In the official technical nomenclature, these Air Exhaust Fan are called centrifugal or radial. And the resemblance to a gastropod mollusk gives them a characteristic body, reminiscent of a spiral wound shell. Like all other fans, centrifugal fans are used to create a flow of air (or other gas), but the principle of their operation is different.
The easiest way to understand how a volute fan works is to tell how a centrifugal fan differs from an axial one. If in the latter the air both at the inlet and at the outlet moves only in one direction - along the axis of the impeller (impeller), then in a centrifugal fan the air is sucked in along the axis of the impeller and is discharged across it.
This dictates its requirements for the shape of the impeller. If in an Air Exhaust Fan it resembles a propeller, then the impeller of a centrifugal fan is like a merry-go-round or a whisk of a mixer: the air gets its acceleration due to centrifugal forces at the tips of the blades.
It is also characteristic of what the exhaust fan consists of. Like an axial fan, it consists of a working part (impeller) and a motor. Exhaust fans work by sucking hot or humid air out of a small, localized area, allowing fresh air to enter from elsewhere (perhaps a doorway or vent) to replace it.
Having figured out what a centrifugal fan is, it is worth giving their classification, since, with the same device, these units have different power, which determines the scope of their application. So, according to the level of the created pressure of the air (gas) mixture, radial Air Exhaust Fan distinguishes:
Before choosing a centrifugal fan based on air pressure, it is necessary to consider the resistance of the duct system. This means that a more efficient Air Exhaust Fan model is important.
If it will be used in pipelines for transporting bulk raw materials or materials (cereals, fertilizers, granular drugs, etc.), then the working pressure is also a selection criterion.
Radial fans also differ in the shape of the blades: backward-curved blades provide greater efficiency and economy, but also more noise than forward-curved blades.
In addition, there are models with an internal impeller and an open one.
The size range of centrifugal fans is very large. The diameters of their bodies vary from 8 cm to 1.5 m, which allows you to enjoy the advantages of these units in different areas. Typically, all centrifugal fans have the same impeller proportions, and the casing connection holes correspond to those of standard air ducts.
Double-sided. It consists of two mirrored fans on the same axis. Air is sucked into them from opposite sides and discharged into one hole. In this regard, the following recommendations are easy to give for the selection of radial radiators. Moreover, this depends on the task and place of application.
This is a standard task for all radial fans. High performance allows them to remove polluted air, exhaust gas mixtures from technological air ducts, industrial, public and domestic premises. Here a natural question arises: which is better: a duct fan or an "exhaust"? You can answer it as follows.
The ducted fan belongs to the axial type, many of them are very compact, which is beneficial when using duct fans in everyday life. But radial fans are easy to locate at a great distance from the exhaust zone, i.e. One centrifugal fan can serve several air intake points at once, moreover, they provide more stable airflow parameters.
When choosing a radial Air Exhaust Fan for the hood, you should consider the following recommendations. Moreover, its engine must be remote so that the exhaust airflow does not pass through the engine. Dust, fumes, grease vapors will not harm the outboard motor. For dusty rooms, models with a dust impeller are common.
Its blades are less often located, so it will be more difficult to clog the impeller with dust or plant fluff; Each type of room is characterized by such an indicator as to the rate of air exchange. It also influences the choice, which we will discuss in more detail below.
These fans perform the opposite function: instead of removing gases and polluted air, they supply clean air into the room. There are many methods for calculating a radial Air Exhaust Fan for installation as supply air, and these methods operate with different parameters. These include:
Air exchange rate, indicating how many times the air in the room should change in one hour. For example, for an industrial kitchen, this indicator is maximum and is 20 units (once an hour). For hallways and bedrooms, this figure is 2 - 3 units.
There is also a simpler answer to the question of how to calculate a centrifugal fan for the supply. Depending on the length of the air ducts, we choose a low, medium, or high-pressure Air Exhaust Fan - this, at least, will give you an idea of the order in which the price of the fan is calculated.
The remaining parameters air flow rate, performance, acoustic characteristics, protection class, will help you choose specialists depending on the specifics of the facility and specific operating conditions. All these conditions indicate that preference should be given to medium and high-pressure fans with an external motor - so that it does not get clogged with paint and dust.
Painting of a variety of products - from furniture and cars to precision technology - takes place in spray booths; the Air Exhaust Fan must remove harmful paint odors and dust. Supply air - to provide air filtration, the required temperature, and drying.
Industrial furnaces, incinerators, and household solid fuel boilers often come with radial fans for fast ignition and high combustion temperatures. Their performance is not as important as the material they come off. Here you can get by with small models with a built-in motor and a metal impeller. Moreover, plastic can deform and burn from the temperature if the Air Exhaust Fan is located too close to the boiler.