Handbook of Civil Engineering Calculations

Percent of turbine BEP speed

FIGURE 8. Constant-head curves for turbine duty. (Chemical

Engineering.)

107 percent of the capacity, 94 percent of the efficiency, and 108 percent of the bhp. To
get the actual performance, convert as before: Qt = 107(1500) =1610 gal/min (6094
L/min); Et = 0.94(74.5) = 70.0 percent; bhp = 1.08(189) = 206 hp (153.7 kW).
Note that the bhp in this last instance is higher than the bhp at the best efficiency point.
Thus more horsepower can be obtained from a given unit by reducing the speed and in-
creasing the flow rate. When the speed is fixed, more bhp cannot be obtained from the
unit, but it may be possible to select a smaller pump for the same application.
Related Calculations. Use this general procedure for choosing a centrifugal
pump to drive—as a hydraulic turbine—another pump, a fan, a generator, or a compres-
sor, where high-pressure liquid is available as a source of power. Because pumps are de-

Percent of turbine BEP speed

FIGURE 9. Constant-head curves for turbine only. (Chemical

Engineering.)

Efficiency Turbine

Turbine BEP

Percent

of

turbine

BEP

capacity

Percent

of

turbine

BEP

efficiency

and BHP