Views: 48 Author: D&D Hardware Publish Time: 2018-04-03 Origin: D&D Hardware
Steel fire doors are "rated" by time (in minutes or hours) that a door can withstand exposure to fire test conditions. Hourly ratings include 1-1/2-hours, 1-hour, 3/4-hour, and 1/3-hour, with the maximum rating required of any swinging type fire door being three hours.
Three-hour (180 minute) doors
A door with a three-hour fire protection rating is usually found in walls that separate buildings or that divide a large building into smaller fire areas. The wall rating is four hours.
1-1/2-hour (90 minute-120minute) doors
Doors rated for 1-1/2 hours are found in 2-hour rated walls. These doors are commonly located in stairwells, or other enclosures of vertical communication through a building. They also occur in boiler rooms and in exterior walls that have potential for severe fire exposure from the outside the building.
One-hour (60 minute) doors
One-hour rated doors are used in walls between rooms, which are also typically onehour rated.
3/4-hour (45 minute) doors
Doors with 3/4-hour fire protection ratings are used in one-hour walls. A 3/4-hour rated door is found in walls of corridors and room partitions. A door with this rating may also be located in the exterior wall of a building subject to moderate fire exposure from the outside of the building.
1/3-hour (20 minute) doors
One-third-hour or 20 minute doors are used in one-hour walls. These doors are used for corridor applications and in other applications where smoke and draft control is a primary concern.
To understand fire door hardware, you must remember that fire doors serve four main purposes:
1) To serve as a regular door at all times;
2) to provide ready egress during a fire;
3) to keep fire from spreading throughout the building;
4) to protect life and property.
1.Hinges
A labeled fire door must be hung on steel bearing-type hinges. The use of steel is necessary since non-ferrous metals become "elastic" at much lower temperatures, which could allow serious dislocation of the door during a fire. There are certain hinge designs made of non-ferrous metals which may be used on fire doors in accordance with the listing information for the particular hinge. These hinges are usually used on doors of lesser fire rating.
The bearing type knuckles on hinges are required in order to provide smooth operation and to minimize wear throughout the lifetime of the opening. Remember, a fire door must close in the event of a fire. Worn hinges will cause the door to sag, effectively preventing the door from closing. Exception: Some manufacturers may provide doors with hinges which are non-bearing type when they are part of a listing assembly.
NFPA 80 allows the use of standard weight (1.34 inches leaf thickness) 4-1/2" hinges on 1-3/4-hour doors up to 4'0" in width and 8'0" in height. Doors over 8' in height shall have heavy weight (.180 inches leaf thickness) 4-1/2" hinges. Some manufacturers have the capability of providing lighter weight hinges on doors over 8' in height as part of a listed assembly. (Consideration should be given to larger hinge sizes for heavy or frequent use doors.)
2.Closing devices
A properly sized closing device is the last of the "basic" fire door hardware requirements. A fire door must be in a closed and latched position to serve as a protective barrier in the event of a fire. For this reason, either spring hinges or a listed door closer is required. When the door is closed, the closer has served its role as a protective device.
D&D Hardware Manufacture of high quality hardware for Fire Rated Doors, Wooden Doors, Metal Doors, Escape Doors, Single Fire Rated Flush Doors, Double Doors, Security Doors, Louver Steel Doors etc.
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