F04 Portable Fire Extinguishers 2 — Questions and Answers
Question 1: What is the primary advantage of a CO2 fire extinguisher over a dry chemical extinguisher when used on energized electrical equipment?
- CO2 leaves no residue that could damage sensitive equipment (Correct answer)
- CO2 is more effective at cooling the fire
- CO2 extinguishers have a longer discharge range
- CO2 is effective on Class A fires
Correct answer: CO2 leaves no residue that could damage sensitive equipment
CO2 discharges as a gas and leaves no residue, making it ideal for energized electrical equipment and sensitive electronics.
Question 2: A wet chemical (Class K) fire extinguisher is specifically designed for use in:
- Electrical panel rooms
- Commercial cooking operations with vegetable or animal oils (Correct answer)
- Warehouses storing flammable liquids
- Locations with Class D metal fires
Correct answer: Commercial cooking operations with vegetable or animal oils
Wet chemical extinguishers create a soapy foam that cools cooking oils and seals the surface, preventing re-ignition — making them essential for commercial kitchens.
Question 3: Which type of portable fire extinguisher is most appropriate for a Class D (combustible metal) fire?
- ABC dry chemical
- Carbon dioxide (CO2)
- Specialized dry powder agent designed for the specific metal (Correct answer)
- Water
Correct answer: Specialized dry powder agent designed for the specific metal
Class D fires involving combustible metals like magnesium or sodium require specialized dry powder agents; water and CO2 can intensify these fires.
Question 4: An extinguisher labeled '2-A:10-B:C' — what does the '2-A' rating indicate?
- The extinguisher weighs 2 pounds
- It is effective on 2 square feet of Class B fire
- It is equivalent to approximately 2.5 gallons of water on Class A fires (Correct answer)
- It has a 2-minute discharge time
Correct answer: It is equivalent to approximately 2.5 gallons of water on Class A fires
The numerical prefix in a Class A rating represents water firefighting equivalency — each unit equals approximately 1.25 gallons of water.
Question 5: Which extinguishing agent should NEVER be used on a fire involving a commercial deep fryer with cooking oil?
- Wet chemical
- Water (Correct answer)
- Purple K dry chemical
- Class K foam
Correct answer: Water
Water causes a violent steam explosion when applied to hot cooking oil, dramatically spreading the fire and creating a dangerous fireball.
Question 6: A stored-pressure dry chemical extinguisher differs from a cartridge-operated unit in that:
- Stored-pressure units have a separate CO2 cartridge to expel the agent
- Stored-pressure units hold the propellant gas pre-mixed with the dry chemical agent in one cylinder (Correct answer)
- Stored-pressure units can only be used on Class B fires
- Stored-pressure units require recharging after each monthly inspection
Correct answer: Stored-pressure units hold the propellant gas pre-mixed with the dry chemical agent in one cylinder
In stored-pressure units, the dry chemical agent and propellant (nitrogen or dry air) are pre-mixed in the same cylinder, while cartridge units keep them separate.
Question 7: Clean agent extinguishers (such as those using Halon alternatives like FM-200) are preferred in server rooms because they:
- Are less expensive than CO2 units
- Have a longer effective range than other extinguishers
- Extinguish fires without leaving residue or depleting oxygen to dangerous levels (Correct answer)
- Are rated for Class D metal fires
Correct answer: Extinguish fires without leaving residue or depleting oxygen to dangerous levels
Clean agents suppress fires chemically without leaving residue and do not reduce oxygen to levels harmful to people who may remain in the space.
F04 Portable Fire Extinguishers 2
What is the primary advantage of a CO2 fire extinguisher over a dry chemical extinguisher when used on energized electrical equipment?