Page 166 - Centrifugal Pumps Design and Application

Pipeline, Waterflood and CO 2 Pumps 143

Figure 10-4. Efficiency increases with hydro-dynamic size.

uid velocity entering the volute throat. By careful selection of this veloc-
ity ratio, pump throughput and optimum efficiency can be moved from
the initial to the ultimate condition (Figure 10-5).
The volute throat velocity can be adjusted by cutting back (chipping)
the stationary volute lip or lips to a predetermined dimension (Figure
10-6). This technique can be used on single- or double-volute pumps.
Similarly, the velocity leaving the impeller can be adjusted by removing
metal (underfiling) from the non-working side of the impeller blade (Fig-
ure 10-7). Through a combination of volute chipping, impeller underfil-
ing, and ultimate installation of a high-capacity impeller, a wide variety
of pump conditions all at optimum efficiency becomes possible (Figure
10-8).