Which statement best describes cavitation in a pump?

• A. Cavitation occurs when the pump operates with high suction pressures.
• B. Cavitation occurs due to debris blocking the impeller.
• C. Cavitation is caused by overheating.
• D. Cavitation involves vapor pockets forming due to low suction pressure.

Answer: (D)

Cavitation happens when the suction pressure at the pump eye drops low enough that the liquid’s vapor pressure is reached, causing tiny vapor pockets to form. As these pockets move into higher-pressure areas inside the pump, they collapse violently, sending shock waves that can erode parts and disrupt flow. This is why the description that vapor pockets form due to low suction pressure best describes cavitation. It isn’t about debris blocking the impeller, nor about overheating, and high suction pressure actually helps prevent cavitation. For pump operation, you’d look at available net positive suction head versus the pump’s required suction head to avoid this condition.