Fire safes are designed to protect their contents from the actual heat of a fire as well as the less obvious potential of damage from the water which will usually be used to extinguish the fire.
They are constructed of two metal sheets, usually steel, that sandwich an insulating material. This insulating material also contains a hydrate which releases water vapor as it is heated by the fire. This release of steam helps to protect the interior of the safe from heat much the same way that perspiration keeps people cool.
There are strips of material where the door meets the body of the safe that are designed to melt at specific temperatures. This seals heat and water out. As the insulation releases steam, some of the steam is vented to the interior of the safe. Specially designed and strategically placed vents release some of this steam to the outside while maintaining positive pressure in the interior to further protect against heat and water.
Fire safes are rated by the number of hours they maintain an internal temperature below 350 degrees while subjected to an external temperature of 1550 degrees. Many AMSEC safes are rated for two hours.
Some safes are designed to withstand fire and burglary. There are many economical tl 30 safes (they resist attack with hand tools for 30 minutes) that offer one hour of fire protection. Used safes are another economical option.
First Security Safe sells high security safes through their Los Angeles location, and online at the First Security Safe website.