Emergency exit
From Wikipedia, the free encyclopedia
An emergency exit in a structure is a special exit for emergencies such as a fire: the combined use of regular and special exits allows for faster evacuation, while it also provides an alternative if the route to the regular exit is blocked by fire, etc.
It is usually a strategically located (e.g. in a stairwell, hallway, or other likely place) outward opening door with a crash bar on it and with exit signs leading to it. The name is an obvious reference to when they're frequently used, however a fire exit can also be a main doorway in or out. A fire escape is a special kind of emergency exit, mounted to the outside of a building.
Local building codes will often dictate the number of fire exits required for a building of a given size. This may include specifying the number of stairs. For any building bigger than a private house, modern codes invariably specify at least two sets of stairs. Furthermore the stairs are completely separate from each other. Some architects meet this requirement by housing two stairs in a "double helix" configuration where two stairs occupy the same floor space, intertwined. It may make no functional sense to have two stairs so close to each other, but it meets the requirements of the building codes.
Knowing where the emergency exits are in buildings you frequent can save your life. Some buildings, such as schools, have fire drills to practice using emergency exits. Many disasters could have been prevented if people had known where fire escapes were, and if emergency exits had not been blocked. For example, in the September 11, 2001 attacks on the World Trade Center, some of the emergency exits inside the building were inaccessible, while others were locked. In the Stardust Disaster and the 2006 Moscow hospital fire the emergency exits were locked and most windows barred shut.
It many countries, it is required that all new commercial buildings include well-marked emergency exits. Older buildings must be retrofitted with fire escapes. In countries where emergency exits are not standard, fires will often result in a much greater loss of life.
Well designed emergency exit signs are necessary for emergency exits to be effective. In the United States fire escape signs usually display the word "EXIT" in large, well-lit, green or red letters. Sometimes an arrow is displayed as well. In the European Union, emergency exit signs use pictorial symbols to convey their meaning. Some signs are self-illuminated, using tritium powered traser light sources.
In the United Kingdom, under the Health and Safety (Safety Signs and Signals) Regulations 1996, signs are required to bear a picture or symbol that clearly illustrates the sign.
[edit] Floor plans showing exit paths
In many places, office buildings have floor plans on display showing exit paths in red and regular hallways in black. Unfortunately, color-blind persons often cannot distinguish dark red from black.
[edit] Problems with emergency exits
Firefighters have cited overzealous guards who told people during a fire that they are not allowed to use emergency exits. The practice is actually quite common in the absence of fires, as well. Some skyscrapers have stairwells with standard emergency exit signs on each door, which then lock upon closing. Users of these stairwells are trapped, whether they know or do not know that the only door that opens from the inside is the one on the ground floor. A further problem becoming very common in the USA (2005) is that retail stores at night close one of their main entrance/exits through makeshift heavy metal barriers, signage, paper notes, or junk placed in front of the exits. Some actually lock their exits. A large array of signage and mechanical exit systems have also been devised, including signage that says contradictorily, "This is not an exit," "Do not use this exit," or warning users that a heavy penalty will be assessed for non-emergency use. Some systems do not allow the exit to be opened until the user signals the intention to exit (through a button or lever) for some amount of time, such as 20 seconds. It is also common for these exits to remain completely locked until somebody tests them.
[edit] External links
[edit] Patents
- US2,724,258 -- Fire exit lock
