Page 79 - Centrifugal Pumps Design and Application

82 Centrifugal Pumps: Design and Application

are to be considered, the throat area should be sized for the standard
impeller and increased by 10% to maintain the efficiency of the high
capacity impeller.
• Since significant energy conversion takes place in the diffusion cham-
ber, the design of this element should be done with extreme care.
• The volute should be designed to maintain constant velocity in the vo-
lute sections,
• The overall shape of the volute sections should be as shown in Figures
5-5, 5-6, 5-7, and 5-8. The use of these figures will save the designer
time and introduce consistency into the design process.
» The volute spiral from the cutwater to the throat should be a stream-
lined curve defined by no more than three radii.

Figure 5-9. Typical layout for circular volute pump.