Riding GF99 instead of mandatory/safety stops

[old frogman]

I don't understand your point. Oxygen is more soluble in blood (and other tissues) than nitrogen and helium. What does that mean in terms of an "oxygen window", and what is the practical effect in terms of decompression?

I explained the oxygen window on page 20.

The significance to decompression is that in the venous system, the CO2 (resulting from metabolised O2) has a lower tension (partial pressure). This lower CO2 tension creates a void for accommodating N2 during ascent. This facilitates ascent with minimal N2 Bubbling.

This partially explains why you can ascend (to some extent) without experiencing decompression stress. In practice asymptomatic bubbles will still form but the oxygen window helps to reduce this.

As stated before, the off gassing is not a product of the oxygen window but a of product of pressure differential caused by the ascent.

The CO2 window is the result of the different solubility of O2 and CO2 which drives the process of O2 flowing from arterial capillaries into tissues and the metabolised product CO2 flowing out tissues into the venous capillaries. It is an isobaric process independent of external pressure. It explains how our cells respirate.

Solubility coefficients at 25C at 1 ATM in water are as follows:
O2 is 0.031
CO2 is 0.76

Consequently, CO2 is about 24 time more soluble than O2. The higher the solubility, the lower the tension of the dissolved gas.

Sorry I cannot make this simpler. Human physiology is complex.

PS. The solubility coefficient of N2 is 0.015. Relative to O2 and CO2 it is less soluble, higher tension and explains why it likes to come out of solution forming bubbles.

 

[tursiops]

The significance to decompression is that in the venous system, the CO2 (resulting from metabolised O2) has a lower tension (partial pressure). This lower CO2 tension creates a void for accommodating N2 during ascent. This facilitates ascent with minimal N2 Bubbling.

So Dalton's Law is not relevant. Interesting explanation.

Added: the original post say Boyle's Law, in error; I meant Dalton's Law.

 

[rjack321]

Human physiology is complex.

Except your whole post is inaccurate. Gasses are independent of each other. The metabolism of O2 does not "make space" for anything else to offgas. Nor does the solubility of CO2 help or hinder the offgassing of nitrogen.

 

[boulderjohn]

I explained the oxygen window on page 20.

Yes, you did. And since then there have been multiple posts explaining that pretty much all authorities have determined that the theory you explained is not valid. It has been pointed out that it violates Dalton's Law.

What you need to do is explain why all the people who have decided it is not valid, people like mark Powell of TDI, Jarrod Jablonski of GUE, and Andrew Georgitsis of UTD, are all wrong. You need to explain why it does not violate Dalton's Law.

 

[Capt Jim Wyatt]

mark Powell of TDI, Jarrod Jablonski of GUE, and Andrew Georgitsis of UTD,

WTF do these laymen know? They aren't physiologists, they aren't physicists, they aren't hyperbaric researchers, they are not Medical doctors. They are simply scuba instructors....

 

[boulderjohn]

WTF do these laymen know? They aren't physiologists, they aren't physicists, they aren't hyperbaric researchers, they are not Medical doctors. They are simply scuba instructors....

Powell did extensive research before writing Deco for Divers, including talk with Michael Powell, formely Doctor Deco on ScubaBoard. Jablonski and Georgitsis were firm advocates of the oxygen window theory being cited here. It took a lot of evidence for them to publicly admit they were wrong.

So, since you seem to be surprising me by indicating support for this theory, why don't you cite the true experts who agree with it?

 

[Capt Jim Wyatt]

why don't you cite the true experts who agree with it?

I have no idea who agrees or disagrees with it. My point was those 3 have less formal hyperbaric medicine training than I do, and I cannot state with certainty whether it exists or not. Certainly, a pressure vacancy exists.

 

[tursiops]

Certainly, a pressure vacancy exists.

That is not enough. It is the pressure in the individual gases that counts, otherwise no graident for that gas to do any movement. You can drop the O2 or the CO2 or whatever as much as you want, but unless the N2 pressure in the tissues/blood drops, there is no pressure gradient to move N2.

 

[boulderjohn]

I have no idea who agrees or disagrees with it. My point was those 3 have less formal hyperbaric medicine training than I do, and I cannot state with certainty whether it exists or not. Certainly, a pressure vacancy exists.

As people keep pointing out in this thread, it violates Dalton's Law.

So what do we who do not have major scientific training do? We have to look for support from people who do have such training. if someone is going to make a claim that appears to violate Dalton's Law, that would be absolutely groundbreaking. You would expect some sort of corroboration from people with solid reputations, but there does not seem to be any such corroboration from anyone with any scientific credentials.

My point about mentioning the other names is that this theory was popular in certain circles 15 years ago, but all the people who promoted it then have dropped it. They didn't drop it and change agency policy on a whim--they obviously got some authoritative advice.

 

[rjack321]

As people keep pointing out in this thread, it violates Dalton's Law.

So what do we who do not have major scientific training do? We have to look for support from people who do have such training. if someone is going to make a claim that appears to violate Dalton's Law, that would be absolutely groundbreaking. You would expect some sort of corroboration from people with solid reputations, but there does not seem to be any such corroboration from anyone with any scientific credentials.

My point about mentioning the other names is that this theory was popular in certain circles 15 years ago, but all the people who promoted it then have dropped it. They didn't drop it and change agency policy on a whim--they obviously got some authoritative advice.

I dunno who they talked to or if they just finally wised up that the "oxygen window" was some mumbo jumbo gas law defying magic. Sadly the internet is forever and as this thread illustrates, there are folks out there still rationalizing it exists.