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 de signs 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 re quired 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.)
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