The main source of blade force in the air is axial from inlet to outlet, so pressure rise is provided by a process called direct blade action. Blade forces must have an additional component in the tangential direction, which has a negative effect on drive torque: it directly causes air to rotate about its axis, regardless of its forward direction. Axial flow fan capacity from 2.83m3/min to 14158m3/min.

      An airfoil axial fan exerts more force on the air, increasing pressure and maintaining efficiency over a wider volume flow range.