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<br />22.1-95. Minimum Size of Underground Drainage Piping.
<br />No portion of the drainage system installed underground or
<br />below a basement or cellar shall be less than 2 inches in dia-
<br />meter.
<br />ARTICLE XIII -VENTS AND VENTING.
<br />22.1-96. Protection of Trap Seals.
<br />The protection of trap seals from siphonage or back pres-
<br />sure shall be accomplished by the appropriate use of soil or
<br />*aste stacks, vents, revents, back vents, loop vents, circuit or
<br />continuous vents, or combinations thereof, installed in accord-
<br />ance with the requirements of this chapter. All floor drains in
<br />floors above basement shall be vented as required for other
<br />fixtures; provided, however, that if a separate sack is run
<br />from the main building drain, and Extended throu-h roof,
<br />stack venting will be sufficient if brancl-ies to stack do not
<br />exceed 25 feet in length.
<br />22.1-97. Terminal.
<br />The vent stack shall terminate independently above the roof
<br />of the building or shall be connected with the extension of
<br />the soil or waste stack (stack vent) at least 6 inches above the
<br />flood level rim of the highest fixture.
<br />22.1-98. Main Stack.
<br />Every building in which plumbing is installed shall have at
<br />least one main stack, which shall run undiminished in size
<br />and as directly as possible, from the building drain through to
<br />the open air above the roof.
<br />22.1-99. Vent Terminals.
<br />(a) Extension Through Roof.
<br />Extensions of vent pipes through a roof shall be terminated
<br />at least 6 inches above it.
<br />(b) Roof Garden.
<br />Where a roof is to be used for any purpose other than
<br />weather protection, the vent extensions shall be run at least
<br />8 feet above the roof.
<br />(c) Flashing.
<br />Each vent terminal shall be made watertight with the roof
<br />by flashing.
<br />(d) Flag Poles.
<br />Vent terminals shall not be used for the purpose of flag
<br />poles, attaching TV aerials, or similar purposes.
<br />(e) Location of Vent Terminal.
<br />No vent terminal from a drainage system shall be directly
<br />beneath any door, window, or other ventilating opening of
<br />the building or of andeet horijacent zontallg of nor
<br />suhhlanuopench eng
<br />tnt
<br />terminal be within 10
<br />unless it is at least 2 feet above the top of such opening.
<br />22.1-100. Extension Outside Building.
<br />No soil, waste, or vent pipe extension shalllb run but
<br />or
<br />placed on the outside of a wall of any 1ebuilding
<br />shall be carried up inside the building except that
<br />in existing
<br />the
<br />buildings soil, waste, and vent pipes may be placed
<br />outside of a wall, whenever impractical to do otherwise.
<br />22.1-1.01. Vent Grades and Connections.
<br />Grade. All vent and branch vent pipes shall be so graded
<br />and connected as to drip back to the soil or waste pipe by
<br />gravity.
<br />22.1-102. Vertical Size.
<br />Where vent pipes connect to a horizontal soil or waste pipe,
<br />the vent shall be taken off above the center line of the soil
<br />pipe.
<br />22.1-103. Height Above Fixtures.
<br />A connection between a vent pipe and a vent stack or stack
<br />vent shall be made at least 6 inches above the flood level rim
<br />of the highest fixture served by the vent. Horizontal vent
<br />pipes forming branch vents, relief vents, or loop vents shall
<br />be made at least 6 inches above the flood level rim of the
<br />highest fixture served.
<br />22.1-104. Bars and Soda Fountain Sink Traps.
<br />•
<br />Traps serving sinks which are part of the equipment of
<br />fountains, and counters need not be vented when
<br />bars, soda
<br />the location and construction of such bars, soda fountains,
<br />and counters are such as to make it impossible so to do. When
<br />such conditions exist, such sinks shall discharge into a floor
<br />sink or hopper which is properly trapped and vented.
<br />22.1-105. Fixtures Back -to -Back.
<br />Two fixtures s -et back to back, within the distance allowed
<br />between a trap and its vent, may be served with one con-
<br />tinuous soil or waste vent pipe, provided that each fixture
<br />double fitting having inlet
<br />wastes separately into an approved
<br />openings at the same level.
<br />22.1-106. Distance Trap May Be Placed from Vent.
<br />No trap shall be placed more than five feet horizontal de-
<br />veloped length from its vent. The distance shall be measured
<br />from the outlet end of the trap seal to the vent opening.
<br />22.1-107. Trap Dip.
<br />The vent pipe opening from a soil or waste pipe, except for
<br />water closets and similar fixtures, shall not be below the top
<br />weir of the trap.
<br />•
<br />22.1-108. Crown Vent.
<br />No vent connection shall be made to the crown of a fixture
<br />trap nor to a fixture drain within two pipe diameters of trap
<br />weir.
<br />22.1-109. Individual Vent.
<br />An individual vent, installed vertically, may be used as a
<br />common vent for two fixture traps when both fixture drains
<br />connect with a vertical drain at the .same level.
<br />22.1-110. Common Vent.
<br />A common vent may be used for two fixtures set on the
<br />same floor level but connecting at different levels in the stack,
<br />provided the vertical drain is one pipe diameter larger than
<br />the upper fixture drain but in no case smaller than the lower
<br />fixture drain, whichever is the larger.
<br />22.1-111. Vents for Fixture Trap Below Trap Dip.
<br />(a) Hydraulic Gradient -Fixture drains shall be vented
<br />within the hydraulic gradient between the trap outlet and
<br />vent connection, but in no case shall the unvented drain ex-
<br />ceed the distance of five feet.
<br />(b) Different Levels -If any stack has fixtures entering
<br />at different levels, the fixtures other than the fixture entering
<br />at the highest level shall be vented, except as may be permit-
<br />ted in other sections of this chapter.
<br />22.1-112. Wet Venting.
<br />(a) Single Bathroom Group on Top Floor.
<br />A single bathroom group of fixtures may be installed with
<br />the drain from a back -vented lavatory serving as a wet vent
<br />for a bathtub or shower stall and for the water closet, pro-
<br />vided:
<br />(1) Not more than one fixture unit is drained into the 11/2"
<br />diameter wet vent, or not more than four fixture units
<br />drain into a 2" diameter wet vent. •
<br />(2) The horizontal branch connects to the stack at the
<br />same level as the water closet drain, or below the water
<br />closet drain on the top floor. It may also connect to the
<br />water closet bend.
<br />(3) Sin eed bathroom
<br />stal h 211 back vent, with max mum of four fixtu e
<br />units draining into it.
<br />(b) Double Bath.
<br />Bathroom groups back-to-back on top floor, consisting of
<br />two lavatories and two bathtubs or showers may be installed
<br />on the same horizontal branch with a common vent for the
<br />lavatories and with no back vent for the bathtubs, showers
<br />or water closets, provided that the wet vent is 2" diameter
<br />and the length of fixture drain does not exceed 5 feet.
<br />(c) Multistory Bathroom Groups.
<br />On the lower floors of a multistory building, the waste pipe
<br />from one or two lavatories may be used as a wet vent for
<br />one or two bathtubs or showers provided that:
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