Drainage, Waste, and Vent Systems Flashcards
7 cards from real Journeyman Plumbers Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Drainage, Waste, and Vent Systems flashcards as text
Which of the following fixtures is assigned the highest drainage fixture unit (DFU) value under the IPC?
Answer: Water closet (flush tank)
A flush-tank water closet is rated at 3 DFUs, which is higher than a lavatory (1), bathtub (2), or kitchen sink (2).
What type of vent is installed downstream of a fixture trap and connects to the vent stack above the fixture's flood level rim?
Answer: Individual vent (back vent)
An individual vent (also called a back vent or revent) connects the fixture's trap arm to the vent stack and runs upward past the fixture's flood level rim.
An island fixture vent loop is required when:
Answer: A sink or similar fixture is installed in an island where a standard vent cannot go up through a wall
Island fixture vent loops route the vent piping under the floor and back up alongside the drain when there is no adjacent wall to run a conventional vent.
What is the minimum size of a vent stack serving a soil stack that receives discharge from water closets?
Answer: 3 inches
When water closets connect to the soil stack, the vent stack must be at least 3 inches in diameter per IPC sizing requirements.
A crown vent is prohibited because:
Answer: Solids can accumulate and block the vent opening at the top of the trap
A crown vent connects at the crown (top) of the trap, where waste material can collect and plug the vent, rendering it ineffective.
Under the IPC, a vent pipe that terminates through an exterior wall must terminate at least how far above the top of the opening it is near?
Answer: 6 inches
A vent terminating through an exterior wall must end at least 6 inches above the top of any nearby opening such as a window or door.
Which of these conditions would cause a trap to lose its water seal due to self-siphonage?
Answer: A fixture drain discharges a full slug of water through a long, unvented trap arm
Self-siphonage occurs when a full flow of water down an unvented or inadequately vented trap arm creates enough suction to pull the water seal out of the trap.