Fire Extinguishers 101 Guide – How & When to Use One

Knowing how to use a fire extinguisher could make the difference between a small fire incident and a disaster. In this article, we explain the different types of fire extinguishers and the applicable use cases for each type.

Types of Fire

Before we look at the different types of fire extinguishers, it’s important to know how fires are classified. Here is a quick chart that shows the different classes of fire. Note that the classification differs slightly by region.

Fire Class Chart

In the US, fire class ratings are defined by the following alphabets: A, B, C, D, and K.

Class A: ordinary combustible materials such as paper, cloth, wood, trash, and plastics

Class B: flammable liquids and gases incl. gasoline and propane

Class C: fires involving live electrical equipment

Class D: combustible metal such as magnesium and sodium

Class K: fires involving cooking oil or fats used in commercial kitchen appliances

These letters are typically found on the side of fire extinguishers. Some fire extinguishers may have multiple fire ratings such as class ABC or class BC.

Class A & B Size Ratings

Another important piece of information that you might want to pay attention is the class A and B numerical ratings. The number represents the size rating of each extinguishing agent. The larger the number, the larger the fire that can be extinguished.

Dry Chemical Fire Extinguisher Size Rating

For class A, the number goes from 1 to 40 and it refers to the amount of extinguisher agent the unit holds. One A is equivalent to 1.25 gallons of water.

For class B, the number goes from 1 to 640 and it refers to the amount of square footage an extinguisher can cover.

What size you pick will depend on a number of factors such as the potential fire risks, the size of the room, and how heavy of a weight the people are able to hold.

Fire Extinguisher Types

You should never use a fire extinguisher without understanding what extinguisher agent it contains. Using the wrong type could aggravate a fire and make the situation worse, especially if you are using the extinguisher in a confined space. The following chart breaks down the different types of fire extinguishers and the types of fire it could be used for.

Fire Extinguisher Type Chart

Dry Chemical fire extinguishers can be used for most class A, B, C, and D fires. Dry chemical agents can help smother a fire by forming a barrier between the fuel (burning material) and the oxygen. One should take care when using a dry chemical extinguisher in an enclosed space as the powder can make it difficult to breathe.

Dry Chemical Fire Extinguisher

Water fire extinguishers should only be used for class A fires. For obvious reasons, water should never be used for class C fires due to the risk of electrocution.

Water Extinguisher

Foam fire extinguishers could be used for class A and B fires. Foam can kill a fire by forming a blanket around the burning material. Foam extinguishers don’t limit visibility but they do have freezing problems.

Foam Extinguisher

Carbon Dioxide fire extinguishers could be used for class B and C fires. Carbon dioxide can kill a fire by displacing the oxygen. Carbon dioxide extinguishers should not be used in enclosed spaces due to the risk of major respiratory issues for people in the space.

CO2 Extinguisher

Residential Fire Incidents During Winter

According to historical data collected by the US Fire Administration, residential fire incidents have occurred more often during the winter. This trend could be due to a number of factors such as the amount of time people spend indoors, and the usage of heating appliances.

According to the USFA report, the most common causes of fire include cooking, heating, electrical malfunctions, and careless actions. The following infographic outlines the type of fire extinguisher that best suits each type of fire incident.

Winter Fire Incidents