Page 35 - Centrifugal Pumps 2E

22 Centrifugal Pumps: Design and Application

Table 2-5
Tabulated Performance of Model Pump
(Model 9-1 n. Diameter Impeller)

Qm H m Eff. m % Wlp m
0 350 0 25
100 349 28 31
200 345 48 36
300 337 52 42
400 325 70 46
500 300 74 57
600 260 73 54
650 235 72 54

Table 2-6
Tabulated Performance of New Pump
1
(New Pump 10 /a-ln. Diameter Impeller)
Q, H, Eff.i % bhpi
0 437 0 50
!40 436 28 55
280 431 49 62
420 421 53 84
560 406 71 81
700 375 75 88
840 325 74 93
910 293 72 94

Applying these factors to the model, the new pump performance at
BEP will be: 700 GPM; 375 ft; 75% efficiency; 94 maximum HP; 3,550
RPM; and lOVs-in. impeller diameter.
To obtain complete H-Q performance refer to Tables 2-5 and 2-6.
The new pump size will be a 4-in. x 6-in. x 10-in. with performance
as shown in Figure 2-7.

All major pump manufacturers have in their files records of pump per-
formance tests covering a wide range of specific speeds. Each test can be
used as a model to predict new pump performance and to design same. In
the majority of cases, the required model specific speed can be found
having the same running speed as required by the new pump. There are
cases, however, where the model pump running speed is different than
required by pump in question.