Water Supply & DistributionQuestion 19 of 360
A water service run has a developed length of 120 feet with an available pressure of 60 psi and a required residual of 15 psi at the highest fixture, which is 25 feet above the meter. Roughly how much pressure remains for friction loss in the piping (ignoring meter and fitting losses)?
a.60 psi
b.45 psi
c.34.2 psi is close; about 34 psi
d.0 psi
Explanation
Elevation loss is 25 ft x 0.433 psi/ft = about 10.8 psi. Starting at 60 psi, subtract 15 psi residual and about 10.8 psi elevation, leaving roughly 60 - 15 - 10.8 = 34.2 psi available for friction. The 60 psi and 0 psi answers ignore the required residual and elevation deductions.
Law Reference: 2022 California Plumbing Code (CPC) §610.0Practice all 360 questions free — no signup required.
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