Cavitation occurs in a pump due to what phenomenon?

• A. Excessive impeller speed
• B. Collapse of vapor bubbles
• C. Overcooling the liquid
• D. Excessive filtration

Answer: (B)

Cavitation happens when the liquid in the pump experiences very low pressure, causing vapor-filled cavities to form and then rapidly collapse as the pressure rises. The violent collapse of these vapor bubbles releases energy that erodes surfaces and creates noise and vibration. So the essential phenomenon is the collapse of vapor bubbles, which is the destructive part of cavitation that occurs after bubbles form in the low-pressure region near the impeller.

Excessive impeller speed can help create the low-pressure area that allows bubbles to form, but the damaging event driving cavitation is the collapse of those vapor bubbles. Overcooling the liquid lowers its vapor pressure and would actually make cavitation less likely, not more. Excessive filtration isn’t a factor in cavitation.