Fire Doors along with hardware are part of a fire protection system in a building or a home that work to make an area as safe as it can be in a fire. It is known as passive fire protection. Fire doors and hardware are constructed to be heat resistant and prevent fires from spreading for a designated amount of time. (3 hour, 1 ½ hour, ¾ hour or 20 min.) Fire doors and hardware are then tested and certified for flame retardation through a testing agency. The most widely recognized agencies are Underwriter’s Laboratories, Inc. (UL ) and Warnock-Hersey (WH).