The most accurate method of determining HL, is using the Darcy-Weisbach's equations.
(1)
Darcy-Weisbach equation (Design Model)
HL = f x L x V2
Where f = Friction factor, dimensionless
64.4 x D
L = Pipe length, feet
V = Velocity, ft/sec
D = Inside diameter, feet
(2)
Darcy-Weisbach equation (Modified Model)
HL= 0.031 x f x L x Q2
Where f = friction factor
d5
L = Pipe length, feet
Q = Flow rate, GPM
d = Inside diameter, in
PROBLEM: Given:
f = 0.035
L = 0.5 mile
V = 300 ft/min
D = 0.5 ft
SG = 0.8260
Determine HL in PSI.
SOLUTION:
L = 0.5 mile x 5280 ft/mile = 2640 ft
V = 300 ft/min x 1min/60sec = 5 ft/sec
V2 = 25 (ft/sec2)
HL = 0.035 x 2640 x 25 = 71.7 FT
64.4 x 0.5
PSI = - HL x SG = 71.7 x 0.8260 = 25.7
2.31
2.31
PROBLEM: Given:
f = 0.92
L = 2 miles
Q = 300 BPH
d = 8 in LWST
SG = 0.8448
Determine HL in PSI.
QM5203
1-21
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