A fire retardant is a substance used to slow or stop the spread of fire or reduce its intensity. This is generally done by chemical reactions that reduce the combustible fuel or delay their combustion. Flame retardants can also cool fuel through physical action or endothermic chemical reactions. Fireback is available in powder form, mixed with water, as a fire-retardant foam and a fireproof gel. Fireback is also available as a coating or spray to apply to an object.
Fire resistant is usually used in fire extinguishers, where they can be applied aerial or from land.
Video Fire retardant
Prinsip operasi
In general, fire retardants reduce the combustible material either by blocking the fire physically or by initiating a chemical reaction that stops the fire.
Physical action
There are several ways in which the combustion process can be hampered by physical action:
- Cooling: Some chemical reactions actually cool the material.
- By forming a protective layer that prevents the underlying material from triggering.
- With dilution: Some retardants release water and/or carbon dioxide when burned. This may dilute the radicals in sufficient flame to exit.
Commonly used fire retardant additives include mixtures of huntite and hydromagnesite, aluminum hydroxide, and magnesium hydroxide. When heated, aluminum hydroxide is dehydrated to form aluminum oxide (alumina, Al 2 O 3 ), releasing moisture in the process. This reaction absorbs a lot of heat, cooling the material put into it. In addition, the alumina residue forms a protective layer on the surface of the material. The mixture of huntite and hydromagnesite works in the same way. They endothermically outline the release of water and carbon dioxide, providing fireproof properties to the material in which they are inserted.
Chemical action
- Reactions in the gas phase: chemical reactions in a flame (ie gas phase) may be subject to interference by fire retardants. Generally, these retardants are organic halides (haloalkan) such as Halon and PhostrEx. The chemicals used in this type of retardant are often toxic.
- The reaction in solid phase: some of the retardants break down the polymer so that they melt and flow away from the fire. Although this allows some materials to pass certain flammability tests, it is unknown whether fire safety is actually enhanced by the production of flammable plastic droplets.
- Char Formation: For carbon-based fuels, solid phase flame retardants cause carbonated char layers to form on the fuel surface. This char layer is much more difficult to burn and prevent further burning.
- Intumescents: This type of inhibitor combines chemicals that cause swelling behind the protective film, providing much better insulation. They are available as plastic additives, and as paints to protect wooden buildings or steel structures.
Maps Fire retardant
Using
Fire extinguishers
Class A foam is used as a fire retarder in 2.5 gallon extinguishers [APW] and [CAFS] to produce new brush fires and grass fires by creating fire fighting. Other chemical retardants are able to produce Class A material and Non-combustible Class B fuels and extinguish class A, class B, and some class D fires. The falling flame retardant slurry is usually applied in front of the flame to prevent ignition, while the suppressing agent fire is used to extinguish the fire.
Surface coating
Objects can be coated with flame retardants. For example, a Christmas tree is sprayed with a retardant. As the tree dries up, it becomes highly flammable and a fire hazard.
The steel structure has a refractory layer around the columns and beams to prevent structural elements weakening during a fire.
Dorms in the US are also considering using this product. Since 2000, 109 people have been killed in campus fire or off-campus student housing across the country, according to Campus Firewatch, an online bulletin. Publisher Firewatch Campus, Ed Comeau, said the January 2000 fires at Seton Hall University in New Jersey drew attention to the dangers of campus fire. A common area in the Seton Hall dormitory was burned after two students turned on banners from bulletin boards. The fire quickly spread to the furniture and killed three students and injured 58 others.
Battle of forest fires
Early fire protection is a mixture of water and thickening, and then includes borate and ammonium phosphate.
Generally, a fire retarder is dropped from the aircraft or applied by a ground crew around the edge of a fire in an attempt to resist its spread. This allows the crew to work to extinguish the fire. However, when necessary, the retardant may also be dropped directly into a flame to cool the fire and reduce the length of the flame.
Air firefighters
Firefighters are a method to combat forest fires by plane. The types of aircraft used include fixed wing aircraft and helicopters. Smokejumpers and rappellers are also classified as air firefighters, sent by parachutes from various fixed wing aircraft, or rappelling from helicopters. Chemicals used to fight fires may include water, water enhancers, or specially formulated flame retardants.
Textile
Materials
Wild retardant
The fire barrier used for forest fires is usually a mixture of water and chemicals designed to moisten the area and chemically slow the progression of fire through vegetation. Usually it is colored so that the application area can be viewed from the air. New gel-based retardants that meet the NFPA Standard 1150 are being used. It dyed another color to distinguish them from traditional red retardant. Their gels and dyes are designed to break down naturally. Phos-Chek is a long-term brand that is currently approved for fire use in the wilderness.
Environmental issues
Some fire retardants contain chemicals that are potentially harmful to the environment, such as PBDEs. Fire retardants used in aircraft and fire resistant objects such as carpets accumulate in humans. (see PBDE # Health Problems).
The forest fire barrier used is generally considered non-toxic, but even less toxic compounds carry risks when organisms are exposed in large quantities. Fire retardants used in firefighting can be toxic to fish and wildlife as well as firefighters by releasing dioxins and furans when inhibited fire retardants are burned during a fire, and falling within 300 feet of a body of water is generally prohibited unless life or property is directly threatened. The US Forest Service is the governing body that conducts research and monitors fire retarding effects on wild land systems in the US.
A study published in June 2014 found that marine bacteria have the ability to produce synthetic PBDE sources that are chemically identical. This chemical is used as a flame retardant, but is known to be toxic to the environment.
See also
- Air firefighters
- Flame retard
- List of refractory materials
- Modular Airborne FireFighting System
- Wildfire fires
References
External links
- Fire Management Notes (1989)
- National Fire Protection Association
- Defense Fire Protection Association
- Using Refractory Materials
- Effect of fire retardant, ammonium polyphosphate, on thermal degradation of poly (methyl methacrylate)
Source of the article : Wikipedia
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