Sizes Of Pipes

House sewer and drain pipes must be at least 4 in. in diameter where water closets discharge into them. Where rain water discharges into them, the house sewer and the house drain up to the leader connections should be in accordance with the following table:

Size Of Pipe For Drainage

Diameter.

Drainage Area, Square Feet.

Inches.

Fall 1/4 In. per Ft.

Fall 1/2 In. per Ft.

6 7 8 9

5,000

6,900

9,100

11,600

7,500 10,300 13,600 17,400

* For flush pipes only.

Least Sizes Of Soil, Waste, And Vent Pipe

Name of Pipe.

Diameter. Inches.

Main and branch soil pipes.........................

4

Main waste pipe...............................................

2

Branch waste pipes for kitchen sinks.............

2

Soil pipe for water closets on 5 or more floors

5

Waste pipe for kitchen sinks on 5 or more floors

3

Bath or sink waste pipe...................................

1 1/2 -2

Basin or urinal waste pipe...............................

1 1/4-1 1/2

Pantry-sink waste pipe ...................................

1 1/2

Safe waste pipe ................................................

1-1 1/2

Water-closet trap .............................................

3 1/4 - 4

Wash tubs, 1 1/2" waste pipe and 2" trap for set of 2 tubs....................................................

1 1/2 - 2

Waste pipe for a set of 3 or 4 tubs...................

2

Main vents and long branches ......................

2

Water-closet vents on 3 or more floors............

3

Vent pipe for other fixtures on less than 7 floors

2

Vent pipe for fixtures on 8 stories or less .......

3

Vent pipe for 9 stories and less than 16..........

4

Vent pipe for 16 stories and less than 21..........

5

Vent pipe for 21 stories and over ...................

6

Branch vents for traps larger than 2 in...........

2

Branch vents for traps 2 in. or less................

1 1/2

For fixtures other than water closets and slop sinks and for more than 8 stories, vent pipes may be 1 in. smaller than above stated.

All vent pipes that pass out through the roof should be increased one size through and above the roof, to allow for ice accumulations inside. In no case should any of these pipes be less than 4 in. in diameter, except in mild climates. Care should be taken to prevent the use of the old-fashioned cast-iron vent caps. If the open end must be protected, wire baskets may be used.

The fresh-air inlet should be of the same size as the drain, up to 4 in.; for 5" and 6" drains, it should not be less than 4 in. in diameter; for 7" and 8" drains, not less than 6 in. in diameter, and for larger drains not less than 8 in. in diameter. The fresh-air inlet orifice should have an area equal to that of the pipe.

Fall For Drain And Waste Pipes

The fall of a drainage system should be so arranged that the velocity of the flow obtained will be not less than about 275 ft. per min. This velocity be closely approximated by pitching the pipes as follows:

Grades For Drain Pipes

Diameter.

Inches.

Fall.

2

1' fall in 20' run

3

1' fall in 30' run

4

1' fall in 40' run

5

1' fall in 50' run

6

1' fall in 60' run

Diameter. Inches.

Fall.

7

1' fall in 70' run

8

1' fall in 80' run

9

1' fall in 90' run

10

1' fall in l00' run