From Big Medical Encyclopedia

DEFLECTOR — the device, the Crimea is supplied an exhaust air duct on escaping of the building for strengthening of an extract and at the same time for protection of vent pipes and the room against penetration of an atmospheric precipitation.

The principle of work of D. is based on use of thermal pressure and action of wind. D.'s productivity depends on its location on a roof, resistance of the movement of air in D. and in an exhaust air duct, heights of a column of the air creating thermal pressure and on efficiency of the installation using a motive energy of wind. The wind flow hits against D. and flows round it, causing thereby in the most part of perimeter of D. formation of a zone of diminished pressure. From here the greatest efficiency is noted at D.'s arrangement in such place of a roof where wind pressure as much as possible.

Optimum location of D. are the highest points of a roof subject to the greatest impact of wind that provides failure of an air flow from edges of the external cylinder D.

It is inexpedient to place D. in the decompression section arising at a flow of the building wind in the fenced space on a roof, between high buildings (in an aerodynamic shadow) since its productivity at the same time considerably decreases.

D.'s design shall guarantee its effective work at any direction and wind force.

Depending on D.'s design can be motionless, shaking and rotating, round and square, stationary and transport. From numerous versions the deflector TsAGI and more productive D. are more often used: acute-angled, with a rassekatel, octahedral, ridge. The deflector TsAGI combines simplicity of the device and safety in operation. The advantage of the device is also that he does not create additional resistance at a calm when work on movement of an exhaust air is made at the expense of a difference of gravitational pressure in the room and out of it.

Bibliography: Bromlya M. F. and Shcheglov V. P. Design of heating and ventilation of production buildings, M., 1965.

Yu. D. Gubernsky.