Design & SizingQuestion 24 of 110
A water main runs 250 ft of developed length and the friction chart shows a loss of 6 psi per 100 ft at the design flow. How much pressure is lost to friction over the full run?
a.6 psi
b.9 psi
c.25 psi
d.15 psi
Explanation
Friction loss = (loss per 100 ft) x (length / 100) = 6 x (250 / 100) = 6 x 2.5 = 15 psi. Friction loss scales directly with developed length, so long runs consume a large share of the pressure budget. This 15 psi must be subtracted from supply along with elevation before checking residual.
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