Air distributors (supply nozzles) are designed to distribute supply air. The supply air can be supplied to the working area; for this, the air distributors must have a short torch and a slight velocity of the outgoing air to eliminate the feeling of a draft. When air is supplied to the upper area of the room, on the contrary, the air outlet speed should be higher so that the fresh air stream reaches the working area.
Air distributors are installed in suspended ceilings, some are mounted at a low height above the working area.
A type of supply ventilation systems is air shower, which provides a concentrated flow of air to the workplace. A workplace is a platform with a diameter of 1 m, on which the worker is at least 4 hours per shift or 2 hours continuously. Such an air supply is necessary for intensive thermal (from 300 to 3000 W/m2 or more) irradiation of workers, or for open production processes with the release of harmful gases and vapors, when it is impossible to arrange local shelters. Actually, the scheme of air douching does not differ from the supply ventilation system, but instead of air distributors, showering rotary nozzles are installed.
Air and thermal-air curtains are designed to protect the gates and open entrances of industrial buildings from the intake of cold air in winter. There are two types of curtains: sliding, in which a flat jet of air is supplied either from below or from the sides of entrances and gates at some angle towards cold air, and mixing, when air from the building is supplied to the vestibule between the double entrance doors. Mixing curtains are used in administrative and public buildings, in passageways, etc. Curtains in which the air is preheated in an air heater are called thermal-air, and curtains that supply air without heating are simply air type.
Air-heating units with full or partial air recirculation are often used in air heating systems.
General exchange exhaust ventilation systems usually remove air from the upper, less often from the middle zone of buildings. Before removal, the air in general exchange exhaust systems usually does not undergo cleaning. General exchange exhaust systems can be channelless if the air is removed by roof fans that are installed on the floors, and ducted. In ducted exhaust ventilation systems, air is sucked into air intake apertures or grilles, it is fed through the ducts to the fan and, after passing the exhaust shaft, enters the atmosphere. To protect the exhaust shaft from atmospheric precipitation, an umbrella is installed above it, and the air ducts are blocked with a flap when the fan is not working.