Design & Sizing第 30 / 110 题
A hot-water line is limited to a maximum velocity of 5 ft/s. Using v = 0.408 x Q / d^2, what is the maximum flow through a pipe with a 0.785 in inside diameter (nominal 3/4 in type L copper)?
a.4.9 gpm
b.7.6 gpm
c.11.3 gpm
d.15.1 gpm
解析
Q = v x d^2 / 0.408 = 5 x (0.785)^2 / 0.408 = 5 x 0.616 / 0.408 = 7.55 gpm, about 7.6 gpm. Hot water is held to a lower 5 ft/s than cold water because higher temperature accelerates erosion-corrosion of copper. Exceeding this flow risks pinholing the line over time.
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