Crash 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.

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.

Motivated by the Sunderland disaster, Robert Alexander Briggs (1868–1963) invented the panic bolt which was granted a UK patent on 13 August 1892.

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.

In the event emergency exits are required, the crash bar works efficiently to allow people to pass through security doors without a reduction in speed.

Crash bars are typically found on doors which are required emergency exits serving a particular type or quantity of occupants.

When the bar is depressed, a chord within the vertical rod gets pulled, which lowers a latch at the top and/or bottom and allows the door to open.

To pass CE certification, bars must function between 100,000 and 500,000 opening cycles depending on the rating the manufacturer is seeking.

Dogging is distinct from simple unlocking, which permits the user to open the door from both sides but still requires performing an action to release the latches.

[12] Because these will not function in a long term power outage, they are most commonly used on secondary doors between a vestibule and the secure part of a building.

Installation of a secondary crash bar equipped exit is often required in large buildings with revolving doors, since these are too slow for a crowd to move through.

Panic bars are required to conform to this standard in order to carry CE marking and thus be sold in the European Economic Area.

The other standard, EN 179, governs door handles, push pads, and other exit devices with emergency release functionality.

However, EN 179 devices shall only be used at locations where people "are familiar with the emergency exit and its hardware and therefore a panic situation is unlikely to appear".

This contrasts strongly with North American architectural design, which years ago switched to using predominantly touch bars (EN 1125 Type B) in new construction.

[19] For example, when used on the rear service door of a business, a worker whose hands are being used to carry bulky items can lean against a bar to release the lock.

This can include coating the bar with silver ions in order to create a chemical environment hostile to unwanted microbes.