U.L. Fire Resistive Rating Classification

The following is an explanation of the Underwriters Laboratories fire resistant container testing procedures on the Class 350F, one hour and Class 350F two hour Fire Labels.


U.L. Label/Class 350F-one hour and Class 350F-two hour. The safe will maintain an interior temperature less than 350F when exposed to fire for a period of one hour at 1700F or for a period of two hours at 1850F. Safe must successfully undergo all other requirements for the Fire Endurance Test, Explosion Hazard Test and the Fire/Impact Test as stated below.


Fire Endurance Test

After heat sensors and paper are placed inside the safe, the unit is locked and exposed to a uniformly distributed fire. The furnace is regulated to reach a maximum temperature of 1700F for a period of one hour, or 1850F for two hours, then allowed to cool without opening the furnace. The interior temperature is recorded throughout the test and during the cooling period until a definite drop is shown and must never exceed 350F.


Once cooled, the unit is opened and examined for usability. The units locking mechanisms and parts fastenings are examined for security and the interior examined for visible evidence of undue heat transmission.

Explosion Hazard Test

The safe is locked and placed into a furnace preheated to 2000F. This temperature is maintained for 30 minutes (2 hour test is 45 minutes) and if no explosion results, the unit is allowed to cool without opening the furnace doors.


Once cooled, the unit is opened and examined for usability. The units locking mechanisms and parts fastenings are examined for security and the interior examined for visible evidence of undue heat transmission.


Fire Impact Test (Manufacturers Option)

After the explosion hazard test the safe is removed from the furnace and within two minutes is dropped 30' onto a riprap of brick on a heavy concrete base. After impact the unit is examined for deformation, rupture of parts, damaged insulation and any other openings into the interior of the unit. Once cooled, the unit is inverted and reheated to 1550F for a period of 30 min. (2 hour test: 45 min. at 1638F).


Once cooled, the unit is opened and examined for usability. The units locking mechanisms and parts fastenings are examined for security and the interior examined for visible evidence of undue heat transmission.

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