What is the portion of a fixture drain located between a trap and its vent called?

The portion of a fixture drain that is located between a trap and its vent is referred to as the trap arm. This section is crucial for the function of the plumbing system, as it connects the trap, which serves to prevent sewer gases from entering the living space, with the vent system that allows air to enter the drainage system and maintains proper pressure. The trap arm must be installed at an appropriate slope to ensure that waste flows efficiently towards the drain while preventing stinky and harmful gases from backing up into the home.

The trap arm plays an important role in ensuring that the trap retains water, providing a seal against odors, and that waste moves effectively to the main drainage system. This component must follow specific building codes regarding its length and slope to ensure effective drainage.