Davy lamp

Davy lamp (drawing)
A type of Davy lamp with apertures for gauging flame height

The Davy lamp is a safety lamp for use in flammable atmospheres, consisting of a wick lamp with the flame enclosed inside a mesh screen. It was invented in 1815[1] by Sir Humphry Davy. It originally burned a heavy vegetable oil. It was created for use in coal mines, to reduce the danger of explosions due to the presence of methane and other flammable gases, called firedamp or minedamp.

Sir Humphry Davy had discovered that a flame enclosed inside a mesh of a certain fineness cannot ignite firedamp. The screen acts as a flame arrestor; air (and any firedamp present) can pass through the mesh freely enough to support combustion, but the holes are too fine to allow a flame to propagate through them and ignite any firedamp outside the mesh.

The news about Davy's lamp was made public at a Royal Society meeting in Newcastle on 3 November 1815, and the paper describing the lamp was formally presented on 9 November.[2] For it, Davy was awarded the Society's Rumford Medal. (Davy's invention had been preceded by that of William Reid Clanny, an Irish doctor at Bishopwearmouth, who had also read a paper to the Royal Society in May 1813. The more cumbersome Clanny safety lamp was successfully tested at Herrington Mill and he too won medals, from the Royal Society of Arts).[3] The first trial of a Davy lamp with a wire sieve was at Hebburn Colliery on 9 January 1816.[4]

Gas detection

The lamp also provided a test for the presence of gases. If flammable gas mixtures were present, the flame of the Davy lamp burned higher with a blue tinge. Lamps were equipped with a metal gauge (photo, right) to measure the height of the flame. Miners could place the safety lamp close to the ground to detect gases, such as carbon dioxide, that are denser than air and so could collect in depressions in the mine; if the mine air was oxygen-poor (asphyxiant gas), the lamp flame would be extinguished (black damp or chokedamp). A methane-air flame is extinguished at about 17% oxygen content (which will still support life) so the lamp gave an early indication of an unhealthy atmosphere allowing the miners to get out before they died of asphyxiation.

Accident rate

The introduction of the Davy lamp led to an increase in mine accidents, as the lamp encouraged the working of mines and parts of mines that had previously been closed for safety reasons.[5]

Men continued to work in conditions which were unsafe due to the presence of methane gas. Although extractor ventilation fans should have been installed to reduce the concentration of methane in the air, this would have been expensive for mine owners, and thus such fans were not installed. A legal requirement for minimum air-quality standards eventually led to the introduction of more ventilation. The lamps also had to be provided by the miners themselves, not the owners, as traditionally the miners bought their own candles from the company store.

Another reason for the increase in accidents was the unreliability of the lamps themselves. The bare gauze was easily damaged, and once just a single wire broke or rusted away, the lamp became unsafe. Even when new and clean, illumination from the safety lamps was very poor, and the problem was not fully resolved until electric lamps became widely available in the late 19th century.

Modern lamps

A modern day equivalent of the Davy Lamp is the Protector Garforth GR6S flame safety lamp which is used for firedamp testing in all UK coal mines. A modified version of this lamp has been used in the Olympic Flame torch relays. It was used in the relays for the Sydney, Athens, Turin, Beijing, Vancouver and Singapore Youth Olympic Games. It was also used for the Special Olympics Shanghai, Pan American and Central African games and for the London 2012 Summer Olympics relay.[6]

Lamps are still made in Eccles, Greater Manchester,[7] in Aberdare, South Wales[8] and in Kolkata, India.[9]

See also

References

  1. ↑ Brief History of the Miner's Flame Safety Lamp at minerslamps.net. Accesses 7 July 20121
  2. ↑ Davy, H. (1816). "On the Fire-Damp of Coal Mines, and on Methods of Lighting the Mines So as to Prevent Its Explosion". Philosophical Transactions of the Royal Society of London 106: 1. doi:10.1098/rstl.1816.0001.
  3. ↑ Knight, David (1992) Humphry Davy: Science and Power. Cambridge, Cambridge University Press, (Chapter 8: The Safety Lamp), ISBN 0-631-16816-8
  4. ↑ Thompson, Roy (2004). Thunder underground: Northumberland mining disasters, 1815-1865. Landmark. p. 121. ISBN 9781843061694. Retrieved 8 January 2013.
  5. ↑ Christopher Lawrence, The power and the glory: Humphry Davy and Romanticism, reference in Andrew Cunningham and Nicholas Jardine, Romanticism and the Sciences Cambridge: University Press, 1990 page 224
  6. ↑ Peck, Tom Let the flames begin: Beckham gets the home fires burning The Independent, 19 May 2012. Accessed 12 July 2012
  7. ↑ Protector Safety Lamp Company, Eccles at Heritage Photo Archive. Accessed 7 July 2012
  8. ↑ Aberdare – Cambrian Lamp Works – E. Thomas & Williams at Rhondda Cynon Taf Library Service. Accessed 7 July 2012
  9. ↑ J. K. Dey and Sons Official website. Accessed 7 July 2012

External links

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Further reading