Page 25 - Centrifugal Pumps 2E
P. 25
Specific Speed and Modeling Laws 13
Table 2-2
Formulas for Refiguring Pump Performance with
Impeller Diameter or Speed Change
Qi, H h bhpi, DI, and N/ = Initial capacity, head, brake horsepower, diameter, and speed.
Q 2, H 2, hhp 2, D?, and N 2 = New capacity, head, brake horsepower, diameter, and speed.
Example
A pump operating at 3,550 RPM has a performance as shown in
solid lines in Figure 2-1. Calculate the new performance of the pump if
the operating speed is increased to 4,000 RPM.
Step 1
From the performance curve, tabulate performance at 3,550 RPM (Ta-
ble 2-3).
Step 2
Establish the correction factors for operation at 4,000 RPM.
Step 3
Calculate new conditions at 4,000 RPM from:
