The Fire Triangle (WJEC GCSE Chemistry)

The Fire Triangle

• The fire triangle is a symbol used to explain the three factors that are needed for a fire to occur:

  • Fuel

  • Heat

  • Oxygen

The fire triangle

The sides of the triangle show what is needed for a fire

• The fire triangle is used in fire prevention and firefighting as removing any one factor (side of the triangle) can stop a fire 

Removing the fuel

• This is the main focus of fire prevention

• Clothing and materials can be treated to make them fire-resistant

• Modern buildings have fire-proof compartments to reduce the spread of fire

  • These can be between the walls, in the ceilings or formed by the use of internal fire doors

• Managed forests and moorlands have fire breaks cut into them 

  • A fire break is a section of the forest or moorland where all the fuel has been cut down / removed

Photo by Clint Patterson on Unsplash

Removing heat

• The main way to remove the heat from a fire is to spray large amounts of water over the fire

  • This is not suitable for electrical fires due to the increased risk of electrical shocks

  • This is not suitable for oil fires as the water can cause the oil to form droplets which increases the surface area of the fire and makes it burn more

Removing oxygen

• Carbon dioxide extinguishers, foam extinguishers and fire blankets can all cover a fire

  • They work by reducing the amount of oxygen available

  • Once the fire uses up all the available oxygen, it will go out

• The reason for closing doors inside a burning building is that the fire is held in a compartment with limited oxygen

  • Opening a door to a fire provides it with fresh oxygen