Classification of fire

For identification, fire are classified according to their properties, which relate to the nature of fuel. The properties of fuel directly corresponds to best means of combating a fire. Without a source of fuel there is no fire hazard, but almost everything in an environment could be a fuel. Fuels occur as solids, liquids, vapors and gases.

Fire can be classified as following

Class A fires: Fuel is solid materials such as wood, plastic, textiles and their products: paper, housing, clothing etc. Solid fuels includes wood, building and synthetics used in furniture.

Class B fires: Fuel is in the form of flammable liquids and gases. Flammable liquids have a flash point below 100 ^oF.

Class C fires: Fires that are caused due to electricity as burning, natural and generated electricity play a large role in causing fire. Electrical lines and equipment can cause fires either by short circuiting or by resistances generating heat.

Class D fires: Fire that is caused due to combustible, easily oxidized metals such as aluminum, magnesium, titanium, and zirconium is categorized as “class D fire”.

Special Categories: This type of fire is caused due to extremely active oxidizers or mixtures, flammables containing oxygen, nitric acid, hydrogen peroxide, and solid missile propellants

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CAUSES OF FIRE HAZARDS

SPONTANEOUS COMBUSTION:

              These are rare but can happen. It happens by self-heating (increase in temperature due      to exothermic internal combustion).

HYPERGOLIC REACTIONS:

It includes pyrophor hypergolic fuels. It occurs when mixing fuels. Oxidizers produce such a rapid heat buildup, causing immediate combustion.

MISHANDLING FLAMMABLE LIQUIDS ANG GASES:

They should be handled with care because any shock can increase its internal molecular kinetic energy causing increase in temperature.

NATURAL AND GENERATED ELECTRICITY:

Electrical lines & equipment cause fires by a short circuit that provides a spark, by arcs, or resistance heat. Lightning strikes start many fires every year.

HEAT FROM HOT SURFACES:

Irons in textile manufacturing & dry-cleaning, coffee pots space heaters, hotplates, etc., all create hot surfaces. Boilers, steam equipment, radiators, pipes, flues/chimneys. Surfaces exposed to direct sunlight become hot surfaces.

ENGINES AND COMPRESSORS:

  Engines produce heat, especially in exhaust pipes. Compressors produce heat           through friction, transferred to their housings.

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