Oxyhydrogen
3132996
226082603
2008-07-16T19:20:10Z
Arthur Rubin
374195
Reverted edits by [[Special:Contributions/75.20.179.22|75.20.179.22]] ([[User talk:75.20.179.22|talk]]) to last version by ClueBot
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'''Oxyhydrogen''' is a mixture of [[hydrogen]] (H<sub>2</sub>) and [[oxygen]] (O<sub>2</sub>) gases, typically in a 2:1 [[Molar concentration|molar ratio]], the same proportion as water.<ref name="encyclopedia"/> This gaseous mixture is used for torches for the processing of [[refractory]] materials.{{Fact|date=May 2008}}
== 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).<ref name="NASA"/> The minimum energy required to ignite such a mixture with a spark is about 20 microjoules.<ref name="NASA"/> At normal temperature and pressure, oxyhydrogen can burn when it is between about 4% and 94% hydrogen by volume.<ref name="NASA">{{Cite book
| last = O'Connor
| first = Ken
| title = NASA Glenn Research Center Glenn Safety Manual
| chapter = Hydrogen
| chapterurl = http://smad-ext.grc.nasa.gov/gso/manual/chapter_06.pdf
}}</ref>
When ignited, the gas mixture converts to [[water vapor]] and [[heat of combustion|releases energy]], which sustains the reaction: 241.8 [[kJ]] of energy ([[lower heating value|LHV]]) for every [[Mole (unit)|mole]] of {{hydrogen|2}} burned. The amount of heat energy released is independent of the mode of combustion, but the [[flame temperature|temperature of the flame]] varies.<ref name="encyclopedia">1911 Encyclopedia. "Oxyhydrogen Flame". ([http://www.1911encyclopedia.org/Oxyhydrogen_Flame Available here] Accessed 2008-01-19.)</ref> The maximum temperature of about 2800 °C is achieved with a pure [[stoichiometric]] mixture, about 700 degrees hotter than a hydrogen flame in air.<ref>{{Cite web
| last = Calvert
| first = Dr. James B.
| title = Hydrogen
| work = University of Denver faculty page
| accessdate = 2008-04-05
| date = 2006-09-09
| url = http://mysite.du.edu/~jcalvert/phys/hydrogen.htm
}} "An air-hydrogen torch flame reaches 2045 °C, while an oxyhydrogen flame reaches 2660 °C."
</ref><ref>{{Cite web
| title = Adiabatic Flame Temperature
| work = The Engineering Toolbox
| accessdate = 2008-04-05
| url = http://www.engineeringtoolbox.com/adiabatic-flame-temperature-d_996.html
}} "Oxygen as Oxidizer: 3079 K, Air as Oxidizer: 2384 K"
</ref><ref>{{Cite web
| title = Temperature of a Blue Flame
| accessdate = 2008-04-05
| url = http://hypertextbook.com/facts/1998/JamesDanyluk.shtml
}} "Hydrogen in air: 2,400 K, Hydrogen in Oxygen: 3,080 K"</ref> 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.<ref name="encyclopedia">1911 Encyclopedia. "Oxyhydrogen Flame". ([http://www.1911encyclopedia.org/Oxyhydrogen_Flame Available here] Accessed 2008-01-19.)</ref>
==Applications - Historical==
[[Image:Limelight diagram.svg|thumb|[[Limelight]]s used an oxyhydrogen flame as a high-temperature heat source]]
===Lighting===
Many forms of oxyhydrogen [[lamp]]s have been described, such as the [[limelight]], which used an oxyhydrogen flame to heat a piece of [[lime]] to [[Black body|white hot]] [[incandescence]].<ref name="WT"/> Because of the explosiveness of the oxyhydrogen, limelights have been replaced by [[electric lighting]].
Oxyhydrogen has been used in working [[platinum]]<ref name="encyclopedia"/> because platinum could be melted (at a temperature of 1768.3 °C) only in an oxyhydrogen flame. These techniques have been superseded by the [[electric arc furnace]].
===Oxyhydrogen torch===
[[Image:Oxyhydrogen flame.JPG|thumb|A flame created by the combustion of the constituent gases in an oxyhydrogen mixture. The only byproduct is [[water (molecule)|water]]]]
An '''oxyhydrogen torch''' is an [[Oxy-fuel_welding_and_cutting#Hydrogen|oxy-gas torch]], which burns hydrogen (the [[fuel]]) with oxygen (the [[oxidizer]]). It is used for cutting and welding [[metal]]s, [[glass]], and [[thermoplastic]]s.<ref name="WT">{{citebook|title=Chemical Discovery and Invention in the Twentieth Century |author= William Augustus Tilden|publisher=Adamant Media Corporation |id=ISBN 0543916464 |pages=80|url=http://books.google.com/books?id=Qu-fYeT8UKoC&pg=PP133&dq=Oxyhydrogen&as_brr=3&ie=ISO-8859-1&output=html&sig=D64FMweelgSeG4jWFBQyjSBtajE}}</ref> An oxyhydrogen torch is used in the glass industry for "[[fire polishing]]"; slightly melting the surface of glass to remove scratches and dullness.{{Fact|date=May 2008}}
The oxyhydrogen flame begins a short distance from the torch tip; if the distance is great enough the torch tip can remain relatively cool.<ref name="GW">{{citebook|title=Brown's Gas Book 2 |author= George Wiseman|publisher=Eagle Research |id=ISBN 1895882192 |pages=59|url=http://books.google.com/books?id=HBCbAQAACAAJ&dq=1895882192}}</ref>
==Applications - Claimed==
===Automotive===
{{see also|water-fuelled car|hydrogen fuel enhancement}}
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.
Many of these claims, ''prima facie'', violate the [[Laws of thermodynamics]]. See [[Conservation of energy]] and [[Electrolysis of water#Efficiency|Electrolysis of water:Efficiency]].
==Production==
A pure stoichiometric mixture is most easily obtained by [[Electrolysis of water|water electrolysis]], which uses an [[electric current]] to dissociate the water molecules:
: electrolysis: 2 H<sub>2</sub>O → 2 H<sub>2</sub> + O<sub>2</sub>
: combustion: 2 H<sub>2</sub> + O<sub>2</sub> → 2 H<sub>2</sub>O
The energy required to generate the oxyhydrogen always exceeds the energy released by combusting it. (See [[Electrolysis of water#Efficiency|Electrolysis of water:Efficiency]]).
===Water torch===
[[Image:Browns gas bubbler.png|thumb|right|A bubbler apparatus used to mitigate potential flashback.<ref name="US patent 4014777">{{US patent reference
| number = 4014777
| y = 1977
| m = 03
| d = 29
| inventor = Yull Brown
| title = Welding
}}</ref>]]
A '''water torch''' is a kind of oxyhydrogen torch, that is fed by oxygen and hydrogen generated on demand by [[water electrolysis]]. The device avoids the need for bottled oxygen and hydrogen, and requires electricity. Some models of water torches mix the two gases immediately after production (vs. the torch tip) making the gas mixture more accurate.<ref name="US patent 4014777"/> This electrolyzer design is referred to as "common-ducted",<ref name="GW"/> and the first was invented by William A. Rhodes in 1966.<ref name="WR">{{US patent reference
| number = 3262872
| y = 1966
| m = 07
| d = 26
| inventor = William Rhodes
| title = Generator Patent
}}</ref> Water torches must be designed to mitigate [[Flashback (welding)|flashback]] by strengthening the electrolytic chamber. Use of an intermediary water [[Oil bubbler|bubbler]] eliminates potential electrolyzer damage from flashback, with a dry [[flashback arrestor]] being ineffective due to flame velocity. The bubbler is connected directly in series with the output gas. A water bubbler is sometimes referred to as a wet flashback arrestor, and effectively captures any remaining [[electrolyte]] in the output gas. Suitable electrolytes include [[Sodium hydroxide|sodium]] or [[potassium hydroxide]], and other salts that ionize well.<ref name="GW"/> Also "the electrolyzer system must be of high enough pressure to keep the gas velocity at the nozzle above the combustion velocity of the flame, or the system will backfire".<ref name="GW"/>
===Brown's design===
[[Image:Seriescellelectrolyzerdesign.png|thumb|right|The series cell design by Yull Brown.<ref name="US patent 4014777"/>]]
Oxyhydrogen gas produced in a common-ducted electrolyzer has been referred to as "Brown's gas",{{Fact|date=May 2008}} after Yull Brown who received a utility patent for a series cell common-ducted electrolyzer in 1977 and 1978 (the term "Brown's gas" is not used in his patents, but "a mixture of oxygen and hydrogen" is referenced).<ref name="US patent 4014777"/><ref name="Brown2">{{US patent reference
| number = 4081656
| y = 1978
| m = 03
| d = 28
| inventor = Yull Brown
| title = Arc-assisted oxy/hydrogen welding
}}</ref>
Brown's torches also used an electric arc to increase the temperature of the flame (called [[Atomic hydrogen welding|atomic welding]]).<ref name="US patent 4014777"/>
== See also ==
* [[Fuel cell]]
* [[Electrolysis]]
* [[Ruggero Santilli]]
* [[Pseudoscience]]
== References ==
{{Reflist|2}}
{{1911}}
== External links ==
* [http://www.key-to-steel.com/Articles/Art75.htm Oxyhydrogen Welding]
[[Category:Fire]]
[[Category:Chemical processes]]
[[Category:Electrolysis|*]]
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[[Category:Hydrogen technologies]]
[[Category:Hydrogen production]]
[[Category:Fuels]]
[[Category:Renewable resources]]
[[Category:Sustainable technologies]]
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