific conditions. It represents the excess energy per unit weight of liquid at the pump inlet that exceeds the vaporization pressure.

The phenomenon of cavitation is due to the gas generated by the liquid at the inlet of the impeller under a certain vacuum pressure during the operation of the pump, forming bubbles. These bubbles, under the impact motion of the liquid particles, cause erosion on the metal surface of the impeller, thereby damaging the impeller and other metals. To prevent cavitation, the following measures can be taken:

Increase import pressure. By increasing the inlet pressure, the fluid pressure can be increased and the occurrence of cavitation can be reduced.

Reduce flow rate. Reducing the flow rate of a fluid can reduce the degree of decrease in fluid pressure, reduce the formation of bubbles, and prevent the occurrence of cavitation phenomena.

Improve equipment structure. By improving the structure of the equipment, the pressure drop of the fluid can be reduced, effectively preventing the occurrence of bubbles and cavitation.

Increase effective cavitation margin. Effective NPSHa is the NPSHa of a device (pipeline), which is related to the installation method of the pump. Increasing its value can enhance the anti cavitation performance of the pump.

Reduce the necessary NPSH. NPSHr is a fundamental parameter of the cavitation performance of the pump itself, and reducing its value can improve the anti cavitation performance of the pump.

Through these measures, cavitation can be effectively prevented and the normal operation of pumps and other fluid machinery can be protected.

Many pumps can increase their self suction height, but they cannot solve the problem of cavitation. The VSP strong vacuum self priming pump has good anti cavitation performance, with a maximum suction height of over 8 meters, and will not produce cavitation phenomenon.