Science
How does a fire extinguisher work?
A fire extinguisher works by removing one of the three things a fire needs: heat, fuel, or oxygen. Most spray a substance that smothers the flames or cools them, breaking the chemical reaction of burning so the fire goes out.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a fire extinguisher works.
Step by step
- 1Fire needs heat, fuel, and oxygen — the 'fire triangle.'
- 2Extinguishers remove at least one of these.
- 3Water cools the fire; foam and CO₂ smother the oxygen.
- 4Dry powder interrupts the burning chemical reaction.
- 5Different fire types need different extinguisher types.
Frequently asked questions
- How does a fire extinguisher put out fire?
- By removing heat, fuel, or oxygen — cooling the flames, smothering them, or chemically interrupting the burning reaction.
- Why are there different types of fire extinguishers?
- Different fires (wood, oil, electrical, metal) need different agents; using water on an oil or electrical fire can be dangerous.
- How does a CO₂ extinguisher work?
- It blankets the fire in carbon dioxide, displacing the oxygen so the flames can't keep burning, and it leaves no residue.