What is a Fire Damper?

As of this writing, there have been 1,142 home fire fatalities, and 140 fatalities in non-residential fires, according to the U.S. Fire Administration. Though this is lower than it has been in the past, partially due to improvements in fire safety, fire suppression, and firefighting, advancements continue to be made, including fire dampers. But what is a fire damper, where are they located in your HVAC system, how are they used, what are the different types, and how are they tested to ensure proper operation? In this article, we'll discuss these issues, giving you solid knowledge of this exceptional fire suppression system.

Understanding Fire Dampers

It's a pretty common idea that walls, floors, and ceilings are relatively solid things, but HVAC systems include ductwork that if left unblocked, provide a way for fire to spread throughout a structure relatively easily. For that reason, fire dampers have been developed to help slow the spread of fire to protect life and property. All fires require oxygen, heat, and fuel to burn. By removing any part of the equation, the fire will go out. Fire dampers help restrict the flow of smoke and fire through the structure, helping to suffocate the fire.

Fire dampers in the most basic form are metal flaps that are kept out of the way for the vast majority of the time your HVAC system is in operation. However, when there is a fire, the temperature rises where the fire damper is located, and when it becomes hot enough, it activates the system. The flaps move into position to block smoke and fire from traveling in the ductwork, while restricting the smoke to the area of the fire, slowing its spread by creating a lower-oxygen environment.

Once the fire has been extinguished and it's time to start repairing the damage that has been done, the fire dampers can be reopened to resume the operation of the ductwork. In some cases, this can require the use of a fire damper opener to move the flaps back out of position. Once the repairs have been completed, including any damage to the ductwork and HVAC system, the fire damper is ready to resume its work in protecting the building and its occupants from smoke and fire.

Where are Fire Dampers Located?

Fire dampers are typically used in areas where fire-rated structures, such as walls, floors, ceilings, or similar fire barriers, have been penetrated by the building's HVAC ductwork system. This can include ductwork, air transfer openings, and similar structures that are intended to pass climate-controlled air through different areas. Fire dampers are placed in these locations to improve the fire suppression concept of compartmentalization.

Fire-rated doors, walls, floors, ceilings, and fire dampers are all used to contain a fire and reduce its spread throughout a structure. They're designed to hold up well against fire, often for a specific period of time, so that people in the structure can be evacuated and emergency services have time to get the fire under control. In addition to life protection, this also limits the damage to the structure, making it less expensive to return to operations following a fire.

Use Cases of Fire Dampers

There are many industries where fire dampers are used much more extensively as a way to improve safety or efficiency outside of active fire situations. These include:

• Mills: Paper and textile mills often use fire dampers to recover heat energy as an input for waste heat recovery boilers.
• Power Generation Plants: In nuclear, hydroelectric, and similar power generation plants, multi-blade fire dampers can be used to control airflow, backdrafts, and pressure.
• Wastewater Treatment Plants: In these plants, precipitators, stacks, inlets, outlets, and flue-gas cleanup operations often use guillotine dampers.
• Transit/Tunnel and Marine Operations: During oil exploration, mining, or passenger transit systems, fire dampers are used in a wide range of situations.

Types of Fire Dampers

Generally speaking, the two main types of fire dampers will depend on the location, position, and activity of the ductwork and the fire damper itself.

Static Fire Dampers

A static fire damper is located in a vertical position in an HVAC unit's ductwork and is held open via air pressure. When a fire is detected, the building's system shuts down the HVAC system. With the lack of airflow, the static fire damper falls shut, compartmentalizing the fire in its location and preventing its spread. These types of fire dampers are typically located where a horizontal run of ductwork passes through a wall.

Dynamic Fire Dampers

Dynamic fire dampers may be located in either horizontal positions within the ductwork, such as ductwork that passes through floors or ceilings. Unlike static fire dampers, which only operate when the entire HVAC system is shut down, dynamic fire dampers can be activated while leaving the rest of the HVAC system in operation. Because of this more complex design, they may require fans to provide backpressure against the system, as well as springs, actuators, and similar components to operate properly in an otherwise active system.

Fire vs Smoke Damper: What's the Difference?

If you've also heard of a smoke damper, you may wonder about the difference between these mechanisms within an HVAC system. Generally speaking, a fire damper is activated by temperature and controls the movement of both fire and smoke throughout the structure via the HVAC system. By comparison, a smoke damper is activated by a smoke detector and is designed to limit the flow of smoke throughout the structure.

How to Test a Fire Damper

Fire damper tests should be conducted every six years in hospitals and every four years in other structures. Specific testing techniques should be available from the manufacturer for optimal results.

If you're working with a fire damper or other HVAC-related component and having issues that may require parts, the experienced professionals at HVAC Jack are ready to help. Contact us today to get started.