Back draft dampers have been specifically designed for use in Air-Conditioning and Ventilation system, these dampers are air operated and are used for air intake and exhaust, and are also used for pressure relief. Back draft dampers are operated by gravity (where pressure or velocity opens and closes the damper) to open and close the damper. These dampers are composed of a set of horizontally mounted blades, they are normally closed and are free to rotate about the horizontal axis. The blades are manufactured from light weight galvanized sheets / Aluminium.