Systems & Code第 36 / 110 题
A basement floor drain sits 3 ft below the elevation of the upstream sewer manhole cover. During a main surcharge, how much backpressure head could push up through that drain if unprotected, using 0.433 psi per foot?
a.0.43 psi
b.3.0 psi
c.13 psi
d.1.3 psi
解析
Backpressure = depth below the surcharge level x 0.433 = 3 x 0.433 = 1.3 psi. Even a modest 3 ft head can flood a basement, which is why fixtures below the manhole rim require a backwater valve. The valve seats against reverse flow while still passing normal drainage.
法律依据: UPC §710.0免费刷完整 110 道题库 — 无需注册。
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