Drainage, Waste & VentQuestion 133 of 360
A tall drainage stack with five or more branch intervals generally requires what to protect trap seals from pressure changes?
a.A vent stack (main vent) installed adjacent to the soil/waste stack
b.An additional cleanout only
c.A larger building trap
d.A backwater valve at each branch
Explanation
A vent stack, or main vent, runs parallel to a tall soil or waste stack and is cross-connected with relief vents at intervals. It equalizes air pressure so that the surge of water down the stack does not siphon or blow out trap seals. Vent stacks are typically required once a stack has several branch intervals.
Law Reference: 2022 California Plumbing Code (CPC) §904.0Practice all 360 questions free — no signup required.
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