4-72,4-79 centrifugal fan, its efficiency and sound level than A are at or better than the Ministry of Machinery Industry to develop the A-level standard. Widely used in various types of medium-sized factories and residential buildings, stadiums and other large-ventilated place. 4-72,4-79 centrifugal fan ventilation for general use, conveying air or other non-flammable, non-corrosive gases, non-sticky substance inside the gas contained in the dust and hard particles is not greater than 150 mg / m3, the temperature does not exceed 80 ℃. F4-72 / 79 for corrosion centrifugal fan, used to transport corrosive gas that can be used fiberglass or steel rotational molding, stainless steel and other materials produced for. B4-72 / 79 for proof centrifugal fan for transporting flammable gas, the motor is equipped with explosion-proof motor, impeller made of cast aluminum or non-metallic materials. FB4-72 / 79 for corrosion proof centrifugal fans, for the transport of corrosive and flammable gases.