Vent pipes shall be of cast iron, galvanized wrought iron, galvanized steel, copper, brass or lead. The type of pipe and fittings shall comply with the standards given in Article IV.
The seal of every fixture trap in a plumbing system shall be protected
by a properly installed individual vent except as otherwise provided in this
article, and except that the topmost fixture may be without a vent if such
fixture is within five feet of the main waste or soil stack.
Every soil or waste stack shall be extended vertically as a stack vent
to at least six inches above the flood-level rim of the highest fixture, then
to the open air above the roof; or the stack vent and the vent stack shall
be joined within the building at least six inches above the flood-level rim
of the highest fixture to the open air.
A vent stack or main vent shall be installed with a soil or waste stack whenever back vents, relief vents or other branch vents are required in two or more branch intervals. The vent stack shall terminate independently in the open air above the roof; or shall be connected with stack vent as prescribed in § 221-234 of this article, and shall connect with the soil or waste stack below the lowest horizontal waste branch or with the building drain.
No vent terminal from a sanitary drainage system shall be directly beneath
any door, window or other ventilating opening of the same or adjacent building,
nor shall any such vent terminal be within 12 feet horizontally of such an
opening unless it is at least three feet above the top of such opening.
Extensions of vent pipes through roof shall terminate one foot above
a gable roof and two feet above a flat roof and shall be properly flashed.
Where the roof is used for any purpose other than weather protection, the
extension shall be run six feet above the roof. No pipe less than two inches
shall be used for a roof extension.
Where there is a possibility of frost closure, the vent extension shall
be at least four inches in diameter. The change in diameter, if required,
shall be made one foot below the roof.
Each fixture trap shall have a protecting vent so located that the maximum
distance from vent intersection with the waste or soil pipe to the dip of
the trap shall be five feet developed length, and the drainpipe between the
trap and vent shall not be used for any other fixtures.
The vent pipe opening from a soil or waste pipe, except for water closets
and similar fixtures, shall not be below the dip of the trap. Branch vent
lines shall be kept above the tops of all connecting fixtures in order to
prevent the use of vent pipes as soil or waste pipes.
No back vent shall be installed within two pipe diameters of the trap
weir.
An individual vent or stack vent, installed vertically, may be installed as a dual vent when both fixture drains connect with a vertical drain or stack at the same level and the developed length of each of the two fixture drains is within the limits stated in § 221-240, and shall meet the requirements as prescribed in § 221-244 of this article. Under those conditions no additional vents for the traps are required.
A dual vent is permissible when it is the equivalent of the two required
individual vents and when it constitutes a vent extension of the vertical
waste from two fixtures. It shall be installed with a sanitary cross and not
closer than six inches to the dip of either trap.
The waste pipe for a lavatory in a bathroom may serve as a vent for a bathtub, provided that none of the piping is less than 1 1/2 inches in diameter. It shall be considered as adequately vented when it is installed in accordance with the provision of § 221-240 of this article.
A wet vent may be installed for venting an extra water closet and lavatory
when approved by the administrative authority, provided that none of the piping
is less than two inches in diameter.
A sink and tray combination shall be considered as adequately vented if above it there are connected to the soil stack fixtures totaling not more than three fixture units when it is installed in accordance with provisions of § 221-240 of this article, provided they are placed over each other, but the interval shall not exceed one story in height, and provided that none of the piping is less than two inches in diameter.
A branch soil or waste pipe to which two and not more than eight water
closets (except blowout type) pedestal urinals, standard service sinks, shower
stalls or floor drains are connected in series may be vented by a circuit
or loop vent which will be taken off in front of the last fixture connection.
Where other fixtures discharge above such branch, each branch shall be provided
with a relief vent taken off in front of the first connection.
Two circuit-vented horizontal branches serving a total of not more than eight fixtures as specified in § 221-248 of this article, in the same branch interval, may have a dual relief vent. Where the vents are joined, the point of joining shall be at least six inches above the flood-level rim of the highest fixture connected to each branch.
Two lines of fixtures back to back (double battery) shall not be installed on the same circuit- or loop-vented horizontal branch, but may be installed on different branches with a dual relief vent in accordance with § 221-249 of this article.
A fixture on the topmost stack branch shall be considered as adequately vented when it is installed in accordance with the provisions of § 221-240 of this article.
A water closet shall be considered as adequately vented if above it
there are connected to the soil stack fixtures totaling not more than one
fixture unit.
Two water closets may discharge into a stack and shall be considered
as adequately vented, provided they are placed over each other, but the interval
shall not exceed one story in height, and the maximum distance of any water
closet shall not exceed five feet developed length from the stack.
When there are more than two water closets on a stack, all excepting
the topmost fixture shall be vented.
Whenever there is a full-size stack already extending through the roof,
a two-inch ventilating pipe may be used for venting an extra water closet.
All soil or waste stacks in buildings over five floors in height shall
be provided with yoke vents at each floor interval measured from the top floor
down. The size of the yoke vent shall be equal to the size of the vent stack
to which it connects. The lower end of the yoke vent shall connect to the
soil or waste stack through a Y-branch below the horizontal branch serving
that floor, and the upper end shall connect to the vent stack through a Y-branch
not less than three feet above the floor level.
All vent and branch vent pipes shall be free of drops and sags and be
so graded and connected as to drip back to the soil or waste pipe or vent
stack gravity.
Where vent pipes connect to a horizontal soil or waste pipe, the vent
shall be taken off above the center line of the soil pipe and the vent pipe
shall rise vertically or at an angle of not more than 45º to the vertical,
to a point at least six inches above the flood-level rim of the fixture it
is venting before off-setting horizontally or before connecting to the branch
vent.
A connection between a vent pipe and a vent stack shall be at least
six inches above the flood level of the highest fixture served by the vent.
Horizontal vent pipes forming branch units, relief vents, circuit vents or
loop vents shall be at least six inches above the flood level of the highest
fixture served.
The length of a vent stack or main vent shall be its developed length
from the lowest connection of the vent system with the soil stack, waste stack
or building drain either to the vent stack terminal, if it terminates separately
in the open air, or to the connection of the vent stack with the stack vent,
plus the developed length of the stack vent from the connection to the terminal
in the open air above the roof, if the two vents are connected with a single
extension to the open air.
The length of a branch vent shall be the developed length from its connection
with the vent stack or stack vent to the fixture drain or horizontal soil
or waste branch served by the branch vent.
The length of a stack vent shall be the developed length from the highest
horizontal or fixture branch connected to the stack to the terminal of the
stack vent in the open air.
A vent stack or main vent shall have a diameter of at least 1/2 the diameter of the soil or waste stack, but in no case less than 1 1/2 inches, and, depending on its developed length and the number of fixture units installed on the soil or waste stack, be in accordance with the table in § 221-267. In determining the developed length of vent pipes, the vent stacks and branches shall be considered continuous.
The diameter of a stack vent shall not be less than the diameter of
the soil or waste stack.
The diameter of an individual vent shall not be less than 1 1/4
inches nor less than 1/2 the diameter of the drain to which it is connected.
The diameter of a relief vent shall not be less than 1/2 the diameter
of the soil or waste branch.
The required size and length of vents for stacks and branches shall
be as follows:
|
Diameter of Pipe
(inches)
|
Maximum Number of Fixture Units Permitted
|
Maximum Developed Length For Each Size
(feet)
|
|---|---|---|
|
1 1/4
|
1
|
30
|
|
1 1/2
|
6*
|
35
|
|
2
|
20
|
60
|
|
2 1/2
|
40
|
100
|
|
3
|
82
|
150
|
|
4
|
250
|
250
|
|
5
|
500
|
300
|
|
6
|
1,250
|
400
|
|
8
|
2,400
|
Unlimited
|
|
* Except six unit traps.
| ||
No water closet, siphon-jet, pedestal, pedestal urinal and blowout shall
be vented with less than two-inch vent pipe.
The diameter of loop vent or circuit vent shall not be less than the
diameter of the horizontal soil or waste branch or the diameter of the vent
stack, whichever is the smaller.
No vent shall be required for a leader trap, a backwater trap, area
drain or subsoil catch basin drain.
When excessive cutting for a vent pipe is necessary, the Plumbing Inspector
may, in his discretion, permit the use of an approved antisiphon trap, but
such permission shall not be construed as granting permission in any other
case.
All main vents or vent stacks shall connect full size at their base to the main soil or waste pipe at or below the lowest horizontal waste branch or with the building drain. All vent pipes shall extend undiminished or increased in size above the roof or shall be reconnected with the main soil or waste vent at least three feet above the highest fixture branch. The pipe above the intersection shall be increased in accordance with the table in § 221-267 of this article. Wherever possible, the base of the vent stack shall receive the wash of the adjoining soil or waste.
Offsets in soil and waste stacks above the highest fixture connection,
and offsets in vent stacks and connections of such vent stacks to a soil or
waste pipe at the bottom or to the building drain, shall be made at an angle
of at least 45º to the horizontal, except that where it is impractical,
because of structural conditions, to provide a forty-five-degree angle, the
Plumbing Inspector may permit a reduction in the angle under such condition
as he may prescribe.
A branch serving any fixture on the lowest floor on the upper section
of the stack shall be connected to the lower section of the soil or waste
stack.
