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Flammability hazards are based upon a material's susceptibility to burning. Conditions present need to be considered as well as the combustibility characteristics of the fuel. Firefighter turnouts are generally the appropriate protective clothing for flammability hazards. There may, however, be conditions where firefighters even in full turnouts cannot be adequately protected because of the volume of fire or flame impingement on containers. Each situation needs to be thoroughly evaluated based upon the flammability hazards present. Some flammable chemicals may also be toxic, and toxicity should be taken into account before emergency personnel are sent into a scene where toxic materials may be present or on fire.
- 4 - Materials that are flammable gases, flammable cryogenics or liquids with flash points below 73 degrees Fahrenheit and boiling points below 100F, (Class IA liquids). Also included are gases, liquids and solids that may spontaneously ignite when exposed to air. Examples of Flammable Hazard 4 chemicals include hydrogen, acetylene, vinyl chloride, trichlorosilane, propylene oxide, picric acid, phosphorus, natural gas, hydrogen cyanide, formaldehyde gas, ethylene oxide, carbon disulfide, carbon monoxide and ethyl ether.
- 3 - Liquids having a flash point below 73F and having a boiling point at or above 100F. Liquids having a flash point at or above 73F and a boiling point at or above 100F (Class IB and Class IC liquids). Also included are solid materials that because of their physical form can form explosive mixtures when suspended in air. Examples of Flammable Hazard 3 liquids and solids include acetonitrile (methyl cyanide), acrolein, aluminum powder, benzene, gasoline, calcium carbide, methyl isocyanate and potassium.
- 2 - Liquids having a flash point at or above 100F but below 200F (Class II and Class IIIA liquids). Solid materials that burn rapidly but do not form explosive mixtures with air. Flash point solids, which give off flammable vapors. Examples of Flammability Hazard 2 liquids and solids include glacial acetic acid, cresols, lithium aluminum hydride, nitrobenzene and phenol.
- 1 - Chemicals that will burn in air when exposed to temperatures above 1,500F for five minutes. Liquids and solids which have a flash point at or above 200F (Class IIIB liquids). Most ordinary combustible materials. Examples of Flammability Hazard 1 materials include trichloroethylene, polychlorinated biphenyls, phosphorus pentasulfide, paraformaldehyde, methyl bromide, magnesium and anhydrous ammonia.
- 0 - Materials which generally will not burn under normal circumstances.
Instability hazards (reactivity) addresses the degree of inherent vulnerability of materials to release energy. It applies to materials capable of rapidly releasing energy by themselves, through self-reaction or polymerization. It does not deal with water-reactive materials. Organic peroxides need to be evaluated with NFPA 432 Code for the Storage of Organic Peroxide Formulations.
Instability does not take into account the unintentional combination of materials, which may occur during fire or other conditions. During storage, unintentional mixing should be considered in order to establish appropriate separation or isolation. The degree of instability hazard is meant to indicate to emergency personnel if an area should be evacuated, if firefighting should be conducted from a location of cover, if caution is required when approaching for extinguishment, based upon extinguishing agent, or if a fire can be fought using normal procedures. Ranking of instability hazards is based upon a materials ease, rate and quantity of energy release.