Since we did a run-down on burglar safe ratings, I thought it might be a good idea to do a rundown on fire-safe ratings. As with burglar ratings, the UL is THE authority for trustworthy ratings, although there are several other authorities that also provide ratings to a range of safes. Because of its prevalence and industry standard, we’re only going to look at UL ratings.
The basic ratings for UL fire-safes are Class A, Class B, Class C, Class D, and Class E. To get these ratings the UL conducts a series of tests on the safe including a Fire Endurance Test, an Explosion Hazard Test, and a Fire Impact Test.
The Fire Endurance Testmeasures the degree of resistance in which the safe has to high-heat temperatures, ranging from1500 degrees F to 2000 degrees F. After going through testing, the contents of the safe (generally paper) must be usable and handle-able without breaking to achieve a certain rating.
| TIME IN FURNACE | TEMPERATURE REACHING | |
| Class A | 4 hours | 2000 degrees Fahrenheit |
| Class B | 2 hours | 1850 degrees F |
| Class C | 1 hour | 1700 degrees F |
| Class D | 1 hour | 1700 degrees F |
| Class E | 30 minutes | 1550 degrees F |
The Explosion on Hazard Testmeasures whether or not the design of a safe protects the contents of the safe in the case of a sudden, high-heat explosion. Sometimes in explosions, the high-temperature will cause hydrogen-air-stram mixtures in the insulting material to explode and rupture the insulation and safe walls. By testing the heat-sensitivity of a safe for 30 minutes at 2000 degrees F, the UL tests for explosion sensitivity.
The Fire Impact Test measures the resistance a safe has when in a heated condition and how it handles a fall of approximately 3 stories after being heated to a high temperature. After the fall, it is once again heated up and THEN the contents are checked.
