Cavitation describes the occurrence and dissipation of vapor bubbles in liquids. They occur most often because of solid objects that are in the liquid medium and moving fast – similar to the impellers of centrifugal pumps. As soon as the static pressure in the delivery drops under the vaporization pressure of the transported medium, vapor bubbles will form that are being transported with the flowing fluid. If the static pressure increases again, the vapor suddenly condensates within the cavities; the vapor bubble collapses, resulting in large peaks in pressure and temperature.
This phenomenon can cause creeping mechanical damages to the transporting units and other components. The resulting heavy mechanical stress attacks the surface, and if cavitation occurs on a continuous basis, parts will break out of the surface. Besides damages to the transporting units, reduced pump efficiency is also an early consequence.
Common strategies for avoiding cavitation consist of not allowing the temperature of the transported medium to rise above a certain point or not allowing the suction pressure of the pump to become too low. Further measures build on monitoring the pump for differential pressure or typical noise developments.