A loop vent connects which of the following?

In plumbing, a loop vent serves an important function when it comes to the ventilation of drainage systems. Specifically, it connects two or more floor outlet fixtures, allowing for proper venting while maintaining the necessary air flow to prevent negative pressure that could disrupt the system’s functionality.

By connecting multiple fixtures, the loop vent helps ensure that they can all drain effectively without adversely affecting each other. This design helps to prevent potential siphoning action that might occur if one fixture’s drainage is overly reliant on its own venting mechanism, which can lead to slow drainage or even backup issues.

The other options do not accurately describe the function of a loop vent. For instance, the connection of a vertical soil stack to a vent stack or several branch lines back to a main vent refers more to overall venting strategies rather than the specific interconnection of floor outlet fixtures. Similarly, connecting a single fixture to the main drain does not represent the purpose of a loop vent, as its function is inherently cooperative among multiple outlets rather than just a single unit.