"220V Cooling Fan" in the main application range What? You know? On between DC fan air flow and wind pressure on the do not know it, we will start to understand, are you! We all know that air flow and fan of the wind strength ? What is the relationship you and then they bring everyone together to find the answer to this question, we'll then read: "220V Cooling Fan" in practice, the nominal value of the maximum wind not send actual fins obtained air flow, air volume, it does not mean strong ventilation capacity. Due to air flow, air flow path will encounter in their fins obstruction, the impedance will limit the free flow of air. That is when the wind increases, air pressure decreases. Therefore, there must be an optimum operating point operations, namely intersection "220V Cooling Fan" performance curve and drag the curve. At the operating point, the slope of the characteristic curve of the fan to a minimum, change the system characteristic curve was the lowest.