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 stampedes 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. When the bar is depressed, it activates a mechanism which 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. In some places, they are even used when not required by code because they are quicker and easier for users compared with a knob or lever handle.
Video Crash bar
Background
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, 605 people died in the Iroquois Theater Fire in Chicago in December 1903 because iron gates blocked exits. Five years later 174 people in Ohio died in the Collinwood school fire, which led to a national outcry in the U.S. for greater fire safety in buildings.
Maps Crash bar
Implementation and usage
By the end of the 20th century, most countries had building codes (or regulations) which 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. Such a human stampede situation, which has many historical precedents, can cause falls, crushing, and other 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 which provide egress from assembly areas, doors which 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.
Dogging
In some applications, such as storefront entrances, panic bars may be dogged during business hours. Dogging is a common feature on panic bars in which the bar is retracted with a key--freeing the door to swing without latching. This allows customers to apply force to any portion of the door, not just the bar, in order to open it.
Dogging is distinct from simple unlocking, which permits the user to open the door from both ends but still requires performing an action to release the latches. However, in applications where the exterior side contains an immovable dummy lever, it is usually impossible to unlock the crash bar without also dogging it.
Dogging should be avoided in high wind areas where the door is susceptible to blowing open.
Use around the world
European Union
In the European Union, panic bars are governed by the standard EN 1125, Panic exit devices operated by a horizontal bar. As with other EN family standards, the English language version is produced by the British Standards Institution and utilizes the call sign BS EN 1125. Panic bars are required to conform to this standard in order to carry CE marking and thus be sold in the European Economic Area.
In 2008, the standard was updated to include an alpha-numeric labeling scheme. In this system, products are tested to various benchmarks and assigned a letter or number accordingly. Products must achieve minimum quality scores in order to receive general CE approval. The 9 rating categories are:
- Category of Use
- Number of Test Cycles
- Test Door Mass
- Fire Resistance
- Safety
- Corrosion Resistance
- Security
- Projection of device
- Type of device
EN 1125 is one of two standards which govern exit devices in the EU. 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." Examples of places where EN 179 hardware may be used in place of EN 1125 panic bars include small apartment buildings and offices.
United States
The first panic bar, made by Von Duprin, was available by 1908 in many models and configurations.
In the US, building exit requirements are generally controlled by model codes such as the International Building Code and/or the NFPA Life Safety Code. Adoption of regulations varies by location and may occur at the city, county, or state level.
Model codes are usually supplemented with amendments adopted locally. Additional requirements may be imposed on a site from an Authority Having Jurisdiction such as a local fire marshal. Factors considered when mandating exit devices include the number of occupants who would need to leave in an emergency, the availability of other nearby exits, and proximity to any hazards equipment or chemicals.
Differences in European vs North American Design
In Europe, it is notable that most panic bars are of the cross bar type, which are called Type A in the EN 1125 standard. This contrasts strongly with North American architectural design, which years ago switched to using predominantly touch bars (EN 1125 Type B) in new construction.
In Europe, the use of panic bars is generally confined to code required applications. On the other hand, in US and Canadian commercial building design panic bars are frequently used even when not required by code. This is because bars are seen as a simpler opening mechanism for users than a knob or lever handle. And while the public generally prefers automatic door opening solutions to both these options, automatic doors can be costly to install and maintain.
References
Further reading
- United Kingdom
- British Standards relating to Panic Hardware
- United States
- OCCUPATIONAL SAFETY AND HEALTH STANDARDS, 29 cfr 1910.36
- National Fire Protection Association 101, Life Safety Code, 2012;
- 2011 NATIONAL ELECTRICAL CODE (NEC)
External links
- Media related to Push bars at Wikimedia Commons
Source of the article : Wikipedia
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