Industrial Exhaust Fan: Top Advantages at Low Cost

Industrial exhaust fan are those tools that allow a fluid to move within a network of ducts or within machines or production lines. Just as home fans move the air on hot days, industrial fans move it for various industrial processes.

They are mainly characterized by two quantities:

• Fluid flow rate typically expressed in mc / h
• Total pressure that the fan gives to the fluid to overcome the pressure drops and generally expressed in pa or in mmca (mm of water column)

Adaptation of products for different applications

The world of industrial exhaust fan has evolved and adapted to the production and design needs of the various sectors by offering a wide range of products for different applications.

As you will have understood from my statement, fans are not all the same and above all suppliers are not. Each of them has specialized in making machines suitable for their market and their experience by paying particular attention to some details that others would not even take into consideration.

So, you have to pay close attention both to the choice of the machine but also to find one or more suppliers suitable for your market, your needs and the application.

Having said that, let's say that it is possible to have two large product categories:

• Axial fans
• Centrifugal fans

Industrial exhaust fan: axial and centrifugal fan

From an application point of view, axial fans are mainly common to move huge masses of low head air. We find them mainly in mechanical ventilation units, HVAC, general conditioning or for example in road tunnels.

The centrifugal ones, on the other hand, being able to afford higher performance especially in terms of available head, are common in many industrial applications, both process and auxiliary and we can see them in practically all industrial activities and in all suction, conveyance and emission abatement systems.

How do you know if industrial exhaust fan is axial or centrifugal?

The answer is quite simple and mainly concerns the movement that the air makes as it passes through the fan.

In an axial fan, the air substantially does not undergo any "change of direction" between its inlet and its outlet, as you can clearly see:

Axial fan

In a centrifugal fan the air is "centrifuged" towards the outside. It enters the center of the fan and is then pushed towards the passage left open by the blades. In practice, it performs a 90 ° change of direction between its entrance and exit. Look at the three fans below to understand clearly.

Centrifugal plug fans

The fans in the image above are a particular type of industrial exhaust fan which calls plug fan and characterize by the fact that they do not have a casing or scroll around the impeller which is of the centrifugal type.

This particular conformation places them as a "middle way", from a performance point of view of available head, between axial and centrifugal fans.

They are in fact more performing than the axial ones thanks to the centrifugal impeller, but less performing than the purely centrifugal ones due to the lack of the screw which allows to recover every possible Pascal of pressure produced by the impeller.
 

What “conformation” or better execution, can industrial fans have?

Precisely because of industrial exhaust fan indispensability in production processes where the movement of air or fluids in general is fundamental. There are different "conformations" for how the fans are built, which call executions.

The most common executions common for fans

Everyone knows that a fan is a machine made up of a series of blades that rotate thanks to the thrust of an engine. Industrial fans (as Safe Ventilation explains) work in exactly the same way and mainly concern with passing through the pipes of the industrial ventilation system the polluting gases or dust produced by the various industrial processes.

Industrial exhaust fan generally falls into two main types: axial fans and centrifugal fans. Furthermore, since the world of industry is made up of different sectors, the manufacturers of these machines have specialized by designing a wide range of products suitable for different applications.

Types of industrial fans: axial and centrifugal

Axial fans characterize by propeller fans. This forces the extracted air to move parallel to the shaft around which the blades rotate. It is capable of moving large volumes of air at relatively low pressures. There are three main types of axial fans:

• The ducted axial fans: industrial exhaust fan have the impeller inside a cylindrical housing. It allows to manage high pressures thanks to the higher rotation speed compared to the propeller ones;
• Axial wall-mounted fans: are particularly suitable for ventilating closed environments;
• Axial duct fans: locate inside the ventilation ducts and have many advantages including the ability to manage large gaseous masses. It reduces noise or high-pressure stability.
• Centrifugal fans: on the other hand, use the centrifugal force produced by a rotating disk formed by blades mounted at right angles. This allows the air to extract perpendicularly to the angle of intake by the industrial exhaust fan. It causes the air to rotate up to the outlet by deflection or centrifugal force.
• The impeller blades of this type of industrial fans can be: positive, negative or reverse (curved back), straight (radial). For this reason, there are four main types of centrifugal fans:
• Forward curved centrifugal fans: are suitable for treating dusty gases but have a rather low efficiency;
• Centrifugal fans with radial blades: they have a lower power; therefore, they consider the least efficient, however the version with open blades is very performing;
• Backward curved centrifugal fans: they are mainly common to suck in slightly dusty or clean air and are the most performing thanks to the very low noise and low energy consumption industrial exhaust fan guarantee;
• The scirocco blade centrifugal fans: it is capable of sucking up rather large volumes, but it does not have an excellent efficiency.

Differences between axial and centrifugal industrial fans

There are substantial differences between axial and centrifugal industrial fans that can summarize schematically. So, let's see how they differ:

• Operating speed: an axial fan has a decidedly higher operating speed than the centrifugal one;
• Impeller diameter: an axial fan has a smaller impeller diameter than a centrifugal one;
• Efficiency: an axial fan has a lower efficiency than a centrifugal one and therefore results in greater energy consumption;
• Noise: an axial fan is much louder than a centrifugal one;
• Pressure: an axial fan has a higher dynamic pressure than a centrifugal one;
• Peripheral speed: an axial fan has a higher peripheral speed than a centrifugal one.

How to choose an industrial exhaust fan?

There are two fundamental parameters to keep in mind when choosing the most suitable industrial fans:

• The flow rate of the fluid;
• The total pressure that the fan is able to impart to the fluid to overcome the pressure drops of the circuit to which it connects.

To identify the appropriate industrial fan, it is necessary to cross the flow-pressure curve of the fan and the flow-pressure curve of the circuit. The point of intersection between the two curves will indicate the fundamental performances that the industrial exhaust fan must have.