For a 4 inch pipe, the maximum distance from fixture trap to vent is?

For a 4 inch pipe, the maximum distance from fixture trap to vent is?

• A. 6 Feet
• B. 5 Feet
• C. 7 Feet
• D. 8 Feet

Answer: (A)

The distance from a fixture trap to its vent is governed by trap-arm length, which depends on the size of the drain pipe. The larger the pipe, the farther the trap arm can be while still allowing the vent to relieve the air pressure and prevent siphoning. For a 4-inch pipe, the code sets the maximum trap-arm length at six feet. Staying within this six-foot limit helps ensure the trap water seal isn’t siphoned as the fixture drains, keeping the vent functioning properly. Distances longer than six feet would risk siphoning and improper venting, which is why six feet is the maximum. Shorter distances are allowed, but they aren’t the maximum.

The distance from a fixture trap to its vent is governed by trap-arm length, which depends on the size of the drain pipe. The larger the pipe, the farther the trap arm can be while still allowing the vent to relieve the air pressure and prevent siphoning. For a 4-inch pipe, the code sets the maximum trap-arm length at six feet. Staying within this six-foot limit helps ensure the trap water seal isn’t siphoned as the fixture drains, keeping the vent functioning properly. Distances longer than six feet would risk siphoning and improper venting, which is why six feet is the maximum. Shorter distances are allowed, but they aren’t the maximum.