A, B, C, D, K: What You Need to Know About the Five Classes of Fire Extinguishers
Learn about the 5 fire classes (A, B, C, D, K) and which extinguishers to use for each risk. Complete guide by Guard-X Protection incendie, fire safety experts in Greater Montreal.
Did you know that there are five distinct classes of fires, each requiring a specific type of fire extinguisher?
At Guard-X, fire safety experts in Greater Montreal, we’re here to help you understand the differences between fire classes and choose the right portable extinguisher for each situation.
CLASS A — Solid Materials
Recommended extinguisher: Water-based
Class A fires are caused by the combustion of solid materials such as wood, paper, fabric, or plastic.
Two phases of combustion:
- Smoldering: Without flames, producing glowing embers
- Flaming: With visible flames
Even a small draft can reignite a smoldering fire and trigger a full blaze.
CLASS B — Flammable Liquids and Chemicals
Recommended extinguisher: ABC or BC dry chemical
Also known as “grease fires,” Class B fires involve flammable liquids like:
- Gasoline
- Oils and solvents
- Paints and varnishes
- Alcohol and greases
These fires don’t smolder — they ignite or extinguish quickly, depending on the extinguishing agent used.
CLASS C — Energized Electrical Equipment
Recommended extinguisher: Co2 (carbon dioxide)
These fires originate from electrical sources such as:
- Televisions
- Electrical panels or motors
- Transformers, radios, stoves
High risk of electrocution. Never attempt to extinguish a Class C fire without the appropriate extinguisher.
CLASS D — Combustible Metals
Recommended extinguisher: Specialized dry chemical
Common in industrial settings, these fires involve metals such as:
- Aluminum
- Magnesium
- Sodium
- Iron dust
- Potassium
These fires burn extremely hot and violently, requiring specialized intervention.
CLASS K — Cooking Oils and Fats
Recommended extinguisher: Liquid agent (kitchen-specific)
Found in commercial kitchens, these fires are caused by:
- Frying oils
- Animal or vegetable fats
They require extinguishing agents that meet food safety standards, which sets them apart from Class B fires.
Find the Right Fire Extinguishers at Guard-X
A fire can only be effectively controlled if you use the right extinguisher for its class.
At Guard-X, we offer:
- Certified portable extinguishers
- Personalized advice tailored to your specific risks
- Sales, maintenance, and inspections across Montreal, Laval, and surrounding areas