It is suitable for ventilation and fire control of tall buildings,subway tunnel,underground stores,gymanasia,etc.Thos fan is set up with double-speed motor,it operates at a low speed normally and used for ventilation,Once occurrence a fire,the fan is automatically transferred into high-speed and dischange smoke by the eletcric control system,which facilitates safe evacuation of pesonnel on the fire spot.The transporting medium.The air transferred shall not contain any adhesive material,dust and grain and the concentration shall not exceed150mg/m³ when the twmperature shall not exceed 80℃.When used for fire control,the fans can run more than 30minutes continually under the condition that the air smoke temperature is at 280℃.