Sizing tables are often used when sizing vent pipes (Fig. 5.21). There can be many different types of tables to use during a sizing procedure. For example,
|
lVa |
’Л |
lVi |
Unlimited |
|
lVi |
V4 |
1V2 |
Unlimited |
|
2 |
Vi |
1 Vi |
290 |
|
2 |
Vi |
lVi |
Unlimited |
|
3 |
Vi |
1V2 |
97 |
|
3 |
Vi |
2 |
420 |
|
3 |
Vi |
3 |
Unlimited |
|
4 |
Vi |
2 |
98 |
|
4 |
Vi |
3 |
Unlimited |
|
4 |
Vi |
4 |
Unlimited |
|
Drain pipe size (in) |
|
Drain pipe size (in/ft) |
|
Vent pipe size (in) |
|
Maximum developed length of vent pipe (ft) |
FIGURE 5.21 ■ Vent sizing table for Zone Three (for use with individual, branch, and circuit vents for horizontal drain pipes). (Courtesy of McGraw-Hill)
 |
 |
you might use one table to size a vent stack (Fig. 5.22) and another table to size a wet stack vent (Fig. 5.23). Some codes might use one table for both types of vents (Fig. 5.24). Then you might have a different table to use when sizing branch vents or circuit vents (Fig. 5.25). Battery vents may require a different table (Fig. 5.26). Once you have a sizing table to work with, sizing a vent system is not a complicated process.
FIGURE 5.22 ■ Sizing a vent stack for wet-venting in Zone Two. (Courtesy of McGraw-Hill)
|
Pipe size of stack (inches) |
Fixture-unit load on stack |
Maximum length of stack |
|
2 |
4 |
30 |
|
3 |
24 |
50 |
|
4 |
50 |
100 |
|
6 |
100 |
300 |
FIGURE 5.23 ■ Sizing a wet stack vent in Zone Two. (Courtesy of McGraw-Hill)
|
Drain pipe size (inches) |
Fixture-unit load on drain pipe |
Vent pipe size (inches) |
Maximum developed length of vent pipe (feet) |
|
VA |
8 |
VA |
50 |
|
VA |
8 |
VA |
150 |
|
VA |
10 |
VA |
30 |
|
llA |
10 |
VA |
100 |
|
2 |
12 |
VA |
75 |
|
2 |
12 |
2 |
200 |
|
2 |
20 |
VA |
50 |
|
2 |
20 |
2 |
150 |
|
3 |
10 |
VA |
42 |
|
3 |
10 |
2 |
150 |
|
3 |
10 |
3 |
1040 |
|
3 |
21 |
VA |
32 |
|
3 |
21 |
2 |
110 |
|
3 |
21 |
3 |
810 |
|
3 |
102 |
VA |
25 |
|
3 |
102 |
2 |
86 |
|
3 |
102 |
3 |
620 |
|
4 |
43 |
2 |
35 |
|
4 |
43 |
3 |
250 |
|
4 |
43 |
4 |
980 |
|
4 |
540 |
2 |
21 |
|
4 |
540 |
3 |
150 |
|
4 |
540 |
4 |
580 |
FIGURE 5.24 ■ Vent sizing for Zone Three (for use with vent stacks and stack vents). (Courtesy of McGraw-Hill)
|
Drain pipe size (inches) |
Drain pipe grade per foot (inches) |
Vent pipe size (inches) |
Maximum developed length of vent pipe (feet) |
|
1У2 |
Vi |
I1/* |
Unlimited |
|
VA |
% |
ІУ2 |
Unlimited |
|
2 |
lA |
lVi |
290 |
|
2 |
‘A |
VA |
Unlimited |
|
3 |
Vi |
VA |
97 |
|
3 |
Vi |
2 |
420 |
|
3 |
‘/4 |
3 |
Unlimited |
|
4 |
Vi |
2 |
98 |
|
4 |
‘/4 |
3 |
Unlimited |
|
4 |
Vi |
4 |
Unlimited |
FIGURE 5.25 ■ Vent sizing for Zone Three (for use with individual, branch, and circuit vents for horizontal drain pipes. (Courtesy of McGraw-Hill)
