air admittance vent English

Meaning air admittance vent meaning

What does air admittance vent mean?

air admittance vent noun

— (plumbing) a mechanical sewer vent that allows air to enter into the sewage system but does not allow exhaust of sewer gases, to aid the flow of sewage by providing air behind water, where a standard vent stack to atmosphere is not possible, by drawing in interior air but keeping harmful sewer gases contained.