The Condenser - A Closer Look at Fusible Links for Fire Dampers

Fire dampers need to close at a moment's notice, even if there is no power in the building. Learn how fusible links help them close in this quick Condenser read.

A fire damper will have several components that ensure it works when its needed, such as the fire damper sleeve and the fusible link. Fire dampers need the means to respond to a fire. The trigger method must be unpowered and fast. In “Fire Response,” we covered two heat response devices that trigger closure. In this article, we will take a closer look at the fusible links for fire dampers.

Fusible links are thin metal pieces with a loop on each side, for holding the damper’s blades in the open position. For multi-blade fire dampers, the fusible link will be looped onto a spring closure mechanism tied to the damper’s linkage.

For more on life safety dampers, check out these Newsstand articles:

• Life Safety in HVAC - What is a Fire Damper?
• The Four Types of UL Life Safety Dampers
• The Condenser - Fire Reponse for Life Safety Dampers

The loops of the link hold the blade mechanisms in place. The blades are released when the link melts.

For curtain blade fire dampers, the link will join two metal pieces that hold the curtain blade to the top of the damper. The fusible link holds the fire damper open until the air around it gets hot.

Fusible links are fabricated from metals with low melting points. This makes them more susceptible to heat than the fire damper. A standard fusible link is rated for 165 degrees Fahrenheit. When the air reaches this temperature, the fusible link will melt and break apart.

In a multi-blade fire damper, the melting link will release the damper’s spring closure mechanism, which closes the damper. For the curtain blade damper, the link separates the two metal pieces and releases the curtain blade. Dynamic curtain blades will be spring loaded so that they can close against an airstream. The static curtain blade falls on its own. In every configuration, the fusible link provides the trigger for closure.

Fusible links are the standard closure trigger for fire dampers. Links will come with each fire damper, either pre-installed or shipped loose. You can order additional links if you need replacements. The standard temperature rating is 165 degrees Fahrenheit, but manufacturers will also offer links rated for hotter temperatures.

At MCDLG, we offer fusible links rated for 212 degrees Fahrenheit. This is a good option for fire dampers installed near heating units or in areas of the ductwork involved in warm air. Be sure to review your project’s requirements before selecting life safety dampers.

Looking to meet some upcoming requirements? Louvers & Dampers can help. We build multi-blade and curtain blade fire dampers for static and dynamic airflow applications. Contact us today. Let's work together on your next project.