The description of millions of tiny air bubbles forming inside the impeller, not fully submerged, and causing damage describes which phenomenon?

• A. Cavitation
• B. Centrifugal force
• C. Suction lift
• D. Hydraulic shock

Answer: (A)

Cavitation occurs when the pressure in the liquid around the impeller drops below the liquid’s vapor pressure, causing tiny vapor bubbles to form. As these bubbles move into regions of higher pressure near the blades, they collapse violently, releasing powerful energy that erodes metal, creates pitting, and causes damage and vibration. If the impeller isn’t fully submerged or flow conditions create low-pressure zones, bubbles can form inside the impeller and contribute to this damaging process. The other concepts don’t describe bubble formation and damage in this way: centrifugal force is just the outward push from rotation, suction lift is about pulling fluid into the pump, and hydraulic shock is a sudden pressure surge from rapid flow changes.