TDI Advanced Nitrox

[Ari]

Nitrogen is considered Narcotic over 3.2 Atm. partial pressure, which means that at a 21%/79% Nitrox (AKA air) happens at about 30 meters. This is the explanation I was given in Israel for the reason to limiting sport diving to 30 meters.

Nevertheless, different people will suffer narcosis at different depths, based on their personal characteristics and actual condition.

Now days, where mixtures, other than air, are readily available, we can go deeper and still keep our END or PP of Nitrogen (PPN2) lower than this limit, as long as we account for other problems, such as high PPO2.

I guess I am not saying anything new, so I will stop here.

Ari

 

[Ari]

Looks like I replied to one of the earlier posts.

Ari

 

[padiscubapro]

I have to agree with blacknet.

I dive trimix quite often but eliminating deep air is not a valid option for everyone.. outside the US helium is usually very expensive and/or not available at all.. I'll use He whenever it is available (I don't mind the cost) but I travel alot and many times its impossible to get helium. For example I'm going to truk next month, He - you can forget about it... am I going to forgo the wrecks deeper than 130.. hell no... I would love to have He in my mix but just because its not available wount stop me from diving.. Granted I'll have to limit my depth to around 200, but I was diving these depths well before trimix was an option.. If it was a cold water limited viz dive I wouldn't do it anymore, but 86 degree 100+ feet of viz I wouldn't hesitate.. IN these situations for those who want/have to go to these depth with no availability of He, deep air training is a must, otherwise they are going to do it with the benefit of any training.. Most advocates of deep air is bad fail to realize that not everyone has the gas availability outside of the US, also many are hippocrites, I have made a few deep dives with people on air that were preaching deep air is bad but when it came down to doing or not doing a dive based on the availability of He, they did the dives...
I am not advocating deep air, just stating sometimes its the only option and individual choice has to come in...

 

[VTWarrenG]

Guys,

I think I speak for Yoop, roakey, and myself when I say the following:

Air is not bad.

Gases are just tools -- their use is what makes them effective or ineffective. Gases are not inherently good or bad.

I routinely use air to dive shallow than 100 fsw -- there's no reason not to. My surface intervals more than compensate for the additional N2 as compared to EAN36 (which is the "proper mix" for shallow dives). EAN36 costs more and doesn't provide any actual benefits in my usual shore diving profiles.

If I were stuck on a cattle boat that only served air, and was presented with a 200 fsw dive that I already paid for, I would probably back out. Honestly. A 150 fsw dive on air would be no problem, though, I'd just take it easy on the bottom. 150 fsw is my personal threshold of reason for air. Anything deeper on air is nuts, in my opinion, and too patently dangerous to attempt. There's nothing underwater worth my life, and there are always other boats that have clues onboard.

Now blacknet, since he wants references -- I present the NOAA Diving Manual and the US Navy Diving Manual. They are at home, so I can't quote actual phrases, but the books are all about gas selection. If you need any more references to believe deep air is bad, you must not believe the sky is blue.

It's known, and printed in thousands of places, that nitrogen is narcotic. It's also known, and printed in thousands of places, that oxygen is toxic. Deep air suffers from both of these problems. Every printed work on the market agrees. I find it rather funny that Ed has to rib us for not providing references, when virtually every book in the world backs us up. It's like looking for a tree in the midst of a forest. I asked Ed for references, because his opinion is that every accomplished diver is wrong, every agency is wrong, and every book is wrong. Ed believes he knows better, and that deep air is ok. Ed also brandished a couple of juicy quotes that he believed supported him -- but unfortunately his quotes actually supported the rest of us that have sense.

And Ed, since when has the 'better solution' had anything to do with economics? If you're drunk, you can't drive. Yes, the taxi's a lot more expensive -- but I'll be damned if it's not a better solution. Air : Deep diving :: Alcohol : Driving.

It's simple folks. Go read the NOAA and USN manuals for two good references. I bet there are 1000 good quotes in each.

- Warren

 

[AquaTec]

padiscubapro, blacknet, & Ari
Thank you for your replies; they were constructive, and opinionated yet without criticism. That is the type of attitudes that keep new guys like me involved.

To summarize the [productive conversation so far]

1 - Everybody agrees that He is a better option than air for deeper dives
2 - Ari stated some valid points with uncle pug getting into the whys of that point. That is that a PPn2 of 3.2 is considered narcotic
3 - This substantiates what yooper says is that we are training to drive drunk
4 - however this isn't entirely true as Ed has pointed out and I concur that a resistance can be built up to narcosis. And I don't believe it can be a DIRECT comparison to drinking, which is just a convenient parallel for training purposes to OWD
For example in 1982 - 86 I was doing daily dives between 150 - 240 ft on air, these dives were usually my fourth to sixth dives of the day. I was not narced until I hit the 240ft area [all other none hazards aside please] this is as scbapro said a function of availability, and current technology. Since the early 90's I have been throwing some He in the mix for these types of dives.
5 - PADISCUBAPRO makes another good point truuk lagoon does not offer He. To bad because I will be there in April. So do we forgo the dives or do we acquire the skills and then practice on doing those dives. I will bet that every person on the boat I am on does those dives. I just hope that they have received the training somewhere.


So I gather that it make since to train on air if you plan to dive in areas that do not have He. If He is available you would be stupid not to use it. If you personally decide to use air even if only occasionally due to location or lack of product then you had better have some experience and training at it. There is proof out there that divers can/do build up a resistance to Narcosis

Now for an interesting real world example of narcosis

Four weeks ago we did a 200 ft dive at a local site we went slow and easy checking everything out along the way. [On air]
No signs of narcosis a great dive.

Last weekend Myself and my buddy planned another quick jump to 200ft. guess what he couldn't get He again, simply not available [we occasionally have that problem here] I however had enough to put 5% in my tanks, [better than none I thought] so 180ft for 30 minutes ended up being our plan, my END was 166. We ascended towards 180ft and in about 1-1/2 minutes hit 175 and an incredible since of narcosis hit me hard. I called the dive!! And ascended to 160 were like a light switch the feeling was completely gone. We leveled off at 170. Now this had me very curious. Since our plan called for 180 I was committed to doing that deco profile anyways. I played around with narcosis a bit

For my buddy on air the longer he stayed at 170 the stronger the narcosis became.
For me on 21/5 I dropped down to 180 and felt zero effect. If not for that first couple of minutes I would have said that there was no effect at all on this dive. Most of my dive was spent between 170 and 180
For my buddy after about 20 minutes we needed to ascent to 160 at that level he was still slightly narced but more manageable.
At 150 there was nothing.


From this one dive we as a team made a couple conclusions
1 - Narcosis can come on very rapidly
2 - Speed of descent has a great effect on the onset
3 - Ascending will make it completely disappear
4 - Breathing rate has an effect on uploading and off loading
5 - Your susceptibility can change from dive to dive
6 - On a previous dive to 350 we both had and END of 160 and we both felt narced, we believe due to a rapid descent 100+ft/minute
7 - A slow descent or even a pause at depth allowing for nitrogen to build up during a dive may prevent the narcosis from coming on at all. I.e. deep stops to on gas [how’s that for a new theory]
7 - based on the dives I was doing in Hawaii repetitive deep dives will dramatically reduce your susceptibility to narcosis
9 - Don't count on it
10 - We have agreed to set our END no deeper than 150 for deeper dives
11 - Practice diving with narcosis in the shallow end of the pool so that if it does hit suddenly at the deeper end it won't be unmanageable
12 - for each person it’s different; me - sudden build up is bad, buddy - long exposure is bad. For both of us the opposite does not apply

Now before Yooper jumps me this is not anything I have learned from any agency. It is just from years of diving, and my own narcosis effects.
I think it is important for everybody to understand that the training you get from any agency is the very basic skills to allow you to do the diving at that level. Even if you spent six months in a training program. You still need to swim the deep end on your own.
So if we can all discus what we know instead of what the other person doesn't know then we can gain benefit from a forum like this

 

[VTWarrenG]

AquaTec,

You cannot train yourself out of narcosis, for the last time. If you choose to believe it, that's fine -- but stop offering it like "you know better." All the evidence is against you here. You cannot train yourself out of narcosis.

If it's a local dive, you have the option of adding He. It's always available for local dives. You can put it in your garage.

Your list of narcosis inducing conditions is quite correct. It only reaffirms my position that there's no such thing as a "safe" deep air dive. If you can't get a proper breathing mix, because of economics, or availability, or whatever -- you need to bring the He with you. You need to make it available, or you need to call off diving. Deep air diving is NOT SAFE.

You apparently think that Pug, Yooper, roakey, and myself are just a bunch of argumentative detractors. Well -- you're only half right. We're definitely argumentative, but we're trying to keep people safe. We'd like for all of you to be safe, and keep your friends safe. I'd love to have any of you guys as a dive buddy, because at least you CONSIDER what you're doing. I, for one, get frustrated to see people knowingly put themselves in harm's way.

ALL of the evidence indicates that deep air is dangerous. It is NEVER necessary. PLEASE don't do it.

- Warren

 

[AquaTec]

Just a quick note on END
I just ran a couple of quick dive profiles

Travel gas 36%
Deco gas 80%
SAC Rate
dive .75cu ft/ min [this is average]
deco .50 cu ft/ min [this is standard]


Dive 1 - 350ft/20minutes - Bottom gas; 10/50 - END;158ft - Run time; 169 minutes -Total gas consumption; 330 cu ft

Dive 2 - 350ft/20minutes - Bottom gas; 10/63 - END; 93ft - Run time;189 - total gas consumption; 360cu ft

 

[VTWarrenG]

AquaTec,

What's your point? That your plan for 158 fsw END has a shorter runtime than your plan for a 93 fsw END?

- Warren

 

[AquaTec]

I am certainly not trying to be a know better. I don't know ****. That is why i am stirring up this conversation.

My whole point IS that you can not train yourself out of narcosis. you need to train yourself FOR narcosis.
AND AVOID IT AT ALL COST.
As far as the group you have listed I am trying to draw out of you guys good information. but it requires reading between the lines of all the other crap you guys include in your postings

I agree that Deep Air is dangerouse and everything you read will tell you that.

So I am asking this
What is Deep?
Is your opinion of deep refferenced to in the same matterial that you read which stated that deep air is dangerous?
Physiologicaly why is it dangerous? uncle pug and ali started down that path?
Do you beleive its dangerouse just because everybody says it is? or is there good solid evedence that at a certain PPN2 you will explode and die?
This remainds me of when first PADI came out and saying diving below 130 was forbiden cause you will die [not a quote]. I said holly crap I better ascend before its to late.

My Previous post was just to stimulate more constructive interaction. please refran from critisism

 

[AquaTec]

No point really

both dives are do-able dives, maybe the END of 158 goes against your grain. I don't know what if there is no difference in narcosis between 100 & 160 on you as an indavidual. just take a rubix cube to depth with you and see were you stop being able to perform.

What about some feed back on high PP of He = HPNS ? [cases reported at 400ft] but at what Partial Pressure
Longer deco times
Deeper deco stops
30 cu ft more gas

none of this is to prove anything it is just for discutions.
any good piont to bring out of this profile