Cavitation

Cavitation is the formation and violent collapse of vapour bubbles in a liquid when local pressure drops below its vapour pressure, typically inside pumps and valves. The collapsing bubbles cause noise, vibration, efficiency loss and pitting damage to metal surfaces.

When a pump's suction pressure falls too low, the liquid flashes to vapour at the impeller eye; as the bubbles move to a higher-pressure region they implode with enough force to erode metal. Cavitation announces itself as a sound like gravel passing through the pump, accompanied by lost head and shortened bearing and seal life. It is prevented by ensuring sufficient net positive suction head and avoiding throttling on the suction side.

Related terms

Net Positive Suction Head (NPSH) · Water Hammer · Pressure Transmitter