What are the Fire Classes in the US?

Fire Classes in the US

Fire Classes classify fires and define the type of fuel that is involved, as well as the type of extinguishing method used to put it out. In this blog post, we will be discussing the Fire Classes adopted in the US.

Fire Classes in The US: An Overview

1. Class A Fires

Class A fires involve everyday-type combustibles such as:

  • Wood: Furniture, paper, and other wood-based materials.
  • Paper: Books, cardboard, and paper products.
  • Cloth: Fabrics, clothing, and textiles.

Extinguishing Agents:

Water, foam, or dry chemical extinguishers are effective for fire class-A fires.

2. Class B Fires

This includes flammable liquids and gases such as petrol—fuels for vehicles and apparatus; oil—cooking oils and lubricants; paints—solvents and other liquid combustibles.

Extinguishing Agents:

The extinguishing agents for Class B fires include foam, dry chemicals, or carbon dioxide CO2) extinguishers.

3. Class C Fires

Electrical Fires (Class C fires) include energized electrical equipment and wiring, including Appliances—computers, refrigerators, and other electrical devices; wiring—electrical circuits and outlets, transformers—electrical transformers, and panels.

Extinguishing Agents:

A nonconductive extinguisher, such as dry chemicals or CO2, should be used to prevent electrical shock.

4. Class D Fires

These are fires involving flammable metals, including:

  • Magnesium: Some auto and aerospace parts
  • Titanium: Medical equipment, aerospace
  • Sodium and Potassium: Laboratory

Extinguishing Agents:

A special dry powder extinguisher is required, which will smother the Class D fire without coming into contact with the metal.

5. Class K Fires

Class K fires consist of liquids used in cooking, normally found in the kitchen:

  • Vegetable Oils: Normally used in deep fryers and in cooking pans.
    Animal Fats: Grease and fat emanating from cooking meat.

Extinguishing Agents:

Wet chemical extinguishers respond to class K fires. They cool and smother the flames.


Knowing the US. classes of fire and their respective methods for extinguishing is an important part of fire safety and prevention. Each class of fire deals with certain types of fuel. All these classes need to be controlled and extinguished differently.

Frequently Asked Questions

Can any class of fire be extinguished by any fire extinguisher?

No, fire extinguishers are designed for specific courses of fire. Using the wrong type can prove ineffective or dangerous.

What class of fire is the most common in homes?

Class A fires involve ordinary combustibles like wood, paper, and cloth, and are by far the most common in homes.

Are there multipurpose extinguishers?

Yes, some extinguishers are rated and marked for multiple classes, such as A-B-C, and can be used on more than one type of fire.

Why are Class K extinguishers required in kitchens?

Class K extinguishers will be required because they are specially made to handle the very high temperatures of cooking oils and fats that any other extinguisher or water will not be able to extinguish.

How would I know what class extinguishers I have?

Fire extinguishers are marked with symbols and letters representing the classes of fires they can put out.

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