Pump cavitation
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Question: Is the critical condition for pump cavitation, NPASHA = NPSHR, applicable to all fluids? In the factory, there is a pump that facilitates the circulation of the material inside the tanks; under these conditions, the material in the tanks is almost in a vacuum state (it is under reduced-pressure distillation, and the impurity content is very low, with a moisture content of around 0.05%). Under these process conditions, the NPSHA value is 4.5 m
Yes, the material inside the tank is in a nearly vacuum state; therefore, NPSHA is determined by the liquid level and the conditions of the piping. In general, it is advisable to raise the tank.
By using a centrifugal pump with a low speed (such as 1450 rpm), the NPSHR can be significantly reduced. As long as NPSHR is less than NPSHR+ the required margin, it becomes possible to avoid raising the equipment foundation.