Cavitation is a condition that occurs in liquid flow where the internal pressure of the liquid, at some point falls below the vapour pressure and vapour bubbles form and at some other point downstream rises above the vapour pressure again. As this pressure recovers so the bubbles collapse, and Cavitation takes place
It is possible to predict where cavitation will occur by looking at the pressure conditions and the valve recovery factor. However, it is important to recognise that the damage that occurs is dependent on the energy being dissipated and is thus flow dependent.Cavitation sounds like stones passing through the valve.