A.
General.
(1)
Vent pipe sizes shall be determined from Table 860-144,
on the basis of length and fixture units connected.
|
Table 860-144
Size and Length of Vents
| ||||
|---|---|---|---|---|
|
Size of Vent Pipe In Inches
|
Maximum developed length in feet
|
Number of Fixture Units
| ||
|
Branch
|
Main
|
Vented Branch or Main
| ||
|
*1 1/4
|
20 feet
|
20 feet
|
2 Units
| |
|
*1 1/2
|
30 feet
|
100 feet
|
10 Units
| |
|
2
|
40 feet
|
150 feet
|
24 Units
| |
|
2 1/2
|
60 feet
|
300 feet
|
40 Units
| |
|
3
|
80 feet
|
400 feet
|
100 Units
| |
|
4
|
140 feet
|
700 feet
|
500 Units
| |
|
5
|
140 feet
|
700 feet
|
1100 Units
| |
|
6
|
140 feet
|
700 feet
|
1900 Units
| |
|
8
|
200 feet
|
1000 feet
|
3600 Units
| |
|
NOTE:
| ||
|---|---|---|
|
*
|
No water closets permitted on vent piping less
than 2" in diameter.
| |
(2)
In applying vent sizing table above, for water closets
or pedestal urinals, a fixture unit value of eight shall be assigned
to all types of such fixtures, whether flush tank or flush valve supplied.
B.
Minimum diameter of vent piping. No vent pipe shall
be less than 1 1/4 inches in diameter.
C.
Individual vents. The diameter of individual vents
shall be based on the size of trap being vented, but not less than
the following sizes:
|
Size of Vent
(inches)
|
Size of Trap
(inches)
| |
|---|---|---|
|
1 1/4
|
1 1/4
| |
|
1 1/2
|
1 1/2 to 2 1/2
| |
|
2
|
3 and 4
| |
|
1/2 their diameter
|
5 and over
|
E.
Circuit or loop vents. The diameter of circuit or
loop vents shall be based on the number of fixture units connected
as determined from Table 860-144, "Branch or Main."
F.
Size of branch vents. Branch vents which are meant
to include all parts of the venting system other than the main vent,
vent stack, or stack vent shall be sized in accordance within the
limits of length and number of fixture units vented as provided for
in Table 860-144, Branch or Main, except where other-wise provided
for in this chapter. The length of the branch vent for application
with Table 860-144 shall be measured from its connection with the
furthest fixture drain to its connection to a larger vent, vent stack,
stack vent or its terminal in the open air.
Vent pipe and fittings for the venting system shall comply with the provisions of Article V.
The protection of trap seals from siphonage
or back pressure shall be accomplished by the appropriate use of soil
or waste stacks, vents, revents, back vents, loop vents, circuit or
continuous vents, or combination thereof, installed in accordance
with the requirements of this Chapter, so that at no time shall the
trap be subjected to a pressure differential of more than one inch
of water.
A.
Stack vent required. Every soil or waste stack shall
be extended vertically as a stack-vent to the open air above the roof.
B.
Vent stack required. An attendant vent stack or main
vent shall be installed with a soil or waste stack whenever relief
vents, back vents, circuit vents, or other branch vents are required
in a building of three or more branch intervals.
C.
Size and length of vent stacks. Vent stacks or main
vents shall have a diameter of at least one half that of the soil
or waste stack, but not less than one and one half inches in diameter,
and shall be of a larger size in accordance with the limits of length
and number of fixture units vented as determined from Table 860-144,
nor shall they be smaller than the largest branch vent connected thereto.
The length of the main or vent stack for application with Table 860-144,
shall be the total developed length as follow:
(1)
From the lowest connection of the vent stack with
the soil stack, waste stack, or building drain to the terminal of
the vent stack when it terminates separately to the open air.
(2)
From the lowest connection of the vent stack with
the soil stack, waste stack, or building drain to the stack vent plus
the length of the stack vent and vent stack when the two are joined
with a single extension to the open air.
D.
Connections at base and top. All main vents or vent
stacks shall connect full size at their base to the building drain
or to the main soil or waste pipe, at or below the lowest fixture
branch. All vent stacks or main vents shall extend undiminished in
size above the roof, or shall be reconnected with the main soil or
waste stack at least six inches above the flood level of the highest
fixture connection with a single extension from the connection through
the roof.
E.
Buildings with five or more branch intervals above
an offset.
(1)
Offsets of more than 45° from the vertical in
a soil or waste stack shall be vented by installing a relief vent
as a vertical continuation of the lower section of the stack or as
a side vent connected to the lower section between the offset and
the next lower fixture or horizontal branch connection.
F.
Vent headers. Stack-vent and vent stacks may be connected
into a common vent header at the top of the stacks and then extended
to the open air as a direct extension of one stack. This header shall
be sized in accordance with the requirements of Table 860-144, the
number of units being the sum of all units on all vent stacks connected
thereto and the developed length being the longest vent length from
the intersection at the base of the most distant stack to the vent
terminal in the open air.
A.
Extension above roofs. Extension of vent pipes through
a roof shall be terminated at least 12 inches above it. Where a roof
is to be used for any purpose other than weather protection, the vent
shall be at least seven feet above the roof.
B.
Waterproof flashing. Each vent terminal shall be made
watertight with the roof by proper flashing.
C.
Flag poling prohibited. Vent terminals shall not be
used for the purpose of flag poling, TV aerials or similar purposes.
D.
Location of vent terminal. No vent terminal shall
be located directly beneath any door, window, or other ventilating
opening of the building or of an adjacent building nor shall any such
vent terminal be within ten feet horizontally of such an opening unless
it is at least two feet above the top of such opening. Vent terminals
shall not terminate under the overhang of a building.
E.
Extensions through wall. Vent terminals extending through a wall, when approved by the Administrative Authority, shall be at least ten feet horizontally from any adjacent building line and terminate downward. They shall be effectively screened and properly flashed, caulked or otherwise sealed at the wall penetration and shall meet the requirements of Subsection D.
F.
Extension outside building. No soil, waste, or vent
pipe extension shall be run or placed on the outside of a wall of
any new building, but shall be carried up inside the building.
A.
Vent grade. All vent and branch vent pipes shall be
so graded and connected as to drain back to the soil or waste pipe
by gravity.
B.
Vertical rise. Where vent pipes connect to a horizontal
soil or waste pipe, without the benefit of a proper washout, the vent
shall be taken off above the center line of the waste or soil pipe.
The vent pipe shall rise vertically, or at an angle not more than
45° from the vertical, to a point at least six inches above the
flood-level rim of the fixture it is venting, before offsetting horizontally
or before connecting to a branch vent. (Refer to illustration in Chapter
22.[1])
[1]
Editor's Note: The illustrations are on file
in the Health Department.
C.
Height above fixtures. A connection between a vent
pipe and a vent stack or stack-vent shall be made at least six inches
above the flood-level rim of the highest fixture served by the vent.
Horizontal vent pipes forming branch vents, relief vents, or loop
vents shall be at least six inches above the flood-level rim of the
highest fixture served.
A.
Distance of trap from vent. Each fixture trap shall
have a protecting vent so located that the slope and the developed
length in the fixture drain from the trap weir to the vent fitting
are within the requirements set forth in Table 860-150A,, "Distance
of Fixture Trap from Vent".
|
Table 860-150A
Distance of Fixture Trap From Vent
| |||
|---|---|---|---|
|
Size of Fixture Trap
|
Distance
|
Trap to Vent
| |
|
1 1/4 inches
|
2 feet
|
6 inches
| |
|
1 1/2 inches
|
3 feet
|
6 inches
| |
|
2 inches
|
5 feet
|
0 inches
| |
|
2 1/2 inches
|
5 feet
|
0 inches
| |
|
3 inches
|
6 feet
|
0 inches
| |
|
4 inches and over
|
10 feet
|
0 inches
| |
B.
Trap dip. The vent pipe opening from a soil or waste
pipe, except for water closets and similar fixtures, shall not be
below the weir of the trap.
C.
Crown venting limitations. No vent shall be installed
within two pipe diameters of the trap weir.
Hydraulic gradient. Fixture drains shall be
vented within the hydraulic gradient between the trap outlet and vent
connection, but in no case shall the unvented drain exceed the distance
provided for in Table 860-150A, "Distance of Fixture Trap from Vent."
A.
Water closets and pedestal urinals independently connected to soil stack. A single floor set water closet or pedestal urinal independently connected to a soil stack and within the required distance as provided for in Table 860-150A will not require any additional relief. Where two closets, two urinals or any combination thereof are installed on one horizontal branch, they shall be looped or circuit vented as provided for in § 860-156A, "Circuit and Loop Venting of Water Closets and Pedestal Urinals."
B.
Water closets connected to building drain. A single
water closet independently connected to any stack vented portion of
the building drain and not over ten feet from such drain will not
require a relief vent; where more than ten feet, or where more than
one such fixture is located on one branch, there shall be provided
a proper size relief or loop vent. No floor set water closet or similar
floor level connected fixture shall be connected to the building drain
closer than five feet upstream or downstream of a soil or waste stack
in buildings of four or more stories.
A single wall hung water closet shall have the three inch soil, or vent stack directly in back of closet, or have a separate two inch vent, and when closets are located above one another, each shall have a separate two inch vent in back of each closet, except the upper most closet will not require a separate two inch vent provided it connects directly to the stack vent. When more than three wall hung water closets are located on one horizontal branch, they shall be provided with a circuit or loop vent as provided for in § 860-156A in addition to the two inch vent directly in back of each closet, but no other relief vents will be required. Wall hung water closets shall have a separate two inch vent in back of each closet, except that two closets back to back may have a common two inch vent.
A.
Floor drains and similar floor level connected fixtures
above basement floor. The minimum size trap for floor drains above
basement floor shall be three inches, except emergency floor drains
in laundry rooms of single family homes may be two inches and shall
be considered as a plumbing fixture, and be properly vented. Floor
drains, or showers with a trap size of three or four inches upstream
of water closets or similar fixtures may be circuit or loop vented.
When floor drains or showers are placed on a common horizontal branch
with water closets or similar fixtures and located on the downstream
side of such fixtures, they shall be individually vented, or they
shall be isolated on their own waste branch and circuit or loop vented.
Loop or circuit vents shall be sized as provided in Table 860-144,
and they shall vent or take off in front of the last fixture connection,
or be washed out by the fixture they serve, or the vent may be washed
out by a higher connected fixture.
B.
Floor drains and similar fixtures connected to building
drain. A single floor drain or similar floor-level connected fixture
independently connected to any stack vented portion of the building
drain and not over ten feet from such drain will not require a relief
vent; where more than ten feet, or where more than one such fixture
is located on one branch, there shall be provided a proper size relief
or loop vent.
Combination of fixtures on one horizontal branch.
When two water closets, two floor drains, or two similar floor-level
connected fixtures, or any combination of these fixtures are located
on one horizontal branch of the building drain, they shall be provided
with a proper size relief or loop vent.
A.
Battery venting. A branch soil to which two but not
more than eight water closets or pedestal urinals are connected in
a battery, shall be vented by a circuit or loop vent which shall be
taken off in front of the last fixture connection of the battery,
washed out by the fixture it serves, or the vent may be washed out
by a higher connected fixture. In addition, lower floor branches serving
more than three water closets or pedestal urinals shall be provided
with a relief vent taken off in front of the first fixture connection
of the battery, in addition to the required circuit vent. When nine
or more water closets are connected in a battery, an additional relief
vent will be required, and shall be evenly spaced between the first
relief vent and the circuit vent so that there are never more than
eight water closets between a relief, circuit or loop vent.
B.
Dual branches. When water closets or pedestal urinals are located back to back, dual or parallel horizontal branches may be used, provided each branch is separately looped or circuit vented and any other venting requirements as required by Subsection A (refer to illustration located in Chapter 22[1]).
[1]
Editor's Note: The illustrations are on file
in the Health Department.
C.
Fixtures back-to-back in battery. When water closets or pedestal urinals are connected to one horizontal branch through a double wye or a sanitary cross in a vertical position, a common vent for each two fixtures back to back or double connection shall be provided. The common vent shall be installed in a vertical position as a continuation of the double connection. The branch shall be circuit or loop vented as required in Subsection A, but no other relief vents will be required.
D.
Soil branches to stacks which rise more than one story height. Branches to soil stacks which receive the discharge of water closets and similar fixtures which rise more than one story height shall maintain and continue the size of such branches as a circuit or loop vent. The load of such branches shall not exceed that contained in Article XII, Table 860-133B, Maximum Number of Fixture Units on one Horizontal Branch. (Refer to illustration in Chapter 22.[2])
[2]
Editor's Note: The illustrations are on file
in the Health Department.
E.
Vent connections. When the circuit, loop or relief
vent connections are taken off the horizontal branch, the vent branch
connection shall be taken off at a vertical angle or from the top
of the horizontal branch, or otherwise be adequately washed out by
a higher connected fixture drain.
Individual vent as common or dual vent. A common
or dual vent is permitted for two fixture traps when installed on
a vertical continuous waste and vent, or stack vented when the highest
fixture, provided both fixture drains connect with the vertical drain
or stack on the same level and within the distance allowed between
a trap and its vent.
Soil and waste stacks in building have more
than 10 branch intervals shall be provided with a relief or yoke vent
at each tenth interval installed, beginning with the top floor. Where
an odd number of floors above ten are involved, they shall be equally
divided. The size of the relief or yoke vent shall be equal to the
size of the vent stack to which it connects. The lower end of each
relief or yoke vent shall connect to the soil or waste stack through
a wye below the horizontal branch serving that floor, and the upper
end shall connect to the vent stack through an inverted wye or tee
not less than three feet above the floor level.
A.
Sizing and venting of sub-drain and sumps. The system
of drainage piping below the sewer level shall be size, installed,
and vented in a like manner to that of the gravity system. Every sump
or receiving tank shall have a vent pipe, which shall be sized according
to the number of fixture units draining to sump; and in accordance
with Table 860-144 based on branch venting for developed length, but
in no case less than two inches in diameter. Sumps receiving the discharge
of clear water, such as rain water, sub-soil or seepage drainage will
not require a vent.
B.
Separate vents. Vents from pneumatic ejectors or similar
equipment shall be carried separately to the open air as a vent terminal.
Such relief pipe shall be of sufficient size to relieve air pressure
inside the ejector to atmospheric pressure within ten seconds, but
shall not be less than two inches in size.
No vent shall be required for a rain conductor
trap, backwater trap, area drain, sub-soil catch basin trap, or any
outside drain. For further clarification of venting procedures as
outlined in this chapter, refer to illustration in Chapter 22.[1]
[1]
Editor's Note: The illustrations are on file
in the Health Department.
