In food factory, there is high requirement for hygiene. During passing of workers or vehicles, the door need open and close in many times. If the door is very slow, it will take more time for it to open and close. This will lead to more time of air transmission. This is the reason why a high speed door is the best choice in such area. Such door can open in the speed of 1.5m/s. It means the door will finish opening or closing in just several seconds. This save most of the time and than tradtional roller doors, and reduce air flow by 90%.