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Exit sign
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Exit sign
An exit sign is a pictogram or short text in a public facility (such as a building, aircraft, or boat) marking the location of the closest emergency exit to be used in an emergency that necessitates rapid evacuation. Most fire, building, health, and safety codes require exit signs that are always lit.
Exit signs are intended to be unmistakable and understandable by anyone who can see. In the past, this generally meant exit signs that show the word "EXIT" or the equivalent in the local language; increasingly, exit signs around the world are now pictograms, often without supplementary text.
Early exit signs generally either were made of metal and lit by a nearby incandescent light bulb or were a white glass cover with "EXIT" written in red, placed directly in front of a single-bulb light fixture. A flaw in these designs was that in a fire the power to the light often failed. In addition, the fixtures, despite their brightness, could be hard to see through smoke. The biggest problem was that the exit sign was hardly distinguishable from an ordinary safety lighting fixture commonly installed above doors in the past. The problem was partially solved by using red-tinted bulbs instead.
Better signs were soon developed that more resembled today's modern exit sign, with an incandescent bulb in a rectangular box that backlit the word "EXIT" on one or both sides. Larger than its predecessors, this version of the exit sign was easier to see. The sign was still only useful as long as mains power remained on.
As battery-backup systems became smaller and more efficient, some exit signs began to use a dual-power system. Under normal conditions, the exit sign was lit by mains power and the battery was maintained in a charged state. In the event of a power outage, the battery would supply power to light the sign. Early battery-backup systems were big, heavy, and costly. Modern systems are lightweight, can be installed virtually anywhere, and are integrated into the fixture, rather than requiring a separate box. As batteries improved, so did the amount of time that a fixture could remain lit on batteries.
While exit signs were more visible due to large letters, even a 60-watt incandescent bulb shining through a plastic or glass cover could appear somewhat dim under certain conditions. Incandescent bulbs are still in use because they are cheap and common, even though they use more electricity and require more or less frequent replacement. Incandescent bulbs lit 24/7 have a greatly extended lifespan compared to ones that cycle on and off. When used in exit signs, they are often operated at a lower voltage than rated, which further extends their lifetime, at the trade-off of reduced light output and greatly reduced energy efficiency.
With the development of fluorescent lamp and light-emitting diode technology, exit signs could be made even brighter to compensate for the limited visibility in a fire situation, while using less electricity. Fluorescent lamps are used in the same way as incandescent bulbs, back-lighting both sides of an exit fixture from within. LED signs combine a large number of bright light-emitting diodes to illuminate the sign from inside. An exit sign is constantly lit; fluorescent bulbs need to be changed more often than LEDs, although the absence of frequent on/off cycles extends the life of fluorescent lamps significantly. Generally, LEDs have a very long life, and may last for 10 years or more of continuous use, although their brightness may gradually diminish.
Radio-luminescent and phosphorescent signs that require no electricity have also been developed, and have been used since the 1970s. Radio-luminescence uses the radioactive decay of tritium gas to illuminate the sign, while phosphorescence uses light-emitting pigments to glow in the dark. While both of these types of signs meet California State Fire Marshal standards, electricity is used in the vast majority of signs.
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Exit sign AI simulator
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Exit sign
An exit sign is a pictogram or short text in a public facility (such as a building, aircraft, or boat) marking the location of the closest emergency exit to be used in an emergency that necessitates rapid evacuation. Most fire, building, health, and safety codes require exit signs that are always lit.
Exit signs are intended to be unmistakable and understandable by anyone who can see. In the past, this generally meant exit signs that show the word "EXIT" or the equivalent in the local language; increasingly, exit signs around the world are now pictograms, often without supplementary text.
Early exit signs generally either were made of metal and lit by a nearby incandescent light bulb or were a white glass cover with "EXIT" written in red, placed directly in front of a single-bulb light fixture. A flaw in these designs was that in a fire the power to the light often failed. In addition, the fixtures, despite their brightness, could be hard to see through smoke. The biggest problem was that the exit sign was hardly distinguishable from an ordinary safety lighting fixture commonly installed above doors in the past. The problem was partially solved by using red-tinted bulbs instead.
Better signs were soon developed that more resembled today's modern exit sign, with an incandescent bulb in a rectangular box that backlit the word "EXIT" on one or both sides. Larger than its predecessors, this version of the exit sign was easier to see. The sign was still only useful as long as mains power remained on.
As battery-backup systems became smaller and more efficient, some exit signs began to use a dual-power system. Under normal conditions, the exit sign was lit by mains power and the battery was maintained in a charged state. In the event of a power outage, the battery would supply power to light the sign. Early battery-backup systems were big, heavy, and costly. Modern systems are lightweight, can be installed virtually anywhere, and are integrated into the fixture, rather than requiring a separate box. As batteries improved, so did the amount of time that a fixture could remain lit on batteries.
While exit signs were more visible due to large letters, even a 60-watt incandescent bulb shining through a plastic or glass cover could appear somewhat dim under certain conditions. Incandescent bulbs are still in use because they are cheap and common, even though they use more electricity and require more or less frequent replacement. Incandescent bulbs lit 24/7 have a greatly extended lifespan compared to ones that cycle on and off. When used in exit signs, they are often operated at a lower voltage than rated, which further extends their lifetime, at the trade-off of reduced light output and greatly reduced energy efficiency.
With the development of fluorescent lamp and light-emitting diode technology, exit signs could be made even brighter to compensate for the limited visibility in a fire situation, while using less electricity. Fluorescent lamps are used in the same way as incandescent bulbs, back-lighting both sides of an exit fixture from within. LED signs combine a large number of bright light-emitting diodes to illuminate the sign from inside. An exit sign is constantly lit; fluorescent bulbs need to be changed more often than LEDs, although the absence of frequent on/off cycles extends the life of fluorescent lamps significantly. Generally, LEDs have a very long life, and may last for 10 years or more of continuous use, although their brightness may gradually diminish.
Radio-luminescent and phosphorescent signs that require no electricity have also been developed, and have been used since the 1970s. Radio-luminescence uses the radioactive decay of tritium gas to illuminate the sign, while phosphorescence uses light-emitting pigments to glow in the dark. While both of these types of signs meet California State Fire Marshal standards, electricity is used in the vast majority of signs.