Compressing Hydrogen

[broncobowsher]

I was just thinking of hydrogen for open circuit and the support crew watching over you. Hope none of them are smokers. How deep? how much gas will be bubbling at the surface? Better home the boat isn't running diesel, the generator may get unhappy with gulps of extra fuel. It could be interesting to surface only to hear the generator ran away and the surface of the water caught on fire. But by the time you surfaced it all stopped.

 

[iain/hsm]

Nice move, coming up with the qualifier afterwards. Kinda changes the meaning of what you originally wrote.

Yeah sure it does. LOL

 

[iain/hsm]

I don't see why its impossible to figure out safe use of Hydrogen in SCUBA.

Given that the cost of Helium is already pushing people to use rebreathers, how expensive does it have to get for the questions of how to safely handle Hydrogen as an alternative become worth answering?

It's not that it is impossible to fill a scuba size cylinder with a Hydrogen trimix it's just that it's impractical for the shallow scuba depth range. Same for rebreathers unless or until you require a breathing mixture that requires a less than 3% oxygen concentration in the mix then Hydrogen is simply off the table of available gas options. Hence my comment on Neon being a more suitable alternative to helium for scuba applications albeit with the astronomical cost attached.

Hydrogen for breathing using either of the two methods I suggested earlier to avoid any further confusion is relatively cheap to produce and pretty easy to both manufacture and compress. with one of the process also producing oxygen as a by product at the same time. Its just a shame its not inert like helium or neon and with the advantage in reducing HPNS and much less narcotic than than say Krypton Argon and the rest.

Maybe a good time to move from its prodution to its application in deep diving and the need for it to be still a contender in very deep diving gas considerations.

 

[The Ruttmeister]

Maybe a good time to move from its prodution to its application in deep diving and the need for it to be still a contender in very deep diving gas considerations.

Absolutely.

I'm not an expert, or even qualified for deep diving, let alone very deep... But one advantage of Hydrogen that I can see is that it has a very low density, similar to that of Helium. And I have seen people mention that at significant depth that gas density is a significant factor in WOB. With Neon having a density closer to that of Nitrogen, that's an advantage you would be giving up. Is that correct?

Neon being inert has the very obvious advantage of no concerns about reactions at high pressure with anything at all. Hydrogen being so reactive, there would be a need to know what those potential reactions are.

 

[iain/hsm]

Absolutely.

I'm not an expert, or even qualified for deep diving, let alone very deep... But one advantage of Hydrogen that I can see is that it has a very low density, similar to that of Helium. And I have seen people mention that at significant depth that gas density is a significant factor in WOB. With Neon having a density closer to that of Nitrogen, that's an advantage you would be giving up. Is that correct?

Neon being inert has the very obvious advantage of no concerns about reactions at high pressure with anything at all. Hydrogen being so reactive, there would be a need to know what those potential reactions are.

This is going to be a long and boring subject if we're not careful. But for simple headings just to kick off.
Neon has a number of advantages over Helium in recreational diving.
Apart from the fact no one knows anything about it and those that do are getting too old in the tooth.
Also dont confuse the density of a diluent gas with its narcotic effect. Two different and interesting things
We havent yet discusssed the narcotic effect of hydrogen but its nothing like Nitrogen or Helium
Its pretty nasty.
Or the advantage in passive thermal protection Neon offers over helium
Or the advantage in communications
Neon can be used in the range 1-250 msw so making it a possible practical alternative to helium
when the ballon gas folk have finished off all the helium your screwed, but neon is much easier to manufacture and compress with much less blowby and none of the problems with hydrogen over oxygen 3% Its also cheaper than helium (to manufacture)

Also interesting WOB is NOT a major advantage of using Hydrogen over Helium its its ability in reducing HPNS on deep saturation excursions. Albeit the comparison WOB using neon would be another good discussion.

 

[The Ruttmeister]

snip
...the comparison WOB using neon would be another good discussion.

Well, yes that was my point. At depths where replacing the Nitrogen with Helium is partly due to gas density and resulting WOB limits (completely ignoring the fact that those depths are already far below Nitrogen narcosis depths), Neon doesn't give you any help with WOB. No?

I'm curious about the narcotic effects of Hydrogen as I can imagine that the combination of increased complexity for safe handling procedures and new and unpleasant narcosis issues would make most users a bit reluctant...

 

[iain/hsm]

Well, yes that was my point. At depths where replacing the Nitrogen with Helium is partly due to gas density and resulting WOB limits (completely ignoring the fact that those depths are already far below Nitrogen narcosis depths), Neon doesn't give you any help with WOB. No?

Two questions too late for this side of the pond but on the first part: No.
If you want to compare the relative gas density alone. Helium to Neon
First assuming both gas mixes are binary and with a constant p02
Then for a relative gas density of 3.2 (Po2 of 0.3 ATA)
With Neon you would reach at 47 meters depth
With Helium mix you would reach 182 meters depth
Or put another way with neon at 182 metres your at 9.5 relative gas density by comparison to Helium
Clear as mud I guess.

But you now have to define WOB in terms of breathing capacity immersed in water against a negative or positive pressure which will increase your WOB more than the choice of gas will, then add choice of equipment.

Neon compresses "smooth" in the compressor with little losses compaired to helium although Hydrogen needs much less power to compress the same volume.