Gas Mixture Dangers/Complications

[The Iceni]

baenglish73 once bubbled...
I read that He-based gas offer a reduced risk of narcosis and therefore can be used at greater depths. So now I'm curious.

The only con I've read on this board or in attempts to locate the dangers of He is that it is expensive.

Hi Baenglish,

You appear to have discovered mixed gas diving. As Dr Deco (brilliant as ever) and the others have confirmed there are considerable advantages of reducing the ppN2 in the breathing medium and adjusting the ppO2 to about 1.4 bar.

To my simple mind air is not an ideal medium at depth because it is narcotitic and, indeed, carries the risk of oxtox. Hence the origins of mixed gas diving and the discussions on this thread.

Obviously you must do the appropriate courses before you even consider using Helium- Nitrox/Trimix/Rebreather??

 

[Dr Deco]

Dear pt40:

Helium

Helium cannot only reverse the processes of inhalation anesthesia, it produces an “excitement phase” all its own. This is the so called High Pressure Nervous syndrome. The etiology (cause) of this effect is not known but it could possibly bear some resemblance to the “excitement phase” that is experienced during induction in general anesthesia. It could also be simply something else.

None the less, in order to mitigate the tremors that result from quick exposure to high pressures of helium (> 400 fsw), nitrogen is added to the breathing gas. This adds a slight narcotic to balance the effect of the helium.

Thus the “prescription” that you mention (trimix) is not concerned about the excitatory effects of helium but will concentrate primarily on the narcotic effect of nitrogen, the toxicity of oxygen, and the total cost of the helium to be added.

Dr Deco :doctor:

 

[BRW]

Yo Folks,

If you want quantitatives on mixed gas
diving (He, N2, O2), comparative physical
properties as they apply to diving and why and
how to choose "best diving mixtures",
staging comparisons on nitrogen vs helium
mixes, tec data, field results, and
record mix gas dives using modern deco
theory and thinking (RGBM for example) check
any of the following:

1) Technical Diving In Depth -- Best Pubs

2) Basic Deco Theory And Apps (2nd Ed)-- Best
Pubs

3) Reduced Gradient Bubble Model In Depth --
Best Pubs

4) RGBMdiving.com on NET

Just FYI. There's mucho misfact about helium,
deco, and related topics. The above address
same, and meld tests, experiments, theory,
stats, validation, and real diving together.

We have learned much in our "living laboratory"
of tec (and extreme rec) diving, and the above
recount some of it.

Regards,

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr

 

[baenglish73]

BRW

I looked at your website.
Do you actually have all those titles in stock?

I don't know of good scuba-literature distributor, so the normal avenue searches (e.g., Amazon, alibris, addall) came up empty.





Things to do:
Bookmark RGBM, check

 

[MonkSeal]

baenglish73 once bubbled...
I don't know of good scuba-literature distributor, so the normal avenue searches (e.g., Amazon, alibris, addall) came up empty.

I bought "Basic Deco Theory And Apps" and "Reduced Gradient Bubble Model In Depth" at Amazon few weeks ago. Try a search by author: Bruce Wienke.

 

[BRW]

Guys and Gals,

Thanks for your interest in those refs on my earlier email.

Info at the site (RGBMdiving.com) can be downloaded as
per instructions there.

The published books are available at Best (divepubs.com,
I believe off hand, or just search on Best Publishing).

Amazon and Barnes & Noble also stock all 4 books ( search
under Wienke).

Regards,

Bruce Wienke
Program Manager Computational Physics
C & C Dive Team Ldr