The scene shows a model of a ventilation unit with a part of the ventilation system and
additional individual elements of the ventilation system: straight boxes, 90-degree bends, tees and transitions.
Using individual elements, using the construction kit principle, it is possible to assemble a ventilation system of virtually any configuration, height, and length.
The model geometry is prepared for TurboSmooth smoothing. The preview shows two iteration.

In the archive (5 files):

industrial_fan_2021 (corona 6) original.max
industrial_fan_2018 (corona 6).max
industrial_fan (corona 6).FBX
industrial_fan.obj + MTL