ABSTRACT

The job of a centrifugal pump is to generate enough pressure to overcome system hydraulic resistance. But it is the “responsibility” of the

liquid

to get to the pump. If the suction pressure is too low, the hydraulic losses can “eat away” enough pressure so that it could drop below the liquid vapor pressure. (A simplification of boiling mechanism with reduced pressure is shown in Figure 53.) Such formation of vapor bubbles (cavities) is called cavitation. If there is a lot of bubbles in the impeller inlet, the impeller may become “vapor locked,” and the pump will stop delivering flow. If cavitation is less severe, a partial loss of flow will occur, accompanied by noise, pulsations, vibrations, and pump failures.