Fire Extinguisher Classes: A Complete Guide

Views: 2     Author: Site Editor     Publish Time: 2023-08-22      Origin: Site

Fire extinguishers are an important part of fire safety measures. The latter refers to the prevention and minimizing of the impact of fires. It’s an important practice at home, workplaces, or public places. It helps prevent fires from starting, minimize the damage they cause if they start, reduce property damage, and prevent injuries or death in fires.

Complying with fire safety regulations means installing a fire extinguisher and keeping it in good working order. Typically, fire extinguishers are located at the main entrance of a building or in the laundry room for easier access in case a fire breaks out. However, buying the right extinguisher for the fires likely to start on your property is crucial.

Different fire extinguishers are designed for use on specific types of fires. Using the wrong extinguisher can cause a fire to re-emerge after you thought you'd put it out successfully. Here is a complete guide on fire extinguisher classes to make the right purchase decisions. Macrofire Supply is among the best manufacturers and suppliers of superior firefighting equipment.

We produce and supply a diverse range of high-quality extinguishers and chemical agents at competitive prices for customers worldwide. We are ISO-certified and known for excellent customer service. Please, let us know if you need help selecting a fire extinguisher or placing your order.


Fire Basics and Classifications

Fires typically emerge when materials rapidly oxidize in the presence of oxygen and heat, usually resulting in light and more heat. Understanding this triangular relationship is important in preventing or managing fires. If either fuel, heat, or oxygen are missing, fire cannot occur.

The fuel is the material that reacts with oxygen. It can be a liquid, gas, or solid such as wood, paper, natural gas, or gasoline. It requires heat to reach the ignition point. Once it hits its ignition point, it reacts with oxygen and burns. The fire will sustain itself as long as there’s enough oxygen present. Depending on the burning fuel, fires can be grouped into various classes.  

Understanding Fire Extinguisher Classes

Fire extinguisher classes are important for selecting a suitable extinguisher for the type of fire you are trying to stop. Different types of fires have different fuel sources and different burning characteristics. Using the wrong type of fire extinguisher can make a fire worse or even more dangerous.

For example, you can put out a cooking oil fire using water or foam, but the same is not recommended for fires resulting from faulty wiring or short-circuiting electrical equipment. Water and foam conduct electricity and can make an electrical fire worse. Always use the right extinguisher for the fire you are trying to put out. In case of doubts, it’s best to contact the fire department.

NFPA Fire Code Classes

The National Fire Protection Association aka (NFPA), is a non-profit devoted to preventing death, injury, economic loss, and property damage due to fires. It’s based in the US but has a growing international following. Non-US members can access the organization’s latest fire safety codes and standards.  

The organization categorizes fires into class A, B, C, D and K. Class A entails the most common type of fires since they involve everyday combustibles such as paper, wood, cloth, etc. Class B entails fires involving flammable gasses and liquids, while Class C fires entail energized electrical apparatus.

Class D entails that it starts from explosive metals, while class K fires are kitchen fires involving cooking oil and fats. As already mentioned, different extinguishers are designed for specific types of fires.

Class A Extinguishers

Class A fire extinguishers are designed for fighting common fires involving ordinary combustible materials such as paper, wood, cloth, rubber, and some plastics. These fires are common in homes, schools, and businesses.

Examples of class A fires include:

●Kitchen fires resulting from cooking oil,

●Living room fires due to a burning couch,

●Garage fires due to a leaking gas can,

●Dumpster fires due to burning discarded furniture.

These types of fire extinguishers use water foam or dry chemicals. Water extinguishers are the most common class A extinguishers. Water works by cooling fires and cutting off the oxygen supply. However, it shouldn’t be used to put out electrical fires. Foam is a good agent, too; it forms a blanket over the fire, effectively suffocating it.

Extinguishers containing foam are less likely to damage your property. On the other hand, dry chemical extinguishers work by breaking the chain reaction that causes fires. However, dry chemicals can leave a messy white residue on your property. In any case, don't try to fight a fire that’s beyond your control; evacuate the area and call emergency services.

Class B Extinguishers

Class B fires extinguishers are meant for dealing with class B fires. These fires emerge when flammable gasses and liquids, such as propane, gasoline, and oil, ignite in the presence of heat and oxygen.

They are typically characterized by large flames and thick black smoke. These fires can be extremely catastrophic since they often spread quickly and produce toxic fumes.

Examples of class B fires

●Kitchen fires resulting from cooking oil

●Garage fires due to spilled gasoline

●Warehouse fires from paint thinners

●Factory fires due to burning lubricants,

●Laboratory fires due to igniting chemicals.

Dealing with these fires requires extinguishers specifically designed for flammable liquids and gasses. These fire extinguishers contain foam, dry chemical powder, or CO2. Foam cuts off the oxygen supply, thus smothering fires in place. Dry powder forms a layer of powder that absorbs heat and prevents the fuel from burning.

On the other hand, CO2 displaces oxygen in the air, suffocating the flames and, eventually, the fire. When using a fire extinguisher, stand upwind of the fire so you don’t inhale toxic flames.  

Class B fires can be tough to extinguish. They often spread quickly and produce toxic fumes. Never use water on Class B fires. In case the fire is beyond your control, call emergency services.

Class C  Extinguishers

These are designed for putting out Class C fires. These fires emerge from burning energized electrical equipment such as power lines, wiring, and appliances. The fires start when the electrical component is still plugged in and connected to a power source.

Examples of class C fires include:

●Fires caused by faulty wiring,

●Fires caused by short circuits,

●Fires due to overloaded electrical outlets

●Fires resulting from overcharged or overheated devices,

●Fires due to sparking or arcing.

These fires are extremely dangerous because they can still conduct electricity and cause serious injuries or death. They can’t be put out using water or foam because they conduct electricity too.

The most common type of fire extinguisher used for Class C fires is a CO2 or dry powder extinguisher. CO2 is non-conductive and displaces oxygen, thus suffocating the fire.

On the other hand, dry powder coats the burning material and smothers the fire. Call emergency services if you don’t have the right extinguisher or the fire is beyond your control.

Class ABC Extinguishers

ABC extinguishers are designed for dealing with class A, B, or C fires. They belong in the multipurpose extinguisher category and are often bought for use in homes, businesses, and public places.

Examples of fires you can stop with ABC extinguishers include

●Fire due to ordinary flammables such as cooking oil, gas, wood, paper, plastics

●Fires due to igneous gasses and liquids such as gasoline, paint thinners, lubricants, etc.

●Fires due to faulty electrical equipment

●Fires in oil and gas fields

Class ABC extinguishers contain a mixture of ammonium sulfate and mono-ammonium phosphate. When discharged, the dry chemical coats the burning flame, separating it from oxygen. It also cools the fire and breaks down the chain reaction.  

Class BC Extinguisher

Class BC extinguishers are multipurpose, too. But they are meant for dealing with class B and C fires only. These include

●Fires due to combustible liquids and gasses

●Fires due to energized electrical equipment.

These fires are common in homes, schools, and public places. Class BC fire extinguishers use dry chemical agents such as sodium bicarbonate, potassium bicarbonate, or potassium chloride to create an insulating layer of nanoparticles over the flaming liquids or gasses and keep them from burning. They also break down the fuel molecules. Class BC agents are non-conductive and can be used on electrical fires.

Class D Extinguisher

Class D extinguishers are designed for putting out class D fires. These fires involve explosive metals such as potassium, magnesium, and sodium. These metals typically burn at extremely high temperatures and can react violently with water, making them tough to extinguish.

Examples of class D fires include:

●Fires in a foundry due to burning magnesium

●Fires in welding facilities due to burning magnesium

●Lab fires due to sodium spill

●Aircraft fires due to burning titanium

●Fireworks factory fires involving potassium nitrate

Class D fires are typically rare and require class D extinguishers. These extinguishers use dry powders, such as potassium chloride, sodium chloride, or bicarbonate soda, to snuff out the fire and prevent the metal from further reacting with oxygen.  

However, beware of potential explosions when dealing with burning metals. Always wear protective clothing, including goggles, fire-resistant gloves, and a helmet. Above all, never use class D extinguishers on fires involving combustible gasses or liquids, as the powder can react with the fuel to create an explosion.

Class K Extinguishers

Class K extinguishers are designed for fighting class K fires. These fires involve cooking fats, greases, and oil. They are similar to class B fires but require special extinguishing agents lest you splatter the hot oil or fat.

These fires typically occur in commercial kitchens but can also occur in residential kitchens.  Class K extinguishers use wet chemical agents that spread over the surface of the burning oil, cooling it and denying it further oxygen. This extinguishes the fire and keeps it from reigniting.

Selecting The Right  Extinguisher

As mentioned, always use an extinguisher on the fires it was designed to stop. Using an extinguisher on the wrong fire can worsen things or even cause injuries. In other cases, the fore may appear out but can reignite later because you used the wrong extinguisher.

Tips for selecting the right extinguisher:

●Consider the space and size you want to protect. Garages and workshops require large fire extinguishers, while a small extinguisher will be enough for a kitchen.

●Understand the types of fires that are likely to develop in your facility. If you are likely to experience multiple types of fire, buy multipurpose extinguishers. For example, ABC extinguishers are meant for fires involving ordinary combustibles, energized electrical equipment, or flammable liquids and gasses. DC extinguishers are designed for dealing with class C and D fires.

●Consider the rating. Fire extinguishers are rated based on the fire size they can extinguish. Get the right rating.

●Perform regular inspection and maintenance. Keep your extinguisher clean and the pressure gauge in the green zone at all times. Check the hose and nozzle for kinks and clogs, and keep the tamper seal intact. Keep your extinguisher in good working order at all times.

●Follow fire prevention measures: keep combustible materials away from flames and heat sources, store flammable liquids in approved containers and cool well-ventilated areas, install smoke detectors and fire alarms, clean up spills immediately, dispose of flammable liquids properly, do not overload circuits, cover naked electrical wires, keep oil and grease at a safe temperature.


Fire extinguishers come in various classes for specific types of fires. Always read the manual carefully to avoid using an extinguisher on the wrong type of fire. Using the wrong

extinguishers can make fires worse. In other cases, fires might remerge after they appear to have gone out effectively. Consider the size of your facility and the fires that are likely to develop, and get the right extinguisher. If you are unsure what to buy, contact our customer representative for help.

We are an experienced manufacturer and supplier of ISO-certified firefighting products and will gladly help you select the equipment to protect your property. Our team offers online meetings and a tour of our facility. They will also guide you through the process of placing orders and inspecting your delivery to ensure you get the right product.