It is suitable for ventilation and fire control of tall buildings,subway tunnel,underground stores,gymanasia,etc.This 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 pesonal on the fire spot.The transporting medium is air or other non-spontaneous and non-explosive-combustion air with no harm to human.The air transferred shall not contain any adhesive materical,dust and grain and the concentration shall not exceed 150mg/m³ when the temperature shall not exceed 80℃.When used for fire control,the fans can run more than 30 minutes continually under the condition that the air and smoke temperature is at 280℃.