Maximum Operating Depth (M.O.D.) S.C.U.B.A. Diving On Air.

[Rose Robinson]

Hello, Rose. How are you? I appreciate your response.
I wanted to let you in........on a little secret. Please, don't tell anyone.
I sometimes.........ask questions, that I already know the answer too. Shhhhhhhhhhh.
Cheers.

Hello Boston Breaker,

I am fine, if you are fine

That's so funny, aren't you ashamed?

But, I already knew.

You're one of those hardcore, super deep, expedition technical divers with 400 tanks, 900 sets of regulators, at least 15 rebreathers, and under various assumed names, penned all of the technical dive books that most people couldn't even begin to understand.

MOD, the first time I heard that, I thought someone had spelled MUD wrong and wrote it in CAPS because they were mad.

Caught ya. you smarty pants!

Rose

 

[wetb4igetinthewater]

Simon Mitchell linked to a study a year or two ago, the results of which indicated that there might indeed be a benefit to nitrox in regard to narcosis.

Was that the one where they used this device that was able to demonstrate the impairment brought on by narcosis?

Still searching for that one. I kick myself for not downloading/saving links to those. It is out there somewhere....

 

[Boston Breakwater]

The uh, erm, uh MOD of 32% @ 1.4 P02 will be shallower than the same P02 on air and consequently be less narcotic. Phrasing seems pretty clear to me. The difference in potential narcosis between 187' and 111' is pretty significant . Unless I missed something and am entirely incompetent at maths.

Hello. You may have missed? The O.P. has nothing to do with "Nitrox."
Cheers.

 

[100days-a-year]

Thas in response to Maxbottomtimes response to tursiops.
And are you new here? SB threads rarely rarely stay on, near or around topic without chasing rabbits, pontificion and wee bit of drama.

 

[Storker]

I was curious what the MOD is for air (20.95%) using a PPO2 of 1.4

pPx = P*Fx

FO2=0.2095
Max pPO2 = 1.4
P=depth/10+1

The math is fairly easy. CMAS 3* certs are generally (but not universally) limited to 56m, because at 56m, pPO2=1.4 bar if FO2=0.21

 

[tursiops]

Thas in response to Maxbottomtimes response to tursiops.
And are you new here? SB threads rarely rarely stay on, near or around topic without chasing rabbits, pontificion and wee bit of drama.

Hey, it went off topic at posts #6 and 7, but he didn't apparently notice or care at that time!

 

[Angelo Farina]

CMAS 3* certs are generally (but not universally) limited to 56m, because at 56m, pPO2=1.4 bar if FO2=0.21

My CMAS 3* qualification was for 50 meters in AIR.
But was also for 10 meters in pure-oxygen rebreather, which means that at the time (1978) the maximum partial pressure of O2 allowed was 2 bars. For short periods, indeed: if I remember correctly the pure-oxygen rebreather had a time limit of 20 minutes at 10m, then you had to surface, and breath air for 15 minutes before diving again...
So the 50m limit had nothing to do with oxygen toxicity, it was set for other reasons (mostly narcosis and for limiting deco times).

 

[Boston Breakwater]

Enriched Air Misconceptions

Cheers.

 

[Storker]

My CMAS 3* qualification

CMAS 3* certs are generally (but not universally) limited to 56m [...]

Perhaps I should have said "Current CMAS 3* certs are generally (but not universally) limited to 56m"

Besides, national agencies are free to impose restrictions beyond CMAS' standards. My 3* cert only qualifies me to 40m. Which is fine with me, I get uncomfortably narked when I drop significantly below 30m. I have no need to go below 40m without He in my mix.

 

[boulderjohn]

Was that the one where they used this device that was able to demonstrate the impairment brought on by narcosis?

Still searching for that one. I kick myself for not downloading/saving links to those. It is out there somewhere....

I believe this is it.
Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox - PubMed