Lack of control of the environment is often pinpointed as a cause of frustration and stress in confined animals. When the animal cannot control things, such as the feeding time or the lighting program, and when it cannot escape from things it finds unpleasant, it often behaves in a manner that indicates frustration.
Cavitation can also cause excessive pump vibration, which could damage pump bearings, wearing rings, and seals. A small number of centrifugal pumps are designed to operate under conditions where cavitation is unavoidable.
There are two ways of expressing NPSH relative to a centrifugal pumping system: 1  NPSHa: The Net Positive Suction Head Available at the pump impeller inlet. 2  NPSHr: The Net Positive Suction Head Required by the pump to operate without experiencing damaging cavitation and a dramatic reduction in pumping production.