Arkansas (Ar) Master Plumber
Examination – Advanced Plumbing
Systems Classification Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Increase drainage speed
D. Store wastewater
Answer: B
Rationale: The vent system allows air into the drainage system,
preventing trap siphonage and blocking sewer gases from entering
occupied spaces, ensuring safe and efficient drainage operation.
2. Which pipe is commonly used for underground DWV systems?
A. PVC Schedule 40
B. Copper Type L
C. Black steel
D. Galvanized steel
Answer: A
Rationale: PVC Schedule 40 is resistant to corrosion, lightweight, and cost-
, effective, making it the standard for underground drainage, waste, and
vent systems.
3. What does a P-trap primarily prevent?
A. Water hammer
B. Backpressure
C. Sewer gas entry
D. Pipe corrosion
Answer: C
Rationale: A P-trap maintains a water seal that blocks sewer gases from
entering the building while allowing wastewater to pass through.
4. What is the minimum slope for a 3-inch horizontal drain pipe?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1 inch per foot
Answer: B
Rationale: A 3-inch drain typically requires a minimum slope of 1/8 inch
per foot to maintain adequate flow velocity and prevent solids from
settling.
5. Which fixture unit system is used to size plumbing systems?
A. British Thermal Units
B. Hunter’s Curve
C. Fixture Unit Method
D. Pascal System
Answer: C
Rationale: The fixture unit method estimates probable demand, allowing
, accurate sizing of water supply and drainage systems based on usage
patterns.
6. What is the purpose of a cleanout?
A. Increase pressure
B. Allow pipe inspection and rodding
C. Reduce pipe size
D. Trap debris permanently
Answer: B
Rationale: Cleanouts provide access points for maintenance, allowing
plumbers to remove blockages and inspect drainage systems.
7. Which material is most resistant to acidic waste?
A. Cast iron
B. PVC
C. Copper
D. Galvanized steel
Answer: B
Rationale: PVC is chemically resistant to most acids and corrosive
substances, making it ideal for chemical waste drainage systems.
8. What is water hammer?
A. Air in water lines
B. Pressure surge caused by sudden valve closure
C. Low water pressure
D. Pipe corrosion
Answer: B
Rationale: Water hammer is a shockwave created when flowing water is
suddenly stopped, causing pressure spikes that can damage piping
systems.
, 9. Which device prevents backflow in potable water systems?
A. Air gap
B. P-trap
C. Vent stack
D. Cleanout
Answer: A
Rationale: An air gap provides a physical separation between potable
water and potential contaminants, making it the most reliable backflow
prevention method.
10.What is the function of a vent stack?
A. Carry sewage
B. Provide structural support
C. Equalize air pressure in drainage systems
D. Store water
Answer: C
Rationale: A vent stack ensures atmospheric pressure balance in drainage
piping, preventing siphoning and trap seal loss.
11.Which pipe is commonly used for hot water distribution?
A. PVC
B. CPVC
C. ABS
D. Clay
Answer: B
Rationale: CPVC is rated for higher temperatures and is suitable for hot
potable water distribution systems.
Examination – Advanced Plumbing
Systems Classification Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Prevent sewer gases from entering the building
C. Increase drainage speed
D. Store wastewater
Answer: B
Rationale: The vent system allows air into the drainage system,
preventing trap siphonage and blocking sewer gases from entering
occupied spaces, ensuring safe and efficient drainage operation.
2. Which pipe is commonly used for underground DWV systems?
A. PVC Schedule 40
B. Copper Type L
C. Black steel
D. Galvanized steel
Answer: A
Rationale: PVC Schedule 40 is resistant to corrosion, lightweight, and cost-
, effective, making it the standard for underground drainage, waste, and
vent systems.
3. What does a P-trap primarily prevent?
A. Water hammer
B. Backpressure
C. Sewer gas entry
D. Pipe corrosion
Answer: C
Rationale: A P-trap maintains a water seal that blocks sewer gases from
entering the building while allowing wastewater to pass through.
4. What is the minimum slope for a 3-inch horizontal drain pipe?
A. 1/16 inch per foot
B. 1/8 inch per foot
C. 1/4 inch per foot
D. 1 inch per foot
Answer: B
Rationale: A 3-inch drain typically requires a minimum slope of 1/8 inch
per foot to maintain adequate flow velocity and prevent solids from
settling.
5. Which fixture unit system is used to size plumbing systems?
A. British Thermal Units
B. Hunter’s Curve
C. Fixture Unit Method
D. Pascal System
Answer: C
Rationale: The fixture unit method estimates probable demand, allowing
, accurate sizing of water supply and drainage systems based on usage
patterns.
6. What is the purpose of a cleanout?
A. Increase pressure
B. Allow pipe inspection and rodding
C. Reduce pipe size
D. Trap debris permanently
Answer: B
Rationale: Cleanouts provide access points for maintenance, allowing
plumbers to remove blockages and inspect drainage systems.
7. Which material is most resistant to acidic waste?
A. Cast iron
B. PVC
C. Copper
D. Galvanized steel
Answer: B
Rationale: PVC is chemically resistant to most acids and corrosive
substances, making it ideal for chemical waste drainage systems.
8. What is water hammer?
A. Air in water lines
B. Pressure surge caused by sudden valve closure
C. Low water pressure
D. Pipe corrosion
Answer: B
Rationale: Water hammer is a shockwave created when flowing water is
suddenly stopped, causing pressure spikes that can damage piping
systems.
, 9. Which device prevents backflow in potable water systems?
A. Air gap
B. P-trap
C. Vent stack
D. Cleanout
Answer: A
Rationale: An air gap provides a physical separation between potable
water and potential contaminants, making it the most reliable backflow
prevention method.
10.What is the function of a vent stack?
A. Carry sewage
B. Provide structural support
C. Equalize air pressure in drainage systems
D. Store water
Answer: C
Rationale: A vent stack ensures atmospheric pressure balance in drainage
piping, preventing siphoning and trap seal loss.
11.Which pipe is commonly used for hot water distribution?
A. PVC
B. CPVC
C. ABS
D. Clay
Answer: B
Rationale: CPVC is rated for higher temperatures and is suitable for hot
potable water distribution systems.
