Oxyhydrogen
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1 Properties
2 History
3 Applications
3.1 Lighting
3.2 Oxyhydrogen torch
3.3 Automotive
4 Production
4.1 Water torch
4.2 Brown's design
5 See also
6 References
7 External links
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Oxyhydrogen is a mixture of hydrogen (H2) and oxygen (O2) gases, typically in a 2:1 molar ratio, the same proportion as water.[1] This gaseous mixture is used for torches for the processing of refractory materials.[citation needed]

Properties
Oxyhydrogen will combust when brought to its autoignition temperature. For a stoichiometric mixture at normal atmospheric pressure, autoignition occurs at about 570 °C (1065 °F).[2] The minimum energy required to ignite such a mixture with a spark is about 20 microjoules.[2] At normal temperature and pressure, oxyhydrogen can burn when it is between about 4% and 94% hydrogen by volume.[2]
When ignited, the gas mixture converts to water vapor and releases energy, which sustains the reaction: 241.8 kJ of energy (LHV) for every mole of H2 burned. The amount of heat energy released is independent of the mode of combustion, but the temperature of the flame varies.[1] The maximum temperature of about 2800 °C is achieved with a pure stoichiometric mixture, about 700 degrees hotter than a hydrogen flame in air.[3][4][5] When either of the gases are mixed in excess of this ratio, or when mixed with an inert gas like nitrogen, the heat must spread throughout a greater quantity of matter and the temperature will be lower.[1]

History
William Nicholson (chemist) was the first to decompose water into its component gases using electricity in 1800.

Applications
Automotive
See also: water-fuelled car, hydrogen fuel enhancement, Conservation of energy, and Electrolysis of water#Efficiency
Oxyhydrogen is often mentioned in conjunction with devices that claim to increase automotive engine efficiency or to operate a car using water as a fuel. Claims of water as fuel violate the Laws of thermodynamics. Claims of large increases in engine efficiency also violate the Laws of thermodynamics, although the US DOT reports that in "limited laboratory testing a hydrogen injection system installed on an older diesel truck engine operated at a series of constant speeds showed a 4 percent reduction in fuel use and a 7 percent reduction in particulate emissions".[8] The DOT also states that the hydrogen is supplied via electrolysis using the engine’s alternator or 12/24-volt electrical system.[8]