Ventilation collection:
https://3dsky.org/collection/shared/5333943 

CORONA + VRAY (2013)
FBX CORONA + VRAY (2009)

Ceiling ventilation system.
The kit includes an assembled ceiling consisting of several ready-made modules and a set of individual elements for assembling various options.
The model includes a cable tray system, air conditioners, and a fire protection system.
The set uses 6 types of materials that can be applied to any element.
The dimensions of the rectangular ducts are 200 x 150, 300 x 200, 400 x 300 mm.
The diameters of the round ducts are 200, 315, 400, 500, 600 mm.
The main part of the details can be edited using Edit Poly and adjusted to the required dimensions.

Other sets:
https://3dsky.org/users/solomon5555/models