Arkansas Master Plumber Exam –Most Tested Questions with Verified
Answers & Bold Italic Rationales | Latest Updated Study Guide Construction
This comprehensive question bank is designed for candidates preparing for the
Arkansas Master Plumber Examination. It delivers 300 unique, high-yield
questions with verified answers, bold italic rationales, and zero repeated or
rephrased items. The content spans the full Arkansas Master Plumber Exam Core
Knowledge Areas, including plumbing fundamentals, drainage waste and vent
systems, water supply and distribution, gas piping and appliance venting,
combustion and ventilation air, code administration, and Arkansas licensing law.
SECTION 1: PLUMBING FUNDAMENTALS & DEFINITIONS (Q1–Q35)
Q1. What is the primary purpose of a plumbing trap in a drainage system?
A) To increase water pressure at the fixture outlet
B) To prevent sewer gases from entering an occupied building
C) To increase the velocity of wastewater flow
D) To reduce the temperature of wastewater before discharge
Correct Answer: B) To prevent sewer gases from entering an occupied
building
Rationale: A plumbing trap retains a water seal that blocks sewer gases and
odors from entering the occupied portion of a building while still allowing
wastewater to drain.
,Q2. What is the primary function of a plumbing vent system?
A) To supply potable water to fixtures
B) To maintain proper air pressure within the drainage system
C) To increase water temperature for sanitation
D) To filter wastewater before it enters the sewer
Correct Answer: B) To maintain proper air pressure within the drainage
system
Rationale: Venting allows air to enter and leave the drainage system, protecting
trap seals and permitting wastewater to flow properly.
Q3. According to the Arkansas Plumbing Code, what is the minimum slope
required for a 3-inch horizontal drain pipe carrying wastewater?
A) 1/8 inch per foot
B) 1/4 inch per foot
C) 1/2 inch per foot
D) 1 inch per foot
Correct Answer: B) 1/4 inch per foot
Rationale: The 2018 Arkansas Plumbing Code requires a minimum slope of 1/4
inch per foot for DWV pipes 3 inches and larger to ensure proper drainage.
,Q4. In an isometric DWV riser diagram, vent pipes are traditionally shown in which
color?
A) Red
B) Green
C) Blue
D) Yellow
Correct Answer: C) Blue
Rationale: Blue is commonly used to represent vent piping on isometric drawings,
distinguishing them from drains (red) and water supply (green).
Q5. What is the minimum depth of a fixture trap seal according to the Arkansas
Plumbing Code?
A) 1 inch
B) 2 inches
C) 3 inches
D) 4 inches
Correct Answer: B) 2 inches
Rationale: The APC mandates a minimum 2-inch water seal for floor drains and
fixture traps to prevent sewer gas entry.
Q6. Which material is prohibited for use in new water supply piping in Arkansas as
of the 2018 APC?
, A) Copper
B) PEX
C) Galvanized steel
D) CPVC
Correct Answer: C) Galvanized steel
Rationale: Galvanized steel is no longer approved for new water supply systems
due to corrosion and lead concerns.
Q7. What is the minimum drain pipe size required for a water closet under the IPC
as adopted in Arkansas?
A) 2 inches
B) 3 inches
C) 4 inches
D) 1-1/2 inches
Correct Answer: B) 3 inches
Rationale: Per IPC drainage pipe sizing tables, the minimum drain size for a water
closet is 3 inches.
Q8. What is the DFU value for a residential lavatory?
A) 1 DFU
B) 2 DFU
Answers & Bold Italic Rationales | Latest Updated Study Guide Construction
This comprehensive question bank is designed for candidates preparing for the
Arkansas Master Plumber Examination. It delivers 300 unique, high-yield
questions with verified answers, bold italic rationales, and zero repeated or
rephrased items. The content spans the full Arkansas Master Plumber Exam Core
Knowledge Areas, including plumbing fundamentals, drainage waste and vent
systems, water supply and distribution, gas piping and appliance venting,
combustion and ventilation air, code administration, and Arkansas licensing law.
SECTION 1: PLUMBING FUNDAMENTALS & DEFINITIONS (Q1–Q35)
Q1. What is the primary purpose of a plumbing trap in a drainage system?
A) To increase water pressure at the fixture outlet
B) To prevent sewer gases from entering an occupied building
C) To increase the velocity of wastewater flow
D) To reduce the temperature of wastewater before discharge
Correct Answer: B) To prevent sewer gases from entering an occupied
building
Rationale: A plumbing trap retains a water seal that blocks sewer gases and
odors from entering the occupied portion of a building while still allowing
wastewater to drain.
,Q2. What is the primary function of a plumbing vent system?
A) To supply potable water to fixtures
B) To maintain proper air pressure within the drainage system
C) To increase water temperature for sanitation
D) To filter wastewater before it enters the sewer
Correct Answer: B) To maintain proper air pressure within the drainage
system
Rationale: Venting allows air to enter and leave the drainage system, protecting
trap seals and permitting wastewater to flow properly.
Q3. According to the Arkansas Plumbing Code, what is the minimum slope
required for a 3-inch horizontal drain pipe carrying wastewater?
A) 1/8 inch per foot
B) 1/4 inch per foot
C) 1/2 inch per foot
D) 1 inch per foot
Correct Answer: B) 1/4 inch per foot
Rationale: The 2018 Arkansas Plumbing Code requires a minimum slope of 1/4
inch per foot for DWV pipes 3 inches and larger to ensure proper drainage.
,Q4. In an isometric DWV riser diagram, vent pipes are traditionally shown in which
color?
A) Red
B) Green
C) Blue
D) Yellow
Correct Answer: C) Blue
Rationale: Blue is commonly used to represent vent piping on isometric drawings,
distinguishing them from drains (red) and water supply (green).
Q5. What is the minimum depth of a fixture trap seal according to the Arkansas
Plumbing Code?
A) 1 inch
B) 2 inches
C) 3 inches
D) 4 inches
Correct Answer: B) 2 inches
Rationale: The APC mandates a minimum 2-inch water seal for floor drains and
fixture traps to prevent sewer gas entry.
Q6. Which material is prohibited for use in new water supply piping in Arkansas as
of the 2018 APC?
, A) Copper
B) PEX
C) Galvanized steel
D) CPVC
Correct Answer: C) Galvanized steel
Rationale: Galvanized steel is no longer approved for new water supply systems
due to corrosion and lead concerns.
Q7. What is the minimum drain pipe size required for a water closet under the IPC
as adopted in Arkansas?
A) 2 inches
B) 3 inches
C) 4 inches
D) 1-1/2 inches
Correct Answer: B) 3 inches
Rationale: Per IPC drainage pipe sizing tables, the minimum drain size for a water
closet is 3 inches.
Q8. What is the DFU value for a residential lavatory?
A) 1 DFU
B) 2 DFU
