+ Reply to Thread
Page 1 of 2 1 2 LastLast
Results 1 to 10 of 17

Thread: Use of ArgOx for decompression

  1. #1
    RBW Member deep4ac is an unknown quantity at this point deep4ac's Avatar
    Join Date
    Jul 2012
    Location
    Aachen, Germany & Crete, Greece
    Posts
    3
    Hyperion

    Question Use of ArgOx for decompression

    Hi folks,

    I do have a question regarding your experiences and theoretical thoughts on the use of ArgOx (Argon+Oxygen mixes) for improvement of decompression.

    We know from different sources that the solubility of Argon in fat is expected about 2,25 times the one of nitrogen. Other experiments with mice have shown narcosis potential of about 3 times of nitrogen.
    Anyway, last weekend our team has tried the use of Argox50 (50% Oxygen +50% Argon) on decompression (only 35 mins) from 21m upwards without noticing any strong effects of higher narcosis in real life. Work of breathing also seemed to be at reasonable levels without increasing risks of CO2 hits.

    So far so good. As you may imagine our idea behind using Argon for decompression is eliminating any inert gases with which our tissues are already loaded (but O2) from the breathing mix. This is to increase the Delta partial pressures of gases in the tissues and in the breathing gas to speed up off-gasing for faster/safer decompression. Replacing EAN50 or TX50/25 with Argox50 seemed to be the best way to introduce ArgOx in decompression planning as it’s then used widely in the range where it still makes sense from narcosis point of view.

    Now I want to know from you if you have any practical experience or theoretical thoughts on the use of Argon. This would especially be interesting when it comes to the calculation of decompression times. Our first idea was to modify Bühlman with gradient factors and to introduce argon besides nitrogen and oxygen as a third gas. Calculation of factors a and b is in this case would be something that I would be interested in your thoughts. Would it be an safe alternative to just “skip” Argon calculation, use EAN50 for calculation and profit from additional safety margins or do I miss something (e.g. the argon-load itself creating potential risk)? Is it safe (probably not) to just skip argon calculation and use only 50%O2 without any other gas in the deco calculation as argon on-gasing would be so slow it would practically not contribute to decompression calculation as other factors will be leading the calculation? What about isobaric counter diffusion when using Argon?

    I’m looking forward to a good discussion.

    Thanks and best regards

    Michael

  2. #2
    digital nomad GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM is a glorious beacon of light GKAM's Avatar
    Join Date
    May 2005
    Location
    GR from ATH, living mostly in MUC
    Posts
    368
    Hyperion pSCR

    IDA71, HomeBuilts, Ray, RGU/FM

    Re: Use of ArgOx for decompression

    Καλησπέρα!

    AFAIK, the only use of ArgOx in decompression was in a series of experimental dives by Hannes Keller a long time ago. Looking at your initial post something tells me you've been reading up on these.

    Everything is documented in a JAP publication but I doubt this approach has seen much application in the real world. (KELLER, H., AND A. A. BUEHLMANN. Deep diving and short decompression by breathing mixed gases. J. Appl. Physiol. 20(6) :1267-1270.)

    /GKAM

  3. #3
    RBW Member ssk is an unknown quantity at this point ssk's Avatar
    Join Date
    Sep 2008
    Location
    Genoa, Italy
    Posts
    104
    Dolphin, Meg 2.7, Pathfinder,

    LAR VI, Fenzy PO68, Homebuilt

    Re: Use of ArgOx for decompression

    I've used normossic Argox several times at the end of nineties in OC dives, to optimise the 6m deco stop. We started using it as a gas switch in alternative to air. Never had any problem.
    Cheers,
    D.

  4. #4
    SBOD Pilot Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish's Avatar
    Join Date
    Jun 2013
    Location
    Perth, Western Australia
    Posts
    837
    AP Classic SBOD v. AV1c

    Re: Use of ArgOx for decompression

    In a similar vein to switching early from trimix to nitrox to flush the helium out, I'd be concerned about the potential for an ICD induced bend. Possibly less an issue than helium to nitrogen due to the easy solubility of argon compared to nitrogen, but if I were playing the guinea pig with this I'd want a soft change between mix gases rather than BLAM no helium, many argon.

    I suspect that Argon would introduce its own deco issues and that it would be risky to just ignore it in your Buhlmann tables. A third gas seems sensible. Calculating coefficients for a new gas can't be a new thing, there must be some data and/or techniques out there already.

  5. #5
    RBW Member horaceanddumpling is an unknown quantity at this point horaceanddumpling's Avatar
    Join Date
    Aug 2012
    Location
    Sydney
    Posts
    50
    15.5

    Re: Use of ArgOx for decompression

    Let me get this right...
    Your experimenting on yourselves.
    Your trading a known risk for an unknown risk.
    What's the return on that ? Half hours deco ?

    Why?



  6. #6
    SBOD Pilot Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish is a glorious beacon of light Captain Starfish's Avatar
    Join Date
    Jun 2013
    Location
    Perth, Western Australia
    Posts
    837
    AP Classic SBOD v. AV1c

    Re: Use of ArgOx for decompression

    Good point.

    Someone needs a shed full of backpackers (watch Wolf Creek if you don't get the reference) to use as bend-bait guinea pigs.

  7. #7
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
    Join Date
    Feb 2005
    Location
    Vancouver Island BC Canada
    Posts
    3,854
    Hollis Prism 2, Megalodon

    CCR Instructor Trainer

    Re: Use of ArgOx for decompression

    Quote Originally Posted by horaceanddumpling  View Original Post
    Let me get this right...
    Your experimenting on yourselves.
    Your trading a known risk for an unknown risk.
    What's the return on that ? Half hours deco ?

    Why?



    So if no one ever did that we would never see under the water, fly a plane, or drive a car.
    For some people diving is more that just following their computer.
    Cheers,

    Dave....

    www.wedivebc.com

  8. #8
    RBW Member jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner is a glorious beacon of light jturner's Avatar
    Join Date
    Mar 2011
    Location
    East Midlands, UK
    Posts
    135
    APD Evolution

    Re: Use of ArgOx for decompression

    Quote Originally Posted by wedivebc  View Original Post
    So if no one ever did that we would never see under the water, fly a plane, or drive a car.
    For some people diving is more that just following their computer.
    That's true but there's a small matter of benefits to be gained verses risk. This looks like additional risk for minimal benefit - chance the deco risks to save a few minutes at best. Depending on how much risk you like in your diving, I guess you can draw the line where you like but to compare this with those pioneers who were inventing aircraft or cars is a little bit off the mark IMHO!

  9. #9
    RBW Member deep4ac is an unknown quantity at this point deep4ac's Avatar
    Join Date
    Jul 2012
    Location
    Aachen, Germany & Crete, Greece
    Posts
    3
    Hyperion

    Re: Use of ArgOx for decompression

    Quote Originally Posted by jturner  View Original Post
    That's true but there's a small matter of benefits to be gained verses risk. This looks like additional risk for minimal benefit - chance the deco risks to save a few minutes at best. Depending on how much risk you like in your diving, I guess you can draw the line where you like but to compare this with those pioneers who were inventing aircraft or cars is a little bit off the mark IMHO!
    Hi guys,

    thanks for your opinions. And... all this is true. I think there are ways to do the empirical part of this safely, with small incremental step, doppler tests, etc. etc. But this shouldn't be the first thing to discuss before having the theoretical background and expeeriences gained so far on the table. That's why I started the discussion.

    So I would be happy if we bring back the focus to the initial questions and assume that people can take this decision on taking the risk their own or would ask again on your opinion on this in a second step.

    Looking forward to more fruitful discussion.

    Thanks and best regards

    Michael

  10. #10
    RBW Member djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd is a splendid one to behold djd's Avatar
    Join Date
    Feb 2009
    Location
    Florida, USA
    Posts
    57

    Re: Use of ArgOx for decompression

    I suspect that a trimix to argon-oxygen switch during decompression from a bounce dive will be a disadvantage rather than an advantage compared to a trimix to nitrox switch.

    If you introduce a new inert gas during decompression, it will be taken up into body tissues and contribute to the subsequent decompression obligation. One particularly relevant demonstration of this was by Pilamanis et al (2003) who compared staged decompression from sea level (air saturation) to altitude breathing either oxygen or argon-oxygen and found higher DCS incidence with argon-oxygen than oxygen decompression.

    The usual premise for a trimix (or heliox) to nitrox gas switch during decompression from bounce dives is that faster washout of helium than uptake of nitrogen results in a decompression advantage. In fact, the scant experimental evidence is conflicting. The 12 relevant dives reported by Buhlman weakly (not statistically significant) indicate a helium-to-nitrogen inert gas switch during decompression reduces the incidence of DCS while the 48 relevant US Navy dives reported by Survanshi et al. weakly (not statistically significant) indicate a heliox-to-nitrox gas switch during decompression increases the incidence of DCS.

    Presumably the point of switching to argon-oxygen rather than nitrox during decompression would be if argon was taken up more slowly than nitrogen, and would therefore amplify the (possibly non-existent) benefit of the gas switch for bounce diving. However, where it has been measured, argon and nitrogen exchange with body tissues at about the same rate (Ohta et al 1978, Horrigan et al 1979). Therefore there is no theoretical reason to suspect a helium-to-argon inert gas switch would be any better than a helium-to-nitrogen inert gas switch for decompression from bounce dives.

    Although the high fat solubility of argon would suggest that argon should have a slow half-time compared to nitrogen and helium in adipose (fat) tissue (and probably not elsewhere), there is no indication that this results in an advantage for gas switching during decompression from bounce dives. On the contrary, switching to a gas with relatively high fat solubility during decompression may be a disadvantage, as the flux of the soluble gas into a bubble in adipose tissue can be greater than the flux of the less soluble gas out of the bubble, resulting in more rapid bubble growth. This has been demonstrated for helium bubbles following a helium-to-nitrogen gas switch (nitrogen is more soluble than helium) in rat adipose tissue (Hyldegaard and Jensen 2007), and it is possible the effect would be greater with a helium-to-argon switch. Adipose tissue is probably not, itself, a site of DCS, but is probably an important source of VGE, and it is possible that an argon switch may cause more bubble growth than would a nitrogen switch, and result in a higher VGE load, and possible higher risk of VGE-related injury elsewhere.

    There is also scant experimental decompression data. Keller and Buhlmann (1965) report a 300 fsw heliox dive with either argon-oxygen or nitrox decompression, both of similar total decompression times and both without DCS in a very few subject (it is not clear if it was 9 man-dives total or on each profile). These only show that the helium-to-argon switch can be done, not that it has any advantage over a helium-to-nitrogen switch.

+ Reply to Thread
Page 1 of 2 1 2 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts