Page 706 - 2018_IRC

VENTS

SECTION P3113 SECTION P3114
VENT PIPE SIZING AIR ADMITTANCE VALVES
P3113.1 Size of vents. The required diameter of individual P3114.1 General. Vent systems using air admittance valves
vents, branch vents, circuit vents, vent stacks and stack vents shall comply with this section. Individual and branch-type air
shall be not less than one-half the required diameter of the admittance valves shall conform to ASSE 1051. Stack-type
drain served. The required size of the drain shall be deter- air admittance valves shall conform to ASSE 1050.
mined in accordance with Chapter 30. Vent pipes shall be not P3114.2 Installation. The valves shall be installed in accor-
1
less than 1 / inches (32 mm) in diameter. Vents exceeding 40 dance with the requirements of this section and the manufac-
4
feet (12 192 mm) in developed length shall be increased by turer’s instructions. Air admittance valves shall be installed
one nominal pipe size for the entire developed length of the after the DWV testing required by Section P2503.5.1 or
vent pipe. P2503.5.2 has been performed.
P3113.2 Developed length. The developed length of individ- P3114.3 Where permitted. Individual vents, branch vents,
ual, branch and circuit vents shall be measured from the far- circuit vents and stack vents shall be permitted to terminate
thest point of vent connection to the drainage system, to the with a connection to an air admittance valve. Individual and
point of connection to the vent stack, stack vent or termina- branch-type air admittance valves shall vent only fixtures that
tion outside of the building. are on the same floor level and connect to a horizontal branch
P3113.3 Branch vents. Where branch vents are connected to drain.
a common branch vent, the common branch vent shall be
sized in accordance with this section, based on the size of the P3114.4 Location. Individual and branch air admittance
valves shall be located not less than 4 inches (102 mm) above
common horizontal drainage branch that is or would be the horizontal branch drain or fixture drain being vented.
required to serve the total drainage fixture unit (d.f.u.) load Stack-type air admittance valves shall be located not less than
being vented. 6 inches (152 mm) above the flood level rim of the highest
P3113.4 Sump vents. Sump vent sizes shall be determined in fixture being vented. The air admittance valve shall be
accordance with Sections P3113.4.1 and P3113.4.2. located within the maximum developed length permitted for
P3113.4.1 Sewage pumps and sewage ejectors other the vent. The air admittance valve shall be installed not less
than pneumatic. Drainage piping below sewer level shall than 6 inches (152 mm) above insulation materials where
be vented in the same manner as that of a gravity system. installed in attics.
Building sump vent sizes for sumps with sewage pumps or P3114.5 Access and ventilation. Access shall be provided to
sewage ejectors, other than pneumatic, shall be determined air admittance valves. Such valves shall be installed in a loca-
in accordance with Table P3113.4.1. tion that allows air to enter the valve.
P3113.4.2 Pneumatic sewage ejectors. The air pressure P3114.6 Size. The air admittance valve shall be rated for the
relief pipe from a pneumatic sewage ejector shall be con- size of the vent to which the valve is connected.
nected to an independent vent stack terminating as P3114.7 Vent required. Within each plumbing system, not
required for vent extensions through the roof. The relief less than one stack vent or a vent stack shall extend outdoors
pipe shall be sized to relieve air pressure inside the ejector to the open air.
to atmospheric pressure, but shall be not less than 1 / 4
1
inches (32 mm) in size. P3114.8 Prohibited installations. 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 out-
door vent terminals for the sole purpose of reducing clear-
ances to gravity or mechanical air intakes.

TABLE P3113.4.1
SIZE AND LENGTH OF SUMP VENTS
MAXIMUM DEVELOPED LENGTH OF VENT (feet) a
DISCHARGE CAPACITY OF PUMP Diameter of vent (inches)
(gpm)
1 1 1
1 / 4 1 / 2 2 2 / 2 3
10 No limit b No limit No limit No limit No limit
20 270 No limit No limit No limit No limit
40 72 160 No limit No limit No limit
60 31 75 270 No limit No limit
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute (gpm) = 3.785 L/m.
a. Developed length plus an appropriate allowance for entrance losses and friction caused by fittings, changes in direction and diameter. Suggested allowances
shall be obtained from NBS Monograph 31 or other approved sources. An allowance of 50 percent of the developed length shall be assumed if a more precise
value is not available.
b. Actual values greater than 500 feet.

2018 INTERNATIONAL RESIDENTIAL CODE ® 681
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