The FSD-EX Combination Fire/Smoke Round Damper is both UL555 and UL555S Classified. It is rated as a 1-1/2 hour fire damper and a Leakage Class I Smoke damper. It features:
Failsafe design, which enables the damper to automatically assume the desired position when fire or smoke (if smoke detector is present) interrupts operational power.
The EFL heat-actuated release devices permit controlled closure through the actuator and are automatically remote resettable after test, smoke detection, or power failure conditions.