Page 20 - Centrifugal Pumps 2E

8 Centrifugal Pumps: Design and Application

Figure 1-5. Viscous performance change.

Thus, pumps with a change in product density generating the same
head will show a change in pressure, and horsepower absorbed by the
pump will vary directly with the change in specific gravity (Figures 1-7
and 1-8). A pump being purchased to handle a hydrocarbon of 0.5 spe-
cific gravity will normally have a motor rating with some margin over
end of curve horsepower. During factory testing on water with 1.0 spe-
cific gravity, the absorbed horsepower will be two times that of field op-
eration, thus preventing use of the contract motor during the test. In such
instances the pump manufacturers standard test motor is used.

Construction

Pump construction is quite often spelled out on the pump data sheet.
General terms like horizontal, vertical, radial split, and axial split are