"Axial Fan" When the fan has a large capacity pipeline system running unstable work area may occur flow pressure fluctuations, causing severe vibration device, and is accompanied by strong noise, a phenomenon known as asthma vibration. Surge would worsen the fan performance, the device can not maintain normal operating conditions, when the surge frequency and natural frequency device coincide, the resonance will make the device destruction. In order to prevent the occurrence of surge, high-capacity fan piping systems should avoid using performance hump-shaped curve; in any condition, the output flow device should be sufficiently larger than the critical flow QK, never allowed Q < QK; appropriate adjustment method to expand the fan stable work area; line volume control measures are effective.