Hydrox (breathing gas)

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]

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 atomic mass of helium or one half the molecular 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]

  1. ^ InDEPTH (2020-03-04). "Playing with Fire: Hydrogen as a Diving Gas". InDepth. Retrieved 2023-09-08.
  2. ^ InDEPTH (2023-05-31). "N=1: The Inside Story of the First-Ever Hydrogen CCR Dive". InDepth. Retrieved 2023-09-08.
  3. ^ Cite error: The named reference Fife 1979 was invoked but never defined (see the help page).
  4. ^ a b 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. ^ a b Ornhagen H (1984). "Hydrogen-Oxygen (Hydrox) breathing at 1.3 MPa". National Defence Research Institute. FOA Rapport C58015-H1. ISSN 0347-7665.
  6. ^ a b Cite error: The named reference Menduno 2023 was invoked but never defined (see the help page).