Compressed air

This article is about air under pressure. For canisters inaccurately marketed as "compressed air", see gas duster.

Compressed air is air kept under a pressure that is greater than atmospheric pressure. Compressed air in vehicle tyres and shock absorbers is commonly used for improved traction and reduced vibration. Compressed air is an important medium for transfer of energy in industrial processes, and is used for power tools such as air hammers, drills, wrenches, and others, as well as to atomize paint, to operate air cylinders for automation, and can also be used to propel vehicles. Brakes applied by compressed air made large railway trains safer and more efficient to operate. Compressed air brakes are also found on large highway vehicles.

Compressed air is used as a breathing gas by underwater divers. It may be carried by the diver in a high-pressure diving cylinder, or supplied from the surface at lower pressure through an air line or diver's umbilical.[1] Similar arrangements are used in breathing apparatus used by firefighters, mine rescue workers and industrial workers in hazardous atmospheres.

In Europe, 10 percent of all industrial electricity consumption is to produce compressed air—amounting to 80 terawatt hours consumption per year.[2][3]

Industrial use of piped compressed air for power transmission was developed in the mid-19th century; unlike steam, compressed air could be piped for long distances without losing pressure due to condensation. An early major application of compressed air was in the drilling of the Mont Cenis Tunnel in Italy and France in 1861, where a 600 kPa (87 psi) compressed air plant provided power to pneumatic drills, increasing productivity greatly over previous manual drilling methods. Compressed-air drills were applied at mines in the United States in the 1870s. George Westinghouse invented air brakes for trains starting in 1869; these brakes considerably improved the safety of rail operations.[4] In the 19th century, Paris had a system of pipes installed for municipal distribution of compressed air to power machines and to operate generators for lighting. Early air compressors were steam-driven, but in certain locations a trompe could directly obtain compressed air from the force of falling water.[5]

  1. ^ US Navy (1 December 2016). U.S. Navy Diving Manual Revision 7 SS521-AG-PRO-010 0910-LP-115-1921 (PDF). Washington, DC.: US Naval Sea Systems Command. Archived (PDF) from the original on 28 December 2016.
  2. ^ Leino, Raili (24 February 2009). "Paineilma hukkaa 15 hiilivoimalan tuotannon" (in Finnish). Archived from the original on 17 July 2011. Retrieved 24 February 2009.
  3. ^ "Compressed Air System Audits and Benchmarking Results from the German Compressed Air Campaign "Druckluft effizient"" (PDF). Archived from the original (PDF) on 2011-12-24.
  4. ^ Lance Day, Ian McNeil (ed.), Biographical Dictionary of the History of Technology, Routledge, 2002, ISBN 1134650205, p. 1294
  5. ^ Peter Darling (ed.), SME Mining Engineering Handbook, Third Edition Society for Mining, Metallurgy, and Exploration (U.S.) 2011, ISBN 0873352645, p. 705