'Cavitation' in centrifugal pumps occurs when:
Choose the correct answer
Discharge pressure is too high
Local suction pressure drops below vapour pressure — bubbles form and collapse causing pitting and vibration
Pump is running too slowly
Discharge pipe is too short
Correct Answer
B. Local suction pressure drops below vapour pressure — bubbles form and collapse causing pitting and vibration
Why is this the answer?
Cavitation: local pressure drops below vapour pressure → vapour bubbles form → collapse violently on high-pressure side → pitting, vibration, noise, efficiency loss. Prevented by: ensuring NPSH_available > NPSH_required. NPSH_a = (pa−pv)/γ + Hs − hL (atmospheric, vapour, suction head, losses). Cavitation likely when: pump set too high above sump, long suction line, hot liquid, high altitude.
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