What is Cavitation

Cavitation is the formation and then immediate implosion of bubbles in a liquid. They are the consequence of forces acting upon the liquid.

It usually occurs when the local static pressure in a fluid reach a level below the vapour pressure of th liquid at the actual temperature.

Cavitation can be avoided by increasing the distance between the actual local static pressure in the fluid and the vapour pressure of the fluid at the actual temperature.
This can be achieved by:
1. Increasing the total or local static pressure in the system.
2. Reducing the temperature of the liquid.

well cavitation is one of the major problems that affect the performance and functioning of pumps..
whenever at any point in the flow stream,vapour pressure is equal to the saturation pressure at the given temperature of the fluid,Vapur bubbles are formed...these bubbles travel along with the stream to high pressure areas where pressure is of the order of 1000 bar..and the vapour in these bubbles condenses which causes the bubbles to collapse..this produces agitation and stirring effects in the vicinity of the bubble..the liquid thus hammers continuously againt the walls and ultimately leads to material errosion or pitting..this whole process is known as cavitation..
cavitation can be avoided by
1)running the pump at the designed speed.
2)Having high NPSH value for the pump.
3)avoiding pipe bends and sudden change in the crossection of flow.
4)Keeping the temperature of the fluid under limits.

i hope that the description will surely answer your question..