When vacuum of pump inlet is too high( namely, when the absolute pressure is too low), the liquid in the pump inlet would vaporize, resulting in cavitation.
If running under cavitation, the wet parts of the pump would be worn very quickly under the combined effect of cavitation and abrasion. In the case of serious cavitation, the pump will vibrate and make noise. Moreover,the pump may even could not run due to the sharp fall of head, flow capacity and efficiency. Cavitation does great damage to pump and should be avoided.
In order to prevent or reduce cavitation, not only the producer should improve the design and manufacturing, but the users should take planning, design and operation management of the pump station into consideration. To avoid cavitation, the available net positive suction head(NPSHa) must be raised , making it exceed required net positive suction head NPSHr . Measures could be taken as follows:
1). Reduce the geometry suction height(for suction installation pumps), or increase the geometry back flow height(for back flow installation pumps)
2). Reduce suction loss by increasing pipe diameter or decreasing pipe length, elbow and accessories, etc.
3). Prevent long time running under large flow capacity.
4). Under the same rotation speed and flow capacity,it is better to adopt double-suction pump which could decrease inlet velocity and avoid cavitation.
5). When cavitation appears, please turn down the flow capacity or lower the rotation speed.
6). The condition of pump suction tank has important impact on the cavitation.
7). For the pump running under harsh conditions, cavitation resistant materials could be used to prevent the damage of cavitation.