When the "Cross Flow Fan" surge phenomenon occurs when the micro-pressure gauge and speed torque meter display value is changing rapidly and the scope of change in amplitude are great, cyclical changes, in this case to bring to trial persons reading great difficulties. In general, the maximum number is shown as "Cross Flow Fan" normal operating value, and the surging phenomenon almost disappeared, but during the week, the short-lived, very unstable, as a minimum indication of the surging phenomenon occurs when the most serious readings. To switch to a different manufacturer's "Cross Flow Fan", you need to measure fan site size holes.