How to prevent cavitation?

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How to prevent cavitation? To prevent cavitation, it is necessary that the effective NPSH (NPSH)a be greater than the required NPSH (NPSH)γ, and that the effective suction vacuum Ha be less than the pump’s allowable suction vacuum Hs. The specific requirements are: (NPSH)a > (NPSH)γ(1+a), where a ranges from 0.1 to 0.3; or (NPSH)a = (NPSH)γ + S1. The value of S1 is 0.6 to 1.0 m for pumps operating under normal atmospheric pressure, and 2 to 3 m for pumps used in vacuum distillation columns. To meet the above requirements, a pump with a lower required net positive suction head can be selected when choosing a pump. Once the pump has been selected, it is necessary to increase the effective net positive suction head. This is achieved by properly determining the height difference between the liquid level in the suction tank and the pump, so as to have a larger suction head during filling operations, while maintaining a lower suction height during pumping operations ； Select the diameter of the suction pipeline appropriately, and keep it as short and straight as possible to reduce the resistance in the suction system. To prevent cavitation, the following measures are adopted in the pump’s design: a double-suction impeller is used ； Increase the inlet area of the impeller ； Increase the width of the blade inlet edge ； Increase the radius of curvature at the bends of the front and rear cover plates of the impeller ； The inlet edge of the blade extends toward the suction side ； The first stage of the impeller is made of cavitation-resistant material ； Let the pre-induction wheel be ； For existing pumps, measures to prevent cavitation include: ensuring a low rate of change in the cross-sectional area of the flow passage, and keeping the wall surfaces smooth ； The resistance of the inhalation tube should be low ； Choose the suction height correctly ； Epoxy resin coating is applied to the cavitation area.