Air passage
Air outlets, also known as supply and exhaust air outlets, are built-in components that are connected to the air duct network of a ventilation and air-conditioning system, usually in the wall, ceiling or floor openings of a building and, for example, supply air ("fresh" outside air ) or exhaust air to a room ("used" room air ). They are available in different designs and geometries. The difference lies in the way in which they influence the air flow in the room. Physical-technical, architectural and economic aspects are important selection criteria. The comfort of the user often plays a major role in the selection.
Types of ventilation
Structure of the air outlets
EN 12238, which can be used to evaluate air outlets for use with mixed flow, differentiates between four classes of air outlets according to the shape of the relevant air flow: Class I describes air outlets from which the air flow essentially emerges in three dimensions (nozzles and grille), class II for air outlets from which the air flow emerges radially along a surface or as a free jet (ceiling diffusers), class III for air outlets from which the air flow essentially emerges in two dimensions (linear grilles, slits and linear diffusers) and class IV for air outlets at low speeds .
EN 12239, which can be used to evaluate low-speed air outlets for use with displacement flow, distinguishes three types of air outlets according to the place of installation: Type 1 describes a horizontal air outlet i. d. Usually from walls, type 2 air outlets built into the floor for vertical air outlet and type 3 for air outlets built into the ceiling.
Swirl outlet
A swirl diffuser lets the supply air flow into the room in a swirl. This has a high induction effect, which means that the supply air can mix quickly and efficiently with the room air. This type of outlet is therefore particularly suitable for mixed ventilation. Due to the mixing above the occupied zone, high temperature differences between the supply and room air are possible. The rotating guide vanes of the swirl diffuser, which determine the direction for the air, can be adjusted for heating or cooling, depending on the manufacturer. Twist outlets are mostly used as ceiling outlets, but also as wall or floor outlets.
Step swirl diffuser
Step twist outlets are twist outlets that are installed vertically in steps in, for example, festival halls or auditoriums. An inductive air flow is generated by its non-adjustable air guide blades. Since the legs of the user are usually very close to the outlets, it must be ensured that the outlet speeds are low and that the temperature adapts as quickly as possible. The admissible supply air temperature difference is ± 6 K. Due to architectural requirements, step swirl outlets can be round or square.
Ventilation grille
A ventilation grille is the simplest and cheapest way to distribute air in the room by means of an air inlet. To adjust this air intake, ventilation grilles are equipped with adjustable horizontal or vertical air guide blades. They are made of sheet steel, aluminum or plastic and are suitable for ventilation ducts with both rectangular and round cross-sections.
Ventilation grilles are often only used in simple systems (e.g. production hall ventilation), because low induction and radiation effects cannot produce high indoor air quality. The outflow velocities are kept low due to the noise development. With ventilation grilles in the floor, the speed must be less than 1.5 m / s and with slot air outlets a volume flow of up to 100 m³ / h per meter of slot length is possible. When used in wall or ceiling openings, the outflow speeds must be set as required.
Long throw nozzle
Long throw nozzles are used particularly in large halls (e.g. waiting halls at airports, congress halls, etc.). The conical nozzle body accelerates the air by reducing the cross section. A stable core beam ensures great throwing distances, which means that long distances of up to 30 m can be bridged. Due to the smooth internal structure, the volume is low despite the high exit speeds. The speeds are usually around 15 m / s. Jet nozzles are arranged in the side areas of halls, with the air being "thrown" into the room from above when cooling and from below when heating.
Poppet valve
Disk valves are simple and inexpensive. They consist of a ring and a valve disk underneath, which can be adjusted depending on the volume flow requirement. The air flows vertically onto the plate and is distributed around it. Disk valves are used in wet rooms and houses for controlled apartment ventilation.
Displacement air outlet
Displacement air outlets are used particularly in production halls with high levels of pollutants in the air. Displacement ventilation offers a displacement flow with a high volume flow at a very low air speed. This is a maximum of 0.2 m / s. The outlets are usually installed near the floor in the halls, and exhaust air grids are usually used in the ceiling area.
Slot diffusers
The classic among the linear diffusers are slot diffusers. They are particularly suitable for ceiling installation in plasterboard constructions. Long slots can be created by combining several outlets. One to four-lock versions are produced industrially.
hygiene
The components of the air outlets that come into contact with air must be easily accessible, especially when it comes to supply and exhaust air outlets. Air outlets must be easily accessible for cleaning and must also be easy to replace if necessary. If no cleaning or inspection openings are provided in the air line network near the passages, access to the air lines for cleaning purposes must be guaranteed via the air passages. If an air outlet is provided with covers (e.g. fleece), it must be ensured that these substances are exchangeable and that no products can get into the supply air that reduce the quality of the air.
Individual evidence
- ↑ EN 12238 . Ventilation of buildings - air outlets - aerodynamic testing and evaluation for mixed flow applications. Beuth, December 2001, p. 14 .
- ↑ EN 12239 . Ventilation of buildings - air outlets - aerodynamic testing and evaluation for use with displacement flow. Beuth, August 2001, p. 6 .
- ↑ Nicolas Fritsche: Pocket book for ventilation fitters and foremen . 8th edition. VDE Verlag, 2020, ISBN 978-3-8007-5072-6 , p. 76 .
- ↑ Nicolas Fritsche: Pocket book for ventilation fitters and foremen . 8th edition. VDE Verlag, 2020, ISBN 978-3-8007-5072-6 , p. 72 .
- ↑ Nicolas Fritsche: Pocket book for ventilation fitters and foremen . 8th edition. VDE Verlag, 2020, ISBN 978-3-8007-5072-6 , p. 78 .
- ↑ VDI 6022 . January 2017.