A crash bar (also known as a panic exit device, panic bar, or push bar) is a type of door opening mechanism which allows users to open a door by pushing a bar. While originally conceived as a way to prevent crowd crushing in an emergency, crash bars are now used as the primary door opening mechanism in many commercial buildings. The device consists of a spring-loaded metal bar which is fixed horizontally to a door that swings in the direction of an exit. Depressing the bar unlatches the door, allowing occupants to quickly leave the building. Modern fire standards often mandate that doors be fitted with crash bars in commercial and other occupancies where mass evacuation may be slowed by other types of door openers. They are sometimes intended solely for emergency use and may be fitted with alarms. However, in many buildings the crash bar functions as the primary mechanism for opening a door in normal circumstances as well. They may even be used when not required by code because they are quicker and easier for users compared with a knob or lever handle. Background History Following the events of the Victoria Hall disaster in Sunderland, England in 1883 in which 183 children died because a door had been bolted at the bottom of a stairwell, the British government began legal moves to enforce minimum standards for building safety. This slowly led to the legal requirement that venues must have a minimum number of outward opening doors as well as locks which could be opened from the inside. Motivated by the Sunderland disaster, Robert Alexander Briggs (1868–1963) invented the panic bolt which was granted a UK patent on 13 August 1892. However these moves were not globally copied. For example, in the United States, at least 602 people died in the Iroquois Theatre fire in Chicago in December 1903 because of door latch designs that were difficult for fleeing patrons to open. Five years later 174 people in Ohio died in the Collinwood school fire, which led to a national outcry in the United States for greater fire safety in buildings. On 31 December 1929, some 37 years after the panic bolt was patented, 71 children died during the Glen Cinema disaster at a Hogmanay film screening in Paisley, Renfrewshire, Scotland when a smoking cellulose nitrate film canister sparked panic. Children rushing to escape the cinema became crushed