What is fire | Types of fire | fire triangle

Hello peoples , In this Article we are discussing about fire terminologies like What is fire, Types of fire and fire triangle.

What is fire : 

Fire is a reaction ( chemical) in which a material combines with oxygen in the atmosphere to release heat and other reaction products. Fire is combustion accompanied by flame or glow, which escapes its normal confines to cause damage.

Fire is the heat and light of burning. Burning or combustion can be described as a chemical reaction involving a fuel and oxygen. We can classify burning into controlled combustion and uncontrolled combustion.

• Controlled burning/combustion – which can be beneficially used (e.g. cooking, lighting, engines for motor vehicles and aircraft).
• Uncontrolled burning/combustion-which can get started unintentionally and can spread (e.g. house fires, wild fires, forest fires, explosions).

Combustion reactions are exothermic, i.e. they release heat.

In case of combustion reactions involving gases and vapours, the combustible must be present at levels of concentration lying between values known as flammable limits.

With the exception of spontaneous ignition, the process can only begin when an external source of heat is applied to the fuel

Types of fire : 

The different types of fire risks are classified according to the nature of the fuel. The purpose of types of fire is to help in deciding upon the suitability of the types of extinguishing agents available for fire fighting.

The comprehensive classification defines 5 types of fires. A more concise definition can classify fires into only A, B, and C categories.

Class ‘A’ fire :  Fire due to ordinary combustible materials like wood, textiles, paper, rubbish and the like. Class A fires are the most common. The effective agent to extinguish this type of fire is generally water in the form of a jet or spray.

Light hazard—Occupancies like offices, assembly halls, canteens, restrooms, etc. i

Ordinary hazard—Occupancies like saw mills, carpentry shops, book binding shops, i small timber vards, engineering workshops, etc. i

Extra hazard— Occupancies like large timber yards, godowns storing fibrous materials, flour mills, cotton mills, jute mills, large wood working factories, etc.

Class ‘B’ fire :  Fire in flammable liquids or liquefied solids like oils, petroleum products solvents, grease, paint, etc. This type can be divided into two groups, those that are i miscble and immiscible with water. Depending on the types, different extinguishing agents such as water spray, foam, dry chemical powder, carbon dioxide, etc. can be used. For fires involving alcohol, alcohol resistant foam can be used.

Class ‘C’ fire : Fires from flammable gases and for fire involving electrically energized equipment (under NFPA classification) and delicate machinery and the like. This type of fire can be extngushed by smothering with the help of foam, dry chemical powder, carbon dioxide, halon, etc.

Class ‘D’ fires :  Fire from reactive chemicals, active and combustive metals and thei like. Examples are magnesium, sodium, potassium. Extinguishing agents containing wateri are inefrective and sometimes dangerous too.

Carbon dioxide and the bicarbonate classes of dry chemical powders are also hazardous, if applied to most metal lires.  

Class ‘K’ fires : Fires in cooking appliances that involve combustible cooking media Class (vegetable or anumal olls and tats). Class K fires are under NPPA (National Fire Protection Association) USA classification only].

Many fires involve a combination of the types of materials.

What is fire triangle :

Fire results from combination of fuel,heat and oxygen which is combination is called fire triangle

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