Fire rated doors are tested in accordance with the following standards:
UL 10B, Fire Tests of Door Assemblies (neutral or negative pressure)
UL 10C, Positive Fire Pressure Tests of Door Assemblies
NFPA 252, Standard Methods of Fire Tests of Door Assemblies
In the late 1990s, the required test method changed from neutral or negative pressure to positive pressure to more accurately simulate the conditions of a fire in the real world. Today, the IBC requires side-hinged or swinging fire doors to be tested with positive pressure, using either UL 10C or NFPA 252.
Fire rated doors are subjected to endurance testing where the specimen is exposed to extreme heat of up to 1925 degrees F for the maximum 180 minute rating. If the door remains in the frame with no through openings and limits flames, it is certified with an endurance rating of either 20/45/60/90/180 minutes.
After the fire endurance test, the test specimen is subjected to the hose stream test, where a fire hose delivers water at 30 psi from 20 feet away. Note that building codes throughout the US typically stipulate that 20 minute doors are exempt from the hose stream test.
In certain applications, fire doors are also required to limit the transmission of heat from one side to the other to protect building occupants so they can safely exit the building. Known as temperature rise doors, these doors carry a temperature rise rating in addition to the hourly rating. Temperature rise ratings are either 250 degrees F, 450 degrees F or 650 degrees F, indicating the maximum rise above ambient temperature on the non-fire side measured during the first 30 minutes of a standard fire endurance test. A 250 degree F temperature rise rating is considered to be the most stringent, and would meet the requirements of a specification requiring 450 degrees F or 650 degrees F.
Smoke and Draft Control
Some fire rated doors, such as 20 minute doors in fire resistance rated corridors or smoke barriers, may also require testing for smoke infiltration under UL 1784, Standard for Air Leakage Tests of Door Assemblies and Other Opening Protectives.