Fire extinguisher classes and types

Last updated: January 1

Knowing how to use a fire extinguisher can save property and, more importantly, lives. Equally important is knowing what the right type of extinguisher is for a specific hazard.

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Fire extinguisher classes

Fire extinguishers are broken down into classes. Each class is determined by the fuel source of a fire, says the National Association of Certified Home Inspectors (NACHI). There are 5 classes of fire extinguishers, each identified by a letter – A, B, C, D and K.

Here is a closer look at each class.

Class A

Class A extinguishers are designed to put out fires involving ordinary materials, like wood, paper, cloth, trash, and rubber, according to the Fire Equipment Manufacturers’ Association.

Class B

Class B extinguishers are meant to combat fires involving gasoline, paint, oils, tars, and alcohol, says the Fire Equipment Manufacturer’s Association. But they’re not designed to handle fires in cooking oils or grease. Additionally, class Bs typically involve liquids that boil, according to Prosper Fire and Rescue.

Class C

Class C extinguishers are made for fires related to plugged-in electrical equipment, according to the U.S. Fire Administration. These include computers, motors and appliances.

Class D

Class D fires typically occur in factories and entail flammable metals, says the U.S. Fire Administration. Metal types include magnesium, titanium, lithium and more, according to the Fire Equipment Manufacturer’s Association.

Class K

Class K fires typically occur in commercial kitchens and involve cooking oils and grease, according to the Fire Equipment Manufacturer’s Association.

Multipurpose fire extinguishers

Multipurpose fire extinguishers are some combination of A, B and C extinguishers, according to Fire Equipment Manufacturer’s Association. They are commonly found in homes and businesses, adds the U.S. Fire Administration. Your local home improvement store is likely to carry them, and they may be labeled either B-C or A-B-C.

Multipurpose dry chemical extinguishers are the least expensive, says the Santa Clara County Fire Department. They use an ammonium phosphate base which makes it effective on most types of home fires.

Types of fire extinguishers

There are several types of fire extinguishers and each targets specific elements of the fire triangle, which is made up of heat, oxygen and fuel, according to the Northwest Fire Science Consortium.

Below are each type of fire extinguisher and the classes they fall under.

Water mist extinguishers

Water mist extinguishers are designed to fight Class A fires, and sometimes Class C, says the Fire Equipment Manufacturer’s Association. It discharges a fine spray that removes heat from the fire triangle.

Carbon dioxide extinguishers

These extinguishers are designed for Class B and electrical fires, according to the Fire Risk Assessment Network. They remove both the oxygen and heat elements from the fire triangle. They use liquid CO2 that discharges as a gas and is eco-friendly, says the NACHI.

Halogenated extinguishers

Also known as clean agent fire extinguishers, halogenated agents are rated either ABC or BC, says the Santa Clara Fire Department. They’re often found near computers and electronic equipment. They target the heat element in the fire triangle, according to the Fire Equipment Manufacturers’ Association.

Wet chemical extinguishers

Wet chemical extinguishers are designed to combat Class K fires, specifically those involving deep fat fryers and cooking appliances, says the Santa Clara Fire Department. They use discharge a spray, so that grease isn’t splashed around. Wet chemical extinguishers combat fires by targeting the heat element and separating the oxygen and fuel elements of the fire triangle, says the Fire Equipment Manufacturers’ Association.

Dry chemical extinguishers

Dry chemical extinguishers break down into 2 kinds: multipurpose and regular dry chemical, according to the NACHI. Respectively, they handle A, B, C, and B and C fires.

Multipurpose extinguishers take out fires with ammonium phosphate and leave a residue that has to be removed from surfaces. Schools, homes, hospitals and businesses often use them.

Regular dry chemical use sodium bicarbonate. Unlike multipurpose, they’re not toxic and can be wiped from surfaces easily. They work by separating the fuel from the oxygen element of the fire triangle, according to the Fire Equipment Manufacturers’ Association.

Dry powder extinguishers

Dry powder agents work to create a barrier between the oxygen and fuel elements, according to the Fire Risk Assessment Network. They should not be used in closed-in areas, because the powder is easy and dangerous to inhale. It’s also difficult to clean up afterward.

Dry powder agents should only be used on Class D fires, warns the Fire Equipment Manufacturers’ Association. They don’t work on other types of fires.

How to use your fire extinguisher

The operation of a fire extinguisher can be described by the PASS method.

  1. Pull the pin.
  2. Aim at the fire’s base.
  3. Squeeze the lever to spray.
  4. Sweep from side to side.

The Fire Equipment Manufacturers’ Association provides a visual demonstration in more detail.

How many extinguishers should I have in my home?

You should install a fire extinguisher throughout your home, especially in areas that have a greater fire risk, like your kitchen or garage, says SafeHome.org. Check your fire extinguishers every so often to make sure they still work.

You can get training and maintenance info from your local fire department. Also consult the manufacturer’s service, advises the National Fire Protection Agency (NFPA).

Do fire extinguishers expire?

Fire extinguishers do expire, according to the NACHI. There are a few ways they may no longer work correctly. A weak seal may result in the seepage of gas, which can weaken pressure so that it no longer works. Chemicals inside the canister might also harden over time.

It’s difficult to determine a precise expiration date. That’s why testing and maintenance are so important. Additionally, depending on the type of extinguisher, they should be examined at least every year, says the NFPA.

Make sure your home is protected

Unfortunately, nothing is completely full proof. But a home insurance policy can help you pick up the pieces in case the unexpected rears its ugly head. That includes everything from fires and explosions to lawsuits.

Your home is one of the biggest investments you’ll ever make – financially and emotionally. It’s where you live and where you’ll build a life. And it deserves quality protection that fits your needs.