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Where multiple branch vents are connected to a common branch vent, the common branch vent shall be sized in accordance with this section based on the size of the common horizontal drainage branch that is or would be required to serve the total drainage fixture unit load being vented.
(Amend Coun. J. 10-14-21, p. 37722, Art. IX, § 7)
Sump vent sizes shall be determined in accordance with Sections 18-29-916.5.1 and 18-29-916.5.2.
(Amend Coun. J. 10-14-21, p. 37722, Art. IX, § 7)
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 18-29-916.5.1.
Discharge Capacity of Pump (gpm) | Maximum Developed Length of Vent (feet) a | |||||
Diameter of vent (inches) | ||||||
1 1/4 | 1 1/2 | 2 | 2 1/2 | 3 | 4 | |
Discharge Capacity of Pump (gpm) | Maximum Developed Length of Vent (feet) a | |||||
Diameter of vent (inches) | ||||||
1 1/4 | 1 1/2 | 2 | 2 1/2 | 3 | 4 | |
10 | No limit b |
No limit | No limit | No limit | No limit | No limit |
20 | 270 | No limit | No limit | No limit | No limit | No limit |
40 | 72 | 160 | No limit | No limit | No limit | No limit |
60 | 31 | 75 | 270 | No limit | No limit | No limit |
80 | 16 | 41 | 150 | 380 | No limit | No limit |
100 | 10
c | 25 | 97 | 250 | No limit | No limit |
150 | NP | 10
c | 44 | 110 | 370 | No limit |
200 | NP | NP | 20 | 60 | 210 | No limit |
250 | NP | NP | 10 | 36 | 132 | No limit |
300 | NP | NP | 10 c |
22 | 88 | 380 |
400 | NP | NP | NP | 10
c | 44 | 210 |
500 | NP | NP | NP | NP | 24 | 130 |
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 gallon per minute = 3.785 L/m.
NP = Not permitted.
a. Developed length plus an appropriate allowance for entrance losses and friction due to fittings, changes in direction and diameter. Allowances shall be obtained from NBS Monograph 31 or other engineered 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.
c. Less than 10 feet.
(Amend Coun. J. 10-14-21, p. 37722, Art. IX, § 7)
The air pressure relief pipe from a pneumatic sewage ejector shall be connected to an independent vent stack terminating as required for vent extensions through the roof. The relief pipe shall be sized to relieve air pressure inside the ejector to atmospheric pressure but shall be not less than 1 1/2 inches (38 mm) in size.
(Amend Coun. J. 10-14-21, p. 37722, Art. IX, § 7)
No vent will be required on a downspout trap, a subsoil catch basin trap draining by gravity to the house drain or sewer, or a basement floor drain which branches into the house drain at a distance of more than 5 feet from any soil or waste stack. Other floor drains below grade shall be vented at the end of the waste line or individually vented.
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