Fire door

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Fire-resistance rated door, with wire mesh glass window
Industrial grade fire door rated to hydrocarbon curve and blast resistance.
Double fire door immediately after 3 hour fire test inside a 4 hour rated Durasteel wall.
Double fire door after 3 hour fire test in a 4 hour Durasteel wall, during successful 45PSI (3.1 bar) hose stream test leading to a UL Listing.[1]

A fire door is a door with a fire-resistance rating (sometimes referred to as a fire protection rating for closures) used as part of a passive fire protection system to reduce the spread of fire or smoke between compartments and to enable safe egress from a building or structure or ship. In North American building codes, it, along with fire dampers, is often referred to as a closure, which can be derated compared against the fire separation that contains it, provided that this barrier is not a firewall or an occupancy separation.

Components[edit]

Fire doors may be made of a combination of materials, such as:

Both the door leaf (the swinging panel of the door) and the door frame are required to meet the guidelines of the testing agency which provides the product listing. The door frame includes the fire or smoke seals, door hardware, and the structure that holds the fire door assembly in place. Together, these components form an assembly, typically called a "doorset" which holds a numerical rating, quantified in hours of resistance to a test fire. All of the components of the fire door assembly must bear a listing agencies label (with the exception of ball bearing hinges which meet the basic build requirements of ANSI 156.2 and NFPA 80) to ensure the components have been tested to meet the fire rating requirements.

Door hardware[edit]

Door hardware includes, but is not limited to:

  • Automatic closing devices/objects
  • Ball bearing hinges
  • Positive latching mechanism
  • Smoke seals
  • Gas seals

Seals[edit]

Edges of a fire door usually need to have fire rated seals which can be composed of:

When intumescent seals are used in the door design, use of the correct seal is crucial in the fire rating performance the door assembly. Seals may vary in chemical composition, expansion rate, expansion volume, and/or charring characteristics.

Windows[edit]

Some fire doors are equipped with internal windows which also have a rating, or have been incorporated at the time of the door test and be subject to the overall door's product certification. Fire-resistive windows must remain intact under fire conditions and hose stream impact resistance, and can include:

  • Wire mesh glass - usually Georgian wired
  • Liquid sodium silicate fills between two window panes
  • Ceramic glasses
  • Borosilicate glass

Wired glass typically withstands the fire, whereas the sodium silicate liquid also acts to insulate heat transfer, due to the endothermic action of this chemical.

Fire door rating label

Regulations[edit]

All components are required to adhere to product certification requirements that are acceptable to the local Authority Having Jurisdiction (AHJ) by meeting the requirements of the local building code and fire code. The regulatory requirement will change from country to country.

For example in the United Kingdom a fire resisting doorset should be subjected to either a British Standard Fire Test BS 476 Part 22 1987, or a BS/EN 1634-1 2000 test. The results are recorded by the test agency and provided in a report which detail such things as constructional details, distortion data and pressure readings. The numerical fire resistance rating that is required to be installed in a particular building is provided in the Building Regulations approved Document B, or British Standards such as the BS 5588 series (e.g., 30 minutes FD30, or FD30(S) if cold smoke resistance is also required).

Similar technical guidance documents and building regulations are in effect in other countries.

Combustibility[edit]

Fire doors are not necessarily noncombustible. It is acceptable for portions of the door to be destroyed by combustion during exposure to a fire as long as the door assembly meets the fire test criteria of limiting temperature limits on the non-fire side of the assembly. This is in accordance with the overall performance goal of a fire rated door to slow fire propagation from one fire rated compartment to another for only a limited amount of time, during which automatic or manual fire fighting may be employed to limit fire spread, or occupants can exit the building.

Fire door failure[edit]

Fire doors are sometimes rendered unable to provide its listed fire resistance by ignorance of the intended use and associated restrictions and requirements, or by improper use. For example, fire doors are sometimes blocked open, or carpets are run through them, which would allow the fire to travel past the fire barrier in which the door is placed. The door's certification markings are displayed both on the door leaves and the fire door frames, and should not be removed or painted over during the life of the building.

Sometimes fire doors have apparently very large gaps at the foot of them, an inch or two even, allowing air movement, such as in dormitory facilities. This can lead the occupants of a building to question their status as 'real' fire doors. Testing of fire doors include a maximum door undercut of 3/4 inch.[2] Corridors have a fire rating of one hour or less, and the fire doors in them are required by code to have a fire rating of 1/2 or 1/3 hour, the intent of which is mainly to restrict smoke travel.[3]

Normal operation[edit]

Fire door held open by magnet

Most fire doors are designed to be kept closed at all times. Some doors are designed to stay open under normal circumstances, and close automatically in the event of a fire. Whichever method is used, the door's movement should never be impaired by a doorstop or other obstacle. The intumescent and smoke-seal bounding of fire doors should be routinely checked, as should the action of the door closer and latch.

Some fire doors are held open with an electromagnet, which may be wired to a fire alarm system. If the power fails or the fire alarm is activated, the coil is de-energized and the door closes on its own. Wireless, battery operated fire door retainers can also be used to safely and legally hold fire doors open.

Rated fire doors are tested to withstand an ASTM E119 standard time-temperature curve for a specified period.[4] There are 20, 30, 45, 60 and 90-minute-rated fire doors that are certified by an approved laboratory designated as a Nationally Recognized Testing Laboratory (NRTL, e.g., Underwriters Laboratories). The certification only applies if all parts of the installation are correctly specified and installed. For example, fitting the wrong kind of glazing may severely reduce the door's fire resistance period.

Installation[edit]

As well as ensuring the door is hung properly and squarely, it is also very important that where a fire door is installed, any gaps left in the opening between the wall and the door frame must be properly filled with fire resisting material. Fire doors are normally installed by a carpenter.

Annual inspection[edit]

In the United States, the NFPA requires annual inspections of fire-resistance rated door and frame assemblies.[5] Local Authorities Having Jurisdiction must adopt the new edition for this requirement to take effect. Most jurisdictions in the US will be adopting the IBC (International Building Code) model code, which references the NFPA 80 2007 edition requirement, as their local codes.

NFPA 80 5.2.4.requires the following items shall be verified, at minimum:

  1. No open holes or breaks exist in surfaces of either the door or frame.
  2. Glazing, vision light frames & glazing beads are intact and securely fastened in place, if so equipped.
  3. The door, frame, hinges, hardware, and noncombustible threshold are secured, aligned, and in working order with no visible signs of damage.
  4. No parts are missing or broken.
  5. Door clearances at the door edge of the door frame (Wood Door), on the pull side of the door, do not exceed clearances listed in 4.8.4 (the clearance under the bottom of the door shall be a maximum of 3/4") and 6.3.1 (top & edges 1/8") Metal door (top & edges up to 3/16")
  6. The self-closing device is operational; that is, the active door completely closes when operated from the full open position.
  7. If a coordinator is installed, the inactive leaf closes before the active leaf.
  8. Latching hardware operates and secure the door when it is in the closed position.
  9. Auxiliary hardware items that interfere or prohibit operation are not installed on the door or frame.
  10. No field modifications to the door assembly have been performed that void the label.
  11. Gasketing and edge seals, where required, are inspected to verify their presence and integrity.

According to building and fire codes, annual fire door inspections is the responsibility of the building owner. However, as with other mandatory fire inspections, such as the inspection of fire dampers, the fire door inspections are often omitted and many facilities are out of compliance.[citation needed]

The final say on the acceptance of any inspection requires the approval of the AHJ (Authority Having Jurisdiction).

Modifications[edit]

NFPA 80 includes guidelines concerning field modifications of listed hardware, including frames, builder's hardware, doors, thresholds etc. The growing field of access control and electronic entry systems has resulted in some fire doors being field modified without proper listing agency approval. Field modifications of fire listed assemblies must either be inspected by a listing agency representative, or the modification must be performed by personnel certified to perform such work.[6]

See also[edit]

References[edit]

  1. ^ "GSNN.SP-2-003 - Fire Door Assemblies and Window Assemblies". Database.ul.com. 2011-04-22. Retrieved 2013-05-17. 
  2. ^ NFPA 80 Standard for Fire Doors and Other Opening Protectives 2007 Edition, section 4.8.4.1
  3. ^ NFPA 80 Standard for Fire Doors and Other Opening Protectives 2007 Edition, Annex D Fire Door and Fire Window Classifications, section D.5
  4. ^ http://www.astm.org/Standards/E119.htm, "ASTM E119 - 12 Standard Test Methods for Fire Tests of Building Construction and Materials," Retrieved 9/21/12
  5. ^ NFPA 80, 2007 Edition, Standard for Fire Doors, Frames and Other Opening Protectives (5.2.4)
  6. ^ "NFPA article on door modifications". Nfpa.org. 2008-01-03. Retrieved 2010-11-17. 

External links[edit]