P-918.1 General. Vent systems utilizing air admittance valves shall comply with this Section. Stack-type air admittance valves shall conform to ASSE 1050. Individual and branch type air admittance valves shall conform to ASSE 1051. Air admittance valves shall be allowed for permitted alterations to the plumbing system in one and two family dwellings in place of an individual vent for a single fixture drain other than a water closet or any other soil waste.
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P-918.3 Where permitted. An individual, branch and circuit vents shall be permitted to terminate with a connection to an individual or branch-type air admittance valve in accordance with Section P-918.3.1. Stack vents and vent stacks shall be prohibited permitted to terminate to stack-type air admittance valves in accordance with Section P-918.3.2.
P-918.3.1 Horizontal branches. Individual and branch-type air admittance valves shall vent only a single fixtures that are is on the same floor level and connected to a horizontal branch drain or vertical waste stack. Where the horizontal branch is located more than four branch intervals from the top of the stack, the horizontal branch shall be provided with a relief vent that shall connect to a vent stack or stack vent, or extend outdoors to the open air. The relief vent shall connect to the horizontal branch drain between the stack and the most downstream fixture drain connected to the horizontal branch drain. The relief vent shall be sized in accordance with Section 906.2 and installed in accordance with Section 905. The relief vent shall be permitted to serve as the vent for other fixtures.
P-918.4 Location. Individual and branch-type air admittance valves shall be located not less than 4 inches (102 mm) above the horizontal branch drain or fixture drain being vented. Stack-type air admittance valves shall be located not less than 6 inches (152 mm) above the flood level rim of the highest fixture being vented. The air admittance valve shall be located within the maximum developed length permitted for the vent. The air admittance valve shall be installed not less than 6 inches (152 mm) above insulation materials.
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P-918.8 Prohibited installations. Air admittance valves shall not be installed in nonneutralized special waste systems as described in Chapter 8. except where such valves are in compliance with ASSE 1049, are constructed of materials approved in accordance with Section 702.5 and are tested for chemical resistance in accordance with ASTM F1412. Air admittance valves shall not be located in spaces utilized as supply or return air plenums. Air admittance valves shall not be used to vent sumps or tanks except where the vent system for the sump or tank has been designed by an engineer. Air admittance valves shall not be installed on outdoor vent terminals for the sole purpose of reducing clearances to gravity air intakes or mechanical air intakes. Air admittance valves shall not be used in any other applications other than described in Section P-918.1.
Delete Section 919 and Replace as follows: