Water Supply & DistributionQuestion 15 of 360
A branch serves fixtures totaling 8 WSFU. Design velocity should be kept at or below about 8 feet per second to limit erosion and noise. If a given pipe size carries the demand at 6 fps, and the next size down would run at 11 fps, which is the better selection and why?
a.The smaller pipe, because it is cheaper
b.Either pipe; velocity does not matter
c.The larger pipe at 6 fps, because 11 fps exceeds the recommended velocity limit
d.The smaller pipe, because higher velocity prevents scaling
Explanation
Excessive velocity (11 fps) causes erosion, noise, and water hammer, so the larger pipe running at 6 fps is the correct choice for staying at or below roughly 8 fps. Cost and scale-prevention claims do not override the velocity limitation, and velocity always matters in sizing.
Law Reference: 2022 California Plumbing Code (CPC) §610.0Practice all 360 questions free — no signup required.
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