NFPA 10 Portable Fire Extinguisher Exam
ACTUAL EXAM 2026/2027 | Portable Fire
Extinguisher | Verified Q&A | Pass
Guaranteed - A+ Graded
SECTION 1: FIRE CLASSIFICATION AND EXTINGUISHER TYPES (Questions 1-30)
Q1: A maintenance mechanic is working near a 480-volt electrical panel that is sparking and smoking.
There is also a cardboard box and a small puddle of hydraulic fluid on the floor nearby. Which fire
extinguisher classification is the minimum acceptable for this scenario?
A. Class A only – the cardboard is the primary fuel
B. Class B only – hydraulic fluid is flammable and the primary hazard
C. Class C only – the electrical panel is energized and the primary ignition source [CORRECT]
D. Class D – electrical components contain trace metals
Correct Answer: C
Rationale: NFPA 10 Section 5.3 defines Class C fires as involving energized electrical equipment. Even
when other fuels (Class A cardboard, Class B hydraulic fluid) are present, the electrical hazard requires a
non-conductive agent. A Class C extinguisher (or multi-purpose ABC rated for Class C) is required. Class A
or B alone may be conductive and cause electrocution. Class D is for combustible metals only, not
standard electrical components.
Q2: Which extinguishing agent is specifically designed for Class K fires involving commercial cooking oils
and fats?
A. Sodium bicarbonate dry chemical
B. Potassium-based wet chemical [CORRECT]
C. Carbon dioxide (CO₂)
D. Purple-K dry chemical
Correct Answer: B
Rationale: NFPA 10 Section 5.5 specifies that Class K extinguishers use wet chemical agents (potassium
acetate, potassium carbonate, or potassium citrate) that react with cooking oils/fats through
,saponification to create a soapy foam layer. This prevents re-ignition and splattering. Dry chemicals (A,
D) and CO₂ (C) are not approved for Class K fires and may cause dangerous splattering of hot grease.
Q3: A fire involving magnesium shavings in a machining operation requires which specific extinguisher
type?
A. ABC dry chemical
B. CO₂ extinguisher
C. Specialized Class D dry powder agent [CORRECT]
D. Class K wet chemical
Correct Answer: C
Rationale: NFPA 10 Section 5.6 requires specialized Class D dry powder agents (sodium chloride-based
Met-L-X, copper powder, or graphite-based agents) for combustible metal fires. Water, CO₂, and
standard dry chemicals (A, B) can react violently with burning metals, potentially causing explosions or
intensifying the fire. The Class D agent must be specifically listed for the metal type involved.
Q4: Which of the following fuels is classified as a Class B fire hazard?
A. Wood pallets in a warehouse
B. Gasoline in a vehicle maintenance shop [CORRECT]
C. Energized electrical wiring in a server room
D. Cooking oil in a residential kitchen
Correct Answer: B
Rationale: NFPA 10 Section 5.2 defines Class B fires as involving flammable and combustible liquids
including gasoline, oil, grease, paint, solvents, and kerosene. Wood pallets (A) are Class A ordinary
combustibles. Energized wiring (C) is Class C. Cooking oil (D) is Class K in commercial settings (residential
kitchens typically use Class B extinguishers, but commercial requires Class K).
Q5: What is the primary mechanism of extinguishment for water-based extinguishers on Class A fires?
A. Oxygen displacement
B. Chemical flame inhibition
C. Cooling and fuel removal [CORRECT]
D. Radiation shielding
Correct Answer: C
Rationale: NFPA 10 Section 5.1 states that Class A extinguishment relies primarily on cooling (removing
heat) and fuel removal (penetration into porous materials). Water has high heat capacity and converts
,to steam, absorbing heat energy. Oxygen displacement (A) is CO₂ mechanism. Chemical inhibition (B) is
dry chemical mechanism. Radiation shielding (D) is foam characteristic.
Q6: Which fire class rating is always paired with either a Class A or Class B rating and never stands
alone?
A. Class A
B. Class B
C. Class C [CORRECT]
D. Class K
Correct Answer: C
Rationale: NFPA 10 Section 5.3 states that Class C has no numerical rating—it only indicates the
extinguishing agent is non-conductive and suitable for energized electrical equipment. Therefore, Class C
extinguishers always carry either a Class A or Class B rating (e.g., 2-A:10-B:C or 4-A:60-B:C) to indicate
the actual fire suppression capability while confirming electrical safety.
Q7: Purple-K (potassium bicarbonate) dry chemical is specifically noted for which characteristic?
A. Superior Class A penetration
B. High Class B rating and performance on large flammable liquid fires [CORRECT]
C. Non-conductivity for Class C applications
D. Saponification for Class K fires
Correct Answer: B
Rationale: NFPA 10 recognizes Purple-K as a high-performance BC dry chemical with superior Class B
ratings. It is particularly effective on large flammable liquid fires (aircraft hangars, fuel storage) due to
rapid flame inhibition. While non-conductive (C), this is not unique to Purple-K. It does not have Class A
penetration (A) or Class K saponification capability (D).
Q8: In a commercial kitchen with deep fryers, why is a Class B extinguisher prohibited for grease fire
protection?
A. Class B agents are too expensive
B. Class B agents may cause dangerous splattering and fail to prevent re-ignition [CORRECT]
C. Class B agents are not rated for the high temperatures
D. Class B agents react chemically with vegetable oils
Correct Answer: B
Rationale: NFPA 10 Section 5.5 and NFPA 96 prohibit Class B extinguishers for commercial cooking
, grease fires because dry chemicals and CO₂ can cause violent splattering of hot oil and do not provide
the saponification reaction needed to prevent re-ignition. Class K wet chemicals create a stable foam
blanket through chemical reaction with the oil/fat.
Q9: Which extinguisher type uses air-pressurized water (APW) as the primary agent?
A. Standard ABC dry chemical
B. Class A water extinguisher [CORRECT]
C. CO₂ extinguisher
D. Class K wet chemical
Correct Answer: B
Rationale: NFPA 10 Section 5.1 specifies that Class A water extinguishers use air-pressurized water
(APW) stored in the cylinder with air pressure above the water level. ABC dry chemical (A) uses nitrogen
propellant with powder agent. CO₂ (C) uses carbon dioxide as both agent and propellant. Class K (D) uses
stored pressure with liquid wet chemical solution.
Q10: Halotron and other clean agents are primarily used in place of Halon for which reason?
A. Lower cost
B. Environmental regulations phasing out ozone-depleting substances [CORRECT]
C. Superior fire suppression capability
D. Longer discharge range
Correct Answer: B
Rationale: NFPA 10 recognizes Halotron and similar clean agents as replacements for Halon 1211, which
was phased out under the Montreal Protocol due to ozone depletion potential. While effective
(production of Halon ceased in 1994), existing Halon units remain serviceable. Clean agents are not
necessarily lower cost (A) or superior in capability (C) to Halon, but are environmentally compliant
alternatives.
Q11: A laboratory stores sodium metal under mineral oil. If the sodium ignites, which extinguisher
action is most dangerous?
A. Applying Met-L-X dry powder
B. Applying CO₂ *CORRECT+
C. Applying copper-based Class D agent
D. Smothering with dry sand
ACTUAL EXAM 2026/2027 | Portable Fire
Extinguisher | Verified Q&A | Pass
Guaranteed - A+ Graded
SECTION 1: FIRE CLASSIFICATION AND EXTINGUISHER TYPES (Questions 1-30)
Q1: A maintenance mechanic is working near a 480-volt electrical panel that is sparking and smoking.
There is also a cardboard box and a small puddle of hydraulic fluid on the floor nearby. Which fire
extinguisher classification is the minimum acceptable for this scenario?
A. Class A only – the cardboard is the primary fuel
B. Class B only – hydraulic fluid is flammable and the primary hazard
C. Class C only – the electrical panel is energized and the primary ignition source [CORRECT]
D. Class D – electrical components contain trace metals
Correct Answer: C
Rationale: NFPA 10 Section 5.3 defines Class C fires as involving energized electrical equipment. Even
when other fuels (Class A cardboard, Class B hydraulic fluid) are present, the electrical hazard requires a
non-conductive agent. A Class C extinguisher (or multi-purpose ABC rated for Class C) is required. Class A
or B alone may be conductive and cause electrocution. Class D is for combustible metals only, not
standard electrical components.
Q2: Which extinguishing agent is specifically designed for Class K fires involving commercial cooking oils
and fats?
A. Sodium bicarbonate dry chemical
B. Potassium-based wet chemical [CORRECT]
C. Carbon dioxide (CO₂)
D. Purple-K dry chemical
Correct Answer: B
Rationale: NFPA 10 Section 5.5 specifies that Class K extinguishers use wet chemical agents (potassium
acetate, potassium carbonate, or potassium citrate) that react with cooking oils/fats through
,saponification to create a soapy foam layer. This prevents re-ignition and splattering. Dry chemicals (A,
D) and CO₂ (C) are not approved for Class K fires and may cause dangerous splattering of hot grease.
Q3: A fire involving magnesium shavings in a machining operation requires which specific extinguisher
type?
A. ABC dry chemical
B. CO₂ extinguisher
C. Specialized Class D dry powder agent [CORRECT]
D. Class K wet chemical
Correct Answer: C
Rationale: NFPA 10 Section 5.6 requires specialized Class D dry powder agents (sodium chloride-based
Met-L-X, copper powder, or graphite-based agents) for combustible metal fires. Water, CO₂, and
standard dry chemicals (A, B) can react violently with burning metals, potentially causing explosions or
intensifying the fire. The Class D agent must be specifically listed for the metal type involved.
Q4: Which of the following fuels is classified as a Class B fire hazard?
A. Wood pallets in a warehouse
B. Gasoline in a vehicle maintenance shop [CORRECT]
C. Energized electrical wiring in a server room
D. Cooking oil in a residential kitchen
Correct Answer: B
Rationale: NFPA 10 Section 5.2 defines Class B fires as involving flammable and combustible liquids
including gasoline, oil, grease, paint, solvents, and kerosene. Wood pallets (A) are Class A ordinary
combustibles. Energized wiring (C) is Class C. Cooking oil (D) is Class K in commercial settings (residential
kitchens typically use Class B extinguishers, but commercial requires Class K).
Q5: What is the primary mechanism of extinguishment for water-based extinguishers on Class A fires?
A. Oxygen displacement
B. Chemical flame inhibition
C. Cooling and fuel removal [CORRECT]
D. Radiation shielding
Correct Answer: C
Rationale: NFPA 10 Section 5.1 states that Class A extinguishment relies primarily on cooling (removing
heat) and fuel removal (penetration into porous materials). Water has high heat capacity and converts
,to steam, absorbing heat energy. Oxygen displacement (A) is CO₂ mechanism. Chemical inhibition (B) is
dry chemical mechanism. Radiation shielding (D) is foam characteristic.
Q6: Which fire class rating is always paired with either a Class A or Class B rating and never stands
alone?
A. Class A
B. Class B
C. Class C [CORRECT]
D. Class K
Correct Answer: C
Rationale: NFPA 10 Section 5.3 states that Class C has no numerical rating—it only indicates the
extinguishing agent is non-conductive and suitable for energized electrical equipment. Therefore, Class C
extinguishers always carry either a Class A or Class B rating (e.g., 2-A:10-B:C or 4-A:60-B:C) to indicate
the actual fire suppression capability while confirming electrical safety.
Q7: Purple-K (potassium bicarbonate) dry chemical is specifically noted for which characteristic?
A. Superior Class A penetration
B. High Class B rating and performance on large flammable liquid fires [CORRECT]
C. Non-conductivity for Class C applications
D. Saponification for Class K fires
Correct Answer: B
Rationale: NFPA 10 recognizes Purple-K as a high-performance BC dry chemical with superior Class B
ratings. It is particularly effective on large flammable liquid fires (aircraft hangars, fuel storage) due to
rapid flame inhibition. While non-conductive (C), this is not unique to Purple-K. It does not have Class A
penetration (A) or Class K saponification capability (D).
Q8: In a commercial kitchen with deep fryers, why is a Class B extinguisher prohibited for grease fire
protection?
A. Class B agents are too expensive
B. Class B agents may cause dangerous splattering and fail to prevent re-ignition [CORRECT]
C. Class B agents are not rated for the high temperatures
D. Class B agents react chemically with vegetable oils
Correct Answer: B
Rationale: NFPA 10 Section 5.5 and NFPA 96 prohibit Class B extinguishers for commercial cooking
, grease fires because dry chemicals and CO₂ can cause violent splattering of hot oil and do not provide
the saponification reaction needed to prevent re-ignition. Class K wet chemicals create a stable foam
blanket through chemical reaction with the oil/fat.
Q9: Which extinguisher type uses air-pressurized water (APW) as the primary agent?
A. Standard ABC dry chemical
B. Class A water extinguisher [CORRECT]
C. CO₂ extinguisher
D. Class K wet chemical
Correct Answer: B
Rationale: NFPA 10 Section 5.1 specifies that Class A water extinguishers use air-pressurized water
(APW) stored in the cylinder with air pressure above the water level. ABC dry chemical (A) uses nitrogen
propellant with powder agent. CO₂ (C) uses carbon dioxide as both agent and propellant. Class K (D) uses
stored pressure with liquid wet chemical solution.
Q10: Halotron and other clean agents are primarily used in place of Halon for which reason?
A. Lower cost
B. Environmental regulations phasing out ozone-depleting substances [CORRECT]
C. Superior fire suppression capability
D. Longer discharge range
Correct Answer: B
Rationale: NFPA 10 recognizes Halotron and similar clean agents as replacements for Halon 1211, which
was phased out under the Montreal Protocol due to ozone depletion potential. While effective
(production of Halon ceased in 1994), existing Halon units remain serviceable. Clean agents are not
necessarily lower cost (A) or superior in capability (C) to Halon, but are environmentally compliant
alternatives.
Q11: A laboratory stores sodium metal under mineral oil. If the sodium ignites, which extinguisher
action is most dangerous?
A. Applying Met-L-X dry powder
B. Applying CO₂ *CORRECT+
C. Applying copper-based Class D agent
D. Smothering with dry sand
