Alabama Journeyman Plumber
Examination Questions and Correct
Answers (Verified Answers) Plus Rationale
2027 Q&A| Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To increase drainage velocity
D. To eliminate the need for venting
Answer: B. To prevent sewer gases from entering a building
Rationale: A plumbing trap retains a water seal that separates the
drainage system from the occupied space. This water seal helps prevent
sewer gases, odors, and potentially harmful vapors from entering the
building.
2. Which fitting is generally used to change the direction of a
drainage pipe by 90 degrees?
,A. Sanitary tee
B. Coupling
C. Quarter bend or 90-degree elbow
D. Reducer
Answer: C. Quarter bend or 90-degree elbow
Rationale: A 90-degree elbow or quarter bend changes the direction of
piping by approximately 90 degrees. In drainage systems, the type of
fitting used should be appropriate for drainage flow to minimize
turbulence and the possibility of blockage.
3. What is the primary function of a plumbing vent system?
A. To supply potable water
B. To increase water heater temperature
C. To protect trap seals and allow proper drainage-system airflow
D. To reduce the size of drainage pipes
Answer: C. To protect trap seals and allow proper drainage-system
airflow
Rationale: Proper venting permits air to enter and move through the
drainage system, helping maintain atmospheric pressure and
preventing siphonage or backpressure that could destroy trap seals.
, 4. Which material is commonly used for potable-water distribution
piping?
A. Cast iron soil pipe
B. Copper tubing
C. Asphalt-coated drain pipe
D. Unlined steel flue pipe
Answer: B. Copper tubing
Rationale: Copper tubing is widely approved for potable-water
distribution when the appropriate type and installation methods are
used. Drainage and vent materials are not automatically suitable for
potable-water service.
5. What does the term "DWV" stand for?
A. Domestic Water Valve
B. Drain, Waste, and Vent
C. Drinking Water Verification
D. Drainage Water Volume
Answer: B. Drain, Waste, and Vent
Rationale: DWV describes the piping system responsible for carrying
wastewater away from fixtures and providing ventilation for the
, drainage system. Properly designed DWV systems are essential for
sanitary operation.
6. Why should a drainage pipe normally be installed with a slope?
A. To prevent water from flowing
B. To allow gravity to move wastewater toward the sewer or drainage
point
C. To increase static water pressure
D. To eliminate the need for cleanouts
Answer: B. To allow gravity to move wastewater toward the sewer or
drainage point
Rationale: Building drainage systems generally rely on gravity. Proper
slope allows wastewater to flow while helping carry solids through the
pipe without excessive accumulation.
7. What is the purpose of a cleanout in a drainage system?
A. To regulate water pressure
B. To provide access for inspection and removal of blockages
C. To supply air to a water heater
D. To replace a trap
Answer: B. To provide access for inspection and removal of blockages
Examination Questions and Correct
Answers (Verified Answers) Plus Rationale
2027 Q&A| Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent sewer gases from entering a building
C. To increase drainage velocity
D. To eliminate the need for venting
Answer: B. To prevent sewer gases from entering a building
Rationale: A plumbing trap retains a water seal that separates the
drainage system from the occupied space. This water seal helps prevent
sewer gases, odors, and potentially harmful vapors from entering the
building.
2. Which fitting is generally used to change the direction of a
drainage pipe by 90 degrees?
,A. Sanitary tee
B. Coupling
C. Quarter bend or 90-degree elbow
D. Reducer
Answer: C. Quarter bend or 90-degree elbow
Rationale: A 90-degree elbow or quarter bend changes the direction of
piping by approximately 90 degrees. In drainage systems, the type of
fitting used should be appropriate for drainage flow to minimize
turbulence and the possibility of blockage.
3. What is the primary function of a plumbing vent system?
A. To supply potable water
B. To increase water heater temperature
C. To protect trap seals and allow proper drainage-system airflow
D. To reduce the size of drainage pipes
Answer: C. To protect trap seals and allow proper drainage-system
airflow
Rationale: Proper venting permits air to enter and move through the
drainage system, helping maintain atmospheric pressure and
preventing siphonage or backpressure that could destroy trap seals.
, 4. Which material is commonly used for potable-water distribution
piping?
A. Cast iron soil pipe
B. Copper tubing
C. Asphalt-coated drain pipe
D. Unlined steel flue pipe
Answer: B. Copper tubing
Rationale: Copper tubing is widely approved for potable-water
distribution when the appropriate type and installation methods are
used. Drainage and vent materials are not automatically suitable for
potable-water service.
5. What does the term "DWV" stand for?
A. Domestic Water Valve
B. Drain, Waste, and Vent
C. Drinking Water Verification
D. Drainage Water Volume
Answer: B. Drain, Waste, and Vent
Rationale: DWV describes the piping system responsible for carrying
wastewater away from fixtures and providing ventilation for the
, drainage system. Properly designed DWV systems are essential for
sanitary operation.
6. Why should a drainage pipe normally be installed with a slope?
A. To prevent water from flowing
B. To allow gravity to move wastewater toward the sewer or drainage
point
C. To increase static water pressure
D. To eliminate the need for cleanouts
Answer: B. To allow gravity to move wastewater toward the sewer or
drainage point
Rationale: Building drainage systems generally rely on gravity. Proper
slope allows wastewater to flow while helping carry solids through the
pipe without excessive accumulation.
7. What is the purpose of a cleanout in a drainage system?
A. To regulate water pressure
B. To provide access for inspection and removal of blockages
C. To supply air to a water heater
D. To replace a trap
Answer: B. To provide access for inspection and removal of blockages
