Irrigation第 6 / 100 题
A pressure vacuum breaker (PVB) must be installed at what minimum height relative to the highest downstream sprinkler head or outlet?
a.At the same level as the heads
b.6 inches above the highest head
c.12 inches above the highest head
d.36 inches below grade
解析
A pressure vacuum breaker must be installed at least 12 inches above the highest downstream outlet or sprinkler head so atmospheric venting works correctly against backsiphonage. It protects against backsiphonage only, not backpressure. Correct elevation is essential for the device to function.
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