CO Gas Line Utility Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a gas line regulator?
A. To increase gas pressure
B. To filter impurities from gas
C. To reduce and control gas pressure
D. To measure gas flow
Rationale: Regulators are designed to reduce high-pressure gas from
the main supply to a safe, usable pressure for appliances or systems.
2. Which material is commonly used for underground gas piping in
Colorado?
A. Copper
B. PE (polyethylene) plastic
C. PVC
D. Aluminum
Rationale: PE is flexible, corrosion-resistant, and approved for
underground gas service in many areas.
3. What is the minimum depth for burying a plastic gas line under a
residential driveway?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: Local codes typically require plastic gas lines to be buried
at least 18 inches to prevent damage from surface loads.
,4. When performing a pressure test on a new gas line, which medium is
considered safest?
A. Natural gas
B. Air or inert gas
C. Propane
D. Oxygen
Rationale: Using air or an inert gas reduces the risk of fire or
explosion during testing.
5. What is the main hazard associated with natural gas leaks?
A. Corrosion
B. Freezing
C. Explosion and fire
D. Noise pollution
Rationale: Natural gas is highly flammable; leaks can lead to
explosions if ignited.
6. What tool is commonly used to locate underground gas lines?
A. Pipe wrench
B. Sledgehammer
C. Electromagnetic locator or tracer wire
D. Thermometer
Rationale: Locating tools detect tracer wires or metal pipes to prevent
accidental damage.
7. Which color is typically used to mark underground natural gas lines?
A. Blue
B. Green
C. Yellow
D. Red
Rationale: Yellow indicates flammable gas according to standard
utility marking codes.
8. Before connecting a new gas appliance, what must be checked?
A. Voltage
B. Humidity
C. Gas pressure and leak-tightness
D. Water flow
Rationale: Ensuring proper pressure and leak-free connections is
critical for safety and appliance operation.
, 9. Which component prevents backflow of gas into the main supply?
A. Valve
B. Pressure regulator
C. Check valve
D. Flow meter
Rationale: Check valves allow flow in one direction only, preventing
reverse flow.
10. In the event of a gas leak, what is the first step?
A. Light a candle
B. Call a plumber
C. Evacuate the area and notify the gas utility
D. Use water to douse flames
Rationale: Safety protocols require evacuation and alerting
authorities to prevent explosions.
11. Which device measures the volume of gas consumed by a
customer?
A. Pressure gauge
B. Gas meter
C. Flow switch
D. Thermocouple
Rationale: Gas meters record the amount of gas delivered for billing
purposes.
12. What is the function of a drip leg or sediment trap?
A. Regulate pressure
B. Collect moisture and debris from gas
C. Increase gas flow
D. Serve as a backup valve
Rationale: Sediment traps prevent contaminants from entering
appliances, protecting equipment.
13. When soldering copper gas pipes, which type of solder is
required?
A. Leaded solder
B. Silver solder
C. Lead-free solder
D. Tin solder
Rationale: Lead-free solder prevents contamination and meets safety
standards.
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of a gas line regulator?
A. To increase gas pressure
B. To filter impurities from gas
C. To reduce and control gas pressure
D. To measure gas flow
Rationale: Regulators are designed to reduce high-pressure gas from
the main supply to a safe, usable pressure for appliances or systems.
2. Which material is commonly used for underground gas piping in
Colorado?
A. Copper
B. PE (polyethylene) plastic
C. PVC
D. Aluminum
Rationale: PE is flexible, corrosion-resistant, and approved for
underground gas service in many areas.
3. What is the minimum depth for burying a plastic gas line under a
residential driveway?
A. 6 inches
B. 12 inches
C. 18 inches
D. 24 inches
Rationale: Local codes typically require plastic gas lines to be buried
at least 18 inches to prevent damage from surface loads.
,4. When performing a pressure test on a new gas line, which medium is
considered safest?
A. Natural gas
B. Air or inert gas
C. Propane
D. Oxygen
Rationale: Using air or an inert gas reduces the risk of fire or
explosion during testing.
5. What is the main hazard associated with natural gas leaks?
A. Corrosion
B. Freezing
C. Explosion and fire
D. Noise pollution
Rationale: Natural gas is highly flammable; leaks can lead to
explosions if ignited.
6. What tool is commonly used to locate underground gas lines?
A. Pipe wrench
B. Sledgehammer
C. Electromagnetic locator or tracer wire
D. Thermometer
Rationale: Locating tools detect tracer wires or metal pipes to prevent
accidental damage.
7. Which color is typically used to mark underground natural gas lines?
A. Blue
B. Green
C. Yellow
D. Red
Rationale: Yellow indicates flammable gas according to standard
utility marking codes.
8. Before connecting a new gas appliance, what must be checked?
A. Voltage
B. Humidity
C. Gas pressure and leak-tightness
D. Water flow
Rationale: Ensuring proper pressure and leak-free connections is
critical for safety and appliance operation.
, 9. Which component prevents backflow of gas into the main supply?
A. Valve
B. Pressure regulator
C. Check valve
D. Flow meter
Rationale: Check valves allow flow in one direction only, preventing
reverse flow.
10. In the event of a gas leak, what is the first step?
A. Light a candle
B. Call a plumber
C. Evacuate the area and notify the gas utility
D. Use water to douse flames
Rationale: Safety protocols require evacuation and alerting
authorities to prevent explosions.
11. Which device measures the volume of gas consumed by a
customer?
A. Pressure gauge
B. Gas meter
C. Flow switch
D. Thermocouple
Rationale: Gas meters record the amount of gas delivered for billing
purposes.
12. What is the function of a drip leg or sediment trap?
A. Regulate pressure
B. Collect moisture and debris from gas
C. Increase gas flow
D. Serve as a backup valve
Rationale: Sediment traps prevent contaminants from entering
appliances, protecting equipment.
13. When soldering copper gas pipes, which type of solder is
required?
A. Leaded solder
B. Silver solder
C. Lead-free solder
D. Tin solder
Rationale: Lead-free solder prevents contamination and meets safety
standards.
