The FSD36G Combination Fire/Smoke Damper is both UL555 and UL555S Classified. It is rated as a 1-1/2 hour fire damper and a Leakage Class II Smoke damper. It features:
Factory designed to accept a 1 3/4" grille and 3/4" front flange shipped loose.
Triple vee groove blades.
Rated to 2,000 fpm and 4" w.g.
UL approval for dual directional airflow.
Failsafe design, which enables the damper to automatically assume the desired position when fire or smoke (if smoke detector is present) interrupts operational power.
Controlled closure in not less than 3 seconds and no more than 15 seconds to prevent HVAC and duct damage.
Automatic remote reset after test, smoke detection or power failure conditions.
Galvanized steel construction. Note: Consult Ruskin if wall is less than 6" thick