What is the maximum distance from a trap to its vent for a 1 1/2" pipe?

The maximum distance from a trap to its vent for a 1 1/2" pipe is 5 feet. This requirement is established to ensure proper venting and to prevent issues such as siphoning, which can lead to water seal loss in the trap. When the distance exceeds the specified limit, there is a risk that negative pressure created during drainage can pull water out of the trap, allowing sewer gases to enter the building.

Maintaining the correct distance between a trap and its vent is crucial for the effective functioning of the plumbing system. The 5-foot limit allows for sufficient airflow and ensures that the trap maintains its seal, providing the necessary protection against backflow and potential health hazards. Understanding this requirement is an essential aspect of plumbing code compliance and safe plumbing installation practices.