Hydrox (breathing gas)

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Hydrox, a gas mixture of hydrogen and oxygen, is occasionally used as an experimental breathing gas in very deep diving. [1] [2] It allows divers to descend several hundred metres. [3] [4] [5] Hydrox has been used experimentally in surface supplied, saturation, and scuba diving, both on open circuit and with closed circuit rebreathers. [6]

Contents

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 gas (one quarter the mass of helium) but still has a slight narcotic potential and may cause hydrogen narcosis. [4] [5] 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. [6]

History

Although the first reported use of hydrogen seems to be 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. [5]

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. [7] Comex subsequently developed procedures allowing dives between 500 and 700 m (1,640 and 2,297 ft) in depth, while breathing gas mixtures based on hydrogen, called hydrox (hydrogen-oxygen) or hydreliox (hydrogen-helium-oxygen). [8]

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 40 metres (131 ft), 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 160 metres (525 ft), and even today a dive to that depth requires planning and equipment beyond the capabilities of most divers. [9]

Experimental rebreather dive

A 230 m hydrox dive in the Pearse Resurgence in New Zealand was made on 14 February 2023 by Richard Harris, using a Megalodon rebreather. [2] 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 trimix diluent (O2, N2, He), the other with hydreliox (O2, H2, He). It was also the first hydrogen diluent dive in a cave. [6]

Use

Hydrox may be used for combating high pressure nervous syndrome (HPNS), commonly occurring during very deep bounce dives. [10] 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 701 metres (2,300 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". [11]

Biochemical decompression

The United States Navy has evaluated the use of intestinal bacteria to speed decompression from hydrox diving. [12] [13] [14]

See also

Related Research Articles

Nitrox refers to any gas mixture composed of nitrogen and oxygen. This includes atmospheric air, which is approximately 78% nitrogen, 21% oxygen, and 1% other gases, primarily argon. In the usual application, underwater diving, nitrox is normally distinguished from air and handled differently. The most common use of nitrox mixtures containing oxygen in higher proportions than atmospheric air is in scuba diving, where the reduced partial pressure of nitrogen is advantageous in reducing nitrogen uptake in the body's tissues, thereby extending the practicable underwater dive time by reducing the decompression requirement, or reducing the risk of decompression sickness.

<span class="mw-page-title-main">Nitrogen narcosis</span> Reversible narcotic effects of respiratory nitrogen at elevated partial pressures

Narcosis while diving is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain gases at high partial pressure. The Greek word νάρκωσις (narkōsis), "the act of making numb", is derived from νάρκη (narkē), "numbness, torpor", a term used by Homer and Hippocrates. Narcosis produces a state similar to drunkenness, or nitrous oxide inhalation. It can occur during shallow dives, but does not usually become noticeable at depths less than 30 metres (98 ft).

<span class="mw-page-title-main">Trimix (breathing gas)</span> Breathing gas consisting of oxygen, helium and nitrogen

Trimix is a breathing gas consisting of oxygen, helium and nitrogen and is used in deep commercial diving, during the deep phase of dives carried out using technical diving techniques, and in advanced recreational diving.

Heliox is a breathing gas mixture of helium (He) and oxygen (O2). It is used as a medical treatment for patients with difficulty breathing because this mixture generates less resistance than atmospheric air when passing through the airways of the lungs, and thus requires less effort by a patient to breathe in and out of the lungs. It is also used as a breathing gas diluent for deep ambient pressure diving as it is not narcotic at high pressure, and for its low work of breathing.

<span class="mw-page-title-main">Decompression sickness</span> Disorder caused by dissolved gases forming bubbles in tissues

Decompression sickness is a medical condition caused by dissolved gases emerging from solution as bubbles inside the body tissues during decompression. DCS most commonly occurs during or soon after a decompression ascent from underwater diving, but can also result from other causes of depressurisation, such as emerging from a caisson, decompression from saturation, flying in an unpressurised aircraft at high altitude, and extravehicular activity from spacecraft. DCS and arterial gas embolism are collectively referred to as decompression illness.

<span class="mw-page-title-main">Deep diving</span> Underwater diving to a depth beyond the norm accepted by the associated community

Deep diving is underwater diving to a depth beyond the norm accepted by the associated community. In some cases this is a prescribed limit established by an authority, while in others it is associated with a level of certification or training, and it may vary depending on whether the diving is recreational, technical or commercial. Nitrogen narcosis becomes a hazard below 30 metres (98 ft) and hypoxic breathing gas is required below 60 metres (200 ft) to lessen the risk of oxygen toxicity.

<span class="mw-page-title-main">Breathing gas</span> Gas used for human respiration

A breathing gas is a mixture of gaseous chemical elements and compounds used for respiration. Air is the most common and only natural breathing gas, but other mixtures of gases, or pure oxygen, are also used in breathing equipment and enclosed habitats. Oxygen is the essential component for any breathing gas. Breathing gases for hyperbaric use have been developed to improve on the performance of ordinary air by reducing the risk of decompression sickness, reducing the duration of decompression, reducing nitrogen narcosis or allowing safer deep diving.

<span class="mw-page-title-main">Saturation diving</span> Diving decompression technique

Saturation diving is diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas used. It is a diving mode that reduces the number of decompressions divers working at great depths must undergo by only decompressing divers once at the end of the diving operation, which may last days to weeks, having them remain under pressure for the whole period. A diver breathing pressurized gas accumulates dissolved inert gas used in the breathing mixture to dilute the oxygen to a non-toxic level in the tissues, which can cause potentially fatal decompression sickness if permitted to come out of solution within the body tissues; hence, returning to the surface safely requires lengthy decompression so that the inert gases can be eliminated via the lungs. Once the dissolved gases in a diver's tissues reach the saturation point, however, decompression time does not increase with further exposure, as no more inert gas is accumulated.

<span class="mw-page-title-main">Diving medicine</span> Diagnosis, treatment and prevention of disorders caused by underwater diving

Diving medicine, also called undersea and hyperbaric medicine (UHB), is the diagnosis, treatment and prevention of conditions caused by humans entering the undersea environment. It includes the effects on the body of pressure on gases, the diagnosis and treatment of conditions caused by marine hazards and how relationships of a diver's fitness to dive affect a diver's safety. Diving medical practitioners are also expected to be competent in the examination of divers and potential divers to determine fitness to dive.

High-pressure nervous syndrome is a neurological and physiological diving disorder which can result when a diver descends below about 500 feet (150 m) using a breathing gas containing helium. The effects experienced, and the severity of those effects, depend on the rate of descent, the depth and the percentage of helium.

Hydreliox is an exotic breathing gas mixture of hydrogen, helium, and oxygen. For the Hydra VIII mission at 50 atmospheres of ambient pressure, the mixture used was 49% hydrogen, 50.2% helium, and 0.8% oxygen.

Peter B. Bennett was the founder and a president and CEO of the Divers Alert Network (DAN), a non-profit organization devoted to assisting scuba divers in need. He was a professor of anesthesiology at Duke University Medical Center, and was the Senior Director of the Center for Hyperbaric Medicine and Environmental Physiology at Duke. Bennett is recognized as a leading authority on the effects of high pressure on human physiology.

<span class="mw-page-title-main">Edward D. Thalmann</span> American hyperbaric medicine specialist and decompression researcher

Capt. Edward Deforest Thalmann, USN (ret.) was an American hyperbaric medicine specialist who was principally responsible for developing the current United States Navy dive tables for mixed-gas diving, which are based on his eponymous Thalmann Algorithm (VVAL18). At the time of his death, Thalmann was serving as assistant medical director of the Divers Alert Network (DAN) and an assistant clinical professor in anesthesiology at Duke University's Center for Hyperbaric Medicine and Environmental Physiology.

In physiology, isobaric counterdiffusion (ICD) is the diffusion of different gases into and out of tissues while under a constant ambient pressure, after a change of gas composition, and the physiological effects of this phenomenon. The term inert gas counterdiffusion is sometimes used as a synonym, but can also be applied to situations where the ambient pressure changes. It has relevance in mixed gas diving and anesthesiology.

Equivalent narcotic depth (END) (historically also equivalent nitrogen depth) is used in technical diving as a way of estimating the narcotic effect of a breathing gas mixture, such as nitrox, heliox or trimix. The method is used, for a given breathing gas mix and dive depth, to calculate the equivalent depth which would produce about the same narcotic effect when breathing air.

Hydrogen narcosis is the psychotropic state induced by breathing hydrogen at high pressures. Hydrogen narcosis produces symptoms such as hallucinations, disorientation, and confusion, which are similar to hallucinogenic drugs. It can be experienced by deep-sea divers who dive to 300 m (1,000 ft) below sea level breathing hydrogen mixtures. However, hydrogen has far less narcotic effect than nitrogen and is very rarely used in diving. In tests of the effect of hydrogen narcosis, where divers dived to 500 m (1,600 ft) with a hydrogen–helium–oxygen (hydreliox) mixture containing 49% hydrogen, it was found that while the narcotic effect of hydrogen was detectable, the neurological symptoms of high-pressure nervous syndrome were only moderate.

<span class="mw-page-title-main">William Paul Fife</span> US Air Force officer and hyperbaric medicine researcher

Colonel William Paul Fife USAF (Ret) was a United States Air Force officer that first proved the feasibility for U.S. Air Force Security Service airborne Communications Intelligence (COMINT) collection and Fife is considered the "Father of Airborne Intercept". Fife was also a hyperbaric medicine specialist who was known for his pioneering research on pressurized environments ranging from high altitude to underwater habitats. Fife was a Professor Emeritus at Texas A&M University.

<span class="mw-page-title-main">Compagnie maritime d'expertises</span> French offshore diving contractor

COMEX is a French company specializing in engineering and deep diving operations, created in November 1961 by Henri-Germain Delauze and ran by him until his death in 2012.

References

  1. ↑ InDEPTH (2020-03-04). "Playing with Fire: Hydrogen as a Diving Gas". InDepth. Retrieved 2023-09-08.
  2. 1 2 InDEPTH (2023-05-31). "N=1: The Inside Story of the First-Ever Hydrogen CCR Dive". InDepth. Retrieved 2023-09-08.
  3. ↑ Fife, William Paul (1979). The use of Non-Explosive mixtures of hydrogen and oxygen for diving (Report). Vol. TAMU-SG-79-201. Texas A&M University Sea Grant.
  4. 1 2 Brauer RW (ed). (1985). "Hydrogen as a Diving Gas". 33rd Undersea and Hyperbaric Medical Society Workshop. (UHMS Publication Number 69(WS–HYD)3–1–87). Undersea and Hyperbaric Medical Society: 336 pages. Archived from the original on 2011-04-10. Retrieved 2008-09-15.{{cite journal}}: CS1 maint: unfit URL (link)
  5. 1 2 3 Ornhagen H (1984). "Hydrogen-Oxygen (Hydrox) breathing at 1.3 MPa". National Defence Research Institute. FOA Rapport C58015-H1. ISSN   0347-7665.
  6. 1 2 3 Menduno, Michael (1 March 2023). "Hydrogen, At Last?". InDepth. GUE. Retrieved 8 October 2023.
  7. ↑ Comex keeps up the High Pressure, Comex Magazine Archived 2011-07-18 at the Wayback Machine
  8. ↑ Rostain, J. C.; M. C. Gardette-Chauffour; C. Lemaire; R. Naquet. (1988). "Effects of a H2-He-O2 mixture on the HPNS up to 450 msw". Undersea Biomed. Res. 15 (4): 257–70. ISSN   0093-5387. OCLC   2068005. PMID   3212843.
  9. ↑ Clarcke, John (7 March 2021). "Hydrogen Diving: The Good, The Bad, the Ugly". johnclarkeonline.com. Retrieved 7 October 2023.
  10. ↑ Hunger Jr, W. L.; P. B. Bennett. (1974). "The causes, mechanisms and prevention of the high pressure nervous syndrome". Undersea Biomed. Res. 1 (1): 1–28. ISSN   0093-5387. OCLC   2068005. PMID   4619860. Archived from the original on 2010-12-25. Retrieved 2008-09-15.{{cite journal}}: CS1 maint: unfit URL (link)
  11. ↑ Lafay V, Barthelemy P, Comet B, Frances Y, Jammes Y (March 1995). "ECG changes during the experimental human dive HYDRA 10 (71 atm/7,200 kPa)". Undersea Hyperb Med. 22 (1): 51–60. PMID   7742710. Archived from the original on January 16, 2009. Retrieved 2008-09-15.{{cite journal}}: CS1 maint: unfit URL (link)
  12. ↑ Ball R (2001). "Biochemical decompression of hydrogen by naturally occurring bacterial flora in pigs: what are the implications for human hydrogen diving?". Undersea Hyperb Med. 28 (2): 55–6. PMID   11908695. Archived from the original on January 16, 2009. Retrieved 2008-09-15.{{cite journal}}: CS1 maint: unfit URL (link)
  13. ↑ Kayar SR, Fahlman A (2001). "Decompression sickness risk reduced by native intestinal flora in pigs after H2 dives". Undersea Hyperb Med. 28 (2): 89–97. PMID   11908700. Archived from the original on November 22, 2008. Retrieved 2008-09-15.{{cite journal}}: CS1 maint: unfit URL (link)
  14. ↑ Fahlman, A (2000). "On the Physiology of Hydrogen Diving and Its Implication for Hydrogen Biochemical Decompression". PhD Thesis. Carleton University, Ottawa, ON, Canada. Archived from the original on January 16, 2009. Retrieved 2008-09-15.{{cite journal}}: CS1 maint: unfit URL (link)
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