Fire Damper Tips

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.


The picture on the left shows the situation before the damper was opened. The right image show what happened after it was opened and a new link was installed.

A fire damper is an important part of commercial fire safety, preventing the spread of flame and smoke. However, it can lead to a loss of airflow in a building when they close, leading 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. That can sometimes happen as the links get older and become brittle 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 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 4 hours.

When installing any new system, it is a good practice 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 Magnehelic gauge. Keep in mind that you will need a pitot tube adapter on high air velocity systems to get an accurate reading.

If a fire damper is shut, it can be 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

Related Tech Tips

Simple Pump Selection Exercise
Here is another excellent article from Michael Housh, owner of Housh Home Energy and a regular contributor to HVAC School. Thanks, Michael! I thought I would go through a simple example of sizing a hydronic circulator for an application. This is a made-up scenario, but I sketched out a 20’ x 20’ square home with […]
Read more
What if you Only Have One Large Hose?
When evacuating, the FASTEST way is to use two large-diameter hoses connected to two core removal tools and the cores removed. These hoses are then connected to the pump using a tee or evacuation “tree.” However, when you only have one large hose, another acceptable method is to connect the large hose to the suction […]
Read more
The TXV Powerhead and What it Does
We’ll never run out of content to discuss as long as thermostatic expansion valves exist. Deal with it. Today, we’re going to focus on the powerheads of TXVs. This article will focus on what the powerheads do, how they work, and some basic troubleshooting procedures involving TXV powerheads.   What is a powerhead, and where […]
Read more

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

loading

To continue you need to agree to our terms.

The HVAC School site, podcast and daily tech tips
Made possible by Generous support from