Panic Device / Push Bar Lock
A crash bar (also known as a panic bar, exit device, panic device, or a push bar) is a form of lever tumbler lock for unlocking a door during emergency conditions. The mechanism consists of a spring-loaded metal bar fixed horizontally to the inside of an outward-opening door. When the lever is either pushed or depressed, it activates a mechanism which unlatches the door allowing occupants to leave quickly from the building.
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. A crash bar's fast-acting mechanism reduces the risk that a rushing crowd might suddenly become a logjam at the exits. This situation, which has many historical precedents, can cause falls, crushing and injury because the rear of a crowd has no idea that the people at the front of a crowd have come across a door.
All doors which are intended to function as emergency exit doors must have crash bars. For security reasons, most cannot be opened from the outside. However a door handle can be mounted on the opposite side to create a two-way door. This allows the bar to be locked in a neutral (latch open) position, allowing the door to be freely opened from either side.
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