Acoustically insulated centrifugal fan with swing out motor and impeller unit with motor outside of air flow. Double skinned galvanised steel casing with 50 mm thick mineral fibreboard. Intake and exhaust spigots with twin-seal rubber gasket. Swing out motor and impeller unit for easy cleaning and maintenance including stable mounting rails with 4 anti-vibration mounts. High efficiency backward curved centrifugal impeller made from aluminium. Dynamically balanced to DIN 1940 and VDI 2060 class G 6.3. Totally enclosed, maintenance free 3-phase motor, two-speed (star/delta connection) with thermal contacts. Low-noise sealed for life ball bearings.