Axial or Centrifugal Fan - Which Fits Your Facility?
Axial fans move large volumes of air against low resistance, while centrifugal fans build high pressure for long ducts and filters. This guide uses airflow, pressure drop and duct routing to show which fan type suits ventilation and exhaust in halls and equipment rooms.
View fansHow do axial and centrifugal fans differ?
An axial fan draws air in parallel to the shaft and pushes it out in the same direction, much like a propeller. A centrifugal fan draws air in axially but turns it 90° outward, throwing it off the impeller radially. That design difference is the key point: axial types move a lot of air at low pressure, centrifugal types build high pressure at a smaller airflow.
Two figures drive the choice: the required airflow in m³/h and the pressure difference to overcome in pascals (Pa). Pressure drop comes from ducts, bends, filters, grilles and backdraft dampers. The longer and more convoluted the duct routing, the more static pressure the fan must deliver.
When axial, when centrifugal - the decision criteria
The choice follows the ratio of airflow to back pressure. Axial fans work economically up to about 100 Pa of static pressure and deliver very high volumes there. Centrifugal fans take over where resistance rises: ducts longer than 10 m, fine filters or heat recovery demand 300 Pa and more.
- Choose axial for: hall exhaust through a wall opening, cooling of equipment rooms, high air change without a long duct network.
- Choose centrifugal for: extraction systems with filters, point extraction of solder fume or dust, long risers and roof outlets.
- Backward-curved centrifugal: energy efficient, self-limiting power, ideal for clean exhaust air.
- Forward-curved centrifugal (drum rotor): compact, high airflow at medium pressure, but more sensitive to overload.
Sizing, noise and operation in practice
Beyond airflow and pressure, sound level, controllability and maintenance decide the fit. Axial fans become loud and inefficient at high back pressure, while centrifugal fans run more quietly under load. Speed control via a frequency inverter or EC motor saves energy because power draw falls with the cube of speed.
The required airflow follows from room volume times the air change rate. An equipment room needs roughly 4 to 8 air changes per hour, a workshop with emissions considerably more. Add up the pressure drop of every component and include a reserve of 10 to 20 percent.
- Size the duct cross section generously: lower air velocity cuts pressure drop and noise.
- Silencers and flexible connectors reduce structure-borne noise and airflow sound.
- EC motors with 0‑10 V or Modbus allow demand-based operation by CO₂ or temperature.
- A backdraft damper prevents reverse flow and heat loss when the fan is off.
Frequently asked questions
When is an axial fan better than a centrifugal fan?
An axial fan is the right choice when you move large volumes of air against low back pressure, such as through a wall or roof opening to the outside. Up to around 100 Pa of static pressure it runs economically and compactly.
Why does an extraction system need a centrifugal fan?
Filters, long ducts and bends create a high pressure drop of several hundred pascals. Only a centrifugal fan supplies that static pressure reliably and keeps the airflow up even as the filter loads with dust.
How do I calculate the required airflow?
Multiply the room volume in m³ by the required air change rate per hour. An equipment room at 4 to 8 air changes and an emission room at considerably more give you the airflow in m³/h.
What does speed control achieve?
With an EC motor or frequency inverter you match output to demand. Because power draw falls with the cube of speed, even a small reduction saves a lot of energy and lowers the sound level.
Looking for the right fan?
We supply axial and centrifugal fans for ventilation and exhaust in halls and equipment rooms - sized to your airflow and pressure drop.
Correctly sized
Operating point set from airflow and pressure.
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Axial and centrifugal available from one source.
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EC motors and speed control available.
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