FIRE RATINGS EXPLAINED
The National Fire Protection Agency (NFPA) reported that there were 383,500 home fires in the United States
accounting for $5.5 billion of property damage.
The following information applies to both Fire Rated Safes and Burglar/Fire Rated Safes. Remember that a Fire
Safe without a Burglar Rating is not recommended for Burglar Resistance. If you need both Fire and Burglar
resistance, always consider a Burglar/Fire Rated Safe over a Fire Rated safe only.
There are many types of Fire Ratings. Safe Manufacturer's will provide testing from a variety of sources such as:
- Private Laboratory Testing
- K.I.S. (Korean Industrial Standard) Fire Test
- U.L. (Underwriters Laboratory) Class of Fire Protection
There are other Fire Ratings not mentioned such as various European fire rating standards. Many
manufacturers hire a reputable private laboratory to test their fire or burglar/fire safes for a fire rating. Safe's
made in Korea will often have the K.I.S. Fire Test which is a Korean Fire Lab test. The most thorough and
recognized fire test is the U.L. Class of Fire Protection. (see description below)
Here is an example of how the K.I.S. Fire Test is conducted on a safe for a 2 hour fire rating with an
Explosion Test and a Fire Impact (drop test):
K.I.S. (Korea Industrial Standards) rated by the KSG-4500 fire resistance tests. Papers and valuable documents
will remain protected in accordance with the rating standards against fire, explosion and drop impact during fires.
Fire- Safe is tested 2 hours in a furnace with temperature rising to 1850° F.
Explosion- Heated in a furnace to 1852° F in 10 minutes, continued at temperature for 30 more minutes.
Fire Impact- Subjected to standard fire exposure for 45 minutes, dropped 13 feet, returned to furnace upside
down, reheated 1 hour.
Safe's with the K.I.S. or a Private Laboratory Test still provide great fire resistance. However, the U.L. Class of
Fire protection is recognized as the most complete fire testing today. If you are on a budget, we recommend you
consider at least a 1 hour fire rating (minimum) to insure ample protection for your documents or valuables.
U.L. Classes of Fire Protection
Underwriters Laboratories established five fire resistant
classifications for record protection. These classifications
are based on the type, length, and severity of the test given
The classification ratings are:
- 350-4 hour
- 350-2 hour
- 350-1 hour
- Insulated record container 350-1 hour
- Insulated record device 350-1 hour
3 Tests for Fire Protection
Three basic tests are provided by the Underwriters’ Laboratories for the fire resistance of record protection
equipment. These are:
- Fire Endurance Test
- Explosion Hazard Test
- Fire Impact Test
Equipment in classes A, B, and C are subjected to all three tests. Equipment in classes D and E do not take the
fire impact test
Fire Endurance Test
The Fire Endurance est measures the degree of resistance which the safe has to temperatures determined by
standardized fire exposure conditions.
In preparation for the fire endurance test, the safe is placed in a cold furnace so that all exterior surfaces will be
exposed except the bottom. Heat measuring apparatus is installed in the interior of the safe and papers are
loosely distrubted so that they are in contact with all interior surfaces. The doors of the safe are closed and
locked, the furnace is closed and the fire is started.
The heat of the furnace is gradually increased according to set standards of time and temperature. The gas and
air supply is adjusted carefully so that the fire is well distributed over the sample, and thermocouples
symmetrically distributed in the furnace accurately record temperatures so that the test standards are
The test sample remains in the furnace for the period required for the desired classification. At the end of the
time, the fire is extinguished and the sample is allowed to cool without opening the furnace. Here is the test
times and temperatures for the various classifications:
After the test sample has cooled, it is opened and the contents and interior surfaces are examined. The records
must still be usable and the interior must show no signs of undue heat transmission. At no time during the
test must the temperature inside the safe exceed 350 degrees Fahrenheit. The general security of the safe is
also examined. The records are considered “usable” if they can be handled without breaking and if the are
decipherable by ordinary means.
Explosion on Hazard Test
The Explosion on Hazard Test determines whether or not the design of the safe protects it against explosions in
case of sudden intents heat exposure. If the safe construction is faulty, the sudden high temperature will cause
hydrogen-air-stream mixtures in the insulating material to explode and rupture the insulation and safe walls.
This rupture will destroy much of the safe’s resistance to fire.
The test for explosion is relatively simple. The empty, closed furnace is pre-heated to 2000 degrees F. The
furnace is opened, the test sample is inserted, and the furnace is closed again for 30 minutes while the fire is
maintained at 2000 degrees F. After the test, the sample is allowed to cool until it can be handled. If no rupture of
the insulation can be found, the sample passes the test.
The Fire Impact Test
The Fire Impact Test measures the resistance of a safe to impact when in a heated condition. The test
simulates the fall of a safe three floors to the basement of a burning building, then lying in the burning embers
During the test, the sample is placed in a furnace and the fires are lighted. The time and temperature follow the
same standards as for the fire endurance test for the length of time determined by the classification desired. At
the end of the required time in the furnace, the fire is extinguished. The truck and sample is hoisted so that its
bottom is 30 feet above a riprap of brick on a heavy concrete base, then dropped. The drop is made within two
minutes of the time the fire is extinguished.
Pretty rough? Yes, but the test isn’t over yet! When the safe has cooled sufficiently to handle, it is inverted,
reinstalled in the furnace, and again subjected to the standardized time-temperature conditions for a period
determined by the classification desired. After the time is over, the sample is allowed to cool before the furnace
is opened. When the doors are forced open, the records must be in usable condition.
The Underwriters’ Laboratories Inc., is the most highly respected testing and grading agency in the world. Their
testing label of whatever classification means that the safe has passed the highest standards they have
established for safes. The integrity of Underwriters’ Laboratories though the years is a guarantee to the
consumer that no portion of any test which establishes the grade has been slighted in any way.
Caution: Read the Label
On occasion, a particular manufacturer or another association of manufacturers may attach their own grade
label to their equipment. The customer should be aware that such a label on a piece of equipment does not
necessarily mean that the equipment is comparable to another piece of equipment which bears the
Underwriters’ Laboratories grade label.
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