crash bars

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.

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