One of the common standards used for testing fire resistant safes is the Japanese Industrial Standard JIS S 1037. This standard consists of both 1-hour and a 2-hour testing procedures.

1-Hour Fire Test

The firesafe is put into a furnace and heated up to 927C (1700F) over a period of one hour.

2. Drop Test

 At the end of one hour the firesafe is removed from the furnace and dropped from a height of 4 meters onto a concrete and rubble floor. 

The firesafe is allowed to cool and then opened. The internal temperature must not have exceeded 177C (350F) and the contents must be completely undamaged by fire and legible.

2-Hour Fire Test

1. The firesafe is put into a furnace and heated up to 1010C (1850F) over a period of two hours, reaching 927C (1700F) after the first hour. 

2. At the end of two hours the firesafe is removed from the furnace and dropped from a height of 4 meters onto a concrete and rubble floor. 

3. The firesafe is allowed to cool and then opened. The internal temperature must not have exceeded 177C (350F) and the contents must be completely undamaged by fire and legible.

Note: The internal temperature must not exceed 52C for data cabinets.

Many  U.S. safe manufacturers provide ratings based on the UL standards. The standards consider the following tests:

Impact Test - The UL Impact Test calls for the safe to be heated to 1550 degrees for 30 minutes (1638 degrees for a 2 hour fire rated safe) then dropped onto concrete rubble from a height of 30 feet. The safe is then turned upside down and reheated for another 30 minutes (45 minutes for a 2 hour fire rated safe). During this process, it must maintain its integrity and protect all contents in order to pass the UL impact test. 

Explosion Hazard Test - All UL fire-rated safes must undergo this test, during which the unit is inserted into a preheated 2000 degree oven. If the safe is not constructed properly, the rapid heating will likely cause an explosion. 

Cool Down Test - This procedure is a key part of UL's fire testing procedures. After a one or two hour fire rating test, the safe is left in the oven for cool down time with the heat turned off. Because of the intensive heat of one and two hour tests, the temperature inside the safe will continue to rise for up to one hour after the oven is turned off. To pass UL testing, the safe's interior temperature may not exceed 350 degrees at any time during heat up or cool down procedures. 

Safes will be approved according to the following classifications:

FR - Fire resistant, un-rated insulated safe - This product is awaiting UL approval. 

Class 350 1/2 Hour Fire Rating - During this test, the safe is heated for one half hour to reach an exterior temperature of 1550 degrees. Because paper will begin to char at approximately 400 degrees, the unit being tested must maintain an interior temperature of less than 350 degrees during heat up and cool down testing in order to earn its rating. 

Class 350 1 Hour Fire Rating - To earn this rating, the safe is heated for one hour to reach an exterior temperature of 1550 degrees, then put through the cool down test. During this time the safe must maintain an interior temperature of less than 350 degrees. 

Class 350 1 Hour Fire & Impact Label - The safe has passed both UL impact testing and Class 350 1 hour fire testing (see above). 

Class 350 2 Hour Fire Rating - The safe is heated for two hours to reach an exterior temperature of 1550 degrees and must maintain an interior temperature of less than 350 degrees to earn this rating. 

Class 350 2 Hour Rating and Impact Label - The safe has passed both UL impact testing and Class 350 2 hour fire testing (see above).