Basically, Fire is the result of a chemical reaction in which a substance combines with oxygen; destroying its form by the heat generated in the reaction.

A fire needs four main elements to occur

  1. Fuel
  2. Oxygen
  3. Heat
  4. Chemical reaction

Fire Triangle

Extinguishing fires depends on the removal or reduction of one component of the fire triangle. This means considering the three elements of:

Fire triangle

Control of Fire

Types of fire control –

  1. Cooling
  2. Smothering can be achieved by using sand, blanketing, foam application or by the use of chemical extinguishers
  3. Starvation is achieved by removal of the fuel burning in the fire. Any combustible material can be removed or gas or fuel flows shut off
  4. Poisoning the flame

Types of Fire

Classification of fire and hazard types as per NFPA

National Fire Protection Association (NFPA)

5 Types of Fire


Class A fires (designation symbol is a green triangle) involve ordinary combustible materials like paper, wood and fabrics, rubber. Most of the times, this type of fire is effectively quenched by water or insulating by other suitable chemical agent (DCP)


Class B fires (designation symbol is a red square) mostly involve flammable liquids (like gasoline, oils, greases, tars, paints etc) and flammable gases. Dry chemicals and carbon dioxide are typically used to extinguish these fires. Foam use


Class C fires (designation symbol is a blue circle) involve live electrical equipment like motors, generators and other appliances. For safety reasons, nonconducting extinguishing agents such as dry chemicals or carbon dioxide are usually used to put out these fire.


Class D fires (designation symbol is a yellow decagon) involve combustible metals such as magnesium, sodium, lithium potassium etc. Sodium carbonate, graphite, bicarbonate, sodium chloride, and salt-based chemicals extinguish these fires.


Class K fires are fires in cooking appliances that involve combustible cooking media (vegetable, animal oils or fats).

Fire Hazard


In accordance with NFPA, areas are typically classified as being light (low) hazard, ordinary (moderate) hazard, or extra (high) hazard.

3 Types of Hazard

Light (low) hazard areas are locations where the quantity and combustibility of Class A combustibles and Class B flammables is low. In these areas, expected fires have relatively low rates of heat release. Light hazard areas may include offices, classrooms, meeting rooms etc.

Ordinary (moderate) hazard areas are locations where the quantity and combustibility of Class A combustible materials and Class B flammables is moderate. Fires with moderate rates of heat release are expected in these areas. Ordinary hazard locations could be offices, malls, light manufacturing or research operations, parking garages, workshops, or maintenance/service areas.

Extra (high) hazard areas are locations where the quantity and combustibility of Class A combustible material is high or where high amounts of Class B flammables are present. Quickly developing fires with high rates of heat release are expected. These locations could be sites for cars repair, aircraft and boat servicing, painting, dipping, and coating, storage areas (tanks, containers etc).

Workplace Fire Hazard

Common Workplace Fire Hazard

  • Heating, electrical and mechanical equipment
  • Storage and handling of combustible materials
  • Proximity hazards
  • Unauthorized smoking and poor smoking areas
  • Conventional cooking