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8. Внимательно прочитайте текст и переведите его. Обратите внимание на названия химических веществ, встречающиеся в тексте:

Nitrogen – [‘naItrqGqn] - азот

Methane – [‘mJTeIn] - метан

Ethane –[‘eTeIn] - этан

Bromochlorodifluoromethane – бромохлородифлорометан

Bromotrifluoromethane – бромотрифлорометан

TEXT: EXTINGUISHING MEDIA

Classification of extinguishing agents must be flexible and every hazard needs to be considered separately.

Because of its availability and cheapness, water is the best extinguishing medium. Its effectiveness lies in its cooling power and it can be applied in various ways from hand extinguishers, hand pumps, hose reels, hose lines to fixed installations.

Water alone is not always effective as an extinguishing agent. Under certain circumstances, foam is needed. Fire fighting foams are created by the mechanical mixing of foam concentrate, water and air. Foams are well suited for use against flammable liquids because of their light density, high water content, blanketing tendencies and resistance to rapid breakdown. These properties allow foam to be floated over burning flammable liquids, smothering the fire out and cooling hot objects in and near flammable liquids.

Fires may be extinguished by the introduction of an inert gas and so by smothering or reducing the oxygen content below the level that will support combustion. Carbon dioxide and nitrogen are the two gases that lend themselves to this process most readily and they are available in small hand extinguishers, fixed installations and so on.

Volatile liquid compounds of the halogens have great fire extinguishing properties and there are a number of them now available based on the substituted methanes and ethanes. They have been developed by different chemical firms in various countries with the result that CB (chlorobromomethane) was developed in

Germany, BCF (bromochlorodifluoromethane) in Great Britain and BTM (bromotrifluoromethane) in the United States.

Dry chemical extinguishers are among the most common portable fire extinguishers in use today. There are two basic types of dry chemical extinguishers: ordinary and multipurpose. Ordinary dry chemical extinguishers are rated for Class B and Class C fires, while multipurpose dry chemical extinguishers are rated for Class A, Class B, and Class C fires. There is a close relationship between a cloud of dense gas and a cloud of dust or powder. The modern dry powders are getting to be as complex as the vaporizing liquids because the theory of combustion interference is suitable for the powders as for gases.

9. Замените выделенные слова (а) их контекстуальными синонимами (б):

(а) 1. Classification of extinguishing agents must be flexible. 2. Water can be applied in various ways. 3. Fire fighting foams are created by the mechanical mixing of foam concentrate, water and air. 4. Some properties allow foam to be floated over burning flammable liquids. 5. Foams smother the fire out and cool hot objects in and near flammable liquids. 6. There is a close relationship between a cloud of dense gas and a cloud of dust or powder. 7. Volatile liquids have great fire extinguishing properties.

(б) substances; combustible, burning; used, put to practical use; formed, produced; qualities; in the vicinity of, not far from; extinguishing; connection; vaporizing.