9-28 type fan general rule for forging furnace and high-pressure forced ventilation, and is widely used in material handling, applicable and conveying air and non-corrosive, not spontaneous, non-sticky material containing gas, the temperature of the transmission medium, generally do not exceed 80 ℃, dust and hard fine particles contained in the medium is not greater than 150mg / m3. The fan is also used as a cement kiln decomposition process (machine No. 16 above), steel smelting and other special occasions, the use of high-temperature fan (use heat-resistant, high-strength materials).