Fire and Smoke Documentation

Glossary of Terms


Authority Having Jurisdiction – typically a building inspector or Fire Marshal.

Alarm Signaling
With respect to the damper, the smoke detector has two sets of contacts. Upon detection of smoke, one set opens to cut power to the actuator and spring the damper closed. The other set closes and tells the fire alarm panel that a damper has closed. Where area detection is used, the alarm panel handles both sets of operations.
Actuator auxiliary switches are most often used to test the damper, but can be supervised and monitored by the alarm system in an engineered smoke control system.

Air Movement Control Association (AMCA) is an organization of air moving equipment manufacturers. Pottorff, Ruskin, Greenheck, etc are members. They issue various documents concerning quality testing, certification of products, and adherence to standards. Many consultants will specify meeting their standards at the prompting of reps of the manufacturers’ who are members. Many of their documents are well worth studying. AMCA standards do not have the force of an NFPA or UL.

Area Separation
A fire rated wall (expressed in hours) which divides the floor area of a building into acceptable areas for fire containment.

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Balanced Fire Protection
A mixture of sprinklers means of egress, passive fire protection, and smoke control fans and dampers to allow escape from buildings experiencing a fire or other disaster.
Sprinklers are known to fail about 15% of the time in fires. This can be due to water being shut off or a fire overpowering the sprinklers. When water is available, sprinklers are 98% effective. Seismic events can break water mains and gas lines leading to very hazardous situations. Passive methods prevent fire spread from the compartment where it originates. Structural strength prevents collapse. The purpose of the balance is to ensure people can escape from the building to safety. Only secondarily are the protection methods for the property itself, although protecting the building serves to protect people.

Breakaway Connection
A joint connecting a fire damper sleeve and attached duct work which allows collapse of the duct during a fire without the damper being pulled out of the wall.

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Code Action Review Committee. With the IBC allowing trade-offs that reduce fire and smoke barrier walls, dampers, and smoke control by installing more sprinkler heads, a number of groups have formed to work with code committees of IBC to ensure the benefits of dampers are not forgotten.

Ceiling Damper
A ceiling damper is used to protect HVAC openings in a fire rated horizontal ceiling assembly. It closes automatically to restrict the passage of flame & heat.

Combination Fire and Smoke Damper
A combination fire and smoke damper avoids 2 dampers where a wall is both a fire stop and a smoke barrier. The combination must meet the rules of both UL555, fire, and UL555S, smoke. For that reason, it will be jackshafted or linkaged internally since the blades must be in the wall for the fire function and the actuator must be accessible for wiring and repair.

Sub-dividing each floor of a building with fire walls and smoke barrier partitions to restrict
spread of flames & heat in a fire. Where HVAC ducts penetrate the partitions, dampers are installed to stop fire and smoke.

Corridor Damper
A fire and smoke damper are used where ducts penetrate or terminate at horizontal openings in the ceilings of interior corridors. The connections are often round for connection to flex duct. These are actuated.

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Dynamic Fire Damper
Fire damper designed to close against air flow in a system where the fans are kept running in event of a fire. They are approved for both dynamic and static closure. See Static Damper.

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Electric Fuse Link – EFL
It is a Ruskin’s product name for an electric sensor which has a Klixon or thermal disc with a metal and a manual reset button.

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Fire Damper
A normally open damper installed in an air handling system within a fire wall. Note that the blades must be within the plane of the wall. It closes automatically upon the detection of heat to stop the passage of fire. It is tested in accordance with UL555. (A smoke damper is tested in accordance with UL555S.)

Fire Rated Ceiling
A ceiling tested for fire resistance as part of a floor-ceiling, roof-ceiling
or floor-ceiling-wall assembly.

Fire Rated Partition
A partition having an assembly of materials that will be given a fire resistance rating (expressed in hours) to impede the spread of fire from one area to another.

Fire Wall
A continuous (basement to roof) wall having adequate fire resistance rating (expressed in hours) with an adequate structural stability under fire conditions to completely subdivide a building or completely separate adjoining buildings to restrict the spread of fire.

Floor-Ceiling or Roof-Ceiling Assembly
A form of construction comprised of floor-ceiling or roof-ceiling as an assembly which, when fire tested as a unit, has been assigned a fire endurance rating expressed in hours. It is commonly termed a floor-ceiling assembly.

Barber Colman-Siebe-Invensys MA2xx motor gears were sticking open. This was referred to as fretting. AMCA 520 established a test procedure to ensure this would not occur with other motors. Belimo has passed the test with all the FS series. UL may add the AMCA test to its procedures in the future.

Fusible Link
A device that holds a fire damper or fire door open until a designated ambient temperature is reached, then the fire damper or door is released to close. The device could be soldered, strut type, glass bulb type or bi-metallic metal identified by a label, affidavit or listing acceptable as designated by UL Standard 33. Fusible links are normally 165°

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Heat Stop
A method by which temperature rise is retarded for ceiling openings in
a fire rated floor-ceiling or roof-ceiling assembly. Ceiling dampers are on commonly used

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International Building Code, IBC
The model code most commonly used in the states

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Fire dampers are labeled to indicate for use in static or dynamic systems. A dynamic damper indicates air flow direction, max velocity, and pressure difference across the closed damper.

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NFPA National Fire Protection Association
The NFPA is the originator of standards and many provisions of codes. It is composed
of interested parties in all trades, fire departments, state and local officials, manufacturers, consultants, and ASHRAE.

The most used standards/codes are:

  • NFPA 70 – NEC – the National Electrical Code
  • NFPA 72 National Fire Alarm Code
  • NFPA 90A Standard for the Installation of Air-Conditioning and Ventilating Systems
  • NFPA 92A Smoke-Control Systems Utilizing Barriers and Pressure Differences
  • NFPA 92B Smoke Management Systems in Malls, Attria, and Large Spaces
  • NFPA 101 Life Safety Code
  • NFPA 80 Fire Doors and Other Opening Protectives
  • NFPA 204 Smoke and Heat Venting
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Occupancy Separation
A wall, partition, floor-ceiling or roof-ceiling of fire-rated construction used to separate parts of a building.

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Passive Fire Protection
Sprinklers are considered active protection – they contain a fire. Passive protection involves compartmentalization (gypsum covered walls, fire doors), fire stopping all cracks, fire dampers and smoke dampers to prevent fire and smoke transport, large stairwells and egress passages, etc. Engineered smoke control systems with dampers and fans are not fire protection. They are active smoke control.

Primary sensor
The lower or first temperature sensor in a fire damper or a combination. Smoke dampers do not have temperature limits. 165F is used 80% of the time. 185F is seen and 212F is not too uncommon where steam coils are present and would cause nuisance trips. See secondary sensor.

Proportional Fire & Smoke Damper
There are a number of potential uses, for example, in New York the code called for the RA damper to be smoke rated due to filter fires (unless there was a sprinkler head above the filter).

Stairwell pressurization must keep the stairwell pressure positive with respect to the space to prevent smoke from coming into the stairwell from a fire. The pressures specified by codes can vary, but typically the stairwell is not greater than about .05" to .1” higher than the space. The smoke must be restrained, but the doors must be able to open. Usually, the dampers for the stairwell pressurization are not rated dampers and UL555S dampers and actuators are not needed. A duct runs up the stairwell and every few floors the dampers’ actuators are connected to differential pressure sensor-controllers. These dampers are not protecting from smoke passage.

In under floor and any shaft to plenum that goes thru a firewall, a fire and smoke damper maybe required. Where space constraints exist, it may be best to have a rated modulating damper rather than two dampers.

The FSAF24-SR Belimo is a 2-10V proportional actuator.

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Radiation Damper
A UL tested damper which is installed in the air distribution portion of a fire-rated floor-ceiling or roof-ceiling assembly. Not actuated.

Fire dampers have ratings specified in hours, typically 1.5 hours and 3 hours.

Retrofit Rules of Thumb:

  • FSLF 4 sq.ft.
  • FSNF 8-12 sq.ft.
  • FSAF 12-16 sq.ft.
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Sandwich Pressurization System
An engineered smoke control system keep smoke from traveling by exhausting the smoke zone and feeds fresh air into the adjacent zones.

Secondary Sensor
The higher or second temperature sensor located in a fire damper or a combination. Smoke dampers do not have temperature limits. 250°F is used 85% of the time and is the code recommended temperature. 350°F is seen about 15% of the time. See primary sensor.

The sheet metal duct section attached to a damper to allow mounting of controls and breakaway connections to ducts.

Smoke Barrier
A continuous membrane, either vertical or horizontal, such as a wall, floor or ceiling assembly, which is designed and constructed to resist the movement of smoke. A smoke barrier may or may not have a fire resistance rating. Such barriers may have protected openings using dampers.

Smoke Control System
There are two types:

  1. Passive Smoke Control Systems use smoke dampers to close upon detection of smoke to prevent the movement of smoke through a duct opening. Typically a smoke detector in the duct is used, but area smoke detectors to a alarm or smoke panel could be used.
  2. Engineered Smoke Control Systems use curtains, walls and floors as barriers to create pressure differences. By pressurizing the areas where fire is present the spread of smoke into other areas is prevented.

Smoke Control Zone
A space within a building enclosed by smoke barriers or fire barriers on all sides, including the top and bottom.

Smoke Damper
Controls smoke only; there is no duct fusible link, firestat, or sensor. It is controlled by a smoke detector or heat detector signal, fire alarm, or building fire/smoke management system. The damper is installed within 24” of the smoke barrier it protects.

Smoke Proof Enclosure
As defined by the NFPA 101 Life Safety Code, a stair enclosure designed so that the movement of the smoke products of combustion produced by a fire occurring in any part of the building into the smoke proof enclosure shall be limited. The smoke proof enclosure must be a continuous stair enclosed from the highest point to the lowest point by two hour rated fire barriers.

Stairwell Pressurization
Tall stairwells will fill with smoke if a door to a fire floor is open. The stairwell is the means of egress and must allow occupants to escape. A typical stairwell pressurization system has a large capacity fan at the base and its outlet goes to duct run up the stairwell. Dampers are placed every few floors and are controlled by pressure sensors.
When the fire alarm goes off, it energizes the stairwell pressurization system. The fan goes on and the dampers proportion to maintain about .05” higher pressure in the stairwell than on the floors. This prevents smoke from entering the stairwell.

Static Damper
Fire damper designed to close only with fans off. See Dynamic Damper.

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Torque requirement
The torque required for fire and smoke dampers varies with manufacturer, model, temperature tested, and leakage class. The linkage between the jackshaft and the drive blade is a significant factor. Most manufacturers use a geometry that doubles torque delivered to the blade during the first 30 degrees of rotation and drops off to half during the last 30 degrees. For new installation, whatever the damper manufacturer has tested and supplies is required. The same actuator can do 16 sq.ft. at 250F with one manufacturer and 8 sq.ft. at 350F with another. It depends on what was tested.

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UL555, UL555S
UL safety standards for fire, smoke, and combination fire and smoke dampers contain a large amount of information. The precise details do not matter as much as the simple fact that the damper and actuator meet the standard. All building codes require that UL555 (S) dampers be used in fire and smoke barriers.

UL Classes
Classes of dampers are I, II, and III depending on the amount of smoke leakage.
85% in the market are rated for 250°F and 15% for 350°F. Most actuators are rated for 350°F. Class I & II are the lower leakage and are usually specified. The leakage is primarily a damper function and the same actuator torque is applied. The older UL555 standard had higher temperature ratings, but the current document only recognizes 250F and 350F for testing. In addition it had a high leakage rating, class 4, which is no longer allowed.

Uniform Building Code, UBC
The former code for most of the states west of the Mississippi. A few cities still base their local codes on the UBC. See International Building Code.

UUKL is a file on UL’s web site with the names of the companies and the specific products that have UL864 fire alarm listing. Actuators are not part of an alarm system. UL will not investigate or list actuators and dampers under the UL864 standard. Since the actuator is separated from the alarm system by a relay, no damage or failure of the actuator can harm the alarm network.

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