APPLICATIONS Combined supply and extract ventilation systems for various premises where high air capacity at relatively low system resistance is required. FD fans can be used for the direct exhaust of air. FD fans can be mounted onto the external walls. DESIGN FD fan casings are made of steel with polymeric coating and the impeller is made of stainless steel. MOTOR The motor is equipped with ball bearings. SPEED CONTROL Both smooth and step speed control is performed with the thyristor or autotransformer controller. Several fans can be connected to one controller in case the total power and operating current do not exceed the rated controller values. Mounting The fan is installed on the wall surface by means of square mounting plate.