Safety lamp
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A safety lamp is any of several types of lamp, which are designed to be safe to use in coal mines. These lamps are designed to operate in air that may contain coal dust, methane, or firedamp, all of which are potentially flammable or explosive.
The best known early safety lamps are the Davy lamp, invented by Sir Humphry Davy and the Geordie lamp, invented by George Stephenson. Both of those were invented in 1815 and were later superseded by the Gray, Muesler, Marsant, and other lamps; most later lamps are constructed on the principle discovered by Davy, that a flame enveloped in wire gauze of a certain fineness does not ignite firedamp.
Prior to the invention of these safety lamps, miners used canaries to alert them to the presence of gas, and barometers to tell them if atmospheric pressure was low (in which case more methane seeped out of the mine into the air). Alternative methods involved igniting the gas deliberately to cause explosions, thus evacuating the mines of the majority of explosive or easily flammable material present.
Nowadays, safety lamps are mainly electric, and traditionally mounted on miners' helmets, sealed to prevent gas penetrating the casing and being ignited by electrical sparks.
See also
| L i g h t i n g and L a m p s | ||
|---|---|---|
| Incandescent: | Incandescent light bulb>Conventional - Halogen - Parabolic Aluminized Reflector (PAR) |
|
| Fluorescent: | Compact fluorescent lamp>Compact Fluorescent (CFL) - Linear fluorescent - Induction lamp | |
| Gas discharge: | High-intensity discharge lamp>High-Intensity Discharge (HID) - Mercury-vapor - Metal-halide - Neon - Sodium vapor | |
| Electric arc: | Arc lamp - Hydrargyrum medium-arc iodide>HMI - Xenon arc - Yablochkov candle | |
| Combustion: | Carbide lamp>Acetylene/Carbide - Candle - Gas lighting - Kerosene lamp - Limelight - Oil lamp - Safety lamp | |
| Other types: | Sulfur lamp - Light-emitting diode>Light-Emitting Diode (LED) - Optical fiber - Plasma | |
This article incorporates text from the public domain 1907 edition of The Nuttall Encyclopaedia.
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