General Product Overview - Curtain Fire Dampers

The function of a Fire Damper is to close automatically upon detection of heat, in order to protect the integrity of a fire barrier and maintain its fire resistance rating where penetrated by HVAC ductwork or equipment. Failure of these dampers to fully close in the event of a fire may lead to a disastrous loss of life and/or property.

Nailor Dynamic Fire Dampers
• Tested for closure under airflow.
• For use in dynamic HVAC/smoke control systems.
• UL Classified to standard UL 555.
• ULC Classified to standard CAN/ULC-S112. 1 1/2 hour and 3 hour label available for use in fire separations of up to 4 hours.
• Meet all requirements of NFPA 90A and NFPA 92A.

Traditionally (in the 1960's and 70's), HVAC systems were designed to automatically shut down in the event of a fire (until recently a requirement of NFPA 90A), thus allowing fire dampers to close under "static" conditions. Fire and smoke control was based upon the passive compartmentation principle, and the existing version at that time of test standard UL 555 for fire dampers did not address the question of closure under airflow.

Newer "dynamic" smoke control systems require HVAC fans to remain in operation in order to pressurize areas adjacent to a smoke-filled area to stop smoke migration. This may be above and below a fire floor, a stairwell for escape or a safe refuse area for example. The system may also be used to purge smoke to the outside of the building.

HVAC system operation introduces a dynamic load on the damper and static dampers will not close (especially gravity operated in the wall dampers) under medium to high flow conditions.

The 1990 revision of UL 555 (4th Edition) addressed this concern by adding an optional Operation Test for dampers designed to close under airflow. Since April 1, 1992, all UL Labeled Fire Dampers are required to have labels identifying them as STATIC RATED (only for use in systems with fan shut down during emergencies) or as DYNAMIC RATED when intended to close under airflow. For dynamically rated dampers, this label must also indicate airflow direction, maximum rated velocity and the maximum pressure differential across the closed damper.

Nailor manufactures a comprehensive line of static and dynamic curtain fire dampers it's where we got started.