physical risks of hydrogen?

hirudin · 6th December 2005, 18:35

Hi All!

Newbie alert with hypothetical discussion:

I've been reading (oh no!) the threads as well as other info on mixed gas diving... certainly the thread on diving neon was fascinating and there were some great input.

But I was thinking about the use of hydrogen... certainly not a noble gas, it's on the same side of the periodic table as the most active elements on earth and even if you cancel out the explosive factor, you obviously have some very active compounds formed with its use; from your doghnut with your partially hydrogenated trans-fats through to HF which will kill you with a 2% body burn.

I read the Comex articles discussing the use of hydreliox and the physical effects the divers experienced on the dives, but it certainly doesn't seem like a good idea... and I don't like the idea of partially-hydrogenating my own body fat.

Guess I'm just interested in a discussion on the use of hydrogen and it's longer term effects.... just for yuks.

-Jesse-

Genesis · 6th December 2005, 19:53

At mixtures containing over 4% O2 hydrogen can rapidly combine with that oxygen to form water.

(This is commonly called "an explosion" and is really bad if it happens in your breathing loop!)

If you're diving at a depth where a hypoxic mix of < 4% O2 is called for, AND you can keep the loop at that level RELIABLY, then it might be an option. However, you have to make sure there are no "slugs" of O2 around, etc - the technical hurdles associated with not going "boom" are pretty significant, and for shallower depths where the FO2 has to be over 4% are probably insurmountable.

kala · 26th December 2005, 02:18

Quote: (Originally Posted by Genesis)

At mixtures containing over 4% O2 hydrogen can rapidly combine with that oxygen to form water.

(This is commonly called "an explosion" and is really bad if it happens in your breathing loop!)

If you're diving at a depth where a hypoxic mix of < 4% O2 is called for, AND you can keep the loop at that level RELIABLY, then it might be an option. However, you have to make sure there are no "slugs" of O2 around, etc - the technical hurdles associated with not going "boom" are pretty significant, and for shallower depths where the FO2 has to be over 4% are probably insurmountable.

For me CCR diving with hydrogen sounds technically too complicated. But in SCR mode it could be possible, when there is no need to add pure oxygen into loop.

-kala-

abowie · 26th December 2005, 06:23

In comparison to He, H is half as dense, is easily manufactured in limitless quantities and is a whole lot cheaper.

So why doesn't anyone use it for diving?

leadking · 26th December 2005, 22:29

Comex in Marseilles used hydrogen in some of the deepest open water dives on record. I toured their facility last year-very impressive.

abowie · 27th December 2005, 06:43

Quote: (Originally Posted by leadking)

Comex in Marseilles used hydrogen in some of the deepest open water dives on record. I toured their facility last year-very impressive.

Yeah sorry my reply should have read "why doesn't everyone use it".

Those guys are using tiny fractions of O2 in their mixes though, less than the threshold for explosion.

Mdemon · 27th December 2005, 21:03

Do Comex treat it as helium deco-wise? Are there benefits?

If you used hydrogen very deep, would you flush with trimix as you came up and would that give you a deco benefit or would you just get really nasty ICD?

Answers on a postcard...

cramerdn · 18th November 2007, 23:18

It turns out that becuase of all sorts of interesting P Chem concepts O2 and Hydrogen only explode in certain preasure ranges. In other higer or lower preasures only a normal combustion is produced. Both of course require an ignition source. In a mixed gas diving book that is beyond arm reach right now it describes the safe depths that Hydrox can be breathed. Those depths are below 4 atm preasure if my memory is correct.

Crazyduck · 19th November 2007, 02:38

link- Exotic diving gases

Abbo · 19th November 2007, 02:42

There's some interesting reading on "Hydrogen as a breathing gas" by RW Braur at
Rubicon Research Repository: Item 123456789/4862
The safe FO2 limit seems to be around 4.5%. Even if you took your PO2 to 0.7, that would require you to be deeper than 146m, and you'd want a large margin for error.
Hydrogen is narcotic, though not as narcotic as nitrogen.
Hydrogen makes metal brittle, though the effects are part offset by oxygen.
The benefits of Hydrogen (related to it being lighter) don't seem to really manifest until around 300-400m. The world record for SCUBA is, what, 320m? The present record for a rebreather dive is significantly shallower. I would be seriously concerned about the scrubber at those depths.

The move to hydrogen seems to have been brought on largely because of the $ cost of Helium, but rebreathers don't waste much diluent and the $ is tanking. It was also caused because the US once had a near-monopoly on Helium, but that is no longer the case, as deposits are being exploited in the FSU.

6th December 2005, 18:35	#1 (permalink)
hirudin New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: May 2005 Location: rock-hopper Posts: 52	physical risks of hydrogen? Hi All! Newbie alert with hypothetical discussion: I've been reading (oh no!) the threads as well as other info on mixed gas diving... certainly the thread on diving neon was fascinating and there were some great input. But I was thinking about the use of hydrogen... certainly not a noble gas, it's on the same side of the periodic table as the most active elements on earth and even if you cancel out the explosive factor, you obviously have some very active compounds formed with its use; from your doghnut with your partially hydrogenated trans-fats through to HF which will kill you with a 2% body burn. I read the Comex articles discussing the use of hydreliox and the physical effects the divers experienced on the dives, but it certainly doesn't seem like a good idea... and I don't like the idea of partially-hydrogenating my own body fat. Guess I'm just interested in a discussion on the use of hydrogen and it's longer term effects.... just for yuks. -Jesse-
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6th December 2005, 19:53	#2 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,395	Re: physical risks of hydrogen? At mixtures containing over 4% O2 hydrogen can rapidly combine with that oxygen to form water. (This is commonly called "an explosion" and is really bad if it happens in your breathing loop!) If you're diving at a depth where a hypoxic mix of < 4% O2 is called for, AND you can keep the loop at that level RELIABLY, then it might be an option. However, you have to make sure there are no "slugs" of O2 around, etc - the technical hurdles associated with not going "boom" are pretty significant, and for shallower depths where the FO2 has to be over 4% are probably insurmountable.
(Offline)

26th December 2005, 02:18	#3 (permalink)
kala New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Nov 2005 Location: Estonia Posts: 2	Re: physical risks of hydrogen? Quote: (Originally Posted by Genesis) At mixtures containing over 4% O2 hydrogen can rapidly combine with that oxygen to form water. (This is commonly called "an explosion" and is really bad if it happens in your breathing loop!) If you're diving at a depth where a hypoxic mix of < 4% O2 is called for, AND you can keep the loop at that level RELIABLY, then it might be an option. However, you have to make sure there are no "slugs" of O2 around, etc - the technical hurdles associated with not going "boom" are pretty significant, and for shallower depths where the FO2 has to be over 4% are probably insurmountable. For me CCR diving with hydrogen sounds technically too complicated. But in SCR mode it could be possible, when there is no need to add pure oxygen into loop. -kala-
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26th December 2005, 22:29	#5 (permalink)
leadking New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Nov 2005 Location: Minneapolis Posts: 57	Re: physical risks of hydrogen? Comex in Marseilles used hydrogen in some of the deepest open water dives on record. I toured their facility last year-very impressive.
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27th December 2005, 06:43	#6 (permalink)
abowie Fighting Girl Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Land of Oz Posts: 574	Re: physical risks of hydrogen? Quote: (Originally Posted by leadking) Comex in Marseilles used hydrogen in some of the deepest open water dives on record. I toured their facility last year-very impressive. Yeah sorry my reply should have read "why doesn't everyone use it". Those guys are using tiny fractions of O2 in their mixes though, less than the threshold for explosion. __________________ Andrew Bowie Rebreather-friendly Buddy
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27th December 2005, 21:03	#7 (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: 1,926	Re: physical risks of hydrogen? Do Comex treat it as helium deco-wise? Are there benefits? If you used hydrogen very deep, would you flush with trimix as you came up and would that give you a deco benefit or would you just get really nasty ICD? Answers on a postcard... __________________ 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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18th November 2007, 23:18	#8 (permalink)
cramerdn Obey my dog! Current Rebreather/s: Evolution Dolphin Other Rebreather/s: Dolphin Join Date: Dec 2006 Location: Townsville QLD Posts: 626	Re: physical risks of hydrogen? It turns out that becuase of all sorts of interesting P Chem concepts O2 and Hydrogen only explode in certain preasure ranges. In other higer or lower preasures only a normal combustion is produced. Both of course require an ignition source. In a mixed gas diving book that is beyond arm reach right now it describes the safe depths that Hydrox can be breathed. Those depths are below 4 atm preasure if my memory is correct. __________________ "Its better to live one day as a tiger than an entire life as a worm." "But who's ever heard of a worm skin rug?"
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19th November 2007, 02:38	#9 (permalink)
Crazyduck Underwater Mechanic Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Mar 2005 Location: TEXAS, Dallas/ Ft.Worth Posts: 711	Re: physical risks of hydrogen? link- Exotic diving gases __________________ Howdy Senor- What’s Happening! Rob Davie April 2005- Presently in a state of transition from Open Circuit to Closed Circuit. "You will not be punished for your anger; you will be punished by it." - Buddha.
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19th November 2007, 02:42	#10 (permalink)
Abbo Nicholas Smith Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 440	Re: physical risks of hydrogen? There's some interesting reading on "Hydrogen as a breathing gas" by RW Braur at Rubicon Research Repository: Item 123456789/4862 The safe FO2 limit seems to be around 4.5%. Even if you took your PO2 to 0.7, that would require you to be deeper than 146m, and you'd want a large margin for error. Hydrogen is narcotic, though not as narcotic as nitrogen. Hydrogen makes metal brittle, though the effects are part offset by oxygen. The benefits of Hydrogen (related to it being lighter) don't seem to really manifest until around 300-400m. The world record for SCUBA is, what, 320m? The present record for a rebreather dive is significantly shallower. I would be seriously concerned about the scrubber at those depths. The move to hydrogen seems to have been brought on largely because of the $ cost of Helium, but rebreathers don't waste much diluent and the $ is tanking. It was also caused because the US once had a near-monopoly on Helium, but that is no longer the case, as deposits are being exploited in the FSU.
(Online)

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