What is the portion of a fixture drain between a trap and its vent referred to as?

The portion of a fixture drain located between a trap and its vent is known as the trap arm. This segment of plumbing pipe plays a crucial role in the drainage system. It connects the trap, which serves to prevent sewer gases from entering the living space, to the vent system, which allows air to enter the drainage pipes and helps maintain proper pressure and flow.

The trap arm must meet specific requirements defined in plumbing codes, including maintaining a proper slope to ensure that water and waste flow efficiently towards the drain. Additionally, the length of the trap arm is important as it can affect the overall performance of the plumbing system, ensuring that the trap remains filled with water to maintain its seal against gases.

In contrast, other terms refer to different parts of the plumbing system. A drain arm generally refers to the pipe segment leading away from a fixture before the trap, while a waste arm specifically refers to the portion of the drain pipe that carries waste away from the fixture. A connector line is a more generic term that does not specifically denote the section between a trap and vent. Understanding the proper terminology helps in comprehending plumbing layouts and systems effectively.