Nitrox 28 Uncertified

[Splitlip]

Nitrox breathes like air, so no training is needed to breathe it. The danger of Nitrox lies in understanding the other implications, most importantly oxygen toxicity.

Though it's non-standard practice, as long as the correct gas mix is confirmed and the MOD is deeper the hard bottom at the site, there's no real danger to an untrained diver using Nitrox.

However there is a subtle danger in developing the habit of letting others excercise judgement for you. Every diver needs to make his own decisions and control his own destiny, and depending on the decisions of others is per se risky practice.

This would have been my reply.

 

[DevonDiver]

I have not run the calculations but I suspect those dives will be NDL limited using air tables or computer. And they may also be NDL limited if calculated on EAN28, at least at the 30 meters.

But my point is.... you are educated on Nitrox....the suckers diving with these Subex jokers are not. They are unaware of even the need to do a cursory check that their diving program could stack up their CNS clock.

I don't have a CNS table to hand, but I know that 'my' typical diving vacation would consist of max dives per day, deeper and challenging/rewarding sites. If I did EVERY dive on 28%, there would be a creep of CNS clock.

Remember, CNS cumulative is in a 24 hour period... not per day.

1x late morning, 2x afternoon dives....plus night dive....the two deep dives early the next am....and you can easily creep towards the no-no....within a given 24 hour period.

 

[H2Andy]

But my point is.... you are educated on Nitrox....

everybody keeps missing this point

they keep discussing Nitrox with obvious knowledge while forgetting that the issue is that most divers who take on the "air 28" or whatever know absolutely nothing about Nitrox and its issues

the point is that you need to know about Nitrox in order to determine whether 28% is safe for you on this dive and on following dives

if you don't know enough to make that call, you should not be diving this gas

 

[Tigerman]

everybody keeps missing this point

they keep discussing Nitrox with obvious knowledge while forgetting that the issue is that most divers who take on the "air 28" or whatever know absolutely nothing about Nitrox and its issues

the point is that you need to know about Nitrox in order to determine whether 28% is safe for you on this dive and on following dives

if you don't know enough to make that call, you should not be diving this gas

You need to have some basic knowledge, which is all I have as im not certified, of nitrox to even determine *** "Subex air28" is in the first place.

THEN you need to have some knowledge of at a very minimum MOD and wether or not the type of diving youll do will have any actual CNS clock issues before you can begin realizing if its safe or not - Which for the type of diving I do (usually 2, never more than 3 dives a day with 60min+ SI) it should be from what Ive learned by nothing more than reading a bit and talking to people. However, since I dont fancy the "trust me" concept too much, I still wouldnt gear up in nitrox just yet, Ill rather be safe than sorry and get the formal training (and documentation) first.

 

[DevonDiver]

Back to the OP's question....

do you think it is safe to let uncertified divers with little or no knowledge of Nitrox use this Gas.

It is not SAFE for uncertified divers to use 28% nitrox without the appropriate knowledge.

It is not ETHICAL to promote this gas for un-trained divers, by only highlighting it's advantages, but NOT it's disadvantages and potential risks.


From what I read on their website...this Subex organisation seem to be either very unethical or very ignorant. I wouldn't dive with them...ever.

 

[RikRaeder]

I'm not planning to run out and dive with these clowns, nor do I think what they are doing is ethical but; has anyone dived with these guys? Do we know;
1) If they do have some sort of briefing regarding MOD or CNS%?
this information may be communicated quite quickly albeit in a cursory fashion
2) How many dives these guys usually do a day?
not all shops run 4 dives plus a night dive...it could figure into the CNS issue
3) What sites they dive on their special magical voodoo gas
important regarding depth for pp02 and MOD

Again, I do not condone what they are doing. I believe a Nitrox cert is rightfully needed for 22% O2 and above. Since we are talking about safety here, right or wrong, argument is moot without considering the factual data.

 

[maged_mmh]

I'm not planning to run out and dive with these clowns, nor do I think what they are doing is ethical but; has anyone dived with these guys? Do we know;

based on personal experience (BTW, I was EAN certified when I dived with them)

1) If they do have some sort of briefing regarding MOD or CNS%?

No

2) How many dives these guys usually do a day?

2 per day (not 24 hrs) max per diver

3) What sites they dive on their special magical voodoo gas
important regarding depth for pp02 and MOD

Ras Mohamed, Tiran straits, Thistlegrom, ...many more but not usually exceeding 40mt depth - they also advise ppo2 of 1.6 for nitrox 32 & 36 divers.

 

[RikRaeder]

Why thank you...that fills in a few blanks

 

[redacted]

everybody keeps missing this point

they keep discussing Nitrox with obvious knowledge while forgetting that the issue is that most divers who take on the "air 28" or whatever know absolutely nothing about Nitrox and its issues

the point is that you need to know about Nitrox in order to determine whether 28% is safe for you on this dive and on following dives

if you don't know enough to make that call, you should not be diving this gas

I suspect the supplier may have done that and found that at recreational limits of 130ft or 40 meters, the dive limiter is always nitrogen. EAN 28 at 132 ft has ppo2 of 1.4. NDL for air is 10 minutes which get you 10% of the O2 allowable exposure (PADI tables). Even if you dive it as EAN28, you get 13 minutes NDL and still 10%. We probably can look at some other profiles, but my experience with EAN32 and multiple deeper dive in the 100 ft range leave me NDL limited for shallow profiles and O2 limited for deeper profiles (using an older Oceanic Data Plus -- the newer Oceanics have a somewhat more liberal cumulative O2 algorithm).

So, perhaps the question is can anyone find a set of multi-day dive profiles with max depth of 132 ft that can expose a recreational diver (no deco) to too much O2 using EAN28?

 

[DevonDiver]

..... they also advise ppo2 of 1.6 for nitrox 32 & 36 divers.

1.6???

...and yet they claim...."Although we base SUBEX training on our own unique training concept, it is in conformity with all major standards, e.g. CMAS, SSI, PADI and NAUI."

It doesn't sound as if they are conforming with any standards adhered to by the diving industry :shocked2:

So, perhaps the question is can anyone find a set of multi-day dive profiles with max depth of 132 ft that can expose a recreational diver (no deco) to too much O2 using EAN28?

I am back in work tomorrow...will have a play with the tables and see what sort of % I can come up with from realistic dive profiles.

Remember though....you only get 10 minutes using square profile...on a table... when using dive computers....you will multi-level and can be in the water easily for 45-60 minutes. When calculating multi-level CNS%, it is possible to rack up more than 10% CNS for a dive.....