Application of Hazen Williams Equation: Calculating Unit Headloss
What is the unit headloss (ft/1,000 ft) expected in a 16-inch diameter of a PVC pipeline carrying 2700 gpm?
a. 16 b. 4 c. 2 d. 12
The unit headloss expected in a 16-inch diameter PVC pipeline with C=130 and 2700 gpm flow rate is 4 ft/1000 ft.
Option B is correct. Using the Hazen-Williams equation, the unit headloss can be calculated as:
hL = 10.67 * (L/D) * (Q/C)^{1.852}
where:
L = 1000 ft (assumed length)
D = 16 in = 1.333 ft (pipe diameter)
Q = 2700 gpm = 6.439 ft³/s (flow rate)
C = 130 (Hazen-Williams coefficient for PVC)
Substituting in the values and solving for hL, we get:
hL = 10.67 * (1000/1.333) * (6.439/130)^{1.852}
= 4.04 ft/1000 ft
Rounding to two decimal places, the unit headloss is 4 ft/1000 ft, which corresponds to answer choice b.
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