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Understanding Fire Extinguisher Classes: What You Need and Why
Posted by the FSS Team on Jul 25th 2025
Understanding Fire Extinguisher Classes: What You Need and Why
Fire extinguishers are not one-size-fits-all—and knowing the difference can mean the difference between stopping a small flame or fueling a larger fire. At Fire Safety Supply, we believe every home and business should be equipped with the right extinguisher for the environment. This guide breaks down the five main fire extinguisher classes—A, B, C, D, and K—so you can make informed, confident choices.
Class A – Ordinary Combustibles
Best for: Paper, wood, cloth, trash, and plastics
Class A extinguishers are the most common type and are ideal for homes, offices, and schools. They are designed to put out fires involving everyday materials that leave ash when burned. Water-based and dry chemical extinguishers are typically rated for Class A fires.
Class B – Flammable Liquids
Best for: Gasoline, oil, paint, and other flammable liquids
Class B extinguishers are essential in garages, workshops, kitchens, and warehouses. These extinguishers are typically foam or dry chemical, designed to smother liquid fires without spreading the flames.
Class C – Electrical Equipment
Best for: Computers, appliances, wiring, circuit panels
Class C extinguishers are safe to use on live electrical fires, as they do not conduct electricity. These are commonly found in offices, server rooms, and homes with electronics. Most ABC-rated extinguishers cover this class as well.
Class D – Combustible Metals
Best for: Magnesium, titanium, lithium, and other metals
Fires involving metal require a specialized Class D extinguisher that uses a dry powder agent to smother flames. These are used in laboratories, manufacturing facilities, and metalworking shops. Class D extinguishers are not commonly needed in residential settings.
Class K – Commercial Kitchens
Best for: Cooking oils, grease, animal fat
Class K extinguishers are specifically designed for deep fryers and commercial-grade cooking equipment. They discharge a wet chemical that cools the oil and prevents re-ignition. Required in most commercial kitchens by code, these extinguishers are not interchangeable with standard ABC units.
Choosing the Right Extinguisher
Many fire extinguishers are multi-class rated, such as ABC, which covers most residential and commercial needs. However, certain environments—like industrial shops or kitchens—require more specialized protection.
If you are unsure which extinguisher is right for your space, our team at Fire Safety Supply is here to help. We offer professional guidance, inspections, and a full range of products tailored to your unique risks and requirements.