"Axial Fan" total pressure p is static and dynamic pressure dp stp two parts. Centrifugal fan total pressure limit value is only 1500mm (14710Pa), and the outlet flow rate of up to 30m / s or so; and the flow rate Q (ie exit velocity 2v), the smaller the total pressure p. Thus, the fan outlet dynamic pressure can not be ignored, that is not equal to the total pressure static pressure. For example, when the air supply piping all Dynamic Pressure loss (ie loss of export), the pipeline can only rely on static work. For this reason, the introduction of the concept of centrifugal fan total pressure, static pressure and dynamic pressure.