Which Gas is Used in a Fire Extinguisher?

To understand this, you must know the 'Fire Triangle'. A fire needs three things to survive: Heat, Fuel, and Oxygen. If you remove even one, the fire instantly dies. Carbon Dioxide extinguishes a fire using two brilliant methods:

1. Suffocation: CO₂ is physically heavier and much denser than normal oxygen. When you spray it on a fire, the heavy CO₂ falls down like a thick, invisible blanket over the flames. It completely blocks the fire from touching the surrounding oxygen in the air. Without oxygen, the fire suffocates and dies instantly.
2. Extreme Cooling: Inside the metal cylinder, the CO₂ is compressed under massive pressure into a liquid. When you pull the trigger, it shoots out of the nozzle and rapidly expands back into a gas. This rapid expansion causes the gas temperature to drop to a freezing -78°C (turning into dry ice snow). This massive blast of cold instantly removes the 'Heat' from the fire triangle.

• Oxygen: Spraying oxygen on a fire is like throwing gasoline on it. It will cause a massive, explosive fireball.
• Nitrogen: While nitrogen doesn't burn, it doesn't have the heavy density of CO₂ to form a suffocating blanket over the fire.

CO₂ is the absolute best extinguisher for electrical fires and computer server rooms. Because it is a pure gas, it leaves behind absolutely zero residue, water, or foam. Once the fire is out, the CO₂ simply evaporates into the air, leaving the expensive computers completely dry and undamaged.