It’s happened. The worst nightmare imaginable – your building is on fire. But, as everyone rushes to leave via the fire exit, several things are happening deep within the ductwork of the building, unbeknownst to the people, and it very well may be saving all of their lives.
What is a Fire Damper?
When a fire starts, one of the first concerns is keeping it from spreading. An easy access point for the fire is the ventilation ductwork. Wouldn’t it be good if there was some way to stop a fire in its tracks? That’s where fire dampers come in.
A fire damper is a piece of hardware used in any air transfer opening, duct, or other places where fire-rated structures such as walls, floors, or any other fire barrier are penetrated. Without the placement of the fire damper, the fire would quickly sweep through to other spaces and pose a far greater danger to people and property. A fire damper helps limit the fire’s extent and minimize the breadth of damage to the facility and environment.
How Does a Fire Damper Work?
A fire damper works on a simple principle – they close when it gets too hot. Specifically, they close when the temperature in the room or space rises over a set threshold limit to prevent a fire from spreading any further. Typically, they are set at 165 degrees Fahrenheit, but higher in places where the temperature routinely reaches that temperature, such as kitchens or laundromats.
When that temperature is reached, the fusible link, which holds the damper blades of the fire damper in the open position, will open. With the opening of the fusible link, the damper blades will close, thus preventing the fire or smoke from moving any further into the ducts. Once the fire damper has been activated, it will need to be replaced manually.
What is a Fusible Link?
A fusible link is a mechanism that holds the damper blades of the fire damper in the open position. When the fusible link is exposed to the set temperature point, the surround will melt or break apart, and the link will then open. As shown above, the fire damper blades close once the link opens.
Underwriters Laboratories has a standard for fusible links and their manufacturer. UL 33, which states the standard for Heat-Responsive Links for Fire-Protection, makes sure that all thermal links have been tested for reliability and sustainability via oil bath tests, corrosion, oven tests, and load tests.
What are the Types of Fire Dampers?
- Static
- Dynamic
Static Fire Dampers
Static fire dampers are made to cut off the airflow in a building as soon as it senses a fire. Once your building’s fire alert system detects a fire, it will trigger your HVAC system, telling it to turn off. This will cause all of the fans of your HVAC system to stop, which will cause your static fire dampers to close because all of the air pressure in the ducts will vanish.
Once the static fire dampers close, no air will be able to pass through the ducts. Generally, static fire dampers will be found within horizontal barriers. They are made with a curtain-like design.
Dynamic Fire Dampers
While dynamic fire dampers also cut off the airflow to fire and protect your building from fire damage, the way they shut and where you find them differs from static fire dampers.
You will generally find dynamic fire dampers within vertical barriers of your HVAC system. Dynamic fire dampers are spring-loaded, which is how they close. When a fire occurs, the HVAC system where the dynamic fire dampers are utilized will continue to operate. Since a dynamic fire damper must be able to shut against still-circulating air, they have built-in fans that will turn on to activate the spring-loaded system.
How Do You Take Care of Fire Dampers?
Regular maintenance of your fire dampers is not only the smart thing to do, but the National Fire Protection Association requires it. According to the NFPA Code 80, you should have your fire dampers inspected one year after installation and every four years after that unless your building is a hospital. If your facility is a hospital, you will need to schedule your inspections every six years.
What are Smoke Dampers?
While we have been discussing fire dampers, smoke dampers are another essential component of your fire safety prevention plan regarding your HVAC ductwork. Smoke dampers are HVAC fire protection products that reduce the spread of smoke and other gases through your building’s HVAC system during a smoke or fire occurrence. Your smoke damper will shut, preventing any air or smoke from continuing to move through a duct or ventilation opening by a smoke barrier.
Either smoke, fire signal, smoke damper control system, fire system, or a local smoke detector activates it. Once a signal is received, the smoke damper actuator, which holds the damper open, will close it. When a smoke damper is installed within a smoke barrier, it will restrict smoke from passing through the duct when it is called into action during a smoke event.
Smoke dampers also:
- Assist in removing smoke from the building
- Aid pressures within the building to prevent smoke from spreading
- Boost the effectiveness of a gas suppression system
Like fire dampers, smoke dampers need to be inspected, maintained, and repaired, if necessary, to ensure that your fire protection is always up-to-date and ready in case of an unforeseen disaster. Once your smoke dampers are installed, they will need to be inspected at the one-year mark. After that, your smoke dampers should be tested and inspected every four years unless they are in a hospital, and then they will only need to be tested every six years.
Fire dampers and smoke dampers may seem like a small part of your HVAC system, yet they play an integral part in your overall fire protection plan. Making sure you have all the correct pieces for your HVAC plan is essential, and Lloyd Industries is here to help you every step of the way. Don’t hesitate to get in touch with us for any of your HVAC needs. Require a contractor or technician? Check out our vetted list of professionals in your area!
