Classification of ventilation systems is carried out by the method of air movement, purpose and service area.
Content
The method of air movement is natural or artificial ventilation.
Purpose - supply or exhaust ventilation.
Service area - local or general ventilation.
Natural ventilation
The principle of operation is based on the difference in external and internal temperature, as well as due to the thrust created by the wind. The air exchange is affected by the material from which the walls of the building are erected. The wood and brick have good air permeability, this indicator is lower for concrete and cement plaster. To improve the air exchange in the room produce ventilation through windows, transoms and windows.
The natural ventilation can be strengthened by installing ventilation ducts. Usually the channels are laid in bathrooms and in the kitchen. All channels are output to the roof and have a nozzle - a deflector, which increases traction due to wind force. The disadvantage of such a system is that it does not provide a full air exchange, and at a high temperature of outside air, there may be a reverse thrust. To prevent this phenomenon, a fan is installed in the channel.
Artificial ventilation
In this type of ventilation systems, equipment is used that can move air through channels over long distances. The supply and removal of air is carried out in a given volume and does not depend on external conditions (wind force, temperature). Different processing of air (filtration, heating, cooling, etc.) is possible. The equipment of the artificial ventilation system consumes electricity. Consumption costs are proportional to the area of the facility and the capacity of the equipment. In practice, a combination of natural and artificial ventilation is used. Priority type of ventilation is determined at the design stage based on sanitary and hygienic standards and technical and economic indicators.
Forced ventilation
This system ensures the supply of fresh air, which replaces the one being removed. As a rule, the air coming from outside is subjected to preliminary treatment (heating, cooling, humidification, filtration).
Exhaust ventilation
The system is designed to remove exhaust air from the premises. When designing, it is envisaged that there is a supply and extraction of air with strict observance of the balance between them. In this case, the presence of adjacent rooms is taken into account. In separate rooms there can only be an inflow, or only an extract, and air exchange occurs naturally. For ventilation use ventilation ducts and grilles between adjacent rooms.
Local ventilation
The system is designed to supply air to a specific area or directly to the workplace. The use of this system is justified with local allocation of harmful emissions. The use of local systems prevents general pollution and reduces the costs of general exchange ventilation
General ventilation
These systems provide air exchange throughout the room. By the way of air movement, they can be natural, artificial or combined, and, by design, by supply or exhaust. General exchange systems evenly supply and remove air from the room. The choice of equipment depends on the characteristics of air pollution in the room, the requirements for air entering the room and the features of the building and ventilation system. For example, if the duct length is more than 30 m, centrifugal fans are used instead of axial fans. In the presence of harmful emissions heavier than air, the ventilation ducts are laid below or under the floor. At industrial enterprises, it is often necessary to combine general exchange ventilation with local systems.
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