How much deco does 80% remove?

[fins wake]

By the way, in Europe, they go down to 50 metres without much ballyhoo about it.

In France and Italy, yes, the CMAS*** will go down to sixty but with very rigorous training! In, say, the UK many will go down to fifty with considerably less training, but there's some very interesting accident figures to go with that (e.g. all the South Coast pots are filled summer-time and the UK flies against the world statistics as far as DCS is concerned). In the Baltic, only idiots go down to that depth without trimix training and proper gases.

As far as oxygen is concerned, I'll go with Rick and Dr Deco. Use it, but have the training and be careful .... I've seen welders do some pretty interesting things with a lighter and a tank of oxygen ...

K.

 

[Munin]

blacknet once bubbled...
With the modern marvel called the internet it's easy for anyone to find the information they are looking for. Anyone can goto www.gap-software.com and download gap. Anyone can goto www.v-planner.com and download v-plan.

Yeah, I have both. Clearly he doesn't.

Anyone can also STFW and learn all about decompression theory and practice.

Obviously he lacks even a basic understanding of the various methods available for calculating decompression, and is therefore not qualified to be doing the dive. The question wasn't theoretical, it was practical, (did you look at his profile and website?) and handing someone who is untrained a schedule to go and do a decompression dive is seriously dangerous.

He/she did state certs to 50% so that tells me IANTD adv nitrox. I think you missed the boat on what he/she was asking.
Ed

From the TDI website:

Advanced Nitrox
This course examines the use of EAN 21 through 100% (oxygen) for optimal mixes to a depth of 130fsw/40msw. The object of this course is to train divers in the benefits, hazards and proper procedures for utilizing EAN 21 through 100% (oxygen) for dives not requiring staged decompression. (Decompression techniques may be combined with this course at the discretion of the instructor).

130 fsw, no staged decompression. If you look at his website he lists advanced nitrox only. IMO, advanced nitrox alone does not prepare someone for decompression.

So let me get this straight: you are recommending that people conduct decompression dives by asking people on the internet how much time they should remove from their DCIEM table stops? Are you saying that anyone that wants to do technical diving should download V-planner and go out and dive? I think you missed the boat on what I was saying. Yeah, the internet can teach you more about decompression than a class, if you use it correctly, but he hasn't got there yet, as his question implies.

Nobody here has even said anything about using a nitrox mix for bottom gas on a 150. I would never do a cold water deco dive on a narcotic mix. I know some of you will do 150 on air and that's your business, but nobody even suggested using mix for that dive.

 

[BigJetDriver]

fins wake once bubbled... As far as oxygen is concerned, I'll go with Rick and Dr Deco. Use it, but have the training and be careful .... I've seen welders do some pretty interesting things with a lighter and a tank of oxygen ... K.

I, too, will have to echo the words of Fins, Rick, and Doc Deco. As I have said in other threads, oxygen in concentration is a powerful creature. Respect it and don't take unnecessary chances with it!

As Rick pointed out, "The Oxygen Hackers Companion" is a very useful and practical source of info on the subject. Also, the information available from Global Manufacturing on O2 cleaning and prep is very handy! Also too, Bill High's book on Scuba cylinders from PSI, Inc.

Two asides, if I may. One is that, in the Hyperbaric Medicine community, 23% is the limit for concentrations in chambers. For other purposes, I have heard the 26.5% figure used, but Hyper-Dick Rutkowski, who brought the subject to us, uses the 40% figure. (These notes are simply FYI.)

Second, in training, Dick used to say: "Just remember. Welders in Mississippi survive using oxygen!" What he went on to make plain was that one should be cautious, and use proper procedures, but that one does not have to tremble in fear from the very mention of the word "oxygen"!

P.S.---I've seen the cigarette and O2 trick, Fins, and you are right. It's enough to make the hair on the back of your neck stand up straight!!!=-)

 

[Cave Diver]

Rick Murchison once bubbled...

... Uncle Ricky climbs onto soapbox...
I don't know where this dangerous and misleading hair splitting statement got its origin, or why it keeps its life, but the facts are:
Practically nothing is "flammable" by itself. The ingredients for a classic fire are enough heat for ignition, fuel and oxygen. Whether you call the fuel flammable and the oxygen the accelerator or the other way around is irrelevant. Pure oxygen will cause fire where no fire would be without it, as will adding fuel to a pure oxygen environment. You get the same BOOM regardless of your definition.
If you intend to handle rich mixes, and especially if you plan to mix them yourself, please get (at a minimum) a copy of Vance Harlow's Oxygen Hacker's Companion and read it cover-to-cover before proceding.

Actually if you want to know where this dangerous and misleading hair splitting statement got it's origin, you might try reading the very text you referenced.

Excerpt from Vance Harlow's OXYGEN HACKERS Companion:

Chapter 1
THE BASICS
Page 1, Paragraph 4

"O2 is not in itself flammable, but it is a potent oxidizer. It can drastically lower the ignitability of any flammable substance (and this includes many materials that we don't even think of as flammable, such as stainless steel, aluminum, plastics and wallboard) and vastly accelerate and intensify the combustion once it has been initiated. All these effects increase dramatically as the pressure of O2 increases"

 

[Jonathan]

TDI and IANTD Advanced Nitrox are not the same.

TDI "certifies" you to go deeper and user a richer mix than IANTD.

I am not quite sure what fins awake is saying:

In, say, the UK many will go down to fifty with considerably less training, but there's some very interesting accident figures to go with that (e.g. all the South Coast pots are filled summer-time and the UK flies against the world statistics as far as DCS is concerned).

are you saying that there should be more DCS hits than there are or that they have much more than the average? There aren't that many pots near the south coast so it does not take much to fill them - particularly in the summer months.

Jonathan

 

[crispos]

Thank you all for your input. Don't worry, I am not running out to use the first deco software I find. Your cautions are well taken.

 

[fins wake]

are you saying that there should be more DCS hits than there are or that they have much more than the average?

The latter:
http://www.divernet.com/news/items/incidents091202.htm

Yes, I know UK diving is very challenging compared to many parts of the world, and there are a lot of divers out there. But the anecdotal evidence points to many more accidents actually involving deep (and in many cases very deep) diving and involving more actual cases of DCI than in many other countries, even those with very similar and equally challenging conditions.

Here are some of the more recent examples to further illustrate my point:
http://www.divernet.com/news/stories/bends280703.shtml
http://www.divernet.com/news/stories/solentdeath220703.shtml
http://www.divernet.com/news/stories/bends200703.shtml

I could fill up with more examples, but these will do. They're from the last week only ...

In Sweden, a set proportion of diving fatalities will occur every year or so with very inexperienced divers in very shallow water, usually around 10 metres or so. (Last such case was last week). But it's been a long time now since somebody died on a 63 metre dive ... such cases are rare. I venture it's because the majority of divers who do them here (and these dives are done regularly!) are very well-trained, equipped and disciplined (generally to a technical dive level).

I don't aim to flame UK divers at all. Most are very good and many are world-class. (In fact, I'd say that the UK has a higher share of world-class divers than almost any other country relative to its size.)

But I am saying that a larger minority of UK divers seem to push the envelope and do dives that they shouldn't be doing yet (or ever!) than in many other countries.

In Sweden, there are an average of thirty (30) chamber treatments in the whole country every year. That includes everything: recreational, military and commercial diving ... And there are a fair number of dives being done every year anyway ...

 

[Epinephelus]

Cave Diver once bubbled...
Actually if you want to know where this dangerous and misleading hair splitting statement got it's origin, you might try reading the very text you referenced.

KISS...
If you mix substance "A" and substance "B" together and they burn, is the label you put on them relevant? It is the emphasis put on the statement "oxygen is not flammable" that is misleading.
You can take a regular silicone scuba mask and a lit match and play with them all day long in air, and all you'll get is a burned match - add oxygen and the silicone mask will burn merrily - and hot - you get the big flames when you add the oxygen.
While it may be technically correct to say the mask is flammable and the oxygen isn't, if our goal is safety - and the average layperson knows that the mask is not flammable - is it responsible to emphasize that "oxygen is not flammable?"
I think not.
E.

 

[Walter]

sheck33,

"all hearsplitting stuff but the field of physics taught me to do that"

If you're going to split hairs, you should actually split "hairs."

Here's one to split - what is the correct word? "Flammable" isn't it.

 

[BigJetDriver]

Epinephelus once bubbled... While it may be technically correct to say the mask is flammable and the oxygen isn't, if our goal is safety - and the average layperson knows that the mask is not flammable - is it responsible to emphasize that "oxygen is not flammable?"
I think not.
E. [/B]

DEF: "Flammable---capable of catching fire and burning rapidly"---Webster's

DEF: "Inflammable---tending to catch fire easily"---Webster's

DEF: "The Fire Triangle---Fire is a rapid chemical reaction between a FUEL (emphasis in text) and an OXIDIZER (oxygen), and it can only take place if there is a source of IGNITION (heat) to start it."---NOAA Diving Manual, Fourth Edition, page 15-17, paragraph 15.11.2

Divers presumably read this site to get accurate information that, many times, is not readily available through other sources. A perfect example would be the writings of our very own Doc Deco! It therefore behooves us to be as accurate as we possibly can.

Is it responsible to emphasize that oxygen is, in and of itself, NOT flammable? I think SO, as long as we emphasize that many things that we do not ordinarily think of as flammable will burn FIERCELY in the presence of enhanced oxygen environments!

The safe handling of oxygen under more than atmospheric pressures is easily possible through safe procedures. The use of safe O2 handling procedures derives directly from KNOWLEDGE!