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Class 125 Description

UL 125 Fire Safe Rating


Maintaining a proper data backup and storage plan for business financial information, personal or employee data and medical records is a top priority for the small office / home office all the way up to large enterprises. Underwriters Laboratories has developed and maintained several fire testing procedures to ensure data recovery after a fire with a rigorous UL 125 rated standard.

When a fire resistant safe or enclosure is evaluated, the unit is subject to various test conditions that will expose all six sides of the safe to a fire up to 2000° F from 1 hour up to 3 hours depending on the level of fire protection the product offers. This fire test is accomplished by placing the safe inside a furnace that heats all exposed surfaces to the temperature conditions specified in the test standard. Essentially this testing furnace is a giant oven, capable of reaching and sustaining high temperatures over a certain time curve.

Class 125 Rating and Listing Standard

This rating is the requirement for protecting digital information on magnetic media such as DLT or LTO tapes as well as CD's, DVD's and optical disks. Temperatures inside the protected data safe or media safe must be held below 125-degrees Fahrenheit (51.7-degrees Celsius) for the time period specified, such as Class 125-2 Hour, with temperatures up to 2,000-degrees Fahrenheit (1,093.3-degrees Celsius) outside the vault. The temperature reading is taken on six sides of the inside surfaces of the protective safe. Maintaining the temperature below 125-degrees F. is critical because data is lost above that temperature threshold, even if the media or hard drives appear to be intact.

This rating for data safes, vault door and vault structures is verified with the UL 72 time/temperature testing standard.

Test Standard

  • UL 72 -- Tests for Fire Resistance of Record Protection Equipment including safes and filing cabinets.

Fire-resistant record protection equipment is rated as follows:

  1. The type of media it intends to protect.
  2. The length of time it provides this level of protection.
  3. Whether the enclosure provides some level of protection against impact (optional).

There are three different class ratings for this type of evaluation: 350, 150 and 125. Class 350-rated devices protect paper products; class 150-rated devices protect magnetic tapes; and class 125-rated devices protect flexible computer disks.

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