CO Journeyman Plumber Exam Questions
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
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1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent pipe corrosion
C. To prevent sewer gases from entering a building
D. To increase drainage flow
Rationale: A plumbing trap maintains a water seal between the
drainage system and the occupied space. This water seal prevents
sewer gases and odors from entering the building while still allowing
wastewater to drain.
2. Which component is used to protect the potable water supply
from contamination caused by backsiphonage?
,A. Cleanout
B. Trap primer
C. Backflow prevention device
D. Pressure-reducing valve
Rationale: Backflow prevention devices are designed to prevent
contaminated or nonpotable water from reversing direction and
entering the potable water system. The specific device required
depends on the degree and type of cross-connection hazard.
3. What is the primary function of a plumbing vent system?
A. To increase water pressure
B. To carry solid waste
C. To protect trap seals and allow proper drainage-system airflow
D. To supply hot water to fixtures
Rationale: Venting allows air to enter and move through the drainage
system, helping maintain atmospheric pressure and preventing
siphonage or excessive pressure fluctuations that could destroy trap
seals.
4. Which fitting is commonly used to change the direction of a
drainage pipe by approximately 90 degrees?
,A. Coupling
B. Union
C. Elbow
D. Reducer
Rationale: An elbow changes the direction of piping. In drainage
systems, fittings with appropriate sweep characteristics are used to
promote smooth flow and reduce the likelihood of blockages.
5. What is the purpose of a cleanout in a drainage system?
A. To regulate water temperature
B. To increase water pressure
C. To provide access for inspection and cleaning of the piping
D. To prevent thermal expansion
Rationale: Cleanouts provide access to drainage piping so plumbers
can inspect, clear stoppages, and maintain the system without having
to remove fixtures or dismantle extensive portions of the piping.
6. Which type of fitting is generally preferred for changing direction
in a sanitary drainage system because it provides a smoother
transition?
A. Sharp 90-degree elbow
B. Long-sweep fitting
, C. Cap
D. Bushing
Rationale: Long-sweep fittings provide a gradual change in direction,
reducing turbulence and resistance to flow. Drainage systems
generally require fittings designed to facilitate gravity flow and
minimize obstruction points.
7. What is the purpose of a pressure-reducing valve on a water-
supply system?
A. To increase static pressure
B. To remove sediment
C. To reduce excessive water pressure to an acceptable level
D. To prevent sewer gases
Rationale: A pressure-reducing valve automatically regulates
downstream pressure when the incoming supply pressure is too high.
This helps protect fixtures, valves, appliances, and piping.
8. Which device is commonly used to prevent a hose or submerged
outlet from creating a backsiphonage condition?
A. Water hammer arrestor
B. Atmospheric vacuum breaker
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. What is the primary purpose of a plumbing trap?
A. To increase water pressure
B. To prevent pipe corrosion
C. To prevent sewer gases from entering a building
D. To increase drainage flow
Rationale: A plumbing trap maintains a water seal between the
drainage system and the occupied space. This water seal prevents
sewer gases and odors from entering the building while still allowing
wastewater to drain.
2. Which component is used to protect the potable water supply
from contamination caused by backsiphonage?
,A. Cleanout
B. Trap primer
C. Backflow prevention device
D. Pressure-reducing valve
Rationale: Backflow prevention devices are designed to prevent
contaminated or nonpotable water from reversing direction and
entering the potable water system. The specific device required
depends on the degree and type of cross-connection hazard.
3. What is the primary function of a plumbing vent system?
A. To increase water pressure
B. To carry solid waste
C. To protect trap seals and allow proper drainage-system airflow
D. To supply hot water to fixtures
Rationale: Venting allows air to enter and move through the drainage
system, helping maintain atmospheric pressure and preventing
siphonage or excessive pressure fluctuations that could destroy trap
seals.
4. Which fitting is commonly used to change the direction of a
drainage pipe by approximately 90 degrees?
,A. Coupling
B. Union
C. Elbow
D. Reducer
Rationale: An elbow changes the direction of piping. In drainage
systems, fittings with appropriate sweep characteristics are used to
promote smooth flow and reduce the likelihood of blockages.
5. What is the purpose of a cleanout in a drainage system?
A. To regulate water temperature
B. To increase water pressure
C. To provide access for inspection and cleaning of the piping
D. To prevent thermal expansion
Rationale: Cleanouts provide access to drainage piping so plumbers
can inspect, clear stoppages, and maintain the system without having
to remove fixtures or dismantle extensive portions of the piping.
6. Which type of fitting is generally preferred for changing direction
in a sanitary drainage system because it provides a smoother
transition?
A. Sharp 90-degree elbow
B. Long-sweep fitting
, C. Cap
D. Bushing
Rationale: Long-sweep fittings provide a gradual change in direction,
reducing turbulence and resistance to flow. Drainage systems
generally require fittings designed to facilitate gravity flow and
minimize obstruction points.
7. What is the purpose of a pressure-reducing valve on a water-
supply system?
A. To increase static pressure
B. To remove sediment
C. To reduce excessive water pressure to an acceptable level
D. To prevent sewer gases
Rationale: A pressure-reducing valve automatically regulates
downstream pressure when the incoming supply pressure is too high.
This helps protect fixtures, valves, appliances, and piping.
8. Which device is commonly used to prevent a hose or submerged
outlet from creating a backsiphonage condition?
A. Water hammer arrestor
B. Atmospheric vacuum breaker
