The fire damper has an internal accordian folded door, held up by a fusible link. When a fire passes through the duct the fusible link melts at a preset temp and drops the damper by gravity.
Fire dampers are held in place by sheet metal brackets attached to the damper housing. The ducting is held in place by a slotted "S" lock. They may not be screwed, nailed or permanently attached to either the wall or the ducting.
There must be a service access door in the duct to permit checking and servicing the damper.
