D.overview:fan blades adopt special twisted blade design and flange flanging casing, which makes the noise lower and the air volume larger. Notice: used environment should be without inflammable, explosive and corrosive gases , and temperature within 50.E.application:widely used in chemical industry, light industry, food, medicine, metallurgy and other industrial and mining enterprises and various types of civil buildings ventilation, ventilation, cooling the ideal equipment.F.feature:low noise, large air volume, low power consumption, reasonable structure;piping without any bracket, so suitable for installation in the wall or within the pipeline;executive standard:db31t 727-2013