For the purpose of high-quality purification of air masses inpremises, as well as maintaining the microclimate by heating or cooling, mechanical ventilation is used. Industrial premises use industrial fans.
Moving air streams cancarried out by pulling or pumping. Axial exhaust industrial fan can also be installed in cafes, offices, warehouses and other large premises.
Device
The device includes the elements:
- screw and blades (impeller);
- axis;
- the body;
- electric motor to rotate the impeller.
How does the fan work?
The engine is selected for the required numberfan speed. It transmits the rotational energy of the axis with an impeller mounted on it, which by blades moves the air mass in the axial direction. The minimum dimensions of the blades are several tens of centimeters for household models, and the maximum - a few meters for industrial. Axial fans create low air pressure.
The impeller is made of plastic, alloysaluminum or stainless steel. Due to the low weight of the blades, high engine power is not required. Even for industrial fans, it usually does not exceed 800 watts.
Types of axial fans
Axial fans for exhaust ventilation are primarily classified by purpose.
- Wall mounted. Placed inside or at the exit of the ventilation shafts. Improved aerodynamic properties of the devices are achieved if the diffuser is installed at the outlet.
- Ceiling. The impeller is installed on the long axis and produces air circulation in the room.
- Roof. Devices are installed on the roof. They also include smoke exhaust fans.
- Panel or with grill. Mounted on the window pane or wall with a vent. Provide a quick exhaust or filling rooms with fresh air at low power consumption.
- Outdoor. Devices are household appliances for heating or cooling air.
- Household. Fans are built into household appliances (cooling parts of a computer, cooling a car engine, supplying hot air from a hair dryer, etc.).
- Case. Low-noise models of low power are used to circulate air in rooms or to cool electrical appliances.
- Exhaust. Devices intensively suck air, but blow out weakly.
- Forcing. Blow out the air intensely, and suck poorly.
According to the methods of operation and composition of the transported media, the fans are the following: general purpose, for removing smoke, resistant to corrosion or elevated temperature, explosion-proof.
Advantages
Axial fans are widely distributed due to the following advantages:
- low noise level, which ensures the structure of the blades;
- compactness;
- reliability and low price;
- economy;
- simplicity of design and repair.
The axial exhaust fan is high-speed and pumps more centrifugal air, but the pressure drop is lower.
disadvantages
The disadvantage is a slight air pressure,created by the fan. The design is also sensitive to shock axial loads. For high loads, the blades are made of metal or reinforced plastic.
Duct fans for exhaust
Axial duct exhaust fan selectableby several parameters. First of all, it depends on the purpose for which it should be applied. The shape of the housing and the ventilation duct in which it is located should be the same.
They are round, square and rectangular.The first are suitable for household models, the rest - for use in industry. For a square cross-section of the channel, a round case is quite suitable if it is mounted on a suitable grid.
Корпуса вентиляторов выполняются из пластика (household models) and metal (industrial). Preference is given to materials that have reliable corrosion protection, since the air constantly contains moisture and condensate is always present in the ventilation systems.
The main indicator is the performance - how much air is able to pull the device per unit of time. Household model is designed for performance up to 350 m3/ h, and industrial - up to 17 thousand cubic meters.
The flow rate of the moving medium depends on the diameter andthe shape of the blades. The larger their front bend, the more air the fan is able to skip, but this increases the noise level. The back bend blades work almost silently and economically. The noise level of channel fans is not higher than 40 dB.
The performance of the fan depends on the volume of the room and the required rate of air renewal.
Channel fan can be installed in anyplace There are no need for connecting flanges and adapter sleeves. Connection with the box is made with the help of worm clamps. Usually the fan is mounted on the inlet of the duct. So it is easier to maintain. The housing is attached to the ventilation channel with a tight fit, which reduces losses during operation of the device. Fans are designed to bleed air in certain areas, after which the air flow is collected in one duct. This is important for the removal of polluted air generated in the workplace.
Axial exhaust industrial fan hasprotection of the working area with the help of blinds, equipped with manual or automatic drive. During operation, they open, and after shutting down the engine, they close.
Check valves for ventilation
In order to avoid falling into the room during the returnforeign odors from the outside through the vent, install a check valve into it. At the same time the movement of a stream of air in the opposite direction is blocked.
Axial exhaust fan with check valveworks in such a way that air enters only in one direction. As it reverses, the channel overlaps. The locking device may be a grille (louver), a butterfly, a petal or a membrane.
Grilles are installed at the entrance or exitchannel and have a different shape. The butterfly valve consists of two plates fastened with a spring. A petal, or membrane, is a flap that rotates on an axis, closing or opening a channel, depending on which direction the air flow is moving.
Window Axial Fans
Exhaust window axial fans installdirectly into the window or window opening, due to its small size and low weight. The devices are used in industrial and domestic premises, offices, canteens, etc.
To prevent cold air from entering the room, the exhaust fan is equipped with a check valve in the form of louvers, which close when the thrust in the ventilation duct is reversed.
A 220V fan is suitable for home cooking. In industrial systems, a three-phase power supply of 380 V is used.
Supply and exhaust fans
It is advantageous to use axial supply and exhaust fans of reversible type. Depending on the direction of rotation of the blades, dirty air is removed from the room or fresh air is injected.
The check valve is not suitable here, but you can install blinds that will close when the fan is not working.
Для приточных устройств следует предусмотреть electric heating of the injected air. Intake fans in rooms should provide 1-1.5 times air exchange per hour. For the kitchen, the performance of the equipment should provide 6-12-fold air exchange when cooking is done. If there is no fresh air in it, the exhaust fan will rotate without overtaking the air masses. Therefore, the ventilation of the room is provided by opening the window or door to the rooms. When plastic windows are installed, micro-ventilation devices should be provided.
Conclusion
Осевые вентиляторы широко распространены, due to low noise and high performance. For domestic premises, it is advisable to install an axial exhaust fan in the ventilation duct or in the window opening. For a window, a supply and exhaust device of the reverse type is well suited.
