CPD Sanitary Drainage Systems 2 — Questions and Answers
Question 1: What is the minimum slope required for a 4-inch horizontal sanitary drain pipe per 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 horizontal drain pipes 4 inches in diameter.
Question 2: Which type of fitting is NOT permitted for use in horizontal-to-horizontal sanitary drain connections?
- Long-sweep quarter bend
- Wye with eighth bend
- Short-pattern quarter bend (sanitary tee used horizontally) (Correct answer)
- Combination wye and eighth bend
Correct answer: Short-pattern quarter bend (sanitary tee used horizontally)
A sanitary tee used in a horizontal-to-horizontal configuration causes turbulence and is not permitted; wyes and long sweeps are required.
Question 3: In a building sanitary drainage system, what is the primary purpose of a cleanout?
- Prevent sewer gas entry
- Allow access for drain cleaning (Correct answer)
- Act as a pressure relief valve
- Provide an air gap for backflow prevention
Correct answer: Allow access for drain cleaning
Cleanouts provide access points in the drainage piping so that obstructions can be removed with drain-cleaning equipment.
Question 4: The developed length rule for horizontal drain pipes states that a cleanout must be provided every:
- 50 feet
- 75 feet
- 100 feet (Correct answer)
- 150 feet
Correct answer: 100 feet
The IPC requires cleanouts at maximum 100-foot intervals along horizontal drain piping.
Question 5: Which of the following correctly describes the term 'wet vent'?
- A vent pipe that conveys both air and wastewater simultaneously (Correct answer)
- A vent pipe located below the flood-level rim
- A vent exposed to outdoor weather
- A secondary vent added due to pipe submersion
Correct answer: A vent pipe that conveys both air and wastewater simultaneously
A wet vent is a pipe that serves as both a drain for one fixture and a vent for another fixture simultaneously.
Question 6: What does the term 'critical level' mean in relation to a backflow preventer installed on a sanitary system?
- The maximum pipe pressure rating
- The elevation marking below which backflow can occur (Correct answer)
- The pressure differential across the device
- The point at which the device requires replacement
Correct answer: The elevation marking below which backflow can occur
The critical level (CL) marks the flood level reference point on a backflow preventer, below which backpressure or backsiphonage could cause contamination.
Question 7: According to IPC drainage fixture unit (DFU) values, a residential bathtub is rated as how many DFUs?
- 1
- 2 (Correct answer)
- 3
- 4
Correct answer: 2
The IPC assigns a residential bathtub a drainage fixture unit value of 2.
CPD Sanitary Drainage Systems 2
What is the minimum slope required for a 4-inch horizontal sanitary drain pipe per the IPC?