Effect of Temperature on Pump Capacity

We wish to increase the capacity of a centrifugal pump. Should we make the liquid hotter or colder Let s make a few assumptions  

To summarize, the specific gravity of the liquid has increased by 10 percent. The feet of head of liquid has decreased by 10 percent. Since  

AP remains constant. But the lower required feet of head permits the pump to operate further on its performance curve. This produces more volumetric (GPM) flow. It also requires more work to pump the greater flow. So we have to have sufficient excess amperage on the motor driver, to accommodate this maneuver. But that is the price we pay for expanding the pump s capacity, without increasing the impeller diameter. Of course, the larger-diameter impeller might still require more motor amperage. 

There are three types of limits on centrifugal pumps  

Pumps are driven by either fixed-speed or variable-speed machines. In this chapter, we consider all motor-driven pumps as fixed-speed machines. Certainly, there are some variable-speed motors, but these are few and far between, in most process plants. 

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