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The Hazardous Products of Combustion
Fire produces flame, heat, gases and smoke. Each of these combustion products can cause serious injuries or death. Gases. The gases produced by a fire depend mainly on the fire. The most common hazardous gases are carbon dioxide, the product of complete combustion, and carbon monoxide, the product of incomplete combustion. Carbon monoxide is more dangerous of the two. When air mixed with carbon monoxide is inhaled, the blood absorbs the carbon monoxide. This results in oxygen deficiency in the brain and body. Exposure to 1,3% concentration of carbon monoxide will cause unconsciousness in two or three breaths, and death in a few minutes. Carbon dioxide works on the respiratory system. When the oxygen content of air drops from its normal level of 21% to about 15%, human muscular control is reduced. Unconsciousness usually results from oxygen concentration below 10%. Any other gases generated by a fire are of equal concern to firemen. Therefore, anyone entering a fire must wear breathing apparatus. Gas passage from one room to another depends upon a difference in pressure, or a draft. The air and gas flow from the high pressure area to the low pressure area, and through any available opening, even a porous concrete block wall. Gas is also known to pass through a keyhole, cracks around a door, etc. Another dangerous gas passage is through electrical conduct. The conduit can carry gas between rooms, floors and, in rare cases, buildings. This occurs when the size of the conduit is large enough and the pressure differential is great enough to force the gas enter the room. It provides the mixing of the gas into a flammable or explosive mixture. Smoke is a visible product of fire that adds to the problem of breathing. It is made up of carbon and other unburned substances in the form of suspended particles. It also carries the vapour of water, acids and other chemicals, which may be poisonous or irritating when inhaled. Smoke greatly reduces visibility in and above the fire area. It irritates the eyes, nose, throat and lungs. Breathing a low concentration for an extended period of time or a heavy concentration for a short time can cause great discomfort to a fireman. Firemen who do not wear breathing apparatus in the fire area should eventually go out to fresh air. Дата добавления: 2015-09-18 | Просмотры: 1057 | Нарушение авторских прав |