Cavitation is a harmful condition that occurs in the component like a pump or a valve of a hydraulic system when the existing space in the working component is not filled with the system fluid. It is the process of formation and collapse of vapor or air bubbles in the pumped fluid as it passes through the component. Undetected intermittent pump cavitation will eventually cause significant damage to a pump.
Suction head pressure
It is the actual pressure that the fluid experiences at the pump inlet.
It is the minimum pressure needed to prevent liquid from turning into vapour.
Cavitation occurs when the suction head pressure falls below the vapour pressure of the fluid or the saturation pressure of the entrained air in the fluid. This fall in the pressure causes the formation of bubbles in the fluid. Soon the bubbles collapse as the pressure on the fluid goes beyond the vapour pressure of the fluid or the saturation pressure of the entrained air, upon migration to a high-pressure area. The process of formation and collapse of bubbles is nothing but cavitation.
The collapse of bubbles is a violent process. It creates an impacting action on the inside surface of the pump or any other component. It causes component wear and damage. It can cause the vibration of the component. It causes damage to bearings, wearing rings, and seals. It can be prevented by maintaining sufficient fluid level, maintaining filters in good condition, and adjusting the fluid temperature.
Cavitation can be distinguished by the loud popping noise it makes. The collapsing bubbles create certain vibration patterns, which help in detecting the cavitation. Early detection of cavitation minimizes pump damage and reduces downtime.
Reference: JOJI PARAMBATH, Industrial Hydraulic Systems – Theory and Practice, Universal Publishers, Boca Raton, USA, 2016.
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