Massachusetts Plumbers Journeyman Practice Exam

How should the vent be taken off concerning a horizontal soil or waste pipe, and how high should it rise before offsetting horizontally?

1. Above the flood-level rim, two inches

2. Below the drain, six inches

3. Center line, six inches

4. Edge of the pipe, three inches

The correct answer is: Center line, six inches

The correct approach for venting off a horizontal soil or waste pipe involves maintaining proper air flow and preventing potential sewage gases from entering the living space. The guideline to take the vent off at the center line of the pipe ensures that the vent adequately captures gases and provides a suitable point for airflow, optimizing the efficiency of the drainage system. Raising the vent six inches before offsetting horizontally is a standard practice that helps to prevent any backflow of water from the horizontal drain pipe into the vent, which could lead to blockages or venting issues. This height is a common requirement in plumbing codes, aimed at maintaining system functionality and safety. By adhering to these practices, the plumbing system is better equipped to handle pressure changes and maintain a balance between air and wastewater flow, which is essential for proper drainage and health standards.