Page 98 - 2018_IPC

VENTS

Q (gpm)= 27.8 r s 2/3 (1 – r ) D 8/3 ber of total fixtures, decrease by one; for one fixture, apply
ν
s
the full value of Q .
Q (cfm)= 0.134 Q (gpm) h,b
ν
ν
Individual vent developed length shall be increased by 20
where:
percent of the distance from the vent stack to the fixture vent
D = Drainage stack diameter (inches).
connection on the vent branch or header.
Q = Design discharge load (gpm).
w
r s = Waste water flow area to total area. SECTION 920
COMPUTERIZED VENT DESIGN
Q
w
= ------------------------- 920.1 Design of vent system. The sizing, design and layout
27.8 D 83⁄ of the vent system shall be permitted to be determined by
approved computer program design methods.
Individual vent airflow rates are obtained by equally dis- 920.2 System capacity. The vent system shall be based on
tributing Q into one-half the total number of fixtures on the the air capacity requirements of the drainage system under a
h,b
branch or header for more than two fixtures; for an odd num-
peak load condition.
TABLE 919.2
MINIMUM DIAMETER AND MAXIMUM LENGTH OF INDIVIDUAL BRANCH FIXTURE VENTS AND
INDIVIDUAL FIXTURE HEADER VENTS FOR SMOOTH PIPES
INDIVIDUAL VENT AIRFLOW RATE (cubic feet per minute)
DIAMETER OF Maximum developed length of vent (feet)
VENT PIPE
(inches) 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.

2018 INTERNATIONAL PLUMBING CODE ® 81
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