Fire dampers are designed for the purpose of preventing the spread of flames across a rated barrier. A fire damper is installed within the duct where the duct intersects the barrier.

How does a fire damper work?

In general a fire damper works when heat from a fire causes the normal temperature of a room to rise to approximately 165 degrees Fahrenheit i.e. it is designed to close automatically on the detection of heat. The fusible link which is attached to the damper melts causing the dampers' door to close.

Why are fire dampers required?

Why They're Necessary

The dampers prevent the spread of fire through heating, ventilation, and AC ducts, which helps to stop a fire from spreading throughout the rest of the home. They also help to prevent smoke from traveling through the building's ductwork in the event of a fire.