Arkansas AR-PL Plumbing
Contractor Practice Exam |
Questions, Verified Answers &
Detailed Rationales | Complete
Contractor License Exam Prep
Study Guide | Updated 2026
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Prevent pipe corrosion
C. Prevent sewer gases from entering a building
D. Increase drainage velocity
Answer: Prevent sewer gases from entering a building
Rationale: A plumbing trap maintains a water seal that
prevents sewer gases and odors from entering occupied
spaces while allowing wastewater to drain.
2. Which fitting is commonly used to change the
direction of a drainage pipe by 90 degrees?
A. Sanitary tee
B. Quarter bend/elbow
C. Coupling
D. Reducer
Answer: Quarter bend/elbow
Rationale: A quarter bend or elbow changes the
direction of piping, while drainage fittings are selected
based on the direction and type of flow.
3. What is the primary function of a cleanout?
A. Regulate water pressure
B. Prevent backflow
,C. Provide access for cleaning and clearing drainage
piping
D. Supply air to a water heater
Answer: Provide access for cleaning and clearing
drainage piping
Rationale: Cleanouts provide accessible openings that
allow drain lines to be inspected, rodded, or otherwise
cleared of obstructions.
4. Which material is commonly used for potable water
distribution?
A. Cast iron soil pipe
B. ABS drain pipe
C. Copper tubing
D. Vitrified clay pipe
Answer: Copper tubing
Rationale: Copper tubing is widely used for potable
water systems because of its durability, corrosion
resistance, and suitability for drinking-water
applications.
5. What does DWV stand for?
A. Domestic Water Valve
B. Drain Water Volume
C. Drain, Waste, and Vent
D. Distribution Water Vent
Answer: Drain, Waste, and Vent
Rationale: DWV describes the piping system that
removes wastewater and sewage and provides
ventilation for the drainage system.
6. What is the purpose of a vent system?
A. Increase hot-water temperature
B. Increase water pressure
C. Protect trap seals and allow proper drainage-system
,airflow
D. Filter potable water
Answer: Protect trap seals and allow proper drainage-
system airflow
Rationale: Proper venting permits air movement within
the drainage system, helping prevent siphonage,
backpressure, and loss of trap seals.
7. What type of valve is generally used to prevent
reverse flow?
A. Gate valve
B. Globe valve
C. Check valve
D. Ball valve
Answer: Check valve
Rationale: A check valve permits flow in one direction
and closes when flow attempts to reverse.
8. What is the primary purpose of a water heater
temperature-and-pressure relief valve?
A. Increase water pressure
B. Reduce water hardness
C. Protect the water heater from excessive temperature
and pressure
D. Prevent drain blockage
Answer: Protect the water heater from excessive
temperature and pressure
Rationale: The temperature-and-pressure relief valve
opens when unsafe temperature or pressure conditions
occur, helping prevent a dangerous failure of the water
heater.
9. Which fitting is normally used to join two pipes of the
same nominal size in a straight line?
, A. Tee
B. Elbow
C. Coupling
D. Wye
Answer: Coupling
Rationale: A coupling connects two sections of pipe in a
straight run and is normally used when the connected
pipes have compatible dimensions.
10. What is water hammer?
A. Water contamination
B. A pressure surge caused by a sudden change in water
flow
C. A reduction in pipe size
D. A sewer-gas condition
Answer: A pressure surge caused by a sudden change in
water flow
Rationale: Rapidly stopping or changing flowing water
can create a pressure wave that produces banging,
vibration, or damage to piping and fixtures.
11. Which device is designed to protect the potable
water supply from backsiphonage or backflow?
A. Expansion tank
B. Pressure-reducing valve
C. Backflow prevention device
D. Water hammer arrestor
Answer: Backflow prevention device
Rationale: Backflow preventers protect potable water
from contamination caused by unwanted reverse flow.
12. What is the purpose of a pressure-reducing valve?
A. Increase water pressure
B. Reduce excessive incoming water pressure
Contractor Practice Exam |
Questions, Verified Answers &
Detailed Rationales | Complete
Contractor License Exam Prep
Study Guide | Updated 2026
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Prevent pipe corrosion
C. Prevent sewer gases from entering a building
D. Increase drainage velocity
Answer: Prevent sewer gases from entering a building
Rationale: A plumbing trap maintains a water seal that
prevents sewer gases and odors from entering occupied
spaces while allowing wastewater to drain.
2. Which fitting is commonly used to change the
direction of a drainage pipe by 90 degrees?
A. Sanitary tee
B. Quarter bend/elbow
C. Coupling
D. Reducer
Answer: Quarter bend/elbow
Rationale: A quarter bend or elbow changes the
direction of piping, while drainage fittings are selected
based on the direction and type of flow.
3. What is the primary function of a cleanout?
A. Regulate water pressure
B. Prevent backflow
,C. Provide access for cleaning and clearing drainage
piping
D. Supply air to a water heater
Answer: Provide access for cleaning and clearing
drainage piping
Rationale: Cleanouts provide accessible openings that
allow drain lines to be inspected, rodded, or otherwise
cleared of obstructions.
4. Which material is commonly used for potable water
distribution?
A. Cast iron soil pipe
B. ABS drain pipe
C. Copper tubing
D. Vitrified clay pipe
Answer: Copper tubing
Rationale: Copper tubing is widely used for potable
water systems because of its durability, corrosion
resistance, and suitability for drinking-water
applications.
5. What does DWV stand for?
A. Domestic Water Valve
B. Drain Water Volume
C. Drain, Waste, and Vent
D. Distribution Water Vent
Answer: Drain, Waste, and Vent
Rationale: DWV describes the piping system that
removes wastewater and sewage and provides
ventilation for the drainage system.
6. What is the purpose of a vent system?
A. Increase hot-water temperature
B. Increase water pressure
C. Protect trap seals and allow proper drainage-system
,airflow
D. Filter potable water
Answer: Protect trap seals and allow proper drainage-
system airflow
Rationale: Proper venting permits air movement within
the drainage system, helping prevent siphonage,
backpressure, and loss of trap seals.
7. What type of valve is generally used to prevent
reverse flow?
A. Gate valve
B. Globe valve
C. Check valve
D. Ball valve
Answer: Check valve
Rationale: A check valve permits flow in one direction
and closes when flow attempts to reverse.
8. What is the primary purpose of a water heater
temperature-and-pressure relief valve?
A. Increase water pressure
B. Reduce water hardness
C. Protect the water heater from excessive temperature
and pressure
D. Prevent drain blockage
Answer: Protect the water heater from excessive
temperature and pressure
Rationale: The temperature-and-pressure relief valve
opens when unsafe temperature or pressure conditions
occur, helping prevent a dangerous failure of the water
heater.
9. Which fitting is normally used to join two pipes of the
same nominal size in a straight line?
, A. Tee
B. Elbow
C. Coupling
D. Wye
Answer: Coupling
Rationale: A coupling connects two sections of pipe in a
straight run and is normally used when the connected
pipes have compatible dimensions.
10. What is water hammer?
A. Water contamination
B. A pressure surge caused by a sudden change in water
flow
C. A reduction in pipe size
D. A sewer-gas condition
Answer: A pressure surge caused by a sudden change in
water flow
Rationale: Rapidly stopping or changing flowing water
can create a pressure wave that produces banging,
vibration, or damage to piping and fixtures.
11. Which device is designed to protect the potable
water supply from backsiphonage or backflow?
A. Expansion tank
B. Pressure-reducing valve
C. Backflow prevention device
D. Water hammer arrestor
Answer: Backflow prevention device
Rationale: Backflow preventers protect potable water
from contamination caused by unwanted reverse flow.
12. What is the purpose of a pressure-reducing valve?
A. Increase water pressure
B. Reduce excessive incoming water pressure
