Journeyman Plumbers Exam Drainage, Waste, and Venting 3 — Questions and Answers
Question 1: An air admittance valve (AAV) may NOT be used as the sole means of venting in which location?
- Under a kitchen sink cabinet
- In an attic space above insulation
- As the vent for a building sewer (Correct answer)
- On the branch drain of a bathroom group
Correct answer: As the vent for a building sewer
AAVs cannot be used to vent a building sewer because they are one-way devices and do not allow sewer gases to escape to atmosphere.
Question 2: Which pipe material is NOT approved for use in above-ground DWV systems under the UPC?
- ABS plastic
- Cast iron
- Galvanized steel drain pipe (Correct answer)
- PVC Schedule 40
Correct answer: Galvanized steel drain pipe
Galvanized steel is not listed for DWV use because it corrodes internally from waste gases and restricts flow over time.
Question 3: What is the purpose of a relief vent in a tall building stack?
- To prevent back pressure in the upper floors
- To relieve positive pressure at the base of the stack (Correct answer)
- To vent individual fixture traps
- To allow fresh air into the building drain
Correct answer: To relieve positive pressure at the base of the stack
A relief vent connects the soil stack to the vent stack near the base to relieve the positive pressure that builds at the bottom of a tall stack.
Question 4: When two or more water closets are on the same horizontal branch, which venting method is most efficient?
- Individual back venting each closet
- Installing a loop vent
- Using a circuit vent with a relief vent (Correct answer)
- Installing an AAV at each closet
Correct answer: Using a circuit vent with a relief vent
A circuit vent with a relief vent efficiently serves a battery of water closets on the same horizontal branch, reducing pipe runs.
Question 5: What is the minimum vent pipe size for a water closet?
- 1 inch
- 1.5 inches
- 2 inches (Correct answer)
- 3 inches
Correct answer: 2 inches
The minimum vent pipe size for a water closet is 2 inches per most plumbing codes, including the UPC.
Question 6: How far above the flood level rim of a fixture must a vent pipe rise before offsetting horizontally?
- 2 inches
- 4 inches
- 6 inches (Correct answer)
- 1 foot
Correct answer: 6 inches
A vent pipe must rise at least 6 inches above the flood level rim of the highest served fixture before making a horizontal offset.
Question 7: A combination waste and vent system is typically permitted for which type of fixture?
- Water closets and urinals
- Floor drains and floor sinks (Correct answer)
- Bathtubs and showers only
- Lavatories and bidets only
Correct answer: Floor drains and floor sinks
Combination waste and vent systems are commonly permitted for floor drains and floor sinks in commercial settings where wet venting is impractical.
Journeyman Plumbers Exam Drainage, Waste, and Venting 3
An air admittance valve (AAV) may NOT be used as the sole means of venting in which location?