Page 273 - Fair, Geyer, and Okun's Water and wastewater engineering : water supply and wastewater removal

JWCL344_ch07_230-264.qxd 8/2/10 8:44 PM Page 233

7.3 Energy Losses and Gains 233

Pump curve

Head Operating point

System curve H L

H S

Flow rate

Figure 7.2 System Operating Point

180

n 0.95
160
n 0.90
140
n 0.85
120 n 0.80

Head, ft 100

80

60
Best
efficiency
40
point
20
speed
n
full speed
0
0 100 200 300 400
Flow, gpm
Figure 7.3 Relative Speed Factors for Variable-Speed Pumps
Conversion factors: 1 gpm 3.785 L/min; 1 ft 0.3048 m