For proper ventilation, the need to overcome the resistance "220V AC Cooling Fan" ventilation stroke within the fan must overcome the air resistance of the pressure to produce. The measured pressure variation value is called static pressure, i.e. the maximum difference between the static pressure and atmospheric pressure. "220V AC Cooling Fan" is parallel to the surface action of the gas pressure of the object, by measuring the perpendicular to its surface out of the hole. The required gas flow in the form of kinetic energy into a pressure is called dynamic pressure. To achieve the purpose of air supply, the need for static pressure and dynamic pressure. Total pressure and static pressure and dynamic pressure of algebra. The greater the pressure, "220V AC Cooling Fan" air power is stronger.