Drainage, Waste & VentQuestion 24 of 120
A basement floor is below the elevation of the next upstream manhole on the public sewer. What device is required to protect the fixtures on that floor?
a.An air admittance valve
b.A relief vent at the base of the stack
c.A trap primer
d.A backwater valve
Explanation
Fixtures on a floor below the next upstream manhole cover elevation must discharge through an accessible backwater valve so that a surcharged sewer cannot flood the low fixtures. An air admittance valve and a relief vent handle air pressure, not backflow, and a trap primer only keeps a trap seal from evaporating.
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