Air Balance series 280 and 290 ceiling dampers are designed to provide the required fire and heat radiation protection of HVAC penetrations. They protect floorceiling and roofceiling assemblies having a restrained or unrestrained assembly fire resistance rating of 2 hours or less.
The key difference between ceiling dampers and fire dampers is the ability of ceiling dampers to protect against heat radiation in air handling duct outlets penetrating fire resistive ceiling assemblies. During UL's fire endurance test, both types of dampers are exposed to high temperatures. Throughout the test, fire dampers are observed only for integrity of the exposed surface, whereas ceiling dampers are observed both for the integrity of the exposed surface and for the amount of heat transmitted through the damper.
All ULrated ceiling assemblies require a ceiling radiation damper, not a horizontal fire damper. A fire damper is a flame barrier. A ceiling radiation damper is a flame and heat barrier.

To facilitate various installations, a damper to insure adequate clearance for the damper frame extension can be provided. Standard blades in flexible duct installations. Bottom frames are used for ductless and rigid duct frame extensions are used to accommodate installations. Top frame extensions are used an opposed blade balancing damper (OBD).
In most layin or sloped surfacemount diffuser/grille installations, a Thermal Blanket is required with the ceiling damper in order to provide adequate protection.
Air Balance Inc.'s Thermal Blanket is 1/4" thick ceramic fiber, with 8 Ibs./cu. ft. density. The blanket offers highly efficient insulation and possesses high tensile strength and resiliency to withstand vibration and physical abuse. It will not separate, sag, or settle. It is characterized by extreme resistance to thermal shock, and its thermal and physical properties are unaffected by oil or water after drying.