To beat the enemy one must know the enemy right. Likewise, for fire. Fire is not a single faceted enemy. It is a multi-faceted opponent; six faces to be precise.
Fire is classified on the basis of the kind of fuel it burns. Correspondingly there are different extinguishers to tackle different types of fire. The fire and its corresponding extinguishing agent combination must be adhered to, not only for efficient firefighting but also because the incorrect combination might also turn lethal.
The various classes of fires are:
A Class Fire: Solid Fire Fire in solids like wood, cloth, plastic etc. is called A class fire. These are called deep seated fire i.e. the combustible material not only burns at the surface but deep within as well. Since the fire is deep seated there are very high chances of such fire bouncing back. To douse off this category of fire completely, an extinguishing agent must ensure that there is no rekindling of fire by bringing down the temperature to sub combustible levels. ABC powder (MAP) based and water based extinguishers are ideal extinguishing agents to tackle this type of fire. Powder forms a layer on the burning material and smothers the fire. Water on the other hand removes heat from the burning site. B Class of Fire: Fire in Flammable Liquids Flammable liquids have an extremely low ignition point and set ablaze at the slightest trigger. Such fires are extremely volatile. B Class fire can be extinguished by Dry Powder, CO2 and Foam based fire extinguishers and special powder for B class fire (called B+ or Monnex) is adept in handling such fires.
C Class of Fire: Fires in Flammable Gases Flammable gases are explosive in nature. Gaseous fires start instantly and spread vehemently and explosively. A multi-purpose fire extinguisher like ABC dry powder (sometimes called DCP) & specialized gaseous fire fighters like BC & B+ based fire extinguishers can douse off such fires.
D Class of Fire: Fire in Metals Fires in combustible metals are extremely explosive in nature. A highly specialized extinguishing agent is needed to subdue metal fire or else firefighting can be fatal. Class D type fire can be effectively tamed by smothering and heat absorption. It is done by administering a specialized extinguishing agent that contains metal particles. They absorb large amount of heat and melt, forming a covering over the burning surface, thereby dousing the fire.
E Class of Fire: Electrically Started Fire Fires arising out from electrically energized devices are called E class fire and are the most commonly occurring fires these days. Using water on electrical equipment not only spreads the ESF fire but may also causes electrocution. Ideal extinguishing agents for such fires are: Powder based, CO2 based, watermist based and clean gas based fire extinguishers as they are safe to be used on electrical devices with no danger of electrocution.
F Class of Fire also called K class fire: Kitchen Fires Fire caused by super-heated fats is called class F fire; it is a major source of fires in kitchen. Applying water to such fires can lead to spluttering of oil and thus serious injuries to fire fighter. Watermist and foam mist based fire extinguishers are an ideal choice to combat such fires. They kill fire by absorbing heat and bringing the temperature below combustible levels & cutting off oxygen supply without even coming in contact with the oil. When you pick up a fight with fire it is important make sure you choose your armor right or else firefighting can turn fatal. It is always advisable to keep a multi-purpose extinguisher handy at all times. In areas with specific fire risks, the stakeholder must invest in the specialized extinguishers to avert the fire and its corresponding risks.