Cavitation

Whenever the liquid being pumped enters the eye of a centrifugal pump, the pressure is appreciably decreased. The greater the flow velocity via the pump the greater this pressure drop. When the pressure drop is great sufficient, or when the temperature of the liquid is high adequate, the pressure drop might be adequate to cause the liquid to flash to steam whenever the local pressure falls below the saturation pressure for the fluid which is being pumped. Such vapor bubbles are swept all along the pump impeller with the fluid. Since the flow velocity reduces the fluid pressure rises. This causes the vapor bubbles to rapidly collapse on the outer parts of the impeller. The formation of such vapor bubbles and their following collapse is cavitation.

The cavitation can be a very serious trouble for centrifugal pumps. Some of the pumps can be designed to operate with limited quantities of cavitation. Most of the centrifugal pumps cannot withstand cavitation for major periods of time; they are harmed by erosion of the vibration, impeller, or some other cavitation-induced trouble.