Centrifugal or axial fan? Differences, applications, and how to choose the right one

What is a centrifugal fan

A centrifugal fan draw air along their axis and expel it radially, generating a very high pressure increase. This characteristic (high head) makes them indispensable whenever air must travel a long, winding path consisting of bag filters, extended ducts, and multi-stage purification systems.

Their radial impellers are built to resist wear caused by the passage of dust, shavings, and abrasive particles. They are not suitable for all environments, but when system resistance is high, centrifugal fans are unrivaled, reaching heads of up to 5,000 Pa and flow rates between 10,000 and 50,000 m³/h.

What is an axial fan

An axial fan moves air along the propeller’s axis of rotation, just like a large sail pushing a mass of air from one point to another. Its strength is its flow rate, with low static pressures (up to about 1,000 Pa), capable of moving enormous volumes of air, up to 150,000 m³/h or more, with minimal energy consumption.

Its nature makes it unsuitable for systems with structured filters or long ducts, but it excels wherever constant air exchange is required across large open areas such as warehouses, livestock farms, greenhouses, and storage areas. The adjustable propellers also allow performance to be adapted to different seasonal needs without having to replace the unit.

The technical differences that really matter

The distinction between centrifugal and axial fans isn’t just one of form, but of physics. Centrifugal fans convert kinetic energy into static pressure through centrifugal force; axial fans move air while maintaining a lower pressure but working on much larger volumes. In practice, if your system has high resistance (filters, ducts, bends), you need high static pressure and therefore a centrifugal fan. If you need to move a lot of air in an open space without significant obstacles, axial fans are the most efficient choice.

A common mistake is to evaluate only the flow rate without considering the pressure drops in the system. An axial fan installed in a circuit with filters and long ducts will chronically underperform, consuming more energy than expected and lasting much less long.

When the centrifugal fan is the right choice

Centrifugal fans are the natural solution wherever air must overcome significant resistance along its path. In dairies and cured meat factories, for example, high-pressure centrifugal systems extract humid air through filters and exhaust ducts, reducing condensation and bacterial risks. In the woodworking and mechanical engineering industries, open-blade impellers convey dust and shavings towards cyclones and bag filters without clogging. In the chemical and pharmaceutical sectors, the centrifugal configuration allows the motor to be positioned outside the airflow, protecting it from corrosive gases or acid vapors, significantly extending the system’s lifespan.

In environments with combustible dust (flour, sugar, feed, shavings) or flammable gases, the ATEX Directive 2014/34/EU requires the use of certified fans.

Ignoring this requirement is not only a technical risk, but can also result in administrative sanctions and immediate shutdown of the plant.

When the axial fan is the right choice

Axial fans are the most efficient choice wherever the priority is air volume rather than pressure. In livestock farms and greenhouses, they ensure constant and uniform air exchange across large surfaces with minimal energy consumption, stabilizing the microclimate for animals and crops. In industrial warehouses without complex filtration systems, they are the most economical solution, both in terms of purchase and operation. Even in some paint shops, ducted axial fans are used to extract fumes from unpressurized booths, often in combination with simple filtration systems.

The rule of thumb is simple: if the air “flows freely” and the airflow resistance is low, axial fans are almost always the right choice.

Comparison table

How to size a fan correctly

Before even choosing the right fan type, it’s important to gather the right data. The key parameter is the required flow rate, which is calculated by multiplying the room volume by the number of air changes required per hour for the activity performed.

For a 2,000 m² production facility with an average height of 6 m and an activity requiring 8 changes per hour, the volume is 12,000 m³ and the required flow rate is 96,000 m³/h, which can be covered, for example, with two axial fans of 50,000 m³/h each, equipped with inverters for seasonal regulation.

But flow rate is just the starting point. Also considered are pressure drops in the ducts, the presence and type of filters installed, air temperature and humidity, the presence of abrasive or corrosive substances, and industry-specific regulations. Even one of these factors, if overlooked, can lead to incorrect sizing.

Not sure where to start? Use our checklist

We’ve created a practical tool designed for those who need to gather the right information before requesting a consultation, or even just to determine whether their system is sized correctly.

The checklist contains 10 key technical questions about your environment, your system, and your operational needs. No specialized knowledge is required to complete it; if you don’t have all the values ​​at hand, you can let us know and we’ll calculate them together.

We’ve made it available as an online form (no download required) to minimize any barriers. Once completed, we’ll receive it directly and contact you to offer a free, no-obligation technical consultation.

If you prefer the traditional format, you can still download the PDF and email it to us at info@meridianaaspiratori.it.

FAQs and quick answers