Fire Safety Fire Extinguisher Types and Usage 4 — Questions and Answers
Question 1: A grease fire ignites in a commercial kitchen. Which extinguisher type is specifically designed for this hazard?
- Class K (Correct answer)
- Class B
- Class A
- Class C
Correct answer: Class K
Class K extinguishers are designed for cooking oils and fats found in commercial kitchens, using wet chemical agents that saponify grease fires.
Question 2: What does the number on a fire extinguisher label (e.g., '2A:10B:C') indicate?
- The extinguishing capacity and fire class coverage (Correct answer)
- The weight of the extinguisher in pounds
- The maximum distance from which it can be used
- The number of seconds of discharge time
Correct answer: The extinguishing capacity and fire class coverage
The number-letter rating indicates the extinguisher's capacity: the number before 'A' or 'B' reflects the relative firefighting power for that fire class.
Question 3: Which type of fire extinguisher is safe to use on energized electrical equipment?
- CO2 (carbon dioxide) (Correct answer)
- Water mist
- Foam (AFFF)
- Dry chemical (ABC)
Correct answer: CO2 (carbon dioxide)
CO2 extinguishers are non-conductive and leave no residue, making them ideal for energized electrical equipment fires.
Question 4: A dry chemical extinguisher has been partially discharged. What is the correct action?
- Recharge or replace it immediately (Correct answer)
- Mark it as partially used and return it to service
- Shake it to redistribute the agent and reuse
- Only replace it when completely empty
Correct answer: Recharge or replace it immediately
Any extinguisher that has been used, even partially, must be recharged or replaced before being returned to service to ensure it functions fully in an emergency.
Question 5: What is the primary limitation of a water-based extinguisher on a Class B fire?
- Water can spread flammable liquids and worsen the fire (Correct answer)
- Water evaporates too quickly to cool the fuel
- Water reacts chemically with most fuels
- Water is too heavy to reach flammable liquid fires
Correct answer: Water can spread flammable liquids and worsen the fire
Applying water to burning flammable liquids can scatter the burning fuel, spreading the fire rather than extinguishing it.
Question 6: Which extinguisher agent works by interrupting the chemical chain reaction of combustion?
- Dry chemical (monoammonium phosphate) (Correct answer)
- Carbon dioxide
- Water
- Wet chemical
Correct answer: Dry chemical (monoammonium phosphate)
Dry chemical agents disrupt the free radical chain reaction in the combustion process, effectively breaking the chemical cycle that sustains fire.
Question 7: How far from a potential Class B fire hazard should a portable extinguisher typically be located, per NFPA 10?
- Within 50 feet (Correct answer)
- Within 100 feet
- Within 25 feet
- Within 75 feet
Correct answer: Within 50 feet
NFPA 10 requires Class B extinguishers to be placed within 50 feet of flammable liquid hazards to ensure rapid access.
Fire Safety Fire Extinguisher Types and Usage 4
A grease fire ignites in a commercial kitchen.
Which extinguisher type is specifically designed for this hazard?