The primary moving part of an industrial ventilation system is the fan. The industrial ventilation fans are grouped into several categories: centrifugal, axial, and special types. When selecting an industrial ventilation fan, you need to go beyond the pressure and airflow considerations. In addition, you need to factor operating temperatures, drive arrangements, airstream characteristics, and mounting.

The Main Types of Exhaust Fans

Axial fans

The Axial fans are also called “in-line” fans. They operate by transferring large quantities of air with a lower rate of resistance. This means that they simply draw air through the fan. Since axial fans do not generate a lot of static pressure, they are not used for industrial ventilation with air cleaning devices. The main types of axial fans include:

• Propeller fans: These are the commonest types of fans used in general ventilation like the dilution ventilation.
• Tubeaxial fans/ duct fans: This is also a propeller fan designed to fit inside the ductwork with cylindrical housing. The fans operate without straightening and help to transfer air against moderate air pressure of up to 4" w.g. The fans are preferred for clean air applications like exhaust ducts that go through the roof.
• Vaneaxial fans: These fans share their characteristics with propellers designs. Unlike tubeaxial fan designs, vaneaxial models are constructed with a hub and airfoil blades that are installed in the cylindrical housing. The discharge side of the impeller also features straightening vanes. Note that Vaneaxial fans handle higher static pressure of up to 10" w.g and are preferred for clean-air applications. 

Centrifugal fans

These fans are easy to distinguish because of their “squirrel cage” design. They help to transfer small quantities of air but with a high rate of resistance by pushing it via the center of the fan. Then, the air is released via the exhaust at a perpendicular angle. The blade of the fan determines the nature of the three types of centrifugal fans. Here is the categorization of the fan blades:

• Forward inclined blades: In this category, the blades curve towards the direction of rotation. Besides, they are also quiet when running. Because of the short curved blades, fans that use them are not ideal for particulates or dust.
• Radial blades: This category of blades runs straight from the hub. The design is aimed at helping resist material buildup so that they can be used in many types of exhaust systems including those that need to push dirty air.
• Backward inclined blades: Here, the blades curve opposite the direction of rotation. They operate quietly and deliver high mechanical efficiency compared to other types of fans. Since this group of blades is prone to buildup, fans that use them are considered ideal for clean-air or light dust environments.

How to Select the Right Fan for Your System

If you are selecting a fan for your industrial ventilation system, the best method is referencing the original equipment manufacturer. However, you also need to consider the following general guidelines.

• The capacity of the fan. This means things such as flow rate and pressure requirements.
• Airstream considerations. This is the type of materials that will be handled through the fan
• Drive arrangements/power source
• Noise levels of the fan.
• Safety of the fan and accessories requirements.
• Flow control.

Conclusion

If you want to make your industrial working environment ideal for higher productivity, it is important to install the right ventilation system. You should particularly look for the fan that uses the right blade and use the above guide provided to pick the best.