Air admittance valve

Plumbing · Sewage Ejector Pumps · printed page 293 (PDF page 294)

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Air Admittance Valve Venting – Plumbing – Air Admittance Valve Plumbing

Text in the illustration

sealing mechanism is lifted to let air into the system 4 sealing mechanism is closed when there is positive pressure from gases Air admittance valve sealing mechanism illustrations based on Studor images ®
sealing mechanism
basin
basin draining
waste piping under negative pressure - sealing mechanism is lifted to let air into the system
system at rest
sealing mechanism is closed when there is positive pressure from gases
4" min.
trap arm
illustrations based on Studor® images

Generated explanation

The illustration shows an air admittance valve installed on a vertical riser from a basin's trap arm, with a minimum height of 4 inches indicated above the trap arm. Two enlarged valve cross-sections explain its operation. When the basin drains, negative pressure in the waste piping lifts the sealing mechanism and draws air into the system. At rest or under positive pressure from gases, the sealing mechanism closes to prevent gases from escaping through the valve. The basin, drain tailpiece, P-trap, and horizontal trap arm provide the installation context.

Components

air admittance valve sealing mechanism basin faucet drain tailpiece P-trap trap arm valve riser waste piping