A safe is a strongly built container for valuable objects. The two main kinds of safes are the money safe and the record safe. A money safe is designed primarily to provide protection against the theft of valuables. A record safe is designed primarily to ensure that valuables will not be destroyed by fire.
Cash, jewelry, negotiable securities, and similar valuables are stored in a money safe to thwart burglars. The basic money safe has a heavy round door and steel walls that are at least 1 inch (2.5 cm) thick. It can be installed in a wall or welded into place at a desired location. Sometimes the basic money safe is enclosed in a reinforced-concrete block that has a steel cladding, which discourages removal of the safe by burglars and greatly increases the safe's resistance to drills, sledges, explosives, and metal-cutting torches.
A money safe also can be built with special features. For instance, special alloys are used to cover the front and door of a money safe to provide protection against attack with a carbide drill. Similar protection is provided by using Relsom bars, which cause the drill to bind and shatter. Also, layers of copper are used in the front of a safe and around its door to provide protection against attack with an acetylene torch. The copper rapidly carries heat away from the area to which the torch is applied and thus hinders the melting of the plate. Another protective measure is the use of a relocking mechanism that automatically throws two or three emergency bolts into action when the lock of a safe is jarred by cutting tools or explosives.
Personal records, business records, and similar documents are stored in a record safe to protect them from fire. A record safe has rectangular doors and steel walls built thinner than those of a money safe. The walls of a record safe are lined or filled with a thermal insulating material. The insulation markedly decreases the rate of heat transfer to the inside of a safe.
Record safes are classified on the basis of their ability to keep papers intact while subjected to a high temperature in a test furnace, to withstand rupture when placed in the test furnace, and to withstand a 30-foot (10-meter) test fall while still hot. Record safes that pass such tests are given certifications by the Underwriters' Laboratories and the Safe Manufacturers National Association.
The contents of record safes are relatively vulnerable to burglary, and the contents of money safes are relatively vulnerable to fire. Consequently, safes should be used for the purpose for which they are designed.
Various methods for safely keeping treasure, jewels, and other valuables have been in use since the beginning of recorded history. The ancient Egyptians, Greeks, and Romans used wooden boxes to store valuables. Wooden boxes, some bound with iron bands and some equipped with locks, were in use in Europe during the Middle Ages and the Renaissance. Perhaps the first all-metal strongbox was built in France in 1820. It had double walls, the space between which was filled with an insulating material. Daniel Fitzgerald of New York City built a similar safe in 1843. Since then, safes have been improved by using stronger metals, more fire-resistant insulating materials, and more complex locks. In addition, modern safes can be protected by sophisticated alarm systems.