FD-1600 1-1/2 hour fire-rated dampers are approved for mounting in walls constructed of masonry or gypsum wallboard (metal or wood studs) and mounting in cement floors or ceiling. The FD-1600 Fire Damper meets specifications requiring one damper to provide a 1-1/2 hour fire rating. The FD-1600 Fire Damper is tested according to UL Standard 555 for dampers intended for use in Heating, Ventilating, and Air Conditioning (HVAC) duct systems passing through fire-resistant assemblies.