用于消防排烟系统中，当有火警发生时可通过该按钮来紧急开窗排烟。紧急按钮线路在遇到开路或者短路故障，排烟窗会立即自动开启，保障了消防排烟窗系统的可靠性。

Used insmoke exhaust system, to open window and exhaust smoke by manual emergencybutton when firing, smoking window will open automatically when there is somewrong with open circuit or short circuit of emergency button line, Guaranteethe high performance of smoke exhaust system.