Fire Extinguisher Ratings: What Do They Mean and Which One Should You Buy?

Smoke detectors and sprinkler systems are just two measures for keeping fires from getting out of control. In addition, a fire extinguisher is useful to always have near your kitchen to quickly put out a small fire so that it doesn’t spread or cause more damage. Plus, fire extinguishers can work on fires where water can’t put them out, such as fires caused by electrical, grease, gas, or oil sources. Read on for all the need-to-know details about selecting the right fire extinguisher for your home.

Fire Extinguisher Classes

A fire extinguisher's letter class-action identifies the types of fire it can put out. The Underwriters Laboratory (UL) assigns ratings according to the extinguisher's use. Here's a list of common types of fires that ratings are associated with:

• Class A: Fires in combustible materials like wood, cloth, rubber, plastic, or paper

• Class B: Fires in flammable liquids like gas, oil, lacquers, alcohols, flammable gases, and more

• Class C: Electrical fires or fires involving energized electrical equipment

• Class D: Fires in combustible metals (i.e., magnesium, titanium, potassium, and sodium)

• Class K: Kitchen fires in cooking appliances that involve oil or grease

You might want to include an ABC (a combination of Class A, B, and C extinguishers)  extinguisher on your home safety checklist because it can snuff out most common home fires, including electrical fires, by using a fine power to suffocate a fire and prevent reignition. 

Restaurants, manufacturing facilities, and workshops have class D or K extinguishers on-site.

How to Determine the Fire Extinguisher Rating

The number rating corresponds to which fires the extinguisher can handle and accompanies the letter classification. For example, a standard model may have a label that reads, "1-A:10-B:C."

Let's break down what that means:

• “A” refers to the water equivalency of the foam or powder inside the extinguisher. Each number is 1 and 1/4 gallons of water, so with this example, "1-A" equals about 1 and 1/4 gallons of material. Likewise, “2-A” would mean there are roughly 2 and 1/2 gallons.

• “B” equals the square footage of flaming material, so "10-B" would equal approximately 10 square feet of surface area. 

• "C" (the last letter after the colon) means the fire extinguisher uses a non-conductive agent that is safe to use on electrical fires. (This is simply the fire extinguisher’s class). 

Types of Fire Extinguishers

Fire extinguishers come in a variety of ingredients and canister configurations, depending on their function and what types of fires they’re designed to put out. It’s essential to understand how fire extinguishers are labeled and how they work so that you don’t inadvertently select the wrong fire extinguisher and risk an even larger fire or accident with the wrong application. Improve your home’s safety with knowledge about these common types of fire extinguishers:

• Carbon dioxide extinguisher: A CO2 extinguisher works best on electrical fires and flammable liquids.

• ABC powder fire extinguisher: This packs a multipurpose punch and uses a fine chemical powder to blanket the fire and remove oxygen. It has non-conductive material, so it’s safe to use on electrical fires and is also a popular choice for most homes.

• Wet chemical fire extinguisher: Since this extinguisher uses mist to cool the fire and covers the area with a solution to prevent it from reigniting, it’s ideal for Class K (or commercial kitchen) fires involving animal and vegetable fats.

• Water mist fire extinguisher: This extinguisher emits tiny water molecules to suppress the fire and works on most fire classes, including electrical fires.

• Foam fire extinguisher: This type of extinguisher is most effective on class A and B fires. It blankets the fire with foam, preventing vapors from rising and cooling the surface, but it’s unsuitable for gaseous fires.

• Clean agent fire extinguisher: This extinguisher works best on class B and C fires. Plus, it’s safe to use around animals and people and leaves no residue. 

Considerations for Choosing a Fire Extinguisher for Your Home 

While the ABC powder fire extinguisher fits the needs of most homes, you might want to be prepared with multiple types of extinguishers for the different rooms in your house. Don’t forget to factor in how easy the extinguisher is to use and the source of the fire. 

• Room Size and Materials: If you’re placing your fire extinguisher in a smaller room, chances are you won’t need a large extinguisher. In addition, the materials in the room will determine what kind of fire extinguisher you should get. For example, a foam extinguisher would be best if there is a large presence of paper, wood, or cloth.

• Risk: You’ll need to consider how likely a fire is to occur in certain areas. Though kitchens need fire suppression more often than bathrooms, you should still assess the possibility of a Class C or Class D fire in your lavatory.

• Ease of Use: Fire extinguishers come in different sizes, and the heavier ones provide more significant fire mitigation. However, wielding a 10-pound extinguisher may be a lot to handle while simultaneously dealing with a dangerous fire. Consider stocking your home with extinguishers you can easily lift and hold for the time it takes to get a fire under control. 

If you’re unsure which extinguishers to have on hand, contact a local fire sprinkler pro who can help you prepare your home for a fire. 

What’s Next if I Use My Fire Extinguisher to Put Out a Small Fire?

If you have to use a fire extinguisher to put out a small fire, such as on top of a kitchen appliance, you’ll first want to call your local fire department to ensure the fire is extinguished correctly and won’t reignite. 

Next, you’ll want to clean up the residue by sweeping or vacuuming and then scrubbing with a solution of 1-to-1 water to isopropyl alcohol. If there’s a significant amount of lingering smoke damage or residue, consider calling a smoke restoration company near you. 

Finally, you’ll want to replace the used fire extinguisher with a new extinguisher.