The 4-68 series centrifugal fan can be used for indoor ventilation and air exchange in general factories and large buildings. It can be used to input gas or output gas. The gas transported should be a gas that does not exceed 80 degrees Celsius and other unnatural, harmless to human health, and non corrosive to steel materials. The gas must not contain viscous substances, and the amount of dust and hard particles contained must not exceed 150mg/m3. Widely used for ventilation, dust removal, and cooling in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings; Ventilation and induced draft for boilers and industrial furnaces; Cooling and ventilation in air conditioning equipment and household appliances; Drying and selection of grains.