FDNY G98 Handling, Use and Storage of
Flammable Compressed Gases Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales
Question 1: What is the primary hazard associated with flammable compressed
gases?
A) Toxicity
Correct Answer: C Fire and explosion
Rationale: Flammable compressed gases pose a significant risk of fire or explosion
if released in an uncontrolled manner and exposed to an ignition source. The
combination of pressure and flammability creates the potential for rapid
combustion. While some gases may also be toxic or cause asphyxiation, the
primary hazard addressed by the G-98 certificate is the fire and explosion risk .
Question 2: Which of the following gases is considered a flammable compressed
gas?
A) Oxygen
B) Nitrogen
C) Propane
,D) Carbon dioxide
Correct Answer: C Propane
Rationale: Propane is a hydrocarbon that is easily ignitable and stored under
pressure, classifying it as a flammable compressed gas. Oxygen supports
combustion but is not itself flammable—it is an oxidizer. Nitrogen and carbon
dioxide are inert/non-flammable gases .
Question 3: What is the "Lower Flammable Limit" (LFL)?
A) The temperature at which a gas ignites
B) The lowest concentration of gas in air that will ignite
C) The pressure at which a gas becomes unstable
D) The minimum storage temperature for safety
Correct Answer: B The lowest concentration of gas in air that will ignite
Rationale: Below this concentration, the gas mixture is too lean to burn. The LFL
represents the minimum percentage of gas in air required for combustion to
occur. Concentrations below the LFL are safe from ignition, while concentrations
within the flammable range (between LFL and UFL) present a fire or explosion
hazard .
Question 4: Which gas is lighter than air and can accumulate near ceilings?
A) Propane
B) Butane
,C) Hydrogen
D) Acetylene
Correct Answer: C Hydrogen
Rationale: Hydrogen is less dense than air and will rise, potentially gathering in
upper areas of a room or building. This affects ventilation and leak detection
strategies. Propane and butane are heavier than air and will accumulate near the
floor. Acetylene is slightly lighter than air but not as light as hydrogen .
Question 5: How should flammable compressed gas cylinders be stored according
to NFPA standards?
A) Horizontally on the floor
B) In well-ventilated areas away from ignition sources
C) Stacked on top of each other
D) Near electrical panels for easy access
Correct Answer: B In well-ventilated areas away from ignition sources
Rationale: Proper storage prevents gas accumulation and reduces the likelihood
of ignition. Ventilation dilutes any potential leaks while separation from ignition
sources eliminates potential triggers. Cylinders must always be stored upright,
never horizontally or stacked .
Question 6: What is the minimum distance flammable gas cylinders must be kept
from sources of ignition?
, A) 5 feet
B) 10 feet
C) 20 feet
D) 50 feet
Correct Answer: C 20 feet
Rationale: Maintaining a 20-foot separation reduces the risk of heat or sparks
igniting released gas. NFPA guidelines specifically require flammable gas cylinders
to be stored at least 20 feet from potential ignition sources, including open
flames, electrical equipment that could spark, and other heat sources .
Question 7: Flammable gas cylinders should be stored away from:
A) Other cylinders
B) Fire extinguishers
C) Heat and direct sunlight
D) Emergency exits
Correct Answer: C Heat and direct sunlight
Rationale: Heat can increase internal pressure and risk cylinder rupture or
activation of pressure relief devices. Direct sunlight can significantly raise cylinder
temperatures, potentially causing over-pressurization. Cylinders should be stored
in shaded, cool areas .
Question 8: Compressed gas cylinders must be stored:
A) Lying flat on their sides
B) Upright and secured to prevent tipping
Flammable Compressed Gases Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales
Question 1: What is the primary hazard associated with flammable compressed
gases?
A) Toxicity
Correct Answer: C Fire and explosion
Rationale: Flammable compressed gases pose a significant risk of fire or explosion
if released in an uncontrolled manner and exposed to an ignition source. The
combination of pressure and flammability creates the potential for rapid
combustion. While some gases may also be toxic or cause asphyxiation, the
primary hazard addressed by the G-98 certificate is the fire and explosion risk .
Question 2: Which of the following gases is considered a flammable compressed
gas?
A) Oxygen
B) Nitrogen
C) Propane
,D) Carbon dioxide
Correct Answer: C Propane
Rationale: Propane is a hydrocarbon that is easily ignitable and stored under
pressure, classifying it as a flammable compressed gas. Oxygen supports
combustion but is not itself flammable—it is an oxidizer. Nitrogen and carbon
dioxide are inert/non-flammable gases .
Question 3: What is the "Lower Flammable Limit" (LFL)?
A) The temperature at which a gas ignites
B) The lowest concentration of gas in air that will ignite
C) The pressure at which a gas becomes unstable
D) The minimum storage temperature for safety
Correct Answer: B The lowest concentration of gas in air that will ignite
Rationale: Below this concentration, the gas mixture is too lean to burn. The LFL
represents the minimum percentage of gas in air required for combustion to
occur. Concentrations below the LFL are safe from ignition, while concentrations
within the flammable range (between LFL and UFL) present a fire or explosion
hazard .
Question 4: Which gas is lighter than air and can accumulate near ceilings?
A) Propane
B) Butane
,C) Hydrogen
D) Acetylene
Correct Answer: C Hydrogen
Rationale: Hydrogen is less dense than air and will rise, potentially gathering in
upper areas of a room or building. This affects ventilation and leak detection
strategies. Propane and butane are heavier than air and will accumulate near the
floor. Acetylene is slightly lighter than air but not as light as hydrogen .
Question 5: How should flammable compressed gas cylinders be stored according
to NFPA standards?
A) Horizontally on the floor
B) In well-ventilated areas away from ignition sources
C) Stacked on top of each other
D) Near electrical panels for easy access
Correct Answer: B In well-ventilated areas away from ignition sources
Rationale: Proper storage prevents gas accumulation and reduces the likelihood
of ignition. Ventilation dilutes any potential leaks while separation from ignition
sources eliminates potential triggers. Cylinders must always be stored upright,
never horizontally or stacked .
Question 6: What is the minimum distance flammable gas cylinders must be kept
from sources of ignition?
, A) 5 feet
B) 10 feet
C) 20 feet
D) 50 feet
Correct Answer: C 20 feet
Rationale: Maintaining a 20-foot separation reduces the risk of heat or sparks
igniting released gas. NFPA guidelines specifically require flammable gas cylinders
to be stored at least 20 feet from potential ignition sources, including open
flames, electrical equipment that could spark, and other heat sources .
Question 7: Flammable gas cylinders should be stored away from:
A) Other cylinders
B) Fire extinguishers
C) Heat and direct sunlight
D) Emergency exits
Correct Answer: C Heat and direct sunlight
Rationale: Heat can increase internal pressure and risk cylinder rupture or
activation of pressure relief devices. Direct sunlight can significantly raise cylinder
temperatures, potentially causing over-pressurization. Cylinders should be stored
in shaded, cool areas .
Question 8: Compressed gas cylinders must be stored:
A) Lying flat on their sides
B) Upright and secured to prevent tipping
