What is Fire Triangle & Fire Tetrahedron, Types of Fire & Their Extinguishing Method. Interview QnA - Job Availables

Most Frequently asked Interview questions and answers about Fire 

1. What is fire?

2. What is Fire Triangle?

3. What is Fire Tetrahedron?

4. How many types of Fire?

5. What is Fire Extinguishing Principles?

6. What are the 4 types of fire extinguishers and their uses?

Fire is Self sustaining rapid Oxidation of fuel which produces light, heat & combustion by-products.

Fire= Fuel +Oxygen + Ignition Source = Heat + Light + Byproduct.

Fire Triangle: 

The fire triangle is used to show the three elements that when present together can cause a fire to start. These three elements are fuel, heat and oxygen.

Fire Tetrahedron: 

Chain Reaction: The fourth factor which acts as a catalyst in rapid oxidation process is OH(-) radical which is also termed as Chain Carrier which results in Chain reaction of combustion process.

Types Of Fire:  

1. Class 'A'

Class 'A' fire involves Combustible Solids like Paper, Wood, Cloth, Plastic, Rubber, etc. These types of fire leave an ashy residue. The best way to extinguish this type of fire is by removing the heat source.

2. Class 'B'

Class B fire involves flammable or combustible liquids, petrol, kerosene, diesel, oils, solvents, alcohols etc. This type of fire actually burns on the surface of the fuels. Smothering or blanketing the fire source is the best way to extinguish this type of fire. Water should not be used to extinguish this type of fire.

3. Class 'C'

Class 'C' fire involve flammable gases under pressure such as propane, butane and methane etc.

4. Class 'D'

Class D fire involves combustible metals such as magnesium, sodium, potassium, sodium-potassium alloys uranium, and powdered aluminum.

The best way to extinguish this type of fire is smothering the fire.

5. Class 'E' 

Class 'E' - fires involving live electrical apparatus. (Technically ‘Class E’ doesn’t exists however this is used for convenience here)

Fire Extinguishing Method: 

1. Cooling: Cool the burning material

Example: Removal of heat by applying the water

2. Smothering: Exclude oxygen

Example: Removal of Air(oxygen) by applying foam blanket / covering by foam blanket.

3. Starvation: Remove the fuel

Example: Isolation of leaking section of

process line, separating combustible materials adjacent to fire area etc.

4. Chain Inhibition: 

Example: By stopping the chain reaction.(e.g., by applying dry chemical powder)

Fire Extinguisher Type and Their Application:

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