N.Y.C. Admin. Code § PC 919: Section 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:

Q

h,b

=

N

n,b

Q

v

(Equation 9-1)

For SI:

Q

h,b

=

N

n,b

Q

v

(0.4719 L/s)

where:

N

n,b

= Number of fixtures per header (or vent branch) ÷ total number of fixtures connected to vent stack.

Q

h,b

=

Vent branch or vent header airflow rate (cfm).

Q

v

= Total vent stack airflow rate (cfm).

Q

v

(gpm) = 27.8

r

s

2/3

(1 -

r

s

)

D

8/3

Q

v

(cfm) = 0.134

Q

v

(gpm)

where:

D

= Drainage stack diameter (inches).

Q

w

= Design discharge load (gpm).

r

s

= Waste water flow area to total area.

=

Q

w

/ 27.8

D

8/3

Individual vent airflow rates are obtained by equally distributing

Q

h,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

Q

h,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.