Cavitation in Hydraulic Pumps

Last Updated on Tuesday, 10 May 2011 19:12 Written by Camilo H Rueda Monday, 07 February 2011 20:37

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In order to have a hydraulic system working properly, it is necessary to feed the pump with 100% liquid fluid, without anything else.

Cavitation occurs when a liquid fluid is vaporized because excessive vacuum. In general, the place that meets this condition is the suction of the hydraulic pump.

When the fluid vaporizes in the suction of the pump, the amount of fluid vapor varies depending on how high is the vacuum generated, therefore the output flow is going to be affected.

Additionally, the bubbles of vapor that are formed in the suction, once are directed to the outlet where there is pressure, collapse violently causing erosion in the surrounding metal walls inside the pump. This process affects the life of the pump dramatically.

This is what happens with the oil vapor bubbles inside the pump during the transition from negative pressure in the suction side to high pressure at the outlet creating noise and erosion.

The rapid contraction is so strong that a heavy force is generated against the closest surface. If this phenomena occurs for a long period of time, the damage caused will be irreversible and can cause catastrophic failures.

Probable causes for cavitation on hydraulic pumps:

A. Clogged or restricted suction in the pump.

B. Clogged or restricted strainer.

C. Pump too far from tank.

D. Pump too high above tank.

E. Suction pipe or hose diameter too small or too many elbows or reductions.

F. High viscosity of the oil, temperature too low or wrong oil.

G. Excessive RPM on the pump.

H. Oil mixed with water, kerosene, fuel or solvents, at high temperature.