Dynamic 3 Hour Rated Dampers
UL 555 classified 3 hour fire rating
Building codes require fire dampers to maintain the fire-resistance ratings of walls, partitions, barriers, and floors when penetrated by ducts or other transfer openings. Dynamic-rated-fire dampers are for use in HVAC systems that remain operational in the event of a fire emergency. These are UL 555 classified with fire-resistance rating of 3 hours or more.
