If a type I interceptor is 18 feet from the point of connection to the building drain, ___________ is the minimum size vent required?

The minimum size vent required for a type I interceptor that is 18 feet from the point of connection to the building drain is 2 inches. This requirement is rooted in plumbing codes that specify vent sizes based on the distance from the fixture or interceptor to the building drain.

In this case, the 2-inch vent size helps ensure adequate airflow and pressure equalization in the drainage system. Proper venting is crucial because it allows for the free movement of air, preventing the creation of siphons that could impede the flow of wastewater and potentially lead to backups. A vent that is too small may not provide sufficient airflow, leading to operational issues or system failures.

Utilizing a 2-inch vent in this scenario aligns with the best practices outlined in plumbing codes, ensuring efficient performance of the interceptor and the overall drainage system.