How does a fire damper work?
• When a rise in temperature occurs a fire damper will close and prevent the spread of flame through the barrier. Dampers are typically curtain style that will close (shut) when a fusible link melts. The fusible link typically melts when the temperature rises to 165 degrees Fahrenheit. In some circumstances higher degree fusible links (e.g. 212F) are installed in ductwork with consistently higher normal temperatures, such as hot decks in dual duct systems. Fire dampers are certified by Underwriters Laboratories (UL) to carry hourly fire resistance ratings, typically 1.5 to 3 hours.
