FSD are designed to be installed in HVAC ductwork at locations that are designated as fire barrier or fire & smoke barrier. It should not be installed in a smoke extraction ductwork for smoke extraction applications. It is suitable for vertical installation in walls/partitions and horizontal installation in floors having a fire resistance rating of less than 3 hours (as per NFPA 90A). It prevents the spread of fire/smoke inside residential, commercial and industrial buildings. Normally open but can be closed through remote signal from Fire Alarm Control Panel / BMS or closed automatically upon detection of heat. Protects the integrity of a fire/smoke barrier wherever it is penetrated by HVAC ductwork by preventing the spread of fire/smoke.