.webp?width=91&height=70&name=MCDLG%20Logo%20(Resize).webp)
Fire dampers sleeves are required for every fire damper and fire-smoke damper. Learn more about these crucial components with the MCDLG Newsstand.
What is a Sleeve?
Do you know about fire damper sleeves? You may see the term come up in your specifications, like a fire barrier that requires a fire damper with a C-style sleeve. What is “C-style”? What is a sleeve and why is it necessary?
The ends of the sleeve are highlighted in this image.
Sleeves are steel sheets installed around the frame of UL life safety dampers. Sleeves are typically installed by the manufacturer when assembling the damper, although you can choose to install the sleeve in the field. They are a required component for fire-rated dampers, including combination fire-smoke dampers. Fire dampers cannot be installed without a sleeve.
The purpose of the sleeve is to keep the damper secured in place during a fire. Sleeves will have breakaway connectors between the sleeve and the ductwork. Failing structures or debris can strike the ductwork and knock it out of place. Without a sleeve, the ductwork can easily pull the fire damper down with it. This would leave a hole in the fire barrier.
If the duct falls during a fire, the breakaway connectors will separate the duct from the damper.
Sleeve Depth and Material Thickness
The specifics of the sleeve will vary depending on the damper size and on additional components like breakaway duct connections. For example, assume you need a fire damper that will be more than eighty-four inches wide. This damper will require a sleeve made from a thicker gauge steel.
At Louvers & Dampers, we use 20-gauge steel for standard sleeves, but we can build sleeves with10-gauge thickness to accommodate larger units.
We use 20-gauge steel as the standard thickness for damper sleeves. Larger dampers require thicker materials for the sleeve.
Manufacturers will always pick the best material for the job when the sleeve is supplied by the factory. Remember that the sleeve will encompass the damper. The sleeve’s inner dimensions will closely match the outer dimensions of the damper frame. Remember to account for the material thickness of the sleeve when sizing the damper. Material thickness will be a small measurement, but it will be important to know.
You will also need to account for the depth of the sleeve. Sleeve depth can refer to the full length of the sleeve from end to end or to the amount of extra sleeve on either side of the damper. It helps to think of this measurement as the depth of the damper inside the full sleeve.
You can choose where the damper will be placed inside the sleeve, assuming the assembly meets UL’s standards for the sleeve depth. Manufacturers will use a default sleeve depth if you don't specify.
In most installations, the fire damper must be situated inside of the opening of the fire barrier so that it will fully cover the opening when closed. You may choose to install certain fire dampers outside of the barrier, which is known as an out-of-wall installation. There will be additional requirements for these installations, which manufacturers will explain in their installation instructions for out of barrier installation.
Installers can place the damper anywhere within the sleeve, assuming the damper still meets requirements. You can also specify sleeve depth when ordering dampers with sleeves.
If there is a gap during installation, manufacturers may also supply a sleeve extension that covers any gap between the sleeve and the ductwork. Even with this extension, the sleeve must not extend more than sixteen inches past the opening.
There will be other considerations covered in the manufacturer's literature, such as the spacing of fasteners holding the sleeve to the damper. Consult the manufacturer’s literature on sleeves, even for dampers with factory-installed sleeves.
Transition Collars
Transition collars match the shape of the sleeve to the shape of the duct. They can also modify the damper’s place in the air stream. For example, you can connect a rectangular fire damper to a spiral duct by using a round transition. Or you can remove a curtain damper from the airstream with a “C-style” transition. Transitions are commonly used for curtain fire dampers, but they can be added to any fire damper or combination fire-smoke damper.
For a standard transition, the full damper will be in the air stream during standard operation, including the frame. This is referred to as the “A-style” transition. For "B-style" transitions, the height of the collar's opening matches the height of the damper's opening. This design keeps the head of the damper, and the curtain blade stack out of the airstream. This increases the free area in the duct, but the damper's sill is still partially in the air stream.
“C-style” transitions provide 100% free area when paired with a curtain fire damper. The opening of this transition type starts just above the sill of the damper and ends at the curtain blade stack. With a C-style transition, only the free space of the fully open damper is in the air stream.
It is important to closely match the opening size of the transition with the size of the duct, so that they fit together. Manufacturers will provide separate sizing for dampers with B-style and C-style transitions, with the dimensions of the transition opening already factored into the measurement. These dimensions will also include the size of the damper for reference.
Fire dampers and their sleeves are part of your building's fire response, buying precious time for people to safely evacuate during a fire. Every fire damper needs a sleeve. They keep the damper in place during an emergency and ensure that the fire barrier remains intact. It is important to meet all codes and requirements for fire dampers.
Have experience with fire damper sleeves? Share your stories below. We want to hear from you!
Looking to meet some fire safety requirements for your HVAC system? Contact Louvers & Dampers today! We can help you fulfill your requirements with static and dynamic curtain fire dampers. L&D can help you finish your next project.
