Definition
A fire extinguisher that discharges pressurized carbon dioxide (CO2) gas to smother a fire by displacing the oxygen needed for combustion. Effective on electrical fires and flammable liquid fires, it leaves no residue and does not conduct electricity.
Plain English
A fire extinguisher that sprays out CO2 gas, which pushes oxygen away from the fire so the fire goes out. It does not leave any mess behind and is safe to use on electrical equipment.
Context Anchor
Seen in aircraft cabins, maintenance shops, hangars, and ramp areas where fire extinguishers are selected for fuel or electrical fire risks.
Derivation
Carbon dioxide is the chemical compound CO2 -- one carbon atom bonded to two oxygen atoms. Because CO2 is heavier than air and does not support combustion, it blankets a fire and cuts off the oxygen supply, which is one of the three things a fire needs to keep burning (heat, fuel, oxygen).
Why Pilots Care
Extinguishes fires involving electrical systems or flammable liquids without leaving residue that could damage instruments or wiring.
Grounding Statement
When discharged, the extinguisher sends out a cold white cloud of carbon dioxide that surrounds the flame and helps stop it from burning.
Intuition Check
Do not assume a carbon dioxide fire extinguisher cools the fire the same way water does. Its main action is smothering the fire by pushing oxygen away, and the fire can restart if the material stays hot.
Example Sentence 1
The mechanic grabbed the carbon dioxide fire extinguisher when smoke appeared near the aircraft's electrical panel, knowing it would not damage the wiring.
Example Sentence 2
Before flight the pilot confirmed the carbon dioxide fire extinguisher was charged and mounted in the cockpit.