A double sanitary _____ may be used on a vertical soil, waste, or vent line.

A double sanitary tee is specifically designed to connect multiple lines and is appropriate for use on vertical soil, waste, or vent lines. This fitting allows for efficient drainage by directing the flow from one pipe into another while preventing backflow. The design of the double sanitary tee facilitates smooth transitions for both waste and vent piping, helping to minimize clogs and ensuring that sewage and air can flow freely.

Using a double sanitary tee is especially important in vertical applications since it manages the alignment of multiple branches effectively. It allows for two horizontal branches to connect to a vertical pipe and maintains good flow dynamics, which is vital in plumbing systems. By choosing this fitting, plumbers can maintain the integrity and efficiency of the drainage system while adhering to code requirements.