■ Material：Galvanized Steel Sheet ■ Size(W×H):According to air duct sizes ■ Features： ? Usually it is off, When on fire, smoke sensors output electricity signal （DC24V）throughcontrol center, and the electromotor in the actuator acts, valve is automatically closed, outputs the open electric signal. ? Direct current electromotor drives to reset after valve acting. ? Valve can be manually opened and reset.　 ? When the temperature getting up to 280℃，the fuse will act and the valve is automatically closed.