100m air dive & workup, PG

[Bubble_Boy]

I was under the impression that the oxygen in air becomes toxic after 50m .... what happened to that? Do the laws of physics work differently in the Philippines?

 

[Cave Diver]

I was under the impression that the oxygen in air becomes toxic after 50m .... what happened to that? Do the laws of physics work differently in the Philippines?

Oxygen toxicity is a result of time + exposure level.

It's generally accepted that a 1.6 po2 for 45 minutes is the limit for oxygen exposure. As your po2 decreases the recommended allowable exposure time increases.

65m is approximately 1.6 po2 when diving air.

Here is a chart with exposure limits for reference: http://www.anaspides.net/documents/scuba_diving_documents/NOAA CNS Percentage Table.pdf

Of course, just like diving tables, different people will have different reactions to exposure. These limits are thought to work for the majority of the population, but other factors and individual physiology may produce different results.

 

[chriswarren102]

OT is relative to exposure time as well as PP, all deep dives I've done have had relatively short bottom times.

 

[Kevrumbo]

I was under the impression that the oxygen in air becomes toxic after 50m .... what happened to that? Do the laws of physics work differently in the Philippines?

There is speculation that the nitrogen component in deep air mix "buffers" the oxidative & toxic CNS effects of high ppO2 exposure at depth. . .

 

[Cave Diver]

Realistically if you're doing that sort of diving and want a sensible bottom time then its CCR territory otherwise the gas cost and quantities get ridiculous.

...+1

 

[Cave Diver]

There is speculation that the nitrogen component in deep air mix "buffers" the oxidative & toxic CNS effects of high ppO2 exposure at depth. . .

I've heard that speculation before. Has anyone seen any sort of data to support that speculation, or is it just totally SWAG?

 

[DevonDiver]

There is speculation that the nitrogen component in deep air mix "buffers" the oxidative & toxic CNS effects of high ppO2 exposure at depth. . .

I've heard that also... especially in relation to HPNS.

 

[duskdiver]

Although I have been far to deep on air back (72 meters) in the days nowadays I consider it a bad example to others..
There are plenty plenty of examples of very experienced divers having serious issues underwater at these depths on air..it would be arrogant to say that either one of us are immune to this..

Becoming a better diver, better skills, knowing more will eventually lead to NOT diving deep on air.
It is a process...becoming a mature diver!
I must admit that deep down inside...I would like to have tried a 100 meters on air..

 

[Lobzilla]

Although I have been far to deep on air back (72 meters) in the days nowadays I consider it a bad example to others..
There are plenty plenty of examples of very experienced divers having serious issues underwater at these depths on air..it would be arrogant to say that either one of us are immune to this..

Becoming a better diver, better skills, knowing more will eventually lead to NOT diving deep on air.
It is a process...becoming a mature diver!
I must admit that deep down inside...I would like to have tried a 100 meters on air..

Don't worry.

"...There is an old saying that a superior pilot is one who uses his superior judgment so as not to have to use his superior skill."..What makes a 'pilot's pilot'? Attitude and judgment. Recognizing that a pilot's license is simply a license to learn...and all flights are proficiency flights on which something can be learned, and skills can be honed. That is the right attitude. But the best of skills must be coupled with judgment..."

What does that have to do with diving?

As a pilot you have to earn the safe landing - back to the surface. Failure to accomplish this, be it due to lack of skill or lack of judgment, is a bad thing.
As a diver you have to earn the safe ascent - back to the surface. Failure to accomplish this, be it due to lack of skill or lack of judgment, is a bad thing.

The crucial flights/dives are the ones you DO NOT make.

 

[Bubble_Boy]

There are old divers and there are bold divers.
But rarely you will find an old bold diver!