Cfesa Gas Certification Exam PRACTICE
QUESTIONS |ORIGINAL QUESTIONS &
ANSWERS |DETAILED RATIONALES
|HINTED COMPLETE EXAM PREP
GRADED A+*INSTANT DOWNLOAD PDF
1. What is the primary purpose of a gas appliance regulator?
A. Increase gas pressure
B. Maintain the required outlet gas pressure
C. Remove carbon monoxide
D. Increase combustion air
Rationale: A regulator controls and maintains gas pressure supplied
to the appliance within the manufacturer's specified range.
2. Which gas is naturally odorless and is commonly odorized for
leak detection?
A. Carbon monoxide
B. Oxygen
C. Natural gas
D. Nitrogen
Rationale: Natural gas has little inherent odor, so an odorant such as
mercaptan is added to help users detect leaks.
3. What should be done first when a strong gas odor is detected
inside a facility?
,A. Turn on exhaust fans
B. Locate the burner causing the leak
C. Avoid ignition sources and follow the facility's gas-emergency
procedure
D. Light all appliance pilots
Rationale: A gas accumulation can ignite explosively. Personnel
should avoid ignition sources and follow established emergency
procedures.
4. Which gas is heavier than air?
A. Natural gas
B. Hydrogen
C. Propane
D. Helium
Rationale: Propane has a higher density than air and can collect in
low areas.
5. Natural gas is primarily composed of which hydrocarbon?
A. Propane
B. Butane
C. Methane
D. Ethylene
Rationale: Methane is the principal component of conventional
natural gas.
6. What is the main danger of incomplete combustion?
A. Excess oxygen
B. Low humidity
,C. Carbon monoxide production
D. Excess nitrogen
Rationale: Incomplete combustion can produce carbon monoxide, a
toxic, odorless gas.
7. A yellow, lazy burner flame may indicate:
A. Excessive combustion air
B. Insufficient combustion air or contamination
C. Excessive electrical voltage
D. Correct combustion
Rationale: Properly adjusted gas burners generally produce a stable
blue flame. Yellow flames can indicate poor air-gas mixing or
contamination.
8. What is the safest general practice before servicing a gas
appliance?
A. Increase the thermostat setting
B. Shut off the appropriate gas and electrical energy sources as
required
C. Remove the burner immediately
D. Open every gas valve
Rationale: Energy isolation reduces the risk of gas release, ignition,
electrical shock, and unexpected appliance operation.
9. Carbon monoxide is dangerous primarily because it:
A. Is highly visible
B. Has a strong odor
, C. Interferes with oxygen transport in the body
D. Freezes at room temperature
Rationale: Carbon monoxide binds strongly to hemoglobin, reducing
the blood's ability to transport oxygen.
10. What is the purpose of combustion air?
A. Cool the appliance only
B. Supply oxygen required for combustion
C. Increase gas pressure
D. Lubricate the gas valve
Rationale: Gas combustion requires adequate oxygen, which is
supplied through combustion air.
11. Which condition can cause flame rollout?
A. Proper venting
B. Blocked heat-exchanger or flue passages and abnormal
combustion conditions
C. Correct manifold pressure
D. Clean burners
Rationale: Restricted combustion or venting can cause flames to
move outside their intended combustion zone.
12. What is the purpose of a gas shutoff valve?
A. Increase pressure
B. Filter combustion air
C. Stop gas flow
D. Measure temperature
QUESTIONS |ORIGINAL QUESTIONS &
ANSWERS |DETAILED RATIONALES
|HINTED COMPLETE EXAM PREP
GRADED A+*INSTANT DOWNLOAD PDF
1. What is the primary purpose of a gas appliance regulator?
A. Increase gas pressure
B. Maintain the required outlet gas pressure
C. Remove carbon monoxide
D. Increase combustion air
Rationale: A regulator controls and maintains gas pressure supplied
to the appliance within the manufacturer's specified range.
2. Which gas is naturally odorless and is commonly odorized for
leak detection?
A. Carbon monoxide
B. Oxygen
C. Natural gas
D. Nitrogen
Rationale: Natural gas has little inherent odor, so an odorant such as
mercaptan is added to help users detect leaks.
3. What should be done first when a strong gas odor is detected
inside a facility?
,A. Turn on exhaust fans
B. Locate the burner causing the leak
C. Avoid ignition sources and follow the facility's gas-emergency
procedure
D. Light all appliance pilots
Rationale: A gas accumulation can ignite explosively. Personnel
should avoid ignition sources and follow established emergency
procedures.
4. Which gas is heavier than air?
A. Natural gas
B. Hydrogen
C. Propane
D. Helium
Rationale: Propane has a higher density than air and can collect in
low areas.
5. Natural gas is primarily composed of which hydrocarbon?
A. Propane
B. Butane
C. Methane
D. Ethylene
Rationale: Methane is the principal component of conventional
natural gas.
6. What is the main danger of incomplete combustion?
A. Excess oxygen
B. Low humidity
,C. Carbon monoxide production
D. Excess nitrogen
Rationale: Incomplete combustion can produce carbon monoxide, a
toxic, odorless gas.
7. A yellow, lazy burner flame may indicate:
A. Excessive combustion air
B. Insufficient combustion air or contamination
C. Excessive electrical voltage
D. Correct combustion
Rationale: Properly adjusted gas burners generally produce a stable
blue flame. Yellow flames can indicate poor air-gas mixing or
contamination.
8. What is the safest general practice before servicing a gas
appliance?
A. Increase the thermostat setting
B. Shut off the appropriate gas and electrical energy sources as
required
C. Remove the burner immediately
D. Open every gas valve
Rationale: Energy isolation reduces the risk of gas release, ignition,
electrical shock, and unexpected appliance operation.
9. Carbon monoxide is dangerous primarily because it:
A. Is highly visible
B. Has a strong odor
, C. Interferes with oxygen transport in the body
D. Freezes at room temperature
Rationale: Carbon monoxide binds strongly to hemoglobin, reducing
the blood's ability to transport oxygen.
10. What is the purpose of combustion air?
A. Cool the appliance only
B. Supply oxygen required for combustion
C. Increase gas pressure
D. Lubricate the gas valve
Rationale: Gas combustion requires adequate oxygen, which is
supplied through combustion air.
11. Which condition can cause flame rollout?
A. Proper venting
B. Blocked heat-exchanger or flue passages and abnormal
combustion conditions
C. Correct manifold pressure
D. Clean burners
Rationale: Restricted combustion or venting can cause flames to
move outside their intended combustion zone.
12. What is the purpose of a gas shutoff valve?
A. Increase pressure
B. Filter combustion air
C. Stop gas flow
D. Measure temperature
