TDF(Double Inlet Centrifugal Forward Fan)
[with 2 types of housing]

Forward-curved centrifugal fans are special in that they deliver considerably more air volume and also produce higher static pressure than backward centrifugal fans of the same size and speed.(but at the lower efficiencies)[1]
Volume flow from 600 m3/h to 140.000 m3/h
Total Pressure up to 1500 Pa.

Available from the size 7-7 up to the size 30-28.