Handbook of Civil Engineering Calculations

Capacity, L/s

(b)

FIGURE 14. (0) Significant friction loss and lift; (b) system-head curve

superimposed on pump head-capacity curve. (Peerless Pumps.)

3. Plot the no-lift system-head curve and compute the losses
   With no static head or lift, the system-head curve passes through the origin (0,0), Fig. 15.
   For a flow of 900 gal/min (56.8 L/s) in this system, compute the friction loss as follows,
   using the Hydraulic Institute Pipe Friction Manual tables or the method of earlier calcula-
   tion procedures:

ft m

Entrance loss from tank into 10-in (254-mm) suction pipe, Q.5v^2 /2g 0.10 0.03
Friction loss in 2 ft (0.61 m) of suction pipe 0.02 0.01
Loss in 10-in (254-mm) 90° elbow at pump 0.20 0.06
Friction loss in 3000 ft (914.4 m) of 8-in (203.2-mm) discharge pipe 74.50 22.71
Loss in fully open 8-in (203.2-mm) gate valve 0.12 0.04
Exit loss from 8-in (203.2-mm) pipe into tank, v^2 /2g 0.52 0.16

Total friction loss 75.46 23.01

Capacity, gal/min

Total

static

head

Friction

head

Artificial system

head curve

H-Q at constant speed New operating

Flow rate

Head Losses

Head,

HfI

Head,

ft