The fire triangle is a simple model used to explain how fires start and continue to burn.

It's called a triangle because a fire requires three elements to ignite and sustain itself: heat, fuel, and oxygen.

Remove just one of these sides of the fire, and the flame goes out.

Heat

Heat is the energy source that starts a fire. It's often the first element involved, and without enough heat, a fire can't begin or grow.

Every fire has an ignition source, which could be a spark, flame or even a hot surface. To ignite most materials, heat must reach a certain ignition temperature.

Common sources of heat include:

• Sparks or flames
• Hot surfaces or friction
• Electrical faults
• Direct sunlight

Without heat, there's no ignition, and the fire triangle collapses.

Fuel

Fuel is anything that burns. It feeds a fire and keeps it going.

This can include any combustible material, whether it's solid, liquid or gas.

Examples of fuel include:

• Wood and paper
• Fabric and soft furnishings
• Flammable liquids and gases
• Packaging materials or chemicals

If you remove the fuel, the fire has nothing left to consume and it will go out.

Oxygen

Oxygen helps a fire spread by feeding the chemical reaction that keeps it burning. The air we breathe contains around 21% oxygen, and most fires only need about 16% oxygen to stay active.

If oxygen is removed or reduced, the fire is smothered.

How to break the fire triangle

To stop a fire, you need to remove one of the three elements.

That's how fire extinguishers work - they are designed to target at least one side of the triangle.

• Water-based extinguishers cool the heat
• CO2 extinguishers remove oxygen
• Foam and powder extinguishers can help isolate the fuel

Some extinguishers also create a barrier to stop flames from spreading or reigniting.

That's why having the right fire extinguisher to hand can make all the difference.

Beyond the Triangle: The Fire Tetrahedron

Modern fire science introduces a fourth element, the chemical chain reaction. This gives rise to a more advanced model, known as the fire tetrahedron.

This concept is especially important for high-risk environments, like those involving lithium-ion batteries or flammable chemicals, where the reaction itself must be interrupted, not just the fuel, heat, or oxygen.

To understand how fire really behaves in today's world, it's important to learn about both the fire triangle and the fire tetrahedron.

Read our Fire Tetrahedron guide for more.

The Firechief® range includes high-performance fire extinguishers, fire blankets, first aid kits and lithium-ion fire extinguishers suitable for professional, home and leisure use.  For more information, call us on +44 (0)330 999 0019 or email sales@firechiefglobal.com.

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Disclaimer

The information contained within this blog is provided solely for general informational and educational purposes and is not intended as a substitute for professional advice. Before taking any actions based upon this information, we advise the reader to consult any and all relevant statutory or regulatory guidance and, where felt necessary to consult a qualified fire or industry regulation professional. The use or reliance on any information contained herein is solely at the reader’s risk.