A fan is a device in which the blades attached to the rotor move large masses of air. The designs of the fans , which are used to move various gas-air mixtures, are of several types. The most common is a radial centrifugal fan of the "snail" type.
The device of the fan "snail"
The radial centrifugal fan consists of a rotating wheel on which spiral shaped blades are attached. And their number in different models of fans is different. The principle of the snail fan operation is as follows. Through a special inlet, air is sucked into the rotor. Here he is given a rotational motion. And with the help of centrifugal force and rotating blades, the air under pressure rushes to the outlet, located in a special spiral casing. Due to the similarity of this casing to the cochlea, such a radial fan is given its name.
For the manufacture of the shell of the snail fan, stainless steel, structural steel sheets, aluminum alloys, brass and even plastic are used. The shell of the cochlea has a protective coating of polymers, powder paint or other compounds that give the product thermal and chemical resistance.
The impeller of the snail fan has one or two discs on which the blades are attached. Their fastening can be either circular or radial. Blades in different models of fans are bent either backward or forward. On this depends largely on the performance of the fan snail. Such devices are produced in the right and left versions.
The dimensions of the snail fan can be small and larger, the diameter of the device ranges from 25 cm to 150 cm. Such fans are integral or consist of two or three parts. However, for small fans with a solid snail, the angle of its rotation is unimportant: if necessary, it can be deployed and placed in any position, only by unscrewing the fixing bolts. In large models of fans, snails are most often collapsible, and for them the angle of rotation is a very important indicator that should be taken into consideration when buying.
There are three types of centrifugal fans: low, medium and high pressure. Devices of the first type have a pressure of up to 100 kg / m & sup2 and are used in industrial and general industrial systems. Due to their ease of installation and maintenance, such centrifugal fans are in great demand when installed in ventilation systems of high-rise buildings, as well as for various industrial purposes.
The second type is medium-pressure radial fans, they have values from 100 to 300 kg / m & sup2. They are used in all industrial ventilation systems with increased pressure. These devices meet all the requirements of increased fire and technical safety. They are successfully used even where there are various extreme conditions and even the potential threat of explosions. In addition, snail fans are used in a variety of drying chambers and other household appliances.
The third type of snail fan has a high pressure: from 300 to 1200 kg / m & sup2, and
According to their purpose, the snail fans are divided into devices:
- general purpose;
- heat-resistant;
- protected from explosion;
- corrosion-resistant.