Anti-Cavitation Valves

Please be more specific, or you might just get an answer like this one:

Whenever they are needed to prevent cavitation.

Or you can check here, and get back to us.

Whenever the pressure downstream of the valve falls below the vapour pressure of the liquid being controlled at the conditions of flow and temperature at the worst conditions.

If the presure downstream is lower than the vapor pressure then FLASING occurs,that is part of the liquid vaporizes.

For cavitation to occur liquid must go below the vapor pressure and then recover to a pressure higher than the vapor pressure.

There are many number of excellent write up on these on the internet.

Visit the web site of Fisher,Masneilan,Flowserve ,Samson etc.

Agree. Usually vortices lead to such excursions of pressure and cavitation. I was referring to an unsteady state situation. Flash vapourization does result if there is a continuous low pressure condition.

We have seen cavitation damage even at the edge of rigid discs of mechanical heart valves.