To understand how to stop combustion and extinguish a fire, you must first familiarise yourself with the concept of the fire triangle – one of the fundamental principles of fire knowledge and fire safety.
The Fire Triangle – The Basics
Detailing the basic elements of any fire, the fire triangle (also known as the combustion triangle), provides a simple model of understanding the cause and spread of any fire.
The three elements of the fire triangle simplify but succinctly detail the factors present necessary to cause ignition and sustained growth of fire: fuel, heat and oxygen. The chemical reaction between each of the three elements can only occur when all three are present.
Fuel
When we talk about fuel in the context of fire, we mean the material that burns during the fire. There are gas, liquid and solid fuels which burn at different temperatures and different intensities. These include:
- Combustible everyday materials, such as wood, paper, plastic and textiles
- Flammable gases, such as propane, butane and methane
- Flammable liquids, such as petrol, gasoline, and oils (not used in cooking)
- Cooking oils
- Flammable metals, such as calcium, magnesium and magnesium alloys, lithium
Heat
For combustion to occur and a fire to get started, there must also be a source of heat present to ignite the flammable vapours released by the fuel material. In addition to that, heat helps fire spread and last longer. It heats the surroundings, pre-heating and drying any fuel in the fire’s path, making it a lot easier to move and engulf further areas.
Oxygen
Oxygen is a key element that drives the chemical reaction behind fire. For the fuel to burn and release heat, it needs at least 16% oxygen in the air. For reference, ambient air has about 21% oxygen.
The fundamental principle of the fire triangle is that each element is dependent on the other in the creation and growth of any fire, whilst also demonstrating the complete removal of just one element can prevent a fire or extinguish it entirely.
How to Stop Combustion
When considering fire safety, always recall the fire triangle: fuel, heat and oxygen. Remember that removing just one element of the fire triangle from an ongoing blaze can begin its subsidence. Let’s find out how to stop combustion and extinguish a fire by removing each of the three elements necessary for a fire to burn.
Remove Sources of Fuel
For any fire to begin, there must be a fuel source – martial that burns. Typical combustible materials include paper, wood, fabrics, plastic and various types of gases. The use of fire-resistant materials is beneficial as it means that a would-be fire has no fuel source to feed its growth and spread.
Furniture and clothing can be made with fire-resistant materials, as can the fabrication of building materials.
The removal method is not necessarily the most effective solution at extinguishing the fire, merely to stop the growth and prevent the spread: the fire will continue to burn until the available fuel has been consumed or intervention strategies – such as the removal of heat and/or oxygen – have been implemented.
In practice, forest fires – such as in California or the Australian bush – are effectively managed using a method known as firebreak: removing trees from the surrounding area of a forest fire to isolate and centralise the fire until it burns itself out or is extinguished by the emergency services.
Removing Sources of Heat
When you think of fire, you think of heat. Dampening the heat of the fire is an effective method of weakening and eventually extinguishing a fire. Not only does the element of heat create the potential of the ignition of a fire, but it also contributes to the sustainability of an ongoing fire by removing residual moisture from fuel sources and heating the surrounding areas, creating an easier path of spread.
How does heat contribute to the ignition? Believe it or not, every flammable material emits a flammable vapour, which, when exposed to a great amount of heat, creates combustion.
Remove Oxygen
Fires need oxygen to survive as much as we do: removing a fire’s exposure to oxygen will cause the fire to slowly die. Fire blankets and carbon dioxide fire extinguishers are two effective methods of suffocating a fire and restricting its access to oxygen.
Fires only require a minimum atmospheric air-oxygen level of 16%, meaning that the average ambient level of oxygen – being approximately 21% – is a prime environment for the growth of a fire. Where possible, you should always seek to starve a fire of oxygen, be via smothering it in the most appropriate fire extinguisher type, water, or a covering agent such as dirt.
When evacuating a room or building, it is advisable to shut all the doors if you know that you are the last person to escape: preventing the free movement of oxygen as well as restricting a fresh oxygen inflow from outside.
Extinguishing the Fire
As you can see, going back to basics with the fire triangle can simplify the necessary precautions when we talk about fire safety. To stop a fire, you must remove one element of the fire triangle.
The development of fire extinguishers – and their numerous types – has largely been in part due to the principles of the fire triangle, seeking to remove one of the three key components. You should always prepare for your environment: if you may need to cover large distances to tackle a fire, choose a wheeled option. If the extinguisher risks exposure to harsh conditions or damage, opt for a P50 model.
Fire safety training and protocols have also been revised to take heed of the fire triangle, what must be done in case of a fire, as well the necessary planning and steps required to prevent the ignition of fire in the first place. HSE codes of practice on the storage of flammable liquids and the storage/disposal of flammable waste materials – such as textiles and dust – have also been based on the fundamental principles of the fire triangle.
What Fire Extinguisher Do I Need?
The different types of fire extinguishers are designed to extinguish fires based on the type of fuel burning, as described below:
| Fire Class | Fuel | Extinguisher Type |
| Cass A | Flammable solids (paper, fabric, wood, plastic, etc) | FoamWaterWet ChemicalDry powder |
| Class B | Flammable liquids (diesel, grease, petrol, etc) | FoamCO2 gasDry powderWet chemical |
| Class C | Flammable gases (hydrogen, propane, butane, etc) | Dry powder |
| Class D | Flammable metals (potassium, sodium, titanium, etc) | Specialist powder |
| Electrical Fires | Live electricity | CO2 gasDry powder |
| Class F | Cooking fats and oils (mostly in kitchens) | Wet chemical |
It’s important to note that you should attempt to use a fire extinguisher only if you have been trained on how to use a fire extinguisher and if the fire is small and doesn’t yet pose a danger to your health. If the fire is out of control, you should call 999 for help and evacuate the premises immediately.
Fire Safety Equipment and The Fire Triangle
Fire safety equipment is a must in any residential or commercial building and it can be used to extinguish a fire in its early stages. Here’s how different types of fire safety equipment break the fire triangle to extinguish a fire:
- Fire extinguishers – remove heat and/or oxygen from the fire
- Fire blankets – remove oxygen from the fire
However, for any fire safety equipment to be useful, the people who are expected to use it must have been given the appropriate fire safety training to ensure that they know how to safely handle the equipment in the event of a fire emergency.
Fire Safety in the Workplace With Evacuator Alarms
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Did you find this quickfire guide on how to stop combustion and extinguish a fire useful? Learn more about fire safety below
FAQ
What does a fire blanket remove to extinguish a fire?
A fire blanket is used to smother a fire, or in other words, a fire blanket removes the oxygen from the fire triangle to extinguish the fire. Learn how to use a fire blanket here.
What does a fire extinguisher remove to extinguish a fire?
Most fire extinguishers work by cooling down the fire, so they remove the heat element from the fire triangle to extinguish the fire. Foam fire extinguishers are an exception, as they not only remove the heat but also use foam to remove the oxygen, resulting in a double-action fire extinguishing process.
What is the difference between The Fire Triangle and The Fire Tetrahedron?
The fire triangle and the fire tetrahedron are essentially the same thing, with the only difference being that the fire tetrahedron, in addition to the three elements of fire, also depicts the chemical reaction needed to cause fire as an additional side in the visual representation of the fire triangle, making it a pyramid.
