Cavitation can destroy a centrifugal pump, is noisy and is caused by

• A. Inlet pressure that is too low
• B. Outlet pressure that is too low
• C. Inlet pressure that is too high
• D. Outlet pressure that is too high

Answer: (A)

Cavitation starts when the suction-side pressure falls below the liquid’s vapor pressure. In a centrifugal pump, the impeller lowers pressure at the eye, so if the inlet pressure is too low, the local pressure can dip below the liquid’s vapor pressure and vapor bubbles form. When these bubbles move into areas of higher pressure inside the pump, they collapse violently, creating shock waves, noise, vibration, and potential damage to the impeller and other components. That makes low inlet pressure the trigger for cavitation.

So the root cause is inlet pressure that is too low. Outlet pressure changes affect the pump’s head and flow but don’t directly cause cavitation, which is driven by suction-side conditions and the available Net Positive Suction Head relative to the pump’s requirements.