I would like to ask about the working principle of fire dampers.

1. Fire dampers and fire control valves, normally open; they close at 70 degrees. These valves are typically installed where air ducts pass through fire walls, serving to shut off airflow in case of a fire. They can be programmed to send electrical signals – the valve closes when the smoke temperature reaches 70 degrees, which in turn triggers the shutdown of the supply (or backup) fans； 2. Smoke and fire control valve, normally open; closes at 70 degrees. Similar to item 1, but with an additional signal input that allows it to be closed remotely from the control room. It is generally used in air supply systems that serve both normal ventilation and supplemental ventilation during fires; during a fire, it can be used to close rooms that do not require supplemental ventilation ； 3. Fire dampers that shut off at a melting temperature of 280 degrees; they are normally open and generate electrical signals. These are similar to type 1, except for the different melting temperature. They are typically used at the points where smoke exhaust ducts pass through firewalls, and they automatically shut off when the smoke temperature exceeds 280 degrees, thereby enabling the shutdown of the smoke exhaust fans as well.

Is the poster using a valve structure, and how is fire protection achieved in this way?

The structure of a fire damper mainly consists of a valve body and an actuator. The valve body consists of a housing, flanges, vanes, and a vane actuation mechanism, among other components. The actuator consists of a housing, a blade adjustment mechanism, a clutch, a thermal fuse, etc. The actuator of the fire damper controls the rotation of the blade through a metal fusible link and a clutch mechanism. When the temperature of the gas flowing through the pipe reaches the melting point of the fusible metal sheet, the sheet melts and breaks, causing the compression spring and spring pin on its shaft to rapidly push down the clutch pad. At this point, the clutch and the blade adjustment mechanism become disconnected. Due to the two torsion springs installed on the valve body, torque is applied to the blades, causing them to rotate. It can be seen that the actuator of a fire damper operates on the principle of mechanical transmission, requiring no electricity, gas, or other forms of energy; thus, it can ensure fire protection under all circumstances. The opening and closing of the fire damper are determined by the requirements of the system; it remains in an open position both when the system is not in use and when it is operating normally. When the temperature of the gas flowing through the pipe is below the melting point of the selected metal fuse element, the system is operating normally and the valve stays open. The valve closes automatically only when the operating conditions exceed those of normal use, thereby serving a safety function.