What is the maximum distance from trap to vent for a 3" pipe?

The Massachusetts Plumbing Code specifies that the maximum distance from a trap to a vent for a 3" pipe is 8 feet. This is an important requirement to ensure proper drainage and ventilation within the plumbing system.

A trap is designed to prevent sewer gases from entering the interior spaces of a building, while a vent allows air to enter the plumbing system to ensure smooth drainage. If the distance between the trap and the vent exceeds the maximum limit, it can lead to inadequate venting, which may cause slow drainage or siphoning of the trap, ultimately compromising the effectiveness of the plumbing system.

Maintaining the 8-foot maximum distance allows for the proper functioning of both the drainage and venting systems, ensuring that there is enough airflow to prevent any potential issues related to negative pressure that could affect the trap's ability to seal off sewer gases.