Cavitation in Pumps

The formation and collapse of vapor filled bubbles is called cavitation. This process occurs in regions inside of a pump where the pressure drops below the vapor pressure of the fluid (the vapor pressure of the fluid is the pressure at which a fluid begins to boil or vaporize). Cavitation occurs when the Net Positive Suction Head Required (NPSHR) of the pump is not satisfied and can result in significant damage to the pump.

To avoid cavitation always make sure that there is enough pressure at the pump suction, (i.e. Net Positive Suction Head Available, NPSHA) so that the fluid does not boil or vaporize. Always make sure that the pump suction pressure is greater than the liquid vapor pressure, regarding the temperature. Note: If a pump is cavitating, you can close down the control valve on the discharge side of the pump to decrease the flow rate, and lower the NPSH required by the pump. Be sure to allow enough flow through the pump for proper cooling and lubrication.

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