... fans with impeller diameter 450mm to 630mm , and forward curved centrifugal fans with impeller diameters from 250mm to 400mm , the ... configure almost any operation required . In designing the Hyblade axial fan blades , ebm-papst was the first to use a high ... best possible results in terms of noise and efficiency . The forward curved centrifugal fans , with impeller diameters form 250mm to 400mm ,, are ...