"220V Cooling Fan" in the inlet and outlet parallel; their performance ranged from axial fans and centrifugal fans, air volume, air pressure is also large; it out of the wind and into the wind with a tilt angle, if two fans in parallel , the air flow can spread to the entire system. In order to make the most efficient fan, the optimum operating point at 1/3 of the axial flow fan after fan characteristic curve, namely large amount of wind, the wind down of the range. If the cross-flow "220V Cooling Fan" air flow enough, it may also be part of the front third of that small amount of wind, air pressure high range, avoid unstable region in the middle; the optimum operating point of the fan centrifugal fan characteristic curve Fan cooling veneer thickness is the minimum distance from the fan-fold greater than 1;; the first 1/3 part, that the higher pressure range "220V Cooling Fan" of the outlet should be avoided where is on the front of personnel to operate the equipment ; cooling fan power shall not exceed 10% of the overall device power consumption.