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460 Chapter 8

which is negligible. The velocity head can usually be neglected at the outset in
both the suction and discharge sides of the pump.

Pressure Head

The pressure head is given by
32.21b M-ft 14.7 lb F 144 in 2

g c p 1 lb F-s 2 1 in 2 1 ft 2
Hp = —— = ———————————————— = 34.0 ft (10.3 m)
gp 32.2ft 62.3 lb M

Is 2 1 ft 3
This is a useful number to remember. It means that atmospheric pressure can sup-
port a column of water 34 ft (10.3 m) high.

Friction Head

Obtain the friction factor from Figure 8.16 after calculating the Reynolds number
and the relative roughness, s/D, for the pipe. From Table 8.4, the roughness factor
5
4
for steel pipe, e =1.5xlO~ ft (4.57xlO' m).

__ = —————— = 0.4468X10' 3
D 0.3357 ft

pvD 62.3 (2.52) (0.3355)
Re = ——— = ——————————— = 7.981x10 4
H, 6.60x10" 4

FromFigure 8.16,4f= 0.021.
The computations for the friction head, HFS, in the suction side of the pump
are completed in the Table 8.4.1.

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