Description 4-72,4-79, SS4-79 series centrifugal fan, its efficiency and sound level than A are at or better than the Ministry of Machinery Industry developed A-level standards. Widely used in various types of medium-sized factories and civil construction, large stadiums and other places SS4-79 series two-speed centrifugal fan noise to 4-79 Centrifugal with multi-speed three-phase step motors constitute China, the fan in Fans excellent retention characteristics of the prototype, but also has an adjustable speed, air flow and pressure can be varied over a wide range, simple structure, reasonable price advantage, can one machine, save investment and operating costs. 4-72,4-79, SS4 machine -79 series centrifugal fan ventilation for general use, conveying air or other non-flammable, non-corrosive gases, non-sticky substance inside the gas, dust and hard contained particles should not exceed 150mg / m3, the temperature does not exceed 80 degrees Celsius. Note: F4-72 / 79 for anti-corrosion centrifugal fan, used to transport corrosive gas, used for the production of glass fiber reinforced plastic material. B4-72 / 79 for explosion-proof centrifugal fan, used to transport flammable and explosive gas, the motor is equipped with explosion-proof motors, explosion-proof requirements of a higher low iron impeller, requires proof aluminum impeller. FB4-72 / 79 for corrosion proof type centrifugal fans, for the transport of corrosive and flammable gases.