"24V DC Cooling Fan" fan performance parameters pressure refers to the total pressure under standard conditions. Standard state pressure p20? 101.3KPa, temperature t? 20 ℃, relative humidity of 50% ?? atmospheric conditions. Usually the fan inlet is not a normal state, but any non-standard state, the different physical parameters of the air in the two states. "24V DC Cooling Fan" air density change will make the fan total pressure standard state also changes, fan performance curve when applied in a non-standard state, the parameters must be transformed. Similar law states that when a "24V DC Cooling Fan" fan intake status changes, if its conditions are met similar criteria intake fan total pressure state p20, air density is 20;?? Air density non-standard state for? fan total pressure is p,