O2 off-gassing

[ianr33]

Why is the nitrogen compelled to balance?

The nitrogen will "balance" so as to maximize the entropy(disorder) of the system.

Read up on entropy if you want to get really confused. !

 

[CrispyCritter]

It's really a pretty simple matter of diffusion. The greater the difference in concentration between the Nitrogen in one compartment (blood) and another (airspaces in the lungs), the faster the rate of diffusion. Since air has nitrogen in it, the gradient isn't as great between the blood and the lungs, so nitrogen diffusion is slower.

So the reason that O2 is able to diffuse nitrogen faster is simply because it is not diffusing nitrogen back into your system during the gas exchange?

 

[rongoodman]

So the reason that O2 is able to diffuse nitrogen faster is simply because it is not diffusing nitrogen back into your system during the gas exchange?

Yep, pretty much. A mix of 50/50 O2/He would offgas the N2 just as fast, but you would be taking on some He which would later have to be gotten rid of. OTOH, you could get onto the 50/50 quite a bit deeper, 70' as opposed to 20', which would be helpful in reducing bubble formation. It's all wonderfully vague and complicated. There's a very good book, Deco for Divers, by Mark Powell, which is worth looking at if you're really interested.

 

[CrispyCritter]

The nitrogen will "balance" so as to maximize the entropy(disorder) of the system.

Read up on entropy if you want to get really confused. !

I know exactly what you mean! After taking thermodynamics I spent a couple of hours trying to explain entropy to my buddy. I think all he got out of it was that all systems tend to the lowest energy state.

 

[CrispyCritter]

There's a very good book, Deco for Divers, by Mark Powell, which is worth looking at if you're really interested.

Thanks everyone, I guess I was trying to make it more complicated than it is.

That book is definitely on my list, once I am ready for it.

 

[ianr33]

So the reason that O2 is able to diffuse nitrogen faster is simply because it is not diffusing nitrogen back into your system during the gas exchange?

Yes.

You got it.