fire door

This article relies largely or entirely upon a single source. Please help improve this article by introducing appropriate citations of additional sources. (June 2009)

Fire-resistance rated door

A fire door is a type of door or movable barrier used as part of a passive fire protection system within buildings to prevent the spread of fire or smoke between separate sections. It is usually the only means of allowing people to pass through a fire-resistant wall.

Components

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

• timber
• steel
• gypsum (as an endothermic fill)
• vermiculite-boards
• glass sections

Apart from the door leaf (the swinging panel of the door) there is the door frame which also has to meet fire rated regulations, intumescent strips, 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 rating, in hours, specifying the amount of time it is able to resist a fire at a given temperature. 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

Door hardware includes, but is not limited to:

• Automatic closing devices.
• Ball bearing hinges.
• Positive latching mechanism.

Seals

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

• An intumescent strip, which expands when exposed to heat
• Neoprene weatherstripping
• Gaskets to prevent the passage of smoke

Intumescent seals are crucial in maintaining the performance of a fire resistant door, and as such, the correct seal should always be used. Seals may vary in chemical composition, expansion rate, expansion volume, and/or charring characteristics.

Windows

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
• 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.

Regulations

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 sujected 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 house or Institute and given in a report which will also detail such things as constructional details, distortion data and pressure readings. These tests are applicable to the performance of the specimen tested. It is the Building Regulations approved Document B or British Standards such as the BS 5588 series which lays down the criteria for the fire performance such as 30 minutes FD30 or FD30(S) if cold smoke resistance is required.

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

Combustibility

Fire doors are not necessarily all noncombustible. A fire door is but one of many passive fire protection components used to compartmentalise fire and thus keep it in the compartment of origin, so either it runs out of fuel or it is extinguished, or, at the very least, enough time has been bought to enable evacuation of the building.

Fire door failure

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 inappropriate 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. Such neglect is the responsibility of the building owner, who should educate occupants on the safe use of all safety related items, to ensure fire safety and compliance with the fire code.

Sometimes fire doors have apparently very large gaps at the foot of them, an inch or two even, allowing air movement, especially 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^[1]. 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 hr, the intent of which is mainly to restrict smoke travel^[2].

Normal operation

Most fire doors should be kept closed at all times, however some are designed to stay open under normal circumstances, and closing 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.

Fire door held open by magnet

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.

Rated fire doors are tested to withstand a fire for a specified period. There are 20, 30, 45, 60 and 90-minute-rated fire doors that are certified by an approved laboratory (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

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.

Architect's responsibility

In building design drawings with poor identification of which walls do in fact have a fire-resistance rating, it is often necessary to check the door schedule in the specifications to be able to trace what walls are rated and how long they are rated for. This is an indicative sign about the architect and the degree of care taken particularly with items relating to passive fire protection. To avoid confusion about any fire protection measures including fire doors, it is best for the architect to provide a separate set of drawings that clearly outlines which walls and floor have a fire-resistance rating and exactly what that rating is. It is also important to point out especially which walls are firewalls and which walls and/or floors are designated as occupancy separations, as the nature of passive fire protection devices that must be used in those special cases can be substantially different from such devices that are used in ordinary fire separations.

Annual inspection

NFPA 80, 2007 Edition, Standard for Fire Doors, Frames and Other Opening Protectives (5.2.4)^[3], requires annual inspections of fire rated door and frame assemblies. Local Authorities Having Jurisdiction must adopt the new edition for this requirement to take effect. Most jurisdictions in the United States will be adopting the IBC (International Building Code)as the prima facie standard, which references the NFPA 80 2007 edition requirement. The responsibility for annual fire door inspections falls to the building owner or responsible party for properties where listed fire doors are present. The International Fire Door Inspector Association, http://www.ifdia.org, a trade association, with a patent pending online report generation tool, is made up of credible fire door inspectors. The association is a free service to building owners, the AHJ community and vetted fire door inspectors and allows for building owners to find suitable inspectors to carry out inspections. Most members of the IFDIA are either graduates of the IFDIA accredited curriculum (International Accreditation Services http://www.iasonline.org, a sister company of the International Code Council http://www.iccsafe.org), or DHI graduates. There is also the newly formed Certified Association of Fire Door Inspectors http://www.CAFDI.org, made up of individuals who have taken the non accredited Door Hardware Institute Fire Door Assembly Inspection class and obtained certified status from Intertek Testing Services.

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

Modifications

NFPA has very strict guidelines and rules 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 many fire doors being field modified without proper listing agency approval. Any field modification of fire listed assemblies must either be inspected by a listing agency representative, or, the modification must be performed under a Certified Personnel Program.

See also

Wikimedia Commons has media related to: Fire doors

• Fire-resistance rating
• Fire protection
• Fire test
• Passive fire protection
• Certification listing

References