A panic bar is a device 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 that unlatches the door allowing occupants to leave quickly from the building.
By the end of the 20th century, most countries have building codes (or regulations) that require all public buildings have a minimum number of fire and emergency exits. Crash bars are fitted to these types of doors because they are proven to save lives in the event of human stampedes. Panic can often occur during mass building evacuations caused by fires or explosions.
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.
Crash bars are typically found on doors which are required emergency exits serving a particular type or quantity of occupants. Common locations include doors that provide egress from assembly areas, doors that serve many occupants, or doors serving hazardous areas. For buildings subject to the International Building Code, or a locally adopted variation, they are required for certain healthcare, education, or assembly spaces, generally related to the number of occupants exiting through a given door. A door intended only for exit doesn’t need a handle on the outside, and for security, and outside handle is often omitted. However, a door handle can be mounted on the outside 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.