Fire Damper Tips

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Tech Brandon Livingston posted about fire dampers and took some photos shown here. He gave me permission to share this here and his original post inspired this tip. Thanks Brandon.

Before the damper was opened is on the left. After it was opened and new link installed on the right.

A fire damper is an important part of commercial fire safety preventing the spread of flame and smoke but it can lead to a loss of airflow in a building when they close that can lead to a service call.

A fire damper is designed to remain open during normal conditions and slam shut to prevent the spread of flame, heat and smoke during a fire. When the link in the fire damper reaches the rated temperature the link will break and the damper will slam shut. Sometimes this can happen as the links age and become brittle and/or due to vibration over time. Fusible link temperature set points are usually 165°F, 212°F, or 286°F with 165°F being the most common.

Generally, you will find fire dampers where ducts pass through partition walls and /or floors in commercial applications.

Fire dampers commonly come in 1.5 and 3-hour fire ratings. The hour ratings for fire dampers must be 75% of the hour rating for the wall, floor or partition. That is why a fire damper rated for 1.5 hours can be used in a fire barrier rated for up to 2 hours and a fire damper rated for 3 hours can be used in a fire barrier rated up to four hours.

It is a good practice when installing any new system to measure and mark the normal static pressure on the supply and return ductwork once the air balance has been completed. On commercial buildings that you maintain or service regularly it is a good idea to do it once you take over the building to make future service easier. This way whenever a damper shuts you will know very quickly by comparing the current static to the baseline you have established. You can easily check duct static pressure using a quality manometer or magnahelic gauge. Keep in mind that on high air velocity systems you will need a pitot tube adapter to get an accurate reading.

If a fire damper is shut they can very difficult to get open by hand. While it is possible, a tool like the FiDO Fire Damper Opener will come in very handy.

— Bryan

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