Reduced capacity, accompanied by vibration and noise at the suction of a centrifugal pump, results from cavitation in the fluid being pumped. Cavitation describes the formation of __________.

Correct Answer: Option B — vapor pockets

Cavitation occurs when the local static pressure of the fluid falls below its vapor pressure, causing the liquid to flash into vapor. These vapor pockets collapse violently upon reaching higher pressure zones within the pump, causing characteristic noise, vibration, and significant mechanical erosion of the impeller and casing.