Guidance on the Fire Triangle and Tetrahedron
2 min read
Knowing the conditions needed for a fire to start can help you recognise potential hazards, reduce fire risks and understand how fires can be extinguished. One of the simplest ways to explain this is through the fire triangle, which identifies the three essential elements needed for a fire to start. In this article, we’ll explain what the fire triangle is, what each of the fire triangle components represents and how the fire tetrahedron builds on this model.
What is the Fire Triangle?
The fire triangle is a simple diagram that illustrates the three elements needed for a fire to start: heat, fuel and oxygen. All three must be present for combustion (the process of burning) to take place. If one element is missing, a fire cannot start. If a fire is already burning, removing one of these elements can help to extinguish it.
The three sides of the triangle represent the three essential components of fire. Understanding these components is useful when identifying fire hazards and putting appropriate fire prevention measures in place.
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Heat (Ignition)
Heat is the energy needed to raise a material to the temperature at which it can ignite and begin burning. Controlling potential ignition sources is an important part of fire prevention. For example, electrical equipment should be maintained properly and smoking materials should be disposed of safely.
Sources of heat/ignition include:
- Naked flames, such as matches, candles and gas burners.
- Faulty or overheating electrical equipment.
- Smoking materials, including cigarettes and lighters.
- Hot surfaces, sparks and certain industrial processes.
Fuel
Fuel is any material that can burn. Many everyday materials are combustible, meaning they can catch fire when exposed to sufficient heat and oxygen. Reducing the amount of combustible material in an area, keeping storage spaces tidy and storing flammable substances safely can help to reduce fire risks.
Examples of common fuel sources include:
- Paper, cardboard and packaging materials.
- Fabrics, furniture and other furnishings.
- Wood and other building materials.
- Flammable liquids, such as some cleaning chemicals, paints and varnishes.
- Flammable gases, such as propane and butane.
Oxygen
Oxygen is a gas that supports combustion. It’s naturally present in the air around us, meaning oxygen is readily available in most environments where fires can occur.
Some workplaces use oxygen cylinders for medical, industrial or other specialist purposes. Concentrated oxygen can make materials ignite more easily and cause fires to burn more fiercely. Oxygen cylinders are therefore covered by the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) and must be stored, handled and used correctly.
The Fire Tetrahedron
The fire tetrahedron builds on the fire triangle by adding a fourth element: a chemical chain reaction. This provides a more complete explanation of how a fire starts and continues to burn.
The four components of the fire tetrahedron are:
Understanding the fire triangle and fire tetrahedron is an important part of fire safety awareness. By recognising potential sources of heat, fuel and oxygen, you can take practical steps to prevent fires and help keep people safe, whether at work or at home.
Further Resources:
- Fire Safety Courses
- Understanding Fire Safety Signs
- Understanding the Different Types and Uses of Fire Extinguishers
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