AZ ROC – CR-37 Plumbing Contractor
Examination Questions and Correct Answers
(Verified Answers) Plus Rationale 2027 Q&A|
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1. What is the primary purpose of a plumbing trap installed beneath
a fixture?
A. To increase water pressure
B. To prevent sewer gases from entering the building
C. To increase drainage velocity
D. To prevent hot water from reaching the fixture
Answer: B. To prevent sewer gases from entering the building
Rationale: A plumbing trap maintains a water seal between the
fixture and the drainage system. This water seal prevents
objectionable and potentially hazardous sewer gases from entering
occupied spaces.
, 2. Which fitting is commonly used to change the direction of a
drainage pipe by approximately 90 degrees while providing
relatively smooth flow?
A. Sanitary tee
B. Long-sweep elbow
C. Cap
D. Bushing
Answer: B. Long-sweep elbow
Rationale: A long-sweep fitting provides a gradual change in
direction, reducing turbulence and the likelihood of blockage.
Drainage systems generally require fittings designed to maintain
smooth flow rather than sharp directional changes.
3. What is the primary function of a plumbing vent system?
A. Increase water pressure
B. Supply drinking water
C. Protect trap seals and allow drainage-system air circulation
D. Heat the drainage system
Answer: C. Protect trap seals and allow drainage-system air
circulation
,Rationale: Vent piping allows air to enter and leave the drainage
system, helping maintain proper pressure relationships. This protects
fixture trap seals from siphonage or pressure effects that could allow
sewer gases to enter the building.
4. Which material is commonly used for potable-water distribution
piping?
A. Cast-iron soil pipe
B. Copper tubing
C. Asphalt pipe
D. Concrete drainage pipe
Answer: B. Copper tubing
Rationale: Copper tubing is widely used for potable-water systems
because it is durable, corrosion-resistant under appropriate
conditions, and approved for water distribution when properly
installed. Other approved materials may also be used depending on
the application and applicable code.
5. What does the term "DWV" stand for in plumbing?
, A. Domestic Water Valve
B. Drainage, Waste, and Vent
C. Direct Water Volume
D. Drain Water Vacuum
Answer: B. Drainage, Waste, and Vent
Rationale: DWV describes the portion of a plumbing system that
carries wastewater away from fixtures and provides venting. Properly
designed DWV systems are essential for sanitary drainage and
protection of trap seals.
6. Why should a sanitary tee generally not be used on its back for
connecting horizontal drainage piping?
A. It increases water pressure
B. It can create an unfavorable flow path and promote blockage
C. It makes the pipe too strong
D. It prevents venting completely
Answer: B. It can create an unfavorable flow path and promote
blockage
Rationale: Sanitary tees are shaped for appropriate vertical-to-
horizontal drainage transitions and vent connections. Using drainage
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 installed beneath
a fixture?
A. To increase water pressure
B. To prevent sewer gases from entering the building
C. To increase drainage velocity
D. To prevent hot water from reaching the fixture
Answer: B. To prevent sewer gases from entering the building
Rationale: A plumbing trap maintains a water seal between the
fixture and the drainage system. This water seal prevents
objectionable and potentially hazardous sewer gases from entering
occupied spaces.
, 2. Which fitting is commonly used to change the direction of a
drainage pipe by approximately 90 degrees while providing
relatively smooth flow?
A. Sanitary tee
B. Long-sweep elbow
C. Cap
D. Bushing
Answer: B. Long-sweep elbow
Rationale: A long-sweep fitting provides a gradual change in
direction, reducing turbulence and the likelihood of blockage.
Drainage systems generally require fittings designed to maintain
smooth flow rather than sharp directional changes.
3. What is the primary function of a plumbing vent system?
A. Increase water pressure
B. Supply drinking water
C. Protect trap seals and allow drainage-system air circulation
D. Heat the drainage system
Answer: C. Protect trap seals and allow drainage-system air
circulation
,Rationale: Vent piping allows air to enter and leave the drainage
system, helping maintain proper pressure relationships. This protects
fixture trap seals from siphonage or pressure effects that could allow
sewer gases to enter the building.
4. Which material is commonly used for potable-water distribution
piping?
A. Cast-iron soil pipe
B. Copper tubing
C. Asphalt pipe
D. Concrete drainage pipe
Answer: B. Copper tubing
Rationale: Copper tubing is widely used for potable-water systems
because it is durable, corrosion-resistant under appropriate
conditions, and approved for water distribution when properly
installed. Other approved materials may also be used depending on
the application and applicable code.
5. What does the term "DWV" stand for in plumbing?
, A. Domestic Water Valve
B. Drainage, Waste, and Vent
C. Direct Water Volume
D. Drain Water Vacuum
Answer: B. Drainage, Waste, and Vent
Rationale: DWV describes the portion of a plumbing system that
carries wastewater away from fixtures and provides venting. Properly
designed DWV systems are essential for sanitary drainage and
protection of trap seals.
6. Why should a sanitary tee generally not be used on its back for
connecting horizontal drainage piping?
A. It increases water pressure
B. It can create an unfavorable flow path and promote blockage
C. It makes the pipe too strong
D. It prevents venting completely
Answer: B. It can create an unfavorable flow path and promote
blockage
Rationale: Sanitary tees are shaped for appropriate vertical-to-
horizontal drainage transitions and vent connections. Using drainage
