Ознакомительные тексты по различным аспектам современной жизни: Страны, Города, Общество, Политическая система, Высшее образование, Календарь праздников.

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Ventilation systems

Almost all used in the construction of buildings and structures of air communication are hidden from prying eyes or in the thickness of the walls, or in the ventilation shafts or above suspended ceilings, when there is only visible rectangles (or fungi) ventilation grills. In fact, the large objects may be placed thousands of meters of various ducts, with large and very small diameters and cross-section. In addition to the air duct of the ventilation systems are used powerful channel and stationary fans, to ensure the inflow or pump the required volume of air. Unfortunately, at present the stationary ventilation installations are performed only abroad, as in Russia, the production capacity for this simply does not exist. And this is understandable — some of them are the size of a nice house, and usually set on the roofs of large buildings.

In general, the ventilation system can be divided into three main groups:
1. Supply ventilation
2. Exhaust ventilation
3. Fire ventilation (smoke).

Supply ventilation provides a supply of purified special filters the air in ventilated rooms. All air ducts are made of galvanized steel and outside turn into a thermal insulation material, preventing excessive cooling of the air in the premises. Additional insulation prevents the formation of condensation in the contact of warm and cold environments. The wiring and distribution of supply air in the interior provide ventilation sleeves, made of special corrugated pipes of the necessary diameter.

Exhaust ventilation is used to delete used in the premises of the air, which is already saturated with carbon dioxide.

To ensure the optimal balance of incoming and removed air shall apply the automatic valve system, in which, depending on their needs, can be regulated by the supply and removal of air.

Fire ventilation, as a rule, is more complicated than supply and exhaust, in view of the fact that its main function is to maximize long-term work in the conditions of the critical temperature. Used when the ducts are made of a special alloy in the form of welded baskets, with the minimum coefficient of thermal expansion. Valve systems of fire ventilation should provide high efficiency of absorption of products of combustion. However, they serve as the actual «alarm button» for systems and ventilation, immediately stopping their work, because the inflow of fresh air contributes to the strengthening of the combustion process.