Question

What are the three essential requirements to produce fire? How fire extinguisher is useful for controlling the fire?

Answer 1

Three essential requirements to produce fire are as follows:

1. Fuel (combustible substance)
2. Air (or oxygen) and
3. Heat to acquire the ignition temperature.
   The job of fire extinguisher is to cut off the supply of air or to bring down the temperature of fuel or both.
   The most common fire extinguisher is water. But water works only when things like wood and paper are on fire. Water extinguishes fire by cooling the burning substance.
   For fires involving electrical equipment and inflammable materials like petrol, then carbon dioxide (CO₂) is the best extinguisher. 
   CO₂ being heavier than oxygen, covers the fire like a blanket.
   Since the contact between the fuel and oxygen is cut off, so the fire can be controlled. The added advantage of CO₂ is that in most cases, it does not harm the electrical equipment.