Are scuba regulators life-support equipment?

[agilis]

Im a Nitrox instructor and trimix diver. Some agencies (PADI for one) recognize 15fsw as 1.6 PO2 but most agencies including the navy use 20fsw for oxygen. I dive DIR and our last stop is always 20 feet. Not necessarily as big of deal for us because my tech team dives rebreather. I generally fly the unit manually at 1.4 for deco.

I say "decompressing oxygen" to emphasize the fact I need to trust my oxygen reg for deco after a tech dive.

---------- Post added February 4th, 2014 at 08:01 PM ----------



Kudos!

Work of breathing is the main factor. Once I tried an Apeks balanced first stage, I couldn't go back. Contrary to what I said, I think condition plays a big part too. Rental regs often breathe so terribly because they are so abused. But when I said "cheap" I meant the quality of the parts used.

You wrote 'I need to trust that my regulator will give me 100% decompressing oxygen at my 20' stop"

100% oxygen at 20 feet can kill you, decompressing oxygen or just the ordinary kind. I fully understand the physics involved, and the distinctions between PADI and Navy standards are irrelevant. Where you do your offgassing safety stops, whether at 20 feet or 15 feet or 5 meters, also has no relevance to the issue of potential toxicity of 100% oxygen at the depth you mentioned.

 

[tphelps]

how does padi recognize 15ft as 1.6ppo2? Math is math no matter what agency...

and "i dive dir and my tech team dives rebreather" doesnt really go hand in hand.

The MOD of oxygen using 1.6 PO2 is 19.8fsw
((PO2/FO2)x33)-33
i don't disagree with the math, I just remember l did 15 ft for my tech class.
Sorry for the confusion, long DRY day today. I meant to say diving rebreather is cool because you control your PO2 the entire dive.

---------- Post added February 4th, 2014 at 09:19 PM ----------

You wrote 'I need to trust that my regulator will give me 100% decompressing oxygen at my 20' stop"

100% oxygen at 20 feet can kill you, decompressing oxygen or just the ordinary kind. I fully understand the physics involved, and the distinctions between PADI and Navy standards are irrelevant. Where you do your offgassing safety stops, whether at 20 feet or 15 feet or 5 meters, also has no relevance to the issue of potential toxicity of 100% oxygen at the depth you mentioned.

Ok now I understand what you are saying. Yes I agree, there is an inherent risk of diving with oxygen at that depth.

 

[JohnN]

You wrote 'I need to trust that my regulator will give me 100% decompressing oxygen at my 20' stop"

100% oxygen at 20 feet can kill you, decompressing oxygen or just the ordinary kind. I fully understand the physics involved, and the distinctions between PADI and Navy standards are irrelevant. Where you do your offgassing safety stops, whether at 20 feet or 15 feet or 5 meters, also has no relevance to the issue of potential toxicity of 100% oxygen at the depth you mentioned.

The "science" behind Oxtox is hardly definitive. at 20 FSW, PO2 is 1.6.

Apparently you believe this is too high. . . what is your 'magic' number ?

 

[agilis]

The "science" behind Oxtox is hardly definitive. at 20 FSW, PO2 is 1.6.

Apparently you believe this is too high. . . what is your 'magic' number ?

There is none. Too many variables. That's why I wrote 'can' and not 'will'.

 

[Scared Silly]

Some divers may prefer to breathe from a $1099.00 reg, instead of sucking from a cheap reg.

Discriminating divers prefer to breathe from a $719.00 reg with more features than bling while not having their money needlessly sucked out of their wallet.

Speaking of sucking, ....

Nice to see the beav chiming in on such a crucial matter with his usual cutting insight.

Would that be sucking or suckling?

 

[JohnN]

There is none. Too many variables. That's why I wrote 'can' and not 'will'.

The world 'can' end tomorrow also. Not terribly useful, is it?

 

[Tigerman]

The world 'can' end tomorrow also. Not terribly useful, is it?

Actually thats highly unlikely, unlike oxtoxing which has a history of happening. The world WILL end as we know it though, but most likely in something like 5 billion years...

 

[dfx]

The world 'can' end tomorrow also. Not terribly useful, is it?

It's a probability curve. At a ppO2 of 0.2 the probability of toxing is around 0%. At a ppO2 of 3.0 the probability is around 100% (I'm guessing, but you get the point). At 1.6 it's somewhere in between.

 

[dkktsunami]

If you have to ask ...........

 

[agilis]

The world 'can' end tomorrow also. Not terribly useful, is it?

Not nearly as useful as 'breathing 100% oxygen at 20 feet is dangerous because the possibility of a CNS hit is significant' or 'safety margins should not be reduced to levels so narrow that potentially fatal accidents become distinct possibilities.'