All individual branch and circuit vents shall connect to a vent stack, stack vent or extend to the open air.
Each fixture trap shall have a protecting vent located so 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 P3105.1.
TABLE P3105.1
MAXIMUM DISTANCE OF FIXTURE TRAP FROM VENT
SIZE OF TRAP (inches) | SLOPE (inch per foot) | DISTANCE FROM TRAP (feet) |
11/4 | 1/4 | 5 |
11/2 | 1/4 | 6 |
2 | 1/4 | 8 |
3 | 1/8 | 12 |
4 | 1/8 | 16 |
Where the fixture drains connect at different levels, the vent shall connect as a vertical extension of the vertical drain. The vertical drain pipe connecting the two fixture drains shall be considered the vent for the lower fixture drain, and shall be sized in accordance with Table P3107.3. The upper fixture shall not be a water closet.
TABLE P3107.3
COMMON VENT SIZES
PIPE SIZE (inches) | MAXIMUM DISCHARGE FROM UPPER FIXTURE DRAIN (d.f.u.) |
11/2 | 1 |
2 | 4 |
21/2 to 3 | 6 |
Horizontal and vertical wet vents shall be not less than the size as specified in Table P3108.3, based on the fixture unit discharge to the wet vent. The dry vent serving the wet vent shall be sized based on the largest required diameter of pipe within the wet-vent system served by the dry vent.
TABLE P3108.3
WET VENT SIZE
WET VENT PIPE SIZE (inches) | FIXTURE UNIT LOAD (d.f.u.) |
11/2 | 1 |
2 | 4 |
21/2 | 6 |
3 | 12 |
4 | 32 |
The waste stack shall be sized based on the total discharge to the stack and the discharge within a branch interval in accordance with Table P3109.4. The waste stack shall be the same size throughout the length of the waste stack.
TABLE P3109.4
WASTE STACK VENT SIZE
STACK SIZE (inches) | MAXIMUM NUMBER OF FIXTURE UNITS (d.f.u.) | |
Total discharge into one branch interval | Total discharge for stack | |
11/2 | 1 | 2 |
2 | 2 | 4 |
21/2 | No limit | 8 |
3 | No limit | 24 |
4 | No limit | 50 |
The size of a combination drain and vent pipe shall be not less than that specified in Table 3111.3. The horizontal length of a combination drain and vent system shall be unlimited.
TABLE P3111.3
SIZE OF COMBINATION WASTE AND VENT PIPE
DIAMETER PIPE (inches) | MAXIMUM NUMBER OF FIXTURE UNITS (d.f.u.) | |
Connecting to a horizontal branch or stack | Connecting to a building drain or building subdrain | |
2 | 3 | 4 |
21/2 | 6 | 26 |
3 | 12 | 31 |
4 | 20 | 50 |
Drainage piping below sewer level shall be vented in the same manner as that of a gravity system. Building sump vent sizes for sumps with sewage pumps or sewage ejectors, other than pneumatic, shall be determined in accordance with Table P3113.4.1.
TABLE P3113.4.1
SIZE AND LENGTH OF SUMP VENTS
DISCHARGE CAPACITY OF PUMP (gpm) | MAXIMUM DEVELOPED LENGTH OF VENT (feet)a | ||||
Diameter of vent (inches) | |||||
11/4 | 11/2 | 2 | 21/2 | 3 | |
10 | No limitb | 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 |