Twin version, with two double inlet wheels on the same shaft or, in sizes from 710 to 1000, on two separate shafts, connected by a coupling.  Version supported on strong rectangular side frames, made of hot rolled steel sections, fixed on the scroll sides with screws, available from the size 315 up to the size 1000.  Heavy duty bearings on cast iron pillow blocks with grease points.
The standard fan can be freely rotated, to allow installation with orientation 0°, 90°, 180° or 270°, as defined in ISO 13349.
