Basics of Fire and Smoke Damper Installations
Editor's note: NFPA has developed a new fact sheet on the basics of fire and smoke dampers. Download it now!
Heating, ventilating, and air-conditioning systems and other components that support the movement of air throughout buildings are necessary for the day-to-day function of buildings in order to properly heat, cool and (re)distribute air throughout them. Air is distributed in air-conditioning and ventilating systems by ducts and plenums and for the system to reach everywhere it needs to within the building, it may require penetrating fire-resistance rated assemblies or assemblies protected against the transfer of smoke. Like fire doors protecting openings in fire-resistance rated construction, dampers also protect openings where ducts pass through or terminate in or at fire rated assemblies in order to maintain the integrity of the assembly and to prevent fire and smoke from spreading to and contaminating other areas of the building that might be otherwise unaffected.
During a fire, the air distribution system may transport deadly smoke and products of combustion instead of breathable air. If proper design and installation precautions are not taken, smoke, fire gases, heat, and even flame can spread throughout the area served by the duct system. Improper plenum locations, lack of detection equipment in the system, and lack of required fire and smoke dampers in appropriate walls, ceilings, or partitions can lead to tragic situations.
What are fire and smoke dampers and where are they installed?
Fire dampers are installed in ducts passing through or in air outlet openings terminating at shaft walls, fire barriers (such as an occupancy separation wall, horizontal exit walls, corridor walls, corridor ceilings, floor-ceiling assemblies) and other fire resistance–rated assemblies as required by a building or life safety code and other applicable standards. Under severe fire exposure, a duct may eventually collapse or significantly deform, creating an opening in the fire barrier. Fire dampers provide a method of protecting such penetrations and openings.
A fire damper is designed to, and required to, close automatically upon detection of heat (such as a fusible link or heat detector) and to interrupt airflow and to restrict the passage of flame. Fire dampers are required to close against the maximum calculated airflow of that portion of the system in which they are installed. Those that are intended to close under airflow are labeled for use in Dynamic Systems (A dynamic systems is an HVAC system designed to maintain the movement of air within the system at the indication of a fire); those that are intended to close after airflow has stopped by automatically shutting down the fan or airflow in the event of a fire are labeled for use in Static Systems (a static system is an HVAC system designed to stop the movement of air within the system at the indication of a fire). Fire dampers are provided with an hourly fire rating.
Smoke damper’s primary function is to control the movement of smoke in dynamic air distribution systems, and they reduce the possibility of smoke transfer within ductwork or through wall openings. They are installed in ducts passing through, or air outlet openings terminating at, smoke barriers, shaft walls, horizontal exit walls, corridor walls, corridor ceilings, and other barriers designed to resist the spread of smoke as required by a building or life safety code and other applicable standards. Smoke dampers operate automatically on detection of smoke and must function so that smoke movement through the duct is halted. Their activation can be by area detectors that are installed in the related smoke compartment or by detectors that are installed in the air duct systems. Smoke dampers are provided with leakage and temperature ratings.
A combination fire/smoke damper is used when a barrier is both rated for fire resistance as well as designed to restrict the transfer of smoke and will meet both the fire damper and smoke damper requirements.
What standards area applicable?
Multiples codes and standards are applicable to the installation of fire and smoke dampers. Knowing what each document addresses can help map out the provisions for a safe and successful damper installation. It is suggested that these documents be reviewed for further details beyond the summary that is provided here.
- NFPA 101®, Life Safety Code® mandates where smoke dampers are required as well as their ratings, access and identification requirements, and activation requirements. Smoke dampers are required in air-transfer openings (an opening designed to allow the movement of environmental air between two contiguous spaces) in smoke partitions and in air transfer openings and duct penetrations in smoke barriers. Where a smoke barrier is also constructed as a fire barrier, a combination fire/smoke damper must be used. There are multiple exemptions where smoke dampers may not be required in smoke barriers such as where ducts or air-transfer openings are part of an engineered smoke control system and that smoke damper will interfere with the operation of a smoke control system or where ducts penetrate floors that serve as smoke barriers.
- NFPA 5000®, Building Construction and Safety Code® mandates where fire dampers are required and their required ratings as well as access and identification requirements for fire and smoke dampers. Fire dampers are required in the following locations:
- Ducts and air-transfer openings penetrating walls or partitions having a fire resistance rating of 2 or more hours,
- Ducts and air-transfer openings penetrating shaft walls having a fire resistance rating of 1 or more hours,
- Ducts and air-transfer openings penetrating floors that are required to have protected openings where the duct also is not protected by a shaft enclosure,
- Air-transfer openings that occur in walls or partitions that are required to have a fire resistance rating of 30 minutes or more.
- NFPA 90A, Standard for the Installation of Air-Conditioning and Ventilating Systems also mandates additional locations where fire and smoke dampers are required, working in conjunction with the building code and life safety codes. In addition, it mandates the minimum required rating of the fire damper based on its location. Compliance with NFPA 90A is mandated by NFPA 101, NFPA 5000 and NFPA 80.
- NFPA 80, Standard for Fire Doors and Other Opening Protectives and NFPA 105, Standard for Smoke Door Assemblies and Other Opening Protectives apply after it has been determined where a damper is required and how to access and identify it. Users are directed to NFPA 80 and NFPA 105 for additional installation details as well as all requirements for the inspections, testing, and maintenance of the dampers. NFPA 80 covers fire dampers as well as combination fire/smoke dampers and NFPA 105 addresses smoke dampers.
- Fire dampers are tested and listed for use in air-conditioning and ventilating ducts by UL in accordance with UL 555, Fire Dampers. These dampers include single-blade, multiblade, and interlocking-blade types, all actuated by fusible links. Smoke dampers require compliance with UL 555S, Smoke Dampers. Combination fire and smoke dampers will meet the applicable requirements of both UL 555 and UL 555S
Fire and Smoke Damper Installation
First and foremost, dampers must be installed in accordance with the manufacturer’s installation instructions and in accordance with their listing. For new installations, retaining the installation instructions on site can help verify that a damper has been properly installed.
Access to both fire and smoke dampers is required for inspection, testing, and maintenance. Smoke and combination fire and smoke dampers in new construction must be provided with an approved means of access large enough to allow inspection and maintenance of the damper and its operating parts. Access cannot affect the integrity, continuity, or rating of the assembly where its located and must also comply with any access requirements in the mechanical code. Access points must also be provided with permanent identification indicating the type of damper (fire damper, smoke damper, fire/smoke damper). In some situations, where space constraints or physical barriers in new construction restrict access to a damper for periodic inspection and testing, the damper is required to be a single- or multi-blade-type damper and must comply with remote inspection requirements (found in NFPA 80 or NFPA 105.)
After a damper has been installed, an operational test much be completed. This test ensures that the damper has been installed correctly within the air distribution system, is fully functional, closes completely without obstructions and contains all the correct components and devices as part of its assembly. The operational test may be required be conducted under normal HVAC airflow and non-airflow conditions. The damper shall fully close under both test conditions.
Both fire and smoke dampers are important building and life safety equipment that protect people and buildings from the effects of fire. It is critical that they are installed, and accessible, where required throughout buildings and installed properly so that they will operate when required under fire conditions. Without them, fire and smoke could travel throughout the building to spaces otherwise untouched by the fire. Check back for future blogs where we will address the requirements, both in-person and remote, for inspection, testing and maintenance of fire and smoke dampers. For more information on fire and smoke dampers as well as other opening protectives, you can check also out our various training offerings here.