Liquid at a certain temperature, reducing the pressure and the temperature of the vapor pressure, the liquid bubble. This phenomenon is called cavitation bubbles.

Cavitation bubbles generated at, flow to the high pressure, the volume decrease resulting in burst. This due to the pressure of rising bubbles disappear in the liquid in a phenomenon called cavitation bubble collapse.

Pumps in operation in the local area, if the over-current part （usually somewhere in the impeller blade inlet later） for some reason, absolute pressure pumping liquid is reduced to the vaporization of the liquid pressure temperature, liquid vaporization in the beginning, it produces a large number of steam, forming a bubble, when it contains a lot of bubble liquid forward by high pressure areas within the impeller, high pressure liquid bubble around the bubble decreases drastically and fracture. Condensation in the bubble burst at the same time, the liquid particle filled hole at very high speed, in this moment has a very strong effect of water hammer, and the impact of very high frequency against the metal surface impact stress of hundreds to thousands of barometric pressure, impact frequency can reach tens of thousands of times per second, serious breakdown when the wall thickness will be.

The bubble and the bubble rupture the over-current components suffered damage process is the process of cavitation of pump in the pump. Water pump cavitation after addition of over-current components can have damaging effects, but also generate noise and vibration, and lead to a decline in the performance of the pump, serious disruption of liquid pump will not work properly.