Cavitation is best described as which of the following?

• A. Formation of bubbles in areas of high pressure around an impeller, with no damage.
• B. Formation of bubbles or cavities in liquid in areas of relatively low pressure around an impeller, where imploding bubbles trigger shockwaves that can damage the pump.
• C. A rarefaction of the liquid that reduces flow without damage.
• D. Mixing of gas bubbles with liquid without any pressure change.

Answer: (B)

Cavitation happens when the liquid experiences a local drop in pressure below its vapor pressure, causing vapor bubbles to form. These bubbles develop in regions of relatively low pressure around the impeller, and when they move into higher-pressure zones or collapse, they implode violently, sending shockwaves that can pit and erode pump surfaces. This exactly describes bubbles forming in low-pressure areas around an impeller and their imploding collapse causing damaging shockwaves. The other descriptions miss the essential pressure-driven formation and destructive collapse: cavitation isn’t about high-pressure bubble formation, nor is it simply a harmless rarefaction or about gas bubbles mixing without a pressure change.