CO2 retention question

[MASS-Diver]

Sorry, has nothing to do with CO2 and off the main topic. More precisely, I should say, has little to do with CO2. All are interelated. Your exposure is measured in depth and time, not depth alone. However, for recreational dives in both depth and time, I wouldn't think twice about using EAN32 at 60.' All things being equal, you can clear CO2 buildup by resting and doing nothing for a few minutes or just slow things down. In that regard, it's acute. If you've got complex gear, ill-fitting drysuit, harness, etc...or anything that causes you to work excessively hard such as the environment or causes the lack of O2 to your organs, CO2 will build up rapidly and exponentially. Since the rate of production is faster than the rate it's being metabolized and exhaled, symptoms of hypercapnia will eventually present itself. That is not an acute problem that is easily resolved without assistance. Of course each body is different. We USUALLY never want to get to that point...no headaches, no tiredness, nothing but feeling refreshed after the dive.

You are right on, everyone gets narced, it's a matter of degree not kind. The instant you are below the surface, physiologically your body is absorbing higher partial pressures of all gases. A sip of wine has varying effects on each body. Some people are finely tuned or aware of their BAC going from 0.00 to 0.01 to 0.02, etc... Some people aren't aware until 0.08 before feeling effects. Let's say you're the pilot of a small plane, flying a simple route across the state and you are getting ready to take off and are thirsty. Wine is free, bottled water costs $5, and vitamin infused water costs $10, and an energy drink costs $15. You'll be billed at your destination. That's all that's on board and you're traveling with a co-pilot only on a sightseeing flight. Weather appears to be clear, but its always unpredicatable in this state. You've flown this route plenty of times and it's easy. You're generally well rested and feeling ok. Pick your drink. There's are argument to be made with which drink and how you approach potentially changing conditions & environment. How sharp do you want your mind and body to be when executing emergency procedures? Bottomline, you've got some flexibility without compromising other procedures.

On the flip side, sometimes, you've got extra energy drinks, that you need to consume. I've had 21/35 mix that I've needed to 'burn-up' and used that in a recreational environment. Is it ideal? No, since I don't get any time advantage that EAN32 gives me, but there's nothing saying that I must only dive 21/35 in a certain band (excluding MOD).

Sincerely,
H2

OK - but just to be clear, you are saying that reason why on a 90 minute dive to 60' that one should consider a He mix is narcosis related? I don't follow that logic. If I'm narced to point that it's a saftey risk at a certain depth, why is the amount of time I'm at the depth a factor? Either I'm narced at 60' and need He on every dive to that depth, or I'm not and I'm in the shape on a 20min dive as 120min dive.

In terms of the Co2 issue - if I'm diving DIR, my gear is squared away and I can manage it. I find it hard to belive that there are many issues with retention (realted to mix density) at 60' that need to be solved with He mixes.

I'm buy all the reasons for 30/30 at 100' (and maybe even 80'), but at 60', I'm not sure I'm biting, that there's a need to "solve" the problem of diving Eanx32 at this shallow.

 

[HarryH97]

OK - but just to be clear, you are saying that reason why on a 90 minute dive to 60' that one should consider a He mix is narcosis related? I don't follow that logic. If I'm narced to point that it's a saftey risk at a certain depth, why is the amount of time I'm at the depth a factor? Either I'm narced at 60' and need He on every dive to that depth, or I'm not and I'm in the shape on a 20min dive as 120min dive.

In terms of the Co2 issue - if I'm diving DIR, my gear is squared away and I can manage it. I find it hard to belive that there are many issues with retention (realted to mix density) at 60' that need to be solved with He mixes.

I'm buy all the reasons for 30/30 at 100' (and maybe even 80'), but at 60', I'm not sure I'm biting, that there's a need to "solve" the problem of diving Eanx32 at this shallow.

Yes, time is a major factor in your exposure. Narcosis is but one factor that you'll need to consider. It's not quite so simple as I go to 60' and I'm narced and I need He. Once you exceed recreational limits (NLD/MDL) in time at let's say 60' you are signficantly saturating your body with inert gases. So narcosis is a function of depth, time, and gas, not just depth and gas. In that regard, He can significantly help in your deco efficiency. For recreational dives, all I'm saying is that you've got options.

You will not find me telling you what to breathe. That is your decision. Again, if I were diving to 60', I'd use EAN32 within recreational limits. I'd also examine the conditions and environment. If the team has their act together, there shouldn't be CO2 issues, unless this is a serious working dive (flow, currents, poor vis,back eddys, up/down welling, marine life obstacles, etc...). Switching to He will give you an advantage that you may not need if conditions are permissive. I'd also go one step further in supporting your assessment that I'd go much deeper on EAN32 than 60' within recreational exposures at the corresponding depth of course.

If I were going significantly beyond rec limits in my exposure or multiple deeper recreational dives or a combination of the two, I'd use He. But we are talking greater than 90 mins of exposure at 60' before ascending. That is not what I call a typical recreational profile and certainly not something I normally do. This would be a shallow water decompression dive. You can use EAN32, but it's not as clean for deco dives as He. And you can forget about it with deco on Air - why subject your body to so much damage and recovery? If you want to dive it, fine by me. Just saying I don't do it and the reasoning behind it. On the whole, I think we are saying the same thing. Although, there's a requirement to take a look at the global picture in your gas selection, not just it's 60' therefore one MUST dive EAN32. Don't think that I'm selling this, cause I'm not. So you don't have to buy it or "bite it."

Sincerely,
H2

 

[cornfed]

That sounds like a frivolous waste of helium, which is a non-renewable resource.

Non-renewable? Surely you know that helium can be produced by fusing two hydrogen isotopes.

 

[MASS-Diver]

Yes, time is a major factor in your exposure. Narcosis is but one factor that you'll need to consider. It's not quite so simple as I go to 60' and I'm narced and I need He. Once you exceed recreational limits (NLD/MDL) in time at let's say 60' you are signficantly saturating your body with inert gases. So narcosis is a function of depth, time, and gas, not just depth and gas. In that regard, He can significantly help in your deco efficiency. For recreational dives, all I'm saying is that you've got options.

You will not find me telling you what to breathe. That is your decision. Again, if I were diving to 60', I'd use EAN32 within recreational limits. I'd also examine the conditions and environment. If the team has their act together, there shouldn't be CO2 issues, unless this is a serious working dive (flow, currents, poor vis,back eddys, up/down welling, marine life obstacles, etc...). Switching to He will give you an advantage that you may not need if conditions are permissive. I'd also go one step further in supporting your assessment that I'd go much deeper on EAN32 than 60' within recreational exposures at the corresponding depth of course.

If I were going significantly beyond rec limits in my exposure or multiple deeper recreational dives or a combination of the two, I'd use He. But we are talking greater than 90 mins of exposure at 60' before ascending. That is not what I call a typical recreational profile and certainly not something I normally do. This would be a shallow water decompression dive. You can use EAN32, but it's not as clean for deco dives as He. And you can forget about it with deco on Air - why subject your body to so much damage and recovery? If you want to dive it, fine by me. Just saying I don't do it and the reasoning behind it. On the whole, I think we are saying the same thing. Although, there's a requirement to take a look at the global picture in your gas selection, not just it's 60' therefore one MUST dive EAN32. Don't think that I'm selling this, cause I'm not. So you don't have to buy it or "bite it."

Sincerely,
H2

Very interesting. Thanks

 

[StSomewhere]

I'll give NASA, NOAA, NWS, etc. a pass on their helium use. If someone wants to target "frivolous" helium use then the Macy's parade would be a better starting point.

 

[mer]

Non-renewable? Surely you know that helium can be produced by fusing two hydrogen isotopes.

And we get some great energy too boot!!! Just let me know when you've figured out how to
a) get to the sun AND BACK
b) contain a 5 million degree reaction
c) invent cold fusion

 

[Daryl Morse]

Non-renewable? Surely you know that helium can be produced by fusing two hydrogen isotopes.

Okay, you can make helium in a lab. Big deal. I wonder how much helium would cost if it had to be manufactured in a fusion lab. I doubt it would be affordable for diving.

The fact is, virtually all helium comes out of the ground as a byproduct of natural gas from only a few regions in the world. Natural gas is a non-renewable resource.

 

[Daryl Morse]

So, if you added up all the helium ever used in diving, how does it compare to the worldwide helium consumption for a day?

I don't dispute your point, but even if the amount of helium used for diving is relatively insignificant, I don't think that changes the fact that diving helium for 60-100 fsw depths is frivilous. But what the heck, if you want to spend your money to waste helium, I guess that's your right. Personally, I'd rather spend my money on something a bit more beneficial.

 

[JWU42]

Canadians...

 

[lamont]

Diving mixtures accounts for 4% of consumption.

And I'll bet 90% of that is commerical surface-supplied oil rig operations and such...

I'm going to have to work on getting my SAC rate up if I ever hope to make a dent in the worldwide supply of helium...