Section PC 908: Relief Vents – Stacks of More than 10 Branch Intervals

908.1 Where required.

Soil and waste stacks in buildings having more than 10 branch intervals shall be provided with a relief vent at each tenth interval installed, beginning with the top floor.

908.2 Size and connection.

The size of the relief vent shall be equal to the size of the vent stack to which it connects. The lower end of each relief vent shall connect to the soil or waste stack through a wye below the horizontal branch serving the floor, and the upper end shall connect to the vent stack through a tee or inverted wye not less than 3 feet (914 mm) above the floor.

Section PC 909: Fixture Vents

909.1 Distance of trap from vent.

Each fixture trap shall have a protecting vent located so that the slope and the developed length in the fixture drain from the trap weir to the vent fitting are within the requirements set forth in Table 909.1.

   Exception: The developed length of the fixture drain from the trap weir to the vent fitting for self- siphoning fixtures, such as water closets, shall not be limited.

Table 909.1
Maximum Distance of Fixture Trap from Vent

 

Size of Trap (inches)	Slope (inch per foot)	Distance from Trap (feet)
1 1/4	1/4	5
1 1/2	1/4	6
2	1/4	8
3	1/8	12
4	1/8	16

 

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 inch per foot = 83.3 mm/m.

909.2 Venting of fixture drains.

The vent for a fixture drain, except where serving a fixture with integral traps, such as water closets, shall connect above the weir of the fixture trap being vented.

909.3 Crown vent.

A vent shall not be installed within two pipe diameters of the trap weir.