UL 72 Fire Tests

Fire test signThe Underwriters Laboratory of America (UL for short) publishes a range of security and fire resistance standards for products sold both in America and worldwide. Their fire tests – generally referred to as UL 72 – are extremely well regarded in the industry.

There are several variations on the UL 72 test depending on the type of contents the safe is designed to protect. Safes are subjected to temperatures ranging from 843° Celsius to 1093° Celsius, depending on the length of time they are left in the furnace.

UL 72 Class 350: The safe is heated for 30, 60 or 120 minutes (or longer, depending on the time rating given). It is then left to cool naturally in the still-hot furnace. During this time, temperatures within the safe cannot rise above 177° C, which is the temperature at which paper will char or combust. Safes meeting this standard will protect paper against fire damage.

UL 72 Class 150: The safe is heated for 30, 60 or 120 minutes (or longer, depending on the time rating given). It is then left to cool naturally in the still-hot furnace. During this time, temperatures within the safe cannot rise above 65° C and humidity may not reach above 85%. Safes meeting this standard are designed to protect paper and non-paper data records such as photographic records and magnetic tape.

UL 72 Class 125: The safe is heated for 30, 60 or 120 minutes (or longer, depending on the time rating given). It is then left to cool naturally in the still-hot furnace. During this time, temperatures within the safe cannot rise above 55° C and humidity may not reach above 80%. Safes meeting this standard are designed to protect paper and non-paper data records such as floppy disks.

Certain types of equipment may be further tested under UL 72 for their ability to resist explosion under extreme, rapid heating (Explosion Hazard Test) and to examine how they cope with a simulated building collapse (Fire Impact Test).

For the Explosion Hazard Test, the safe is placed in a furnace pre-heated to approximately 1090° C for 30 minutes. Afterwards, it is examined for signs of damage to its workings and interior.

For the Fire Impact Test, the safe is heated in a furnace for between 20 and 60 minutes and then subjected to a drop of approximately 9.1 metres onto a rubble surface. It is then returned to the furnace and heated for a further 20 to 60 minutes. (Exact times and temperatures depend on the classification being sought.)

The product will be rated according to which of these tests it passes (e.g. Fire and Impact Rated, etc).

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