7.5.6.3.Location of Vent Pipes

(1) Except as provided in Sentences (2) and (3), vent pipes that protects a fixture trap shall be located so that (a) the developed length of the trap arm is not less than twice the NPS of the fixture drain, (b) the total fall of the trap arm is not greater than its inside diameter, and (c) the trap arm does not have a cumulative change in direction of more than 135°. (2) The trap arm of water closets, of S-trap standards or of any other fixture that also discharges vertically and depends on siphonic action for its proper functioning shall not have a cumulative change in direction of more than 225°. (3) A vent pipe that protects a water closet or any other fixture that also depends on siphonic action for its proper functioning shall be located so that the distance between the connections of the fixture drain to the fixture and the vent pipe does not exceed (a) 1 m in the vertical plane, and (b) 3 m in the horizontal plane. (4) The maximum length of every trap arm shall conform to Table 7.5.6.3. Table 7.5.6.3. Length of Trap Arm Forming Part of Sentence 7.5.6.3.(4) Nominal Pipe Size of Trap Served, NPS Maximum Length of Trap Arm, m Minimum Slope 1¼ 1.5 1 in 50 1½ 1.8 1 in 50 2 2.4 1 in 50 3 3.6 1 in 50 4 4.9 1 in 50 4 9.8 1 in 100