Last Look "220V Cooling Fan" fan blades of the same fan if other parts remain unchanged, only the blade consists of five blades instead seven blades, wind changes may not add much. But on the fan speed, the seven blades fan speed will be lower than five (under the same ventilation rate), the opposite if seven fan blades, bearing wear, fewer oil spills, the fan life longer. If the five-speed fan blades and seven identical, ventilation seven blades will be even greater. "220V Cooling Fan" the higher the speed, the shorter the life of the corresponding noise is greater. In addition, the thicker the fan blades, the greater the blade bevel, the pressure is greater. Inlet angle blades (45 degrees maximum), one of the important factors in determining the amount of ventilation fan. If you start from the "220V Cooling Fan" design, best airflow also a small increase in the inlet and outlet of the rotation slots to aid air flow design uses some fans do not like the ideal launch.