Engineered Vent Systems
NYC Plumbing Code § PC 919
in effectSection PC 919: Engineered Vent Systems
919.1 General
Engineered vent systems shall comply with this section and Section 28-113.2.2 of the Administrative Code.
919.2 Individual branch fixture and individual fixture header vents.
The maximum developed length of individual fixture vents to vent branches and vent headers shall be determined in accordance with Table 919.2 for the minimum pipe diameters at the indicated vent airflow rates.
The individual vent airflow rate shall be determined in accordance with the following:
Qh,b = Nn,bQv (Equation 9-1)
For SI: Qh,b = Nn,bQv(0.4719 L/s)
where:
Nn,b = Number of fixtures per header (or vent branch) ÷ total number of fixtures connected to vent stack.
Qh,b = Vent branch or vent header airflow rate (cfm).
Qv = Total vent stack airflow rate (cfm).
Qv(gpm) = 27.8rs2/3 (1 - rs)D8/3
Qv(cfm) = 0.134Qv (gpm)
where:
D = Drainage stack diameter (inches).
Qw = Design discharge load (gpm).
rs = Waste water flow area to total area.
= Qw / 27.8D8/3
Individual vent airflow rates are obtained by equally distributing Qh,b into one-half the total number of fixtures on the branch or header for more than two fixtures; for an odd number of total fixtures, decrease by one; for one fixture, apply the full value of Qh,b.
Individual vent developed length shall be increased by 20 percent of the distance from the vent stack to the fixture vent connection on the vent branch or header.
Table 919.2
Minimum Diameter and Maximum Length of Individual Branch Fixture Vents and Individual Fixture Header Vents for Smooth Pipes
Diameter of Vent Pipe (inches) Individual Vent Airflow Rate (cubic feet per minute)
Maximum developed length of vent (feet)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1/2 95 25 13 8 5 4 3 2 1 1 1 1 1 1 1 1 1 1 1 1
3/4 100 88 47 30 20 15 10 9 7 6 5 4 3 3 3 2 2 2 2 1
1 — — 100 94 65 48 37 29 24 20 17 14 12 11 9 8 7 7 6 6
1 1/4 — — — — — — — 100 87 73 62 53 46 40 36 32 29 26 23 21
1 1/2 — — — — — — — — — — — 100 96 84 75 65 60 54 49 45
2 — — — — — — — — — — — — — — — — — — — 100
For SI: 1 inch = 25.4 mm, 1 cubic foot per minute = 0.4719 L/s, 1 foot = 304.8 mm
919.3 A Licensed Professional Engineer shall certify design.
An engineer shall also inspect and certify the system upon completion of the system.
Source: City of New York, Charter, Administrative Code and Rules (American Legal Publishing XML export, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCadmin/0-0-0-163196Fetched: 10/24/2026