51COVD & 51COHD
alumavent

51COVD / 51COHD Type CO Dynamic Fire Damper (Oval)

The Alumavent 51COVD/51COHD is a 1-1/2 hour label dynamic fire damper, UL/ULC approved for use in HVAC systems where fans remain operating in the event of a fire alarm. The Type CO blade configuration is specifically designed for oval ductwork, with blades positioned outside of the duct airflow path, and the interlocking curtain type blade design is suitable for use in fire separations with a fire resistance rating of 2 hours or less.


Standard Construction

MaterialGalvanized steel
CertificationUL Certified
Fire Rating1.5 hour
OperationDynamic
Damper ShapeOval ductwork
Blade DirectionVertical, Horizontal
Depth4-1/4" (108 mm)
FrameRoll formed 20 GA. Galvanized Steel with hemmed edge

Custom configurations available

This product can be manufactured in alternative materials, sizes, and mounting options to meet your project requirements. Contact us to discuss specifications.

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Available Accessories

SleeveFactory supplied in 22, 20, 18, or 16 GA.; sleeve length required at time of order
Access DoorFactory mounted in a common sleeve
Fusible Link212°F (100°C) alternative available
Retaining Angles1-1/2" x 1-1/2" Quick-Fit

Additional Notes

The 51COVD/51COHD is UL/ULC certified for use as a 1-1/2 hour dynamic fire damper in HVAC systems.

The 51COVD/51COHD is designed for installation in fire-rated wall and floor assemblies using oval ductwork in systems where fans are not shut down on fire alarm activation. Unlike static fire dampers, dynamic fire dampers are tested and rated to close reliably against live airflow, making them the required choice for systems that maintain fan operation during a fire event. The Type CO configuration accommodates oval duct geometry while keeping the blades outside of the airflow path during normal operation. The interlocking curtain blade closes under spring tension when the fusible link releases.