How Does a Backdraft Damper Work? Working Principle, Types and Applications How does a backdraft damper work? A backdraft damper works by allowing air or gas to flow in one direction while automatically restricting reverse airflow. The pressure generated by forward airflow opens the damper blades, while reduced or reversed airflow allows the blades to return to the closed position. Depending on the design, gravity or springs may be used to assist the closing action....