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Installation of axial fans

When installing axial fans, it is important to try to give the fan the best possible conditions in order to be able to provide the desired performance. Below is some advice on the way.


Axial fans are relatively sensitive to uneven air supply to the impeller. With different flow rates in the inlet, turbulence can occur near the impeller, resulting in power losses.
Therefore, sharp pipe bends should be avoided close to the fan installation.
Free-suction fans should be equipped with a conical inlet (alt. with a bellmouth) to avoid that turbulence occurs near the duct walls.
In general, changes in the cross-section of the ducts shortly before the fan should be carried out in such a way that no flow separations can occur.

The flow after the fan is significantly reduced if there are cross-sectional reductions shortly after the impeller. This is especially important to take into account for axial fans without guide vanes, where the air leaves the fan with a rotating motion.

Overall, upstream flow obstructions should be avoided, as they can create turbulence leading to noise level increases.

Mounting direction

Axial fans follow the Eurovent standard and the installation position can be as A, B, AU, AD, BU and BD.
This is specified when ordering in order to be able to adapt any engine bearings and impeller weights.
Normally, fans are delivered with the air direction wheel–motor, which gives the best flow through the fan. The reverse with the engine first causes a disturbed inlet flow which can result in higher noise levels, poorer efficiency and performance.

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