Water Supply & Distribution第 46 / 120 题
A pressure vacuum breaker protects a lawn irrigation zone whose highest sprinkler head is 42 in above grade. What is the minimum height above grade for the vacuum breaker?
a.4 ft 6 in
b.4 ft 0 in
c.3 ft 6 in
d.5 ft 6 in
解析
A pressure vacuum breaker must be at least 12 in above the highest downstream outlet, so 42 in + 12 in = 54 in, or 4 ft 6 in. The 3 ft 6 in answer is simply the head height with no clearance added. The 4 ft 0 in answer adds only 6 in, which is the atmospheric vacuum breaker rule, and 5 ft 6 in adds 24 in, more than the code requires.
法律依据: IPC §608.13免费刷完整 120 道题库 — 无需注册。
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