Drain, Waste, & Vent Systems Flashcards
7 cards from real Master Plumber 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 Drain, Waste, & Vent Systems flashcards as text
Under the IPC, what is the minimum height above the roof surface for a vent pipe termination in a climate where frost closure is not a concern?
Answer: 12 inches
Vent pipe terminations must extend at least 6 inches above the roof surface, or 12 inches if within 10 feet of a roof-mounted equipment intake.
Which condition most commonly causes a trap seal to be lost by evaporation rather than siphoning or back pressure?
Answer: A fixture that is seldom used for extended periods
Infrequently used fixtures allow water in the trap to evaporate over time, breaking the seal and allowing sewer gases to enter the building.
What is the function of a revent (individual vent or back vent) in a DWV system?
Answer: It provides a separate vent connection from a trap back to the vent stack to prevent siphonage
A revent connects the trap arm or drain of a fixture to the vent stack, providing a dedicated air path to prevent trap siphonage caused by negative pressure.
According to the IPC, at what interval must cleanouts be installed in a horizontal drain run?
Answer: Every 100 feet
The IPC requires cleanouts to be installed every 100 feet on horizontal drain piping to ensure the entire run can be accessed for clearing.
A double sanitary tee (double tee-wye) fitting is used when connecting back-to-back fixtures to permit flow in which directions simultaneously?
Answer: From both sides into a common vertical drop
A double sanitary tee allows simultaneous waste discharge from fixtures on both sides of a wall into a shared vertical drain, each entering the tee from opposite sides.
What minimum trap seal depth is required by the IPC for all fixture traps?
Answer: 2 inches
The IPC mandates a minimum trap seal depth of 2 inches to provide an adequate water barrier against sewer gas entry into occupied spaces.
Which venting method allows a vertical drain stack to also serve as its own vent without a separate vent pipe?
Answer: Philadelphia vent (stack venting)
Philadelphia (stack) venting uses the drainage stack itself as the vent for fixtures connecting directly to it, eliminating separate individual vent pipes under certain conditions.