Arkansas Master Plumber Exam Verified
Questions, Correct Answers, and Detailed
Explanations for Science Students||Already
Graded A+
1. What is the minimum slope required for a 2-inch horizontal drain
pipe?
A) 1/8 inch per foot
B) 1/4 inch per foot
C) 1/2 inch per foot
D) 1 inch per foot
Answer: B) 1/4 inch per foot
Rationale: The Arkansas Plumbing Code requires a minimum slope of
1/4 inch per foot for horizontal drains 2 inches in diameter to ensure
proper drainage.
2. A plumbing system is considered a “fixture unit” when it:
A) Receives water from a private well
B) Contributes a standardized load to the system
C) Is located outdoors
D) Only serves industrial facilities
Answer: B) Contributes a standardized load to the system
Rationale: Fixture units are used to calculate the load on water and
drainage systems; each type of fixture is assigned a specific value.
3. What is the maximum distance a cleanout can be installed from
the end of a building drain?
A) 50 feet
B) 75 feet
,C) 100 feet
D) 125 feet
Answer: C) 100 feet
Rationale: According to the Arkansas Plumbing Code, cleanouts must
be installed at a maximum of 100 feet from the end of the building
drain.
4. What type of vent is installed horizontally and connects to the
main vent stack above the flood level rim of fixtures?
A) Circuit vent
B) Relief vent
C) Loop vent
D) Individual vent
Answer: D) Individual vent
Rationale: Individual vents rise vertically from each fixture’s trap and
connect to the main vent stack above the flood rim.
5. What is the minimum size water service pipe for a typical single-
family dwelling?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1 1/4 inch
Answer: B) 3/4 inch
Rationale: Most codes, including Arkansas, require a minimum 3/4-
inch water service for a single-family dwelling to ensure adequate
flow.
,6. Which material is NOT typically allowed for underground potable
water service piping?
A) Copper
B) PVC
C) Galvanized steel
D) PEX
Answer: C) Galvanized steel
Rationale: Galvanized steel is prone to corrosion and is generally
prohibited for underground potable water lines.
7. What is the required air gap for a potable water connection to a
tank-type water heater?
A) 1/2 inch
B) 1 inch
C) 2 inches
D) 3 inches
Answer: B) 1 inch
Rationale: The air gap prevents backflow contamination; codes
typically require a minimum of 1 inch above the flood rim.
8. A pressure relief valve on a water heater must discharge to:
A) The nearest floor drain
B) The outdoors or approved receptor
C) The main sewer line
D) A hose connection
Answer: B) The outdoors or approved receptor
Rationale: This prevents scalding hazards or flooding inside the
building.
, 9. What is the minimum trap arm length for a 1 1/2-inch drain?
A) 12 inches
B) 18 inches
C) 24 inches
D) 30 inches
Answer: C) 24 inches
Rationale: The trap arm length ensures proper venting and prevents
siphoning, per code tables.
10. What is the proper method for joining PVC drain pipes?
A) Soldering
B) Threaded coupling
C) Solvent cement
D) Compression fitting
Answer: C) Solvent cement
Rationale: PVC pipes are joined with primer and solvent cement for a
watertight seal.
11. How often must backflow preventers be tested in commercial
installations?
A) Monthly
B) Annually
C) Every 2 years
D) Every 5 years
Answer: B) Annually
Rationale: Annual testing ensures that backflow preventers function
correctly to protect potable water.
Questions, Correct Answers, and Detailed
Explanations for Science Students||Already
Graded A+
1. What is the minimum slope required for a 2-inch horizontal drain
pipe?
A) 1/8 inch per foot
B) 1/4 inch per foot
C) 1/2 inch per foot
D) 1 inch per foot
Answer: B) 1/4 inch per foot
Rationale: The Arkansas Plumbing Code requires a minimum slope of
1/4 inch per foot for horizontal drains 2 inches in diameter to ensure
proper drainage.
2. A plumbing system is considered a “fixture unit” when it:
A) Receives water from a private well
B) Contributes a standardized load to the system
C) Is located outdoors
D) Only serves industrial facilities
Answer: B) Contributes a standardized load to the system
Rationale: Fixture units are used to calculate the load on water and
drainage systems; each type of fixture is assigned a specific value.
3. What is the maximum distance a cleanout can be installed from
the end of a building drain?
A) 50 feet
B) 75 feet
,C) 100 feet
D) 125 feet
Answer: C) 100 feet
Rationale: According to the Arkansas Plumbing Code, cleanouts must
be installed at a maximum of 100 feet from the end of the building
drain.
4. What type of vent is installed horizontally and connects to the
main vent stack above the flood level rim of fixtures?
A) Circuit vent
B) Relief vent
C) Loop vent
D) Individual vent
Answer: D) Individual vent
Rationale: Individual vents rise vertically from each fixture’s trap and
connect to the main vent stack above the flood rim.
5. What is the minimum size water service pipe for a typical single-
family dwelling?
A) 1/2 inch
B) 3/4 inch
C) 1 inch
D) 1 1/4 inch
Answer: B) 3/4 inch
Rationale: Most codes, including Arkansas, require a minimum 3/4-
inch water service for a single-family dwelling to ensure adequate
flow.
,6. Which material is NOT typically allowed for underground potable
water service piping?
A) Copper
B) PVC
C) Galvanized steel
D) PEX
Answer: C) Galvanized steel
Rationale: Galvanized steel is prone to corrosion and is generally
prohibited for underground potable water lines.
7. What is the required air gap for a potable water connection to a
tank-type water heater?
A) 1/2 inch
B) 1 inch
C) 2 inches
D) 3 inches
Answer: B) 1 inch
Rationale: The air gap prevents backflow contamination; codes
typically require a minimum of 1 inch above the flood rim.
8. A pressure relief valve on a water heater must discharge to:
A) The nearest floor drain
B) The outdoors or approved receptor
C) The main sewer line
D) A hose connection
Answer: B) The outdoors or approved receptor
Rationale: This prevents scalding hazards or flooding inside the
building.
, 9. What is the minimum trap arm length for a 1 1/2-inch drain?
A) 12 inches
B) 18 inches
C) 24 inches
D) 30 inches
Answer: C) 24 inches
Rationale: The trap arm length ensures proper venting and prevents
siphoning, per code tables.
10. What is the proper method for joining PVC drain pipes?
A) Soldering
B) Threaded coupling
C) Solvent cement
D) Compression fitting
Answer: C) Solvent cement
Rationale: PVC pipes are joined with primer and solvent cement for a
watertight seal.
11. How often must backflow preventers be tested in commercial
installations?
A) Monthly
B) Annually
C) Every 2 years
D) Every 5 years
Answer: B) Annually
Rationale: Annual testing ensures that backflow preventers function
correctly to protect potable water.
