Hand Holding Fire Extinguisher Handle

Fire Extinguishers are around us all the time and we should always know where the nearest one is. All extinguishers, however, are not created equal. There are different sizes and different types of fire extinguishers intended to fight different classes of fires.

To be truly fire smart, the right fire extinguisher has to be installed in the right location. This will maximize the effectiveness of a fire extinguisher in the event of a fire.

Fire basics and why the type of fire matters

Fire Tetrahedron – Elements required for Fire

The theory of fire is based on what is called the Tetrahedron. It outlines the four elements required for a fire to be present. By removing one of these elements, the fire cannot continue and is thus extinguished. The four elements are:

  • Fuel
  • Heat
  • Oxygen
  • Chain Reaction

A fire extinguisher works on the principle that it will remove one or multiple of these elements and stop the fire in its tracks. There are different types of fuel for the fire and that is where the different classes of fire extinguishers come in. The reason for the different classes becomes quite obvious with the example of using a water extinguisher on an electrical fire. This will cause a hazard to the user.

There are five main classes of fires, which we will discuss further in this article.There is a specific extinguisher for each class and some cover multiple classes. The classes are:

  • Class A – Ordinary Combustibles, such as paper or wood
  • Class B – Flammable Liquids, such as gasoline
  • Class C – Live Electrical Fire – Serves as the cause for a Class A or B fire. If the electrical is removed, it is no longer a Class C fire.
  • Class D – Combustible Metals, such as Magnesium or Sodium
  • Class K – Grease Fires

Types of Fire Extinguishers

With a basic understanding of fires and why different fire extinguishers are necessary, let’s discuss the six main types of extinguishers and their uses:

A-B-C Fire Extinguishers

ABC Fire Extinguishers contain a fine powder, commonly mono-ammonium phosphate. It is the most common fire extinguisher found in just about every building. This type of extinguisher has the advantage that it is highly versatile as it can be used on Class A, B and C fires. The principle and ABC extinguisher operates under is that it blankets the fire and aims to starve the fire of its Oxygen. The powder is not an electrical conductor and can effectively interrupt the chain reaction in a gas or liquid fire.

Wet Chemical Fire Extinguishers

Wet Chemical Fire Extinguishers primarily fight Class K or grease fires. The chemical inside of a Class K extinguisher is a solution primarily composed of potassium, which fights the fire in two separate ways. The chemical will act to cool the fire initially, starving the fire of the heat component. Upon contact with the grease or cooking medium, the chemical starts to foam and blankets the area, which is intended to prevent re-ignition of the fire. While we chemical extinguishers are your perfect choice for a kitchen, they can also be effective on Class A fires.

Water-mist Fire Extinguishers

Water Mist Fire Extinguishers are the newest type of fire extinguisher. These extinguishers work across almost all classes of fire. When used, the water fire extinguisher releases a fine mist of water, which attacks several elements of the fire tetrahedron.

First, it starves the first of oxygen, as the fine water particles take up space and decrease the oxygen levels near the fire. Second, the water will cool the fire and affect the heat component, as water naturally does. What is unique about water extinguishers is that the water generally has had all minerals removed (de-ionized), which means it can also be used on electrical fires, as it does not act as a conductor. That means that water fire extinguishers are effective for Class A, B, C and K fires.

Clean Agent Fire Extinguishers

Clean agents are a type of gas fire extinguisher. The extinguisher contains a liquid, which, when discharged, will convert to its gaseous form. The gas is non-conductive, leaves no residue and dissipates very quickly which makes it Eco-friendly. The gas used is usually a Hydrochlorofluorocarbon, marketed as Halotron. The extinguishing agent reduces the oxygen levels and impedes the chain reaction of the fire. As it doesn’t leave any residue, it is ideal for server and electrical equipment or Class B and C fires.

Carbon Dioxide Fire Extinguishers

A CO2 Extinguisher is another type of clean agent extinguisher, as it does not leave any residue. The extinguisher disperses the oxygen from the fire and replaces it with the CO2 contained within. This effectively suffocates the fire, making it the perfect choice for Class B and C fires.

Foam Fire Extinguishers

A foam extinguisher contains a liquid, which foams and expands upon contact with the air. The foam then blankets the fire, which starves the fire of its fuel. The foam has a cooling effect as well, as it does contain some water. Foam extinguishers can be used on Class A and are excellent for Class B fires, though lose their effectiveness for gaseous fires.

Are you protected?

Now that you have more information about the types of fire extinguisher that are out there, take a look around and see what fire extinguishers your business has. Make sure you have a fire extinguisher for every hazard class that may be present in your facility.

Another important aspect to fire extinguishers and fire safety is getting the extinguishers maintained and inspected, and ensuring everyone is properly trained on how to use a fire extinguisher.

Nexus Fire & Safety can assist with fire extinguisher layout and ensuring the right extinguisher for the hazard is present. Our team is fully certified and can provide training for your staff. We are also equipped to maintain and test your fire extinguishers, ensuring they are ready for use, should you need them.

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