Safety lamp
A safety lamp is any of several types of lamp that provides illumination in coal mines and is designed to operate in air that may contain coal dust, methane, or firedamp, all of which are potentially flammable or explosive. Before the invention of the electric light around 1900, miners used open flame lamps to provide illumination. These could ignite flammable gasses which collected in mines, causing explosions. Safety lamps used various techniques to prevent the flame from igniting the surrounding atmosphere, reducing the danger of explosion. Flame safety lamps have been replaced in mining with sealed explosion-proof electric lights.
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[edit] First safety lamps
The first safety lamp was invented by William Reid Clanny, an Irish physician, who announced his discovery[1] on May 20, 1813 at the Royal Society of Arts in London. It used bellows and water to isolate the gases in a glass cylinder, but it was not tried out in a colliery until 1815 and was not found practical for use in mines.[2] Within months of this demonstration, two improved designs had been announced: one by George Stephenson, which later became the Geordie lamp, and the Davy lamp, invented by Sir Humphry Davy. 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.
Sir Humphry Davy was awarded the Rumford Medal and £1,000 by the Royal Society in 1816 and a £2,000 prize by the country's colliery owners,[3]:22 who also awarded 100 guineas (£105) to Stephenson. However the Newcastle committee also awarded Stephenson a £1,000 prize collected by subscription.[3]:26 Dr. Clanny was awarded a medal by the Royal Society of Arts in 1816.[2]
Both the Davy and Stephenson lamps were fragile. The gauze in the Davy lamp rusted in the damp air of a coal pit and became unsafe, while the glass in the Stephenson lamp was easily broken, and allowed the flame to ignite firedamp in the mine. Later designs, including the Gray, Mueseler and Marsaut lamps tried to overcome these problems by using multiple gauze cylinders, but glass remained a problem until toughened glass became available.[4]
The light given out by these lamps was poor, a problem not solved until the introduction of electric lighting around 1900 and the introduction of battery-powered helmet lamps in 1930 .
[edit] Early illumination
Before the invention of these safety lamps, miners used candles with open flames. This gave rise to frequent explosions. For example, at one colliery (Killingworth) in the north east of England, 10 miners were killed in 1806, 12 in 1809. In 1812, 90 men and boys were suffocated or burnt to death in the Felling Pit near Gateshead and 22 in the following year.[5] Phosphorescent sources of light were used in continental Europe and flint or steel mills introduced by Carlisle Spedding before 1750 had been tried with limited success.[2] Later, barometers were used to tell them if atmospheric pressure was low (in which case more methane seeped out of the coal seams into the mine galleries).
An alternative method of removing firedamp (methane) involved igniting the gas deliberately to cause explosions, thus evacuating the mines of the majority of explosive or easily flammable material present but this was also hazardous.
The lack of good lighting was a prime cause of a painful eye affliction (nystagmus).
[edit] Modern lamps
Nowadays, safety lamps are mainly electric, and traditionally mounted on miners' helmets (such as the wheat lamp) or the Oldham headlamp, sealed to prevent gas penetrating the casing and being ignited by electrical sparks.
Although its use as a light source was superseded by electric lighting, the flame safety lamp has continued to be used in mines to detect methane and blackdamp, although many modern mines now also use sophisticated electronic gas detectors for this purpose.
As a new light source, LED has many advantages for safety lamps, including longer burn time and less energy required. Combined with new battery technologies, such as the lithium battery, it gives much better performance in safety lamp applications. It is replacing conventional safety lamps.[citation needed]
[edit] See also
[edit] References
- ^ "Brief History of the Miner's Flame Safety Lamp". Minerslamps.net. http://www.minerslamps.net/homepage/safetylamphistory.htm. Retrieved 2011-12-11.
- ^ a b c "History of Miner's lamps". Welshminerslamps.com. http://www.welshminerslamps.com/info_lamp_history.shtml. Retrieved 2009-10-22.
- ^ a b Davies, Hunter (2004). George Stephenson. The History Press. ISBN 9780750937955.
- ^ "Mining lamp catalog". Geopedia.fr. http://www.geopedia.fr/minelamps-us-p0.htm. Retrieved 2009-10-22.
- ^ Smiles, Samuel (1862). Life of the Engineers. p. 116.
This article incorporates text from the public domain 1907 edition of The Nuttall Encyclopædia.
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