Helium the Perfect Diver's Gas

[K Mejean]

I'm more than a bit confused by the OP. Is this not the person who has been arguing for deep air? That we all should be diving deep air so that we can get acclimated to narcosis?

Color me confused.


Does it really matter? He asked a question. I don't see how why his personal feelings on diving air would be an issue when asking for the opinions of the tech community?


But back to the OP's question -- Why not teach Helium from the getgo?

A. It doesn't take a rocket scientist know that He is a LOT more expensive than other gases.
While I agree and I'm sure everyone else here will as well that He is more expensive the question I would have would be can you put a price on being safer? I think if we are willing to spend the money we do on "tech gear" and everything else for this sport the additional cost of He shouldn't be much of a factor.


B. Advantage -- what is the advantage of an He mix over 32% at most "real" recreational depths? Anything much above 100' seems to be OK for most divers so why even add He to the mix?

I agree with you here. I don't know that the He would be a benefit to most recreational divers. Allthough the spearfishing community could definately benefit from the use of He. I know people that go out to the middle grounds and other deep places to shoot fish. Right or wrong they are doing it and at the depths they are diving they come back and tell stories about being narced out of their minds. They need more training and better gas mixes for sure.




Yes, this is technical diving forum but the OP talked about He mixes for "open-circuit and CCR diving at all depths" so it would appear to be an appropriate response here.

C. Is there any Technical Diving Agency that does NOT teach He use for deep dives? I'm not saying they might not also teach deep air, but don't they all teach Trimix? If they do, doesn't this negate the OP's premise?


I could be mistaken here and if I am I have no doubt several people will come along and correct me but the agency I am certified through does OW to around 60' and then AOW to around 130'. Weather any of us like it or not that is the "max reacreational depth". That being said I think He could be a benifit for anyone being taught at an Advanced level or beyond. Weather they use it after they have received training is up to them but they would have one more tool at their disposal to make them safer.
Just my 2 cents.

 

[ianr33]

The size of the bubbles formed in Helium are smaller

Do you have some references to back up that statement?

 

[DCBC]

I think ICD is real, but its not an issue affecting (most) sport deco divers doing reasonably typical profiles/switches. It is a commercial/saturation/chamber deco consideration.

I agree that unless recreational divers are pushing the envelope, ICD isn't really an issue. The primary problem lies in using trimix for recreational divers diving deep with OC who have a relative fast descent and nitrogen is used in the mix to counter HPNS.

ICD isn't necessarily a consideration in commercial saturation as far as HPNS is concerned, as a slow rate of descent and staged compression techniques are employed (sometimes a day or two to get to depth). This isn't feasible if the diver starts and concludes the dive on the same day.

The saturation diver has no need to utilize Nitrogen at all, as everything can be done on Heliox with the advantage of being warm, fed, hydrated and dry with unlimited gas and time to ascend safely in the DDS Habitat. The only variable is the O2 percentage. Cost factors are also kept in check through helium reclamation.

 

[DCBC]

I'm more than a bit confused by the OP. Is this not the person who has been arguing for deep air? That we all should be diving deep air so that we can get acclimated to narcosis? Color me confused.

Peter, don't be confused. I think I explained my perspective on deep air. This surrounded the scenario of Diver A becoming acclimatized to a degree of narcosis and Diver B never having this opportunity, diving trimix, then returning to air and experiencing narcosis. Diver A is more prepared to deal with the narcosis than Diver B. Enough said. On to this question...

Why not teach Helium from the getgo?

What is the advantage of an He mix over 32% at most "real" recreational depths? Anything much above 100' seems to be OK for most divers so why even add He to the mix?

When an 80\20 Heliox mixture is compared to an 80\20 Nitrox, the Heliox mixture allows additional no-decompression times of: 60m@40', 80m@50', 70m@60', 35m@70', 20m@80', 15m@90', 10m@100'-130', as an example.

I know about the cost, but other than cost (which isn't a factor at all for some people), why not Helium?

Is there any Technical Diving Agency that does NOT teach He use for deep dives? I'm not saying they might not also teach deep air, but don't they all teach Trimix? If they do, doesn't this negate the OP's premise?

What premise is that?

 

[DCBC]

Do you have some references to back up that statement?

It is scientific fact that the size of Helium molecules are small. It's diffusion rate through solids is three times that of air.

Here are a couple of articles that you may find interesting:

Nishi, R.Y., Development of new helium-oxygen decompression tables for depths to 100msw

Wienke, B.R., Diving decompression models and bubble metrics: Modern computer syntheses

The efficacy of Comex 30 He-O2 vs. US Navy treatment tables for DCI (Comparison between USN6 and Cx30 recompression schedules for DCI)

 

[ianr33]

It is scientific fact that the size of Helium molecules are small. It's diffusion rate through solids is three times that of air.

Here are a couple of articles that you may find interesting:

Nishi, R.Y., Development of new helium-oxygen decompression tables for depths to 100msw

Wienke, B.R., Diving decompression models and bubble metrics: Modern computer syntheses

The efficacy of Comex 30 He-O2 vs. US Navy treatment tables for DCI (Comparison between USN6 and Cx30 recompression schedules for DCI)

Totally agree about the size of helium ATOMS and its diffusion rate. Dont see how that relates to the size of bubbles that may form in the body. (Have always assumed that bubbles will be a mixture of N2 and He) I suppose the surface tension has an affect but I'm sure the math gets tricky.

Thanks for the references,will try and take a look at them.

 

[rjack321]

I agree that unless recreational divers are pushing the envelope, ICD isn't really an issue. The primary problem lies in using trimix for recreational divers diving deep with OC who have a relative fast descent and nitrogen is used in the mix to counter HPNS. .

HPNS is another one of those things which sounds all boogy man like but for all practical purposes will never be an issue for a recreational diver on OC or most rec CCR divers either for that matter.

 

[rjack321]

Peter, don't be confused. I think I explained my perspective on deep air. This surrounded the scenario of Diver A becoming acclimatized to a degree of narcosis and Diver B never having this opportunity, diving trimix, then returning to air and experiencing narcosis. Diver A is more prepared to deal with the narcosis than Diver B. Enough said. On to this question...

There's no reason to train divers for narcosis deep. We can do long shallow highly narced dives with no deco obligation. Surely an hour+ narced with no actual deco obligation would be more beneficial than a mere 20mins at depth?

Pump up the arg-ox and let's go diving!

 

[DCBC]

HPNS is another one of those things which sounds all boogy man like but for all practical purposes will never be an issue for a recreational diver on OC or most rec CCR divers either for that matter.

I hope that's the case. Commercial divers have experienced HPNS well before 500' with slow descents. With the rapid descents of recreational divers, Personally I'd be concerned after 350'.

 

[DCBC]

There's no reason to train divers for narcosis deep. We can do long shallow highly narced dives with no deco obligation. Surely an hour+ narced with no actual deco obligation would be more beneficial than a mere 20mins at depth?

Pump up the arg-ox and let's go diving!

My point is training them for narcosis regardless of depth. Heliox is my thing, so anytime.