Inline centrifugal duct fan is a straight through radial fan. It is compact, with a high capacity and very easy to install. The fan can cope with high pressure and long duct runs, whilst still operating at an acceptable sound level. The fan speed can be controlled by voltage or frequency variation regulators. Several fans can be connected to the same controller provided the total nominal current of the fans does not exceed the rating of controller. The Circular Inline fans are moisture resistant and are approved for installing in humid or damp environments. The fans are rated IP44 when installed in a duct system. They must not be used for transporting grinding dust, soot or similar air borne particles. The casing is manufactured from pre-galvanized steel. Automatic thermo-contacts open if the temperature within the motor windings becomes excessive. Fan is equipped with CE certified external rotor single phase asynchronous motor.