Axial exhaust fan used in industry

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

For the purpose of high-quality purification of air masses in the premises, as well as maintaining the microclimate by heating or cooling them, mechanical ventilation is used. Industrial fans are used in production facilities.

The movement of air flows can be carried out by pulling or forcing. The industrial axial exhaust fan can also be installed in cafes, offices, warehouses and other large premises.

Device

The device includes elements:

• screw and blades (impeller);
• axis;
• case;
• motor to rotate the impeller.

How does a fan work?

The engine is selected according to the required number of fan revolutions. It transfers the energy of rotation of the axis with the impeller installed on it, which moves the air mass in the axial direction with the blades. The minimum dimensions of the blades are several tens of centimeters for household models, andmaximum - a few meters for industrial. Axial fans generate low air pressure.

The impeller is made of plastic, aluminum alloy or stainless steel. Due to the low weight of the blades, a large engine power is not required. Even for industrial fans, it usually does not exceed 800 W.

Types of axial fans

Axial fans for exhaust ventilation are primarily classified according to their purpose.

1. Wall. Placed inside or at the exit of ventilation shafts. Improved aerodynamic properties of devices are achieved if a diffuser is installed at the outlet.
2. Ceiling. The impeller is mounted on a long axis and circulates air in the room.
3. Rooftop. Devices are installed on the roof. They also include smoke exhaust fans.
4. Panel or with grate. Are mounted on a window leaf or a wall with an air vent. Provides quick extraction or filling of rooms with fresh air at low energy costs.
5. Outdoor. The devices are household appliances for heating or cooling air.
6. Household. Fans are built into household appliances (cooling computer parts, cooling a car engine, supplying hot air from a hair dryer, etc.).
7. Case. Low-noise, low-power models are used to circulate air in rooms or to cool electrical appliances.
8. Exhaust. Devices suck in air intensively, but blow out weakly.
9. Forcing. blow outthe air is intense, but the suction is weak.

According to the methods of operation and the composition of the moving media, the fans are as follows: general purpose, for smoke removal, resistant to corrosion or elevated temperature, explosion-proof design.

Dignity

Axial fans are widely used due to the following advantages:

• low noise level thanks to blade design;
• compact;
• reliability and low price;
• economy;
• Ease of construction and repair.

The axial exhaust fan is high-speed and pumps air more than centrifugal, but the pressure drop is lower.

Flaws

The disadvantage is the slight air pressure generated by the fan. The design is also sensitive to impact axial loads. For high loads, the blades are made of metal or reinforced plastic.

Duct exhaust fans

Axial duct exhaust fan is selected according to several parameters. First of all, it depends on the purpose for which it is to be applied. The shape of the case and the ventilation duct in which it is placed must 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 section of the channel, a round body is quite suitable if it is fixed onsuitable grid.

Fan housings are made of plastic (household models) and metal (industrial). Preference is given to materials that have reliable protection against corrosion, since the air constantly contains moisture and condensation is always present in ventilation systems.

The main indicator is performance - how much air the device can pull out per unit of time. The household model is designed for a capacity of up to 350 m33/h, and the industrial model is up to 17 thousand cubic meters.

The flow rate of the transported medium depends on the diameter and shape of the blades. The larger their front bend, the more air the fan is able to pass, but the noise level increases. Blades with a back bend work almost silently and economically. The noise level of duct fans is not higher than 40 dB.

The performance of the fan depends on the volume of the room and the required frequency of air renewal in it.

Duct fan can be installed anywhere. It does not require connecting flanges and adapters. Connection to the box is made using worm clamps. Typically, the fan is mounted on the inlet of the duct. This makes it easier to maintain. The housing is attached to the air duct with a snug fit, which reduces losses during operation of the device. Fans are designed to extract air in certain areas, after which the air flow is collected in one duct. This is important to remove polluted air generated in workplaces.

Axial industrial exhaust fan has protectionworking area with blinds equipped with manual or automatic drive. During operation, they open, and after the engine is turned off, they close.

Check valves for ventilation

To prevent foreign odors from entering the room through the ventilation duct during reverse draft, a check valve is installed in it. This blocks the flow of air in the opposite direction.

Axial exhaust fan with check valve works in such a way that air flows in only one direction. As soon as it changes to the opposite, the channel overlaps. The locking device can be a lattice (blind), butterfly, petal or membrane.

Grates are installed at the inlet or outlet of the channel and have a different shape. The butterfly valve consists of two plates fastened by a spring. The petal, or membrane, is a damper that rotates on an axis, blocking or opening the channel, depending on which direction the air flow is moving.

Window axial fans

Exhaust window axial fans are installed directly in the window or window opening due to their small size and light weight. 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 blinds that close when the draft in the ventilation duct changes toreverse.

A 220V powered fan is suitable for home cooking. Industrial applications use 380V three-phase power.

Inlet and exhaust fans

It is advantageous to use reversible axial supply and exhaust fans. Depending on the direction of rotation of the blades, dirty air is removed from the room or fresh air is blown in.

A non-return valve will not work here, but you can install shutters that will close when the fan is not running.

For supply air devices, electric heating of the forced air should be provided. The supply fans in the rooms should provide 1-1.5 air changes 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 distilling the air masses. Therefore, ventilation of the room is provided by opening a window or door to the rooms. When plastic windows are installed, micro-ventilation devices should be provided in them.

Conclusion

Axial fans are widely used due to their low noise level and high performance. For domestic premises, it is advisable to install an axial exhaust fan in a ventilation duct or in a window opening. A reversible air handling unit is well suited for a window.