Irrigation第 7 / 100 题
An atmospheric vacuum breaker (AVB) has which key installation limitation?
a.It must never be under continuous pressure and cannot have valves downstream
b.It can protect against backpressure
c.It may be installed below the sprinkler heads
d.It requires two check valves
解析
An atmospheric vacuum breaker protects only against backsiphonage and must be installed downstream of the last control valve with no shutoff valves after it. It cannot be under continuous pressure for more than about 12 hours and must sit above downstream outlets. It is the simplest and least expensive backflow device.
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