Page 86 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 2 .12 Pump Best Practices

Fig 2.12.5 Ethelyne Mollier diagram

significantly increases its temperature can cause the liquid to
A fluid will remain a liquid as long as its vapor pressure is less than change to a vapor.
the pressure acting on the liquid
What can reduce the pressure of a liquid, or significantly
increase its temperature inside a pump? To answer this question,
the entire cross section of a pump must be examined. In
Fig 2.12.6 Maintaining a liquid
Figure 2.12.8, the flow path from the pump suction flange to the
decreased while the temperature is held constant (see impeller vane is plotted against pressure in the pump. It can be
Figure 2.12.7). If the pressure of the water is less than its vapor seen that the pressure decreases from the suction to the leading
pressure, water vapor will form. Therefore, any action inside edge of the impeller vanes, then increases rapidly once the liquid
a pump that either reduces the pressure of a liquid or is inside the impeller vanes e where vane tip speed (U) and

Fig 2.12.7 Causes of liquid phase change e H 2 O

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