Fire
Definition
Fire is a rapid redox reaction which is accompanied by Heat, Smoke and flame.
Fire Pyramid
Four elements are necessary to iginite fire and continue it.
1. Fuel
2. Oxygen or Oxydiser
3. Heat or Source of fire
4. Chain reaction in fire which continues fire.
Incomplete Fire produces carbon monoxide which is toxic and creates invisibility.
Fire Extinguishing
Fire can be stopped
1. Stop or remove fuel.
2. Remove oxygen below 14 ~ 18% by adding inert gas like CO2 or Nitrogen
3. Remove heat faster than libration.
4. Break chain reaction by removing free redicals in Fire. For this Dry chemical powder or Halogenated Hydrocarbons are used. (Hydrogenated Hydrocarbons are banned in some countries)
Stages of Fire & Dire detectors
1. Incipient stage : Ionisation takes place in this phase. Ionization re detector can detect this re.
2. Smouldering stage: Smoke generation this this step. Photoelectric re sensor can detect this stage of fire
3. Flame stage: Flame startes in this step smoke is reducing and heat is increasing. Infrared sensor can sense this stage.
4. Heat stage: Heat, ame, smoke, and gases are generated in this phase.
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