PC Plumber Water & Drainage 2 — Questions and Answers
Question 1: What is the minimum slope required for a 4-inch horizontal drain pipe under the IPC?
- 1/16 inch per foot
- 1/8 inch per foot (Correct answer)
- 1/4 inch per foot
- 1/2 inch per foot
Correct answer: 1/8 inch per foot
The IPC requires a minimum slope of 1/8 inch per foot for 4-inch horizontal drain pipes.
Question 2: Which type of pipe joint is used to connect cast iron soil pipe using a rubber gasket and stainless steel clamp?
- Caulked lead joint
- No-hub coupling (Correct answer)
- Spigot and bell joint
- Compression fitting
Correct answer: No-hub coupling
No-hub couplings use a neoprene rubber sleeve and stainless steel clamp to connect cast iron no-hub pipe.
Question 3: A P-trap must have its water seal depth within which range?
- 1 to 2 inches
- 2 to 4 inches (Correct answer)
- 4 to 6 inches
- 6 to 8 inches
Correct answer: 2 to 4 inches
P-trap water seals must be between 2 and 4 inches deep to prevent sewer gas entry while remaining self-cleaning.
Question 4: What is the purpose of an air admittance valve (AAV) in a drainage system?
- To pressurize the drainage stack
- To allow air into the drain to equalize pressure without a traditional vent (Correct answer)
- To prevent backflow in the main sewer line
- To reduce water hammer in supply lines
Correct answer: To allow air into the drain to equalize pressure without a traditional vent
An AAV opens under negative pressure to admit air into the drain system, eliminating the need for a traditional vent pipe through the roof.
Question 5: When installing a shower drain, the drain flange must be set at what height relative to the finished floor?
- 1/2 inch above
- Flush with or slightly below (Correct answer)
- 1 inch above
- 2 inches below
Correct answer: Flush with or slightly below
The shower drain flange must be set flush with or slightly below the finished floor surface to ensure proper drainage.
Question 6: What is the maximum distance a fixture trap can be from its vent under most plumbing codes?
- 2 feet
- 6 feet
- 8 feet (Correct answer)
- 10 feet
Correct answer: 8 feet
For a 1.5-inch trap, most codes allow a maximum trap-to-vent distance of 8 feet to prevent siphoning.
Question 7: Which drainage fitting must be used when changing direction from horizontal to vertical in a drain line?
- Long sweep 1/4 bend (Correct answer)
- Short sweep 1/4 bend
- Sanitary tee
- Wye with 1/8 bend
Correct answer: Long sweep 1/4 bend
A long sweep 1/4 bend (long turn elbow) is required when transitioning from horizontal to vertical to maintain flow and prevent clogs.
PC Plumber Water & Drainage 2
What is the minimum slope required for a 4-inch horizontal drain pipe under the IPC?