WATCHING AN IMPELLER CAVITATE HELPS PEERLESS PINPOINT A PUMP'S NPSH Product improvement takes many forms at Peerless. Here you see an example of one of the more complex studies—that of cavitation. By employing stroboscopic lights, Peerless engineers photographically record cavitation conditions as NPSH on the pump is slowly diminished. Initial stages of cavitation are indicated* in figure 1. Little noise or reduction in pump performance will be noted at this stage of operation. A further drop in NPSH causes, the condition shown in figure 2. Normally some noise will be evident in the pump and a reduction in efficiency would now become apparent. Figure 3 shows an example of severe cavitation taking place. Although the pump will still operate under these condiPutting Ideas to Work
Peerless Pump HYDRODYNAMICS ©DIVISION &
tions, it will be noisy and have a decidedly reduced head and efficiency. By carefully reviewing the results of these tests, Peerless engineers are often able to contribute valuable help to customers in preparing their pump systems to achieve proper NPSH and thus avoid costly downtime and pump reconditioning. Further, these studies often result in superior design characteristics of volute and impeller which in turn allow use of a lower NPSH. Pinpointing an impeller's NPSH is just one more way in which Peerless works to build you a pump of superior performance. It is, too, a good reason why a Peerless pump in your installation will work better, last longer, call for fewer service checks.
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A plastic end plate mounted at the suction permits proper positioning of a high speed camera. In photo above, plate is removed so impeller can be seen.
PEERLESS PUMP • HYDRODYNAMICS DIVISION • F M C C O R P O R A T I O N 301 West Avenue 26, Los Angeles 31, California Gentlemen: Please send me your technical paper "What is NPSH." Name-
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