+ Reply to Thread
Page 1 of 4 1 2 3 4 LastLast
Results 1 to 10 of 34

Thread: Difference between an N2 and He Bend

  1. #1
    RBW Founder schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford has a reputation beyond repute schford's Avatar
    Join Date
    Jan 2005
    Location
    UK
    Posts
    3,557

    Difference between an N2 and He Bend

    Could some one elaborate on whether there is actually a difference between these types of bend and how you tell which you have?

    I am assuming as He is a lighter gas and it is quicker on gassing and off gassing then it could potentially be worse as it could come on quicker plus I guess theoretically you could get a bend whilst in the water on your shallow stops if you had ascended too quickly where as an N2 bend would not be noticable until on dry land?

    Stuart

  2. #2
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
    Join Date
    Jan 2005
    Location
    Kent
    Posts
    5,205
    JJ Hybrid

    Inspo, Hammer Head, KISS rEvo

    I am no expert but as I understand it a bend is a bend but due to the nature of He, using 02 at ambient presure is enough to treat an He bend where as for a Nitrogen bend you need to go to the pot.

    I THINK (but i may be exposing my level of ignorance here)

    Ultimatly the growth of the bubbles tears tisues and these benifit from 02 for recovery but He dosent actualy benifit from gradient of 02 to off gas the HE as there is no HE in the air we breath so even air would off gas it.

    ATB

    Mark Chase

  3. #3
    Subsea Systems koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai's Avatar
    Join Date
    Jul 2005
    Location
    Sydney, Australia
    Posts
    351
    as I understand it a bend is a bend but due to the nature of He, using 02 at ambient presure is enough to treat an He bend
    I wouldn't agree with this at all. How does 1ATA of O2 compress the helium bubbles? Compression is part of the essential treatment of any decent bend, and surely recommended treatment for ANY bend.

    Jason.

  4. #4
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
    Join Date
    Jan 2005
    Location
    Kent
    Posts
    5,205
    JJ Hybrid

    Inspo, Hammer Head, KISS rEvo

    Quote Originally Posted by koputai
    I wouldn't agree with this at all. How does 1ATA of O2 compress the helium bubbles? Compression is part of the essential treatment of any decent bend, and surely recommended treatment for ANY bend.

    Jason.
    Again I stress I have no expertise in this area apart from practical experience and discussion with other mix gas divers. If in doubt go to the pot. I am sure I would. However for the purpose of discussion.....

    The recompression of the bubbles doesnít appear to be such an issue with Helium. It off gases fast so the problem is the damage done by the expansion of the bubbles rather than the bubbles them selves which are long gone by the time you can get to the pot.

    In the group I dive with there has twice been helium bends. On both occasions the diver was bent on the 6m stop?? Which is a bit of a give away that itís an He bend. Both divers fixed it with 02 on the boat. In one case that I had all the details on, the diver was bent at 6m loosing feeling in his arm. Fortunately the boat had a lift so he managed to get back on. His arm and shoulder looked black and blue with a terrible rash and apparently it hurt like hell. He breathed down two tins of 02 on the boat and the pain, bruising and rash all dissipated permanently.
    There doesnít appear to have been any residual problems.

    ATB

    Mark Chase

  5. #5
    Uri uri is an unknown quantity at this point uri's Avatar
    Join Date
    Apr 2005
    Location
    Sandhurst UK
    Posts
    39
    Quote Originally Posted by schford
    Could some one elaborate on whether there is actually a difference between these types of bend and how you tell which you have?

    I am assuming as He is a lighter gas and it is quicker on gassing and off gassing then it could potentially be worse as it could come on quicker plus I guess theoretically you could get a bend whilst in the water on your shallow stops if you had ascended too quickly where as an N2 bend would not be noticable until on dry land?

    Stuart

    I've always been taught that there's no difference between a Nitrogen and a Helium bend. But I know for a fact that a Helium bend is more expensive. ;)

    U.

  6. #6
    Quote Originally Posted by uri
    I've always been taught that there's no difference between a Nitrogen and a Helium bend. But I know for a fact that a Helium bend is more expensive. ;)

    U.
    damned straight brother!!!

    my gp will agree to that hahahhahahahahahahaah

  7. #7
    Acme Serpentine Lubricant lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland has a reputation beyond repute lizardland's Avatar
    Join Date
    Mar 2005
    Location
    North...
    Posts
    2,372
    Quote Originally Posted by Mark Chase
    using 02 at ambient presure is enough to treat an He bend where as for a Nitrogen bend you need to go to the pot.

    I THINK (but i may be exposing my level of ignorance here)
    You are joking, right? Please tell me that...

    By that reasoning, if everyone dived on heliox we wouldn't need chambers at all.

  8. #8
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
    Join Date
    Jan 2005
    Location
    Kent
    Posts
    5,205
    JJ Hybrid

    Inspo, Hammer Head, KISS rEvo

    Quote Originally Posted by lizardland
    You are joking, right? Please tell me that...

    By that reasoning, if everyone dived on heliox we wouldn't need chambers at all.

    No I am not joking. Yes I have been involved in Helium bends and no they didnít go to the pot for treatment. However personally I would go to the pot.

    Breathing pure 02 at ambient will oxygenate the blood and provide valuable 02 to damaged tissue. The HE doesnít really need the enhanced 02 gradient to off gas quickly and recompression of He bubbles is not an issue as within a very short period of time the bubbles will dissipate.

    This is the basis of my comments which based on experience rather than knowledge. Is there any basis to your comment? What is the advantage to going in the pot? Assuming it took an hour or more to get to the pot and you have been breathing pure 02 for that hour, what benefit will the recompression offer? Are there any bubbles left to crush? Is there any advantage of increasing the PP02? Whatís the cut of period between how long it takes to get to the pot and if its worth it?

    Let me make this clear. Self treat or not I would always recommend a check up by the Hyperbaric doctor but I am discussing a the difference between two types of bend here.

    I would ONLY consider a He bend to be and HE bend if I was obviously bent below 6m in depth. No mater what the type of pain or rash any bend that occurred above that or on the boat I would treat as a Nitrogen bend.

    I am open eared to knowledgeable explanation on this but one liners like the above donít help much.

    ATB

    Mark Chase

  9. #9
    Subsea Systems koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai is just really nice koputai's Avatar
    Join Date
    Jul 2005
    Location
    Sydney, Australia
    Posts
    351
    Look at it this way. If O2 at 1 ATA is good enough treatment for helium bends, then why do any stops deeper than the required nitrogen stops? Surely the time you spend on the shallower nitrogen stops would be more than adequate for the offgassing of the helium.
    Come on, the whole idea of doing deeper stops for helium is because pressure is part of the whole picture.
    I'm sorry, this view seems ludicrous to me. And yes, I have first hand experience of a helium bend.

    Regards,
    Jason.

  10. #10
    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
    Join Date
    Jan 2005
    Location
    Kent
    Posts
    5,205
    JJ Hybrid

    Inspo, Hammer Head, KISS rEvo

    Quote Originally Posted by koputai
    Look at it this way. If O2 at 1 ATA is good enough treatment for helium bends, then why do any stops deeper than the required nitrogen stops? Surely the time you spend on the shallower nitrogen stops would be more than adequate for the off gassing of the helium.
    Come on, the whole idea of doing deeper stops for helium is because pressure is part of the whole picture.
    I'm sorry, this view seems ludicrous to me. And yes, I have first hand experience of a helium bend.

    Regards,
    Jason.

    Most OC divers are off gassing at low partial pressures of 02 as they are only at 1.4 or 1.6 for a very short period of time during the deep stops. The very deep stops they are probably still on Mix. On very deep (for me) dives I would use 21/45 as a deco gas for the 60m to 32m deco range.

    Helium on gases faster massively increasing tissue loadings and forcing deep stops. If the same level of nitrogen had been absorbed at the same rate you would have exactly the same stops. This has everything to do with M values and tissue loadings and not really a lot to do with the gas as such (mind you I am sure there is some highly technical stuff about surface tension of the bubble or something thatís important too :D)

    You could deco out on a set point of 1.0 no problem it would just take longer. 40min at 60m on 1.3 decoing out on 1.0 would take 110mins where as on 1.3 it would take 66mins.

    There absolutely no need for high PP02 for deco. The DIR boys look at decoing out on trimix back gas in emergencies at PP02s less than air?? However elevated PP02 works a lot faster and thatís why we use it.

    Something that cropped up last year but has since vanished was the discussion on the Hyperbaric units ditching pure 02 for the treatment of bends and moving over to 50/50 Heliox for treatment?? It would be nice to get some more info on that.

    Donít get angry with me for posting these questions, theories etc they are just that noting more. Most divers in their right mind would go to the pot if they suffered a bend I am just asking is it beneficial for a He bend and if so why?


    ATB

    Mark Chase

+ Reply to Thread
Page 1 of 4 1 2 3 4 LastLast

Posting Permissions

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