They are made to avoid fire from spreading out for few hours, providing enough time for secure egress. Fire rating of doors
Fire ranked doors are classified in accordance with the variety of hours they can withstand a fire. A high quality fire ranked door can withstand fire up to 3 hours. Fire ranked doors with the lowest fire rating of 1 hour can be installed in the typical openings of a house that have moderate risk of fire direct exposure. The door framework comprises of the door hardware and the structures that support the door. Structures compatible with a fire door must have similar fire ranking as the door leaf. Timbers with high thermal immune homes are sometimes made use of for making doors of low fire score. Wood is a preferred material for building the frameworks of the fire door. A fire ranked door may have a home window constructed out of ceramic glass, borosilicate glass or wire mesh glass. These inner home windows also have separate fire rankings. The fire resistant property of the integrated window must be considered while examining the total fire resistance ability of a door. They are missing in doors with 3 hour fire score. Temperature level surge score
Along with withstanding fire, top quality fire rated doors avoid transmission of heat to the surface area of the door that is not subjected to the fire. While the Fire Rating Door specifies the number of hours the door can withstand the fire, the temperature level increase rating indicates the maximum temperature that the unexposed surface area can reach in half an hour.