A centrifugal impeller with backward curved blades is powered by a single-phase external rotor motor.The motor is equipped with overheating protection.The motor is equipped with ball bearings for a long service life designed for at least 40 000 operating hours.The casing is made of cold sheet metal and corrosion-resistant with coating.external rotor motor, runs smoothly and lasting for longtime. Streamlined fan blade design make the powerful air volume and high efficiency. Air volume will up to 1900m³/h.size are available too φ315. CE certified.