The FSD36FA 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 is specifically designed for supply or return ducts with grille outlet. It features:
Rated to 2,000 fpm and 4" w.g.
Through the grille access to damper and all accessories.
Airfoil blades, which have greater strength, less static pressure, superior sealing ability, superior fire protection ability, and produce less noise.
Failsafe design, which enables the damper to automatically assume the desired position when fire interrupts operational power.
The EFL or PFL heat-actuated release devices permit controlled closure through the actuator and are automatically remote resettable after test, smoke detection, or power failure conditions.