View source for Physics:Hydrox (breathing gas)

{{short description| Breathing gas mixture experimentally used for very deep diving }}
'''Hydrox''', a gas mixture of [[Chemistry:Hydrogen|hydrogen]] and [[Chemistry:Oxygen|oxygen]], is occasionally used as an experimental [[Chemistry:Breathing gas|breathing gas]] in very deep diving.<ref>{{Cite web |last=InDEPTH |date=2020-03-04 |title=Playing with Fire: Hydrogen as a Diving Gas |url=https://gue.com/blog/playing-with-fire-hydrogen-as-a-diving-gas/ |access-date=2023-09-08 |website=InDepth |language=en-US}}</ref><ref name="N=1" >{{Cite web |last=InDEPTH |date=2023-05-31 |title=N=1: The Inside Story of the First-Ever Hydrogen CCR Dive |url=https://gue.com/blog/n1-the-inside-story-of-the-first-ever-h2-ccr-dive/ |access-date=2023-09-08 |website=InDepth |language=en-US}}</ref> It allows divers to descend several hundred metres.<ref name="Fife 1979" /><ref name=uhms33>{{cite journal |author=Brauer RW (ed). |title=Hydrogen as a Diving Gas. |journal=33rd Undersea and Hyperbaric Medical Society Workshop. |issue=UHMS Publication Number 69(WS–HYD)3–1–87 |publisher=[[Organization:Undersea and Hyperbaric Medical Society|Undersea and Hyperbaric Medical Society]] |year=1985 |pages=336 pages |url=http://archive.rubicon-foundation.org/4862 |access-date=2008-09-15 |archive-url=https://web.archive.org/web/20110410225311/http://archive.rubicon-foundation.org/4862 |archive-date=2011-04-10 |url-status=usurped }}</ref><ref name=FOA1984>{{cite journal |author=Ornhagen H |title=Hydrogen-Oxygen (Hydrox) breathing at 1.3 MPa |journal=National Defence Research Institute |volume=FOA Rapport C58015-H1 |issn=0347-7665 |year=1984 }}</ref> Hydrox has been used experimentally in surface supplied, saturation, and scuba diving, both on open circuit and with closed circuit rebreathers.<ref name="Menduno 2023" />

Precautions are necessary when using hydrox, since mixtures containing more than  four percent of oxygen in hydrogen are explosive if ignited. Hydrogen is the lightest [[Physics:Gas|gas]] (half the weight of [[Chemistry:Helium|helium]]) but still has a slight narcotic potential and may cause [[Chemistry:Hydrogen narcosis|hydrogen narcosis]].<ref name=uhms33/><ref name=FOA1984/> Also like nitrogen, it appears to mitigate the symptoms of high pressure nervous syndrome (HPNS) on deep bounce dives, but reduces the density of the gas, unlike nitrogen.<ref name="Menduno 2023" />

==History==
Although the first reported use of hydrogen seems to be [[Biography:Antoine Lavoisier|Antoine Lavoisier]] (1743–1794) experimenting on guinea pigs, the actual first uses of this gas in diving are usually attributed to trials by the Swedish engineer, Arne Zetterström in 1945.<ref name=FOA1984/>

Zetterström showed that hydrogen was perfectly usable to great depths. Following a fault in using the surface equipment, he died during a demonstration dive. The study of hydrogen was not resumed until several years later by the United States Navy and by the Compagnie maritime d'expertises (Comex), initially during their Hydra I and Hydra II experiments, in 1968 and 1969.<ref>[http://www.comex.fr/fileadmin/telechargement/Comex_4_us_web.pdf Comex keeps up the High Pressure, Comex Magazine] {{webarchive|url=https://web.archive.org/web/20110718202455/http://www.comex.fr/fileadmin/telechargement/Comex_4_us_web.pdf |date=2011-07-18 }}</ref> Comex subsequently developed procedures allowing dives between {{convert|500 and 700|m|ft|0|abbr=on}} in depth, while breathing gas mixtures based on hydrogen, called hydrox (hydrogen-oxygen) or [[Physics:Hydreliox|hydreliox]] (hydrogen-helium-oxygen).<ref name="Rostain et al 1988"/>

=== Memorial dives ===

In July 2012, after about a year of preparation and planning, members of the Swedish Historical Diving Society and the Royal Institute of Technology Diving Club, performed a series of hydrox dives in memory of Arne Zetterström, who was accidentally killed during the ascent from his record dive using hydrox in August 1945. The memorial dives were performed using the same breathing mixture of 96% hydrogen and 4% oxygen as was developed and tested by Zetterström in the 1940s. The dives were made to a depth of {{convert|40|m|0}}, just deep enough to be able to use the oxygen-lean gas mixture. Project Leader Ola Lindh commented that in order to repeat Zetterström's record the team would need to make a dive to {{convert|160|m|ft|0}}, and even today a dive to that depth requires planning and equipment beyond the capabilities of most divers.<ref name="Clarke 2021" />

=== Experimental rebreather dive ===
A 230&nbsp;m hydrox dive in the Pearse Resurgence in New Zealand was made on 14 February 2023 by Richard Harris, using a Megalodon rebreather.<ref name="N=1" /> This dive is estimated to be the 54th reported experimental hydrogen dive conducted in the last 80 years by military, commercial and technical divers, and the first reported hydrogen dive using a rebreather. Two Megalodon rebreathers connected at the bailout valve were used for the dive. One with [[Physics:Trimix (breathing gas)|trimix]] diluent (O<sub>2</sub>, N<sub>2</sub>, He), the other with [[Physics:Hydreliox|hydreliox]] (O<sub>2</sub>, H<sub>2</sub>, He). It was also the first hydrogen diluent dive in a cave.<ref name="Menduno 2023" />

==Use==
Hydrox may be used for combating high pressure nervous syndrome (HPNS), commonly occurring during very deep bounce dives.<ref name=hpns>{{cite journal |last=Hunger Jr |first=W. L. |author2=P. B. Bennett. |title=The causes, mechanisms and prevention of the high pressure nervous syndrome |journal=Undersea Biomed. Res. |volume=1 |issue=1 |pages=1–28 |date=1974 |issn=0093-5387 |oclc=2068005 |pmid=4619860 |url=http://archive.rubicon-foundation.org/2661 |access-date=2008-09-15 |archive-url=https://web.archive.org/web/20101225053451/http://archive.rubicon-foundation.org/2661 |archive-date=2010-12-25 |url-status=usurped }}</ref> and as a low density breathing gas to minimise work of breathing at extreme depths.

The COMEX experimental series culminated in a simulated dive to {{convert|701|m|ft}}, by Théo Mavrostomos on 20 November 1990 at Toulon, during the COMEX Hydra X decompression chamber experiments. This dive made him "the deepest diver in the world".<ref name="pmid7742710">{{cite journal |vauthors=Lafay V, Barthelemy P, Comet B, Frances Y, Jammes Y |title=ECG changes during the experimental human dive HYDRA 10 (71 atm/7,200 kPa) |journal=Undersea Hyperb Med |volume=22 |issue=1 |pages=51–60 |date=March 1995 |pmid=7742710 |url=http://archive.rubicon-foundation.org/2203 |archive-url=https://web.archive.org/web/20090116042348/http://archive.rubicon-foundation.org/2203 |url-status=usurped |archive-date=January 16, 2009 |access-date=2008-09-15}}</ref>

==Biochemical decompression==
The United States Navy has evaluated the use of [[Biology:Gut flora|intestinal bacteria]] to speed decompression from hydrox diving.<ref name="pmid11908695">{{cite journal |author=Ball R |title=Biochemical decompression of hydrogen by naturally occurring bacterial flora in pigs: what are the implications for human hydrogen diving? |journal=Undersea Hyperb Med |volume=28 |issue=2 |pages=55–6 |year=2001 |pmid=11908695 |url=http://archive.rubicon-foundation.org/2421 |archive-url=https://web.archive.org/web/20090116042359/http://archive.rubicon-foundation.org/2421 |url-status=usurped |archive-date=January 16, 2009 |access-date=2008-09-15}}</ref><ref name="pmid11908700">{{cite journal |vauthors=Kayar SR, Fahlman A |title=Decompression sickness risk reduced by native intestinal flora in pigs after H2 dives |journal=Undersea Hyperb Med |volume=28 |issue=2 |pages=89–97 |year=2001 |pmid=11908700 |url=http://archive.rubicon-foundation.org/2373 |archive-url=https://web.archive.org/web/20081122051954/http://archive.rubicon-foundation.org/2373 |url-status=usurped |archive-date=November 22, 2008 |access-date=2008-09-15}}</ref><ref name=andreas>{{cite journal |author=Fahlman, A |year=2000 |title=On the Physiology of Hydrogen Diving and Its Implication for Hydrogen Biochemical Decompression |journal=PhD Thesis. Carleton University, Ottawa, ON, Canada. |url=http://archive.rubicon-foundation.org/6579 |archive-url=https://web.archive.org/web/20090116042504/http://archive.rubicon-foundation.org/6579 |url-status=usurped |archive-date=January 16, 2009 |access-date=2008-09-15 }}</ref>

==See also==
*{{annotated link|Chemistry:Breathing gas}}
**{{annotated link|Chemistry:Argox}}
**{{annotated link|Physics:Heliox}}
**{{annotated link|Physics:Hydreliox}}
**{{annotated link|Chemistry:Nitrox}}
**{{annotated link|Physics:Trimix (breathing gas)|Trimix}}
*{{annotated link|Chemistry:Gas blending}}

==References==
{{reflist|refs=

<ref name="Clarke 2021" >{{cite web |url=https://johnclarkeonline.com/2021/03/07/hydrogen-in-diving-the-good-the-bad-the-ugly/ |title=Hydrogen Diving: The Good, The Bad, the Ugly |date=7 March 2021 |first=John |last=Clarcke |website=johnclarkeonline.com |access-date=7 October 2023 }}</ref>

<ref name="Rostain et al 1988" >{{cite journal |last=Rostain |first=J. C. |author2=M. C. Gardette-Chauffour |author3=C. Lemaire |author4= R. Naquet.  |title=Effects of a H2-He-O2 mixture on the HPNS up to 450 msw |journal=Undersea Biomed. Res. |volume=15 |issue=4 |pages=257–70 |date=1988 |issn=0093-5387 |oclc=2068005 |pmid=3212843 }}</ref>

<ref name="Fife 1979" >{{cite report |first=William Paul |last=Fife |title=The use of Non-Explosive mixtures of hydrogen and oxygen for diving |volume=TAMU-SG-79-201 |publisher=Texas A&M University Sea Grant |date=1979 }}</ref>

<ref name="Menduno 2023" >{{cite web |url=https://gue.com/blog/hydrogen-dreamin/ |title=Hydrogen, At Last? |website=InDepth |publisher=GUE |first=Michael |last=Menduno |date=1 March 2023 |access-date=8 October 2023 }}</ref>

}}

==External links==
*[https://web.archive.org/web/20071013071223/http://www.comex.fr/suite/ceh/histo/historique%20CEH%20anglais.pdf COMEX Hydra - Hyperbaric Experimental Centre]
*[http://www.mejeme.com/dive/articles/mixhistory.htm Diving With Gas Mixes Other Than Air, Larry "Harris" Taylor]
*[https://web.archive.org/web/20080914174633/http://www.techdiver.ws/exotic_gases.shtml#3.1 Fact sheet and links]


[[Category:Breathing gases]]
[[Category:Hydrogen technologies]]

{{Sourceattribution|Hydrox (breathing gas)}}