3 most common types of dampers
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If a fire were to occur in your facility, your HVAC systems should be designed to automatically shut down and control pressure differentials across smoke barriers. Fire, smoke and combination fire/smoke dampers play a huge role in this engineered compressed smoke management by working to impede the spread of smoke to adjacent areas of the building. Where your HVAC system penetrates fire and smoke barriers, dampers are installed to sustain the integrity of the barrier ratings. Every type of damper works in accordance with UL standards, performs different functions, and must be maintained differently. In order for dampers to perform properly, knowledge of their differences, and proper application is imperative for facility managers and third party inspectors.

Here is an overview of the three most common types of dampers:

Fire Dampers
Fire Dampers are installed in fire walls, fire barriers, fire partitions, and horizontal assemblies. They work to help stop the spread of flame through your air ducts. A fire damper closes once the temperature of the duct becomes high enough to melt the fusible link, which holds it open. Most fire dampers have fusible links that melt at 165° F.

The basic standard used to evaluate fire dampers is UL 555, Standard for Safety of Fire Dampers.
Smoke Dampers
Smoke dampers are installed in smoke barriers and smoke partitions. Smoke dampers work to resist the passage of smoke and stop the circulation of air and smoke through a duct. Smoke dampers operate by either an electrical or pneumatic actuator and are controlled by smoke detectors and fire alarms. They can also be set up to be positioned from a remote command station.

The basic standard used to evaluate smoke dampers is UL 555S, Standard for Safety of Smoke Dampers.

Combination Fire/Smoke Dampers
A combinational damper is used in locations where both a fire damper and smoke damper are required. Although they look very similar to a smoke damper, they work to prevent the passage of both flame and smoke. They close upon the detection of heat or smoke and seal the opening. (It’s important to note that codes have recognized the best method of compartmentalization is through the use of this type of damper because of it’s ability to close by both the detection of heat and smoke.)

The basic standard used to evaluate combination fire/smoke dampers is both UL 555 and UL 555S.

Maintenance of Dampers
To ensure your dampers are continually working, periodic maintenance is required by NFPA code. This maintenance should include removal of debris from the damper, manual cycling of dampers released by fusible link, and cycling of damper and actuator assemblies.

NFPA 80 (Fire Damper) & NFPA 105 (Smoke Damper) Inspection and Repair Requirements

NFPA 80 19.4.1 & NFPA 105 6.5.2 – Each damper shall be tested and inspected one year after installation.
NFPA 80 19.4.1.1-2 & NFPA 105 6.5.2.1-2 – The test and inspection frequency shall then be every 4 years, except in hospitals, where the frequency shall be every 6 years.
NFPA 80 19.4.2 & NFPA 105 6.5.3 – All tests shall be completed in a safe manner by personnel wearing personal protective equipment
NFPA 80 19.5.3 & NFPA 105 6.6.3 – If the damper is not operable, repairs should begin without delay.
NFPA 80 19.3.4 & NFPA 105 6.5.11 – All inspections and testing shall be documented, indicating the location of the fire damper, date of inspection, name of inspector, and deficiencies discovered.
NFPA 80 19.4.10 & NFPA 105 6.5.12 – All documentation shall be maintained and made available for review by the AHJ.

In Summary
Because dampers work and are tested differently, it’s crucial to choose individuals and contractors to perform your inspection who are knowledgeable about dampers and have a track record of inspecting and repairing each type. A non-compliant damper can be detrimental to the performance of your smoke control system and will be cited during any AHJ (Authorities Having Jurisdiction) survey. If a fire were to ever happen in your facility, dampers are an integral part of containing the fire and minimizing life and property loss.
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