Cavitation

Canonical Definition

The formation and violent collapse of vapour-filled cavities (bubbles) in a hydraulic fluid when local pressure drops below the fluid's vapour pressure. Cavitation occurs primarily at hydraulic pump inlets (suction cavitation) where excessive restriction — caused by a partially closed inlet valve, undersized inlet line, plugged suction strainer, or excessively cold viscous oil — reduces inlet pressure below the vapour pressure threshold. Bubble collapse generates intense local pressure spikes (up to several thousand bar) that erode pump and valve component surfaces, produce high-frequency noise, and generate metallic wear particles that contaminate the fluid.

Engineering Context

Cavitation is a pump-destructive phenomenon that develops rapidly once it begins. Indicators include high-frequency whining or rattling noise from the pump, discoloured pump components, and rapidly increasing metal particle counts in oil samples. Prevention centres on ensuring adequate inlet line sizing, maintaining oil level, using correct oil viscosity grade for ambient temperature, and keeping suction strainers clean. Suction strainers should not exceed 120 µm mesh to protect pumps while maintaining free flow.

Related Technologies

Protection Systems

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