Fire Extinguisher Types

What is in a Fire Extinguisher?

Different fire extinguisher types may have some design variations, but they generally feature the same components and operate in similar fashion.

The extinguishing agent comes out of the extinguisher to eliminate fires. It is fed out of the extinguisher's tank via a pickup tube once an expellant (often from a compressed gas canister) is released into the tank. The expellant is released when the safety pin is removed and the discharge lever is squeezed. To aim, users hold the extinguisher by the carrying handle and point the discharge nozzle at the base of a fire. A pressure gauge displays the pressure inside the tank, making it clear if a leak exists or the extinguisher's been used.

Fire Extinguisher Ratings

An ABC Fire Extinguisher might have a UL Rating of 4-A:80-B:C. But what do these fire extinguisher ratings mean? The numbers in the UL Rating are a relative measurement of how effective a given extinguisher is at fighting certain classes of fires, based on proper fire extinguisher training.

• A: The number in front of the "A" measures water equivalency. One A is equivalent to 1.25 gallons of water, so a unit with a 4A rating has an equivalent of 5 gallons of water to battle Class A fires.
• B: The number in front of the "B" is a relative measure of the area an extinguisher can cover.
• C & K: These letters indicate that an extinguisher can be used effectively against these fire classes.

In practical terms, that means that if Fire Extinguisher 1 has a 4-A:80-B:C rating and Fire Extinguisher 2 has a 1-A:10-B:C rating, Fire Extinguisher 1 is...

• 4x more potent against Class A fires
• 8x more potent against Class B fires
• Both extinguishers can combat class C fires.

Fire Extinguisher Sizes

The size of a fire extinguisher indicates the amount of extinguishing agent it holds and is most often measured in pounds. Sizes can range from as small as 2.5 lb. to as large as 350 lb. While the largest extinguishers will come with built-in wheels to make transportation manageable, size is always important to consider.

What size fire extinguisher does my business need?

Fire extinguisher sizing for your operation will depend on a variety of factors, including...

• Fire Risks: Be aware of the unique hazards within your operation. The size of a fire that may occur in an office building could be much different than one in a manufacturing plant that specializes in hazardous materials.
• Room Size and Materials: The size of a room and how it's organized are important as well. A small reception area with limited combustible materials will require a smaller extinguisher than a spacious section of a warehouse that is packed snugly with combustible products.
• Employee Ability: A fire extinguisher is only as effective as the individual controlling it, so be sure that your employees can handle the one that you choose. A large, high-capacity fire extinguisher might work well for your application, but relying on one that is too heavy or bulky for your workers to use creates a dangerous situation.

Common fire extinguisher sizes and their approximate weight

• 2-A:10B:C - 4 lb.
• 3-A:40B:C - 5 lb.
• 4-A:60B:C - 10 lb.
• 10-A:80B:C - 20 lb.

What is the Difference Between a Rechargeable and Non-Rechargeable Fire Extinguisher?

• Rechargeable fire extinguishers are built to be reused. Note that when a rechargeable fire extinguisher is used, it needs to be recharged before going back into service.
• Non-rechargeable fire extinguishers are often less expensive, but built in a manner that allows them to be used only once. Even if only partially discharged, a non-rechargeable fire extinguisher must be replaced after it is used.

*Each type of extinguisher must be serviced whenever its seal is broken for any reason (like usage, aging, and tampering). Additionally, a certified company or AHJ (Authority Having Jurisdiction) must service the unit annually.

Fire Extinguisher Frequently Asked Questions

How long do fire extinguishers last?

Fire extinguishers are generally warranted for somewhere between 5 - 15 years, but be sure to review your model's warranty for specific information.

Where do you recharge fire extinguishers?

Whether needed as part of regular maintenance or immediately after use, your extinguisher should be recharged by a trained professional from a fire protection company.

How do you dispose of fire extinguishers?

If the extinguisher is charged, call your local fire department and ask if they take recycled canisters. If not, take the extinguisher to a hazardous waste disposal site.

if the extinguisher is empty, squeeze the lever to ensure all the pressure is released and remove the head. You can then drop off the shell at your local recycling facility.