Fire class
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A fire class is a system of categorizing fire with regard to the type of material and fuel for combustion. Class letters are often assigned to the different types of fire, but these differ between territories; there are separate standards for the United States, Europe, and Australia. The fire class is used to determine the types of extinguishing agents that can be used for that category.[1]
Ordinary combustibles: Class A (US/EU/AU)
Class A fires consist of ordinary combustibles such as wood, paper, fabric, and most kinds of trash. They may be extinguished by water, wet chemical suppression, or dry chemical powder.[2][3]
Flammable liquids: Class B (US/EU/AU)
Class B fires are those where the fuel is flammable or combustible liquid. The US system includes flammable gases in their "Class B".
The most effective way to extinguish a liquid fire is by inhibiting the chemical chain reaction of the fire, which can be done by dry chemical or
Flammable gases: Class B (US) / Class C (EU/AU)
Fires where the fuel is flammable or combustible gas are classified as "Class C" in the European/Australian system, and "Class B" along with flammable liquids in the US system. Due to the gaseous nature of the fuel, these fires are difficult to extinguish. The most effective techniques for the control of a flammable gas fire are to stop the flow of fuel (by turning off any gas taps or valves) or to displace the oxygen. Control of fires involving flammable gases where the gas source cannot be controlled must be carefully managed. If the flames are extinguished, but the gas continues to leak, an explosive atmosphere may be created, and the gas may find a source for reignition outside of the originally affected area. Strategies employed to manage these fires may include trying to direct or contain the fire to prevent the ignition of other fuels whilst work is done to control the fuel supply.
Metal: Class D (US/EU/AU)
Class D fires involve combustible metals – especially alkali metals like lithium and potassium, alkaline earth metals such as magnesium, and group 4 elements such as titanium and zirconium.[2]
Metal fires represent a unique hazard because people are often not aware of the characteristics of these fires and are not properly prepared to fight them. It is also not always clear what type of metal is burning. Therefore, even a small metal fire can spread and become a larger fire in the surrounding ordinary combustible materials. Certain metals
Special care must be taken when extinguishing metal fires. Water and other common firefighting agents can exacerbate metal fires and make them worse. The National Fire Protection Association recommends that metal fires be fought with dry powder extinguishing agents that work by smothering and heat absorption.[citation needed] Different metals require different extinguishing agents and for a particular metal, agents cannot necessarily be substituted for one another. The most common agents are sodium chloride granules and graphite powder. In recent years, powdered copper has also come into use. These dry powder extinguishers should not be confused with those that contain dry chemical agents. The two are not the same, and only dry powder should be used to extinguish a metal fire. Using a dry chemical extinguisher in error, in place of dry powder, can be ineffective or actually increase the intensity of a metal fire.
Electrical: Class C (US) / Class E (AU) / Unclassified (EU)
Fires predominantly involving electricity have different classifications in each of the three systems. They are classified as a "Class E" fire under the Australian system, "Class C" under the American system,
Electrical fire may be fought in the same way as an ordinary combustible fire, but water, foam, and other conductive agents are not to be used. While the fire is or possibly could be electrically energized, it can be fought with any extinguishing agent rated for electrical fire.
Cooking oils and fats (kitchen fires): Class F (EU/AU) / Class K (US)
Fires involving cooking oils and fats are classified as "Class F" under the European and Australian systems, and "Class K" under the American system. Though such fires are technically a subclass of the flammable liquid/gas class, the special characteristics of these types of fires, namely the higher flash point, are considered important enough to recognize separately. Some special extinguishers designed for this use smother the fire by turning the oil into a foam. As with Class B fires, a solid stream of water should never be used to extinguish this type because it can cause the fuel to scatter, spreading the flames. Commercial kitchens may also have a fire suppression system built into the exhaust hood to release an extinguishing agent onto the stove top, releasing automatically with a fusible link or manually using a pull station. Sometimes fire blankets are used to stop a fire in a kitchen or on a stove.
See also
References
- OCLC 62785313.
- ^ OCLC 62785313.
- ^ a b c "Choosing and using fire extinguishers". U.S. Fire Administration. 2017-12-12. Archived from the original on 2019-05-30. Retrieved 2019-05-30.
- ^ "which class of fires consists of flammable liquids". Treadwell. Treadwell. 2021-03-18. Retrieved 2021-05-13.
In the European/Australian system, flammable liquids are designated "Class B" having flash point less than 100°C.
- ^ Husebye, Johanna Magdalena (2023-01-21). "«Det brenner!» roper Marie (84) – men Jan (81) kommer seg ikke ut". NRK (in Norwegian Bokmål). Retrieved 2023-02-12.
External links
- Classification of Portable Fire Extinguishers, Occupational Safety and Health Administration
- Evacuation Plans and Procedures eTool, Occupational Safety and Health Administration
- Information on Fire Extinguishers, The Fire Safety Advice Centre
- Australian Fire Classes, Futura Fire – Australia
- For Fire Extinguishers, Wollongong Extinguisher Service-Australia