HELIOX where to find information?

Padowan · 24th March 2006, 09:21

I seem to remember that IBCD is not just a function of molecule size, but also related to the relative solubility of the gasses into the different tissue types, which can lead to tissue super-saturation.

Drmike · 24th March 2006, 09:25

Follow this link to see the US Navy Heliox CCR deco tables

http://www.supsalv.org/pdf/Chapter17b.pdf

IIRC they evaluated these with a 2% predicted bend rate.

jhaaja · 24th March 2006, 09:46

I think that it is not wise to change to gas that has a lot more helium in it if you are not descending. ICD can also become an issue on that kind of switch.

JH

Mdemon · 24th March 2006, 15:46

Quote: (Originally Posted by jhaaja)

I think that it is not wise to change to gas that has a lot more helium in it if you are not descending. ICD can also become an issue on that kind of switch.

JH

Curious, but why?

jhaaja · 24th March 2006, 18:35

Quote: (Originally Posted by Mdemon)

Curious, but why?

Because helium gradient will rise and helium will start absorbing fast into the tissues. This might rise the tissue pressures enough to make bubbles.

JH

hoppyinca · 25th March 2006, 15:05

Quote: (Originally Posted by jaap)

OK

...On the other hand if I understand the opinion of Dr Bruce Wienke (RGBM, isn't he also a CCR diver?) on this, going to a higher He-fraction is good and reducing it is bad while ascending. If I recall correctly from an OC deco discussion, his conclusion was that the best deco was from only increasing the O2 while reducing the N2 with the same fraction (thus holding the He-fraction rel constant)...

I would have to agree here...
While I am by no means an expert I was privy to a convo w/ Dr Wienke at DEMA 2005, which confirmed the above statement.

basically increase the O2, the one gas which is metabolized, keep everything else constant to prevent over/ super sat conditions...

just my 2 pennies worth... keep in mind I JUST got CCR certified...

Hoppy

Drmike · 25th March 2006, 15:36

Steve B has put up a simple to follow explanation here :

http://www.scubaengineer.com/isobari..._diffusion.htm

Which explains it as being all about keeping the overall gass loading the same after switching taking into acount the solubility differences in the gasses

J. V. · 25th March 2006, 15:44

Quote:

basically increase the O2, the one gas which is metabolized, keep everything else constant to prevent over/ super sat conditions...

Yep. That's exactly what we do with a rebreather, specially by using one diluant.

Heliox is efficient and easy to use in a rebreather, so perhaps the question is why not use heliox in a rebeather.

Marc T · 26th March 2006, 10:33

Quote: (Originally Posted by Drmike)

Steve B has put up a simple to follow explanation here :

http://www.scubaengineer.com/isobari..._diffusion.htm

Which explains it as being all about keeping the overall gass loading the same after switching taking into acount the solubility differences in the gasses

using the same "computation", you can see that using heliox on deco ( ethen after a trimix dive ) is safe in any case.

Thta's my opinion, and a heliox for bail out is a good solution in most cases but not sure its true

sannerman · 27th March 2006, 09:00

I have a question fore DrJM and J. V. (and other as well using HeliOx), what program do you use to calculate profiles with? And DrJM do you use your VR3 on the dives or are you using pre calculated tabels? (I guess thet you carry bailout/emergency tabels with in case everythig gets FUBAR (****ed Up Beyond All Repair ;-) )).

And any one using the US Navy tabels?

From a still frosen and snowy Sweden

Need open water NOW!

/Z

24th March 2006, 09:21	#21 (permalink)
Padowan Proper Boffin Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Kent, UK. Posts: 518	Re: HELIOX where to find information? I seem to remember that IBCD is not just a function of molecule size, but also related to the relative solubility of the gasses into the different tissue types, which can lead to tissue super-saturation. __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
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24th March 2006, 09:25	#22 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,303	Re: HELIOX where to find information? Follow this link to see the US Navy Heliox CCR deco tables http://www.supsalv.org/pdf/Chapter17b.pdf IIRC they evaluated these with a 2% predicted bend rate. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 24th March 2006 at 09:28.
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24th March 2006, 09:46	#23 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 884	Re: HELIOX where to find information? I think that it is not wise to change to gas that has a lot more helium in it if you are not descending. ICD can also become an issue on that kind of switch. JH
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24th March 2006, 15:46	#24 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,931	Re: HELIOX where to find information? Quote: (Originally Posted by jhaaja) I think that it is not wise to change to gas that has a lot more helium in it if you are not descending. ICD can also become an issue on that kind of switch. JH Curious, but why? __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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24th March 2006, 18:35	#25 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 884	Re: HELIOX where to find information? Quote: (Originally Posted by Mdemon) Curious, but why? Because helium gradient will rise and helium will start absorbing fast into the tissues. This might rise the tissue pressures enough to make bubbles. JH
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25th March 2006, 15:05	#26 (permalink)
hoppyinca New Member Current Rebreather/s: MK 15.X Other Rebreather/s: Join Date: Jun 2005 Location: Laguna Niguel, CA USA Posts: 252	Re: HELIOX where to find information? Quote: (Originally Posted by jaap) OK ...On the other hand if I understand the opinion of Dr Bruce Wienke (RGBM, isn't he also a CCR diver?) on this, going to a higher He-fraction is good and reducing it is bad while ascending. If I recall correctly from an OC deco discussion, his conclusion was that the best deco was from only increasing the O2 while reducing the N2 with the same fraction (thus holding the He-fraction rel constant)... I would have to agree here... While I am by no means an expert I was privy to a convo w/ Dr Wienke at DEMA 2005, which confirmed the above statement. basically increase the O2, the one gas which is metabolized, keep everything else constant to prevent over/ super sat conditions... just my 2 pennies worth... keep in mind I JUST got CCR certified... Hoppy
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25th March 2006, 15:36	#27 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,303	Re: HELIOX where to find information? Steve B has put up a simple to follow explanation here : http://www.scubaengineer.com/isobari..._diffusion.htm Which explains it as being all about keeping the overall gass loading the same after switching taking into acount the solubility differences in the gasses __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 25th March 2006 at 15:41.
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25th March 2006, 15:44	#28 (permalink)
J. V. Custom Title Allowed! Current Rebreather/s: rEvo Other Rebreather/s: Not Bought Yet rEvo Join Date: Mar 2006 Location: Lot & Savoie Posts: 239	Re: HELIOX where to find information? Quote: basically increase the O2, the one gas which is metabolized, keep everything else constant to prevent over/ super sat conditions... Yep. That's exactly what we do with a rebreather, specially by using one diluant. Heliox is efficient and easy to use in a rebreather, so perhaps the question is why not use heliox in a rebeather. __________________ -------------------- Jacques NPSFQQA-EDS IT # 007 (remué non agité)
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26th March 2006, 10:33	#29 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 485	Re: HELIOX where to find information? Quote: (Originally Posted by Drmike) Steve B has put up a simple to follow explanation here : http://www.scubaengineer.com/isobari..._diffusion.htm Which explains it as being all about keeping the overall gass loading the same after switching taking into acount the solubility differences in the gasses using the same "computation", you can see that using heliox on deco ( ethen after a trimix dive ) is safe in any case. Thta's my opinion, and a heliox for bail out is a good solution in most cases but not sure its true
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27th March 2006, 09:00	#30 (permalink)
sannerman Let´s Go Down For a While Current Rebreather/s: Classic Kiss MK 15.X Other CCR Other Rebreather/s: Classic Kiss MK 15.X Other CCR Join Date: Apr 2005 Location: Sweden Posts: 98	Re: HELIOX where to find information? I have a question fore DrJM and J. V. (and other as well using HeliOx), what program do you use to calculate profiles with? And DrJM do you use your VR3 on the dives or are you using pre calculated tabels? (I guess thet you carry bailout/emergency tabels with in case everythig gets FUBAR (****ed Up Beyond All Repair ;-) )). And any one using the US Navy tabels? From a still frosen and snowy Sweden Need open water NOW! /Z __________________ Det är hårt på sjön, fast hårdare på land www.pagi.se
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