UL 555/555S 1.5 hr./Class III, V-Groove Blade, 2,000 fpm and 4″ w.g. max.
The FSD35 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 III Smoke damper. It features: Triple V-Groove Blades. Maximum rating of 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. 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. Galvanized steel construction.