Air consumption and decompression

[kasdeva]

I am working my way through Buhlmann and VPM-B decompression models. The theory is not trivial and I suspect it will take me some time to have some understanding of how the models behave. That said, I notice that nowhere is air consumption during a dive ever taken into consideration or the size of the lungs relative to the weight of a person.

Does the amount of gas I pump through my lungs have no effect on the rate of ingassing or offgassing? I am trying to fit Henry's law into this but I cannot quite get my head around it yet.

Keeping Henry's law in mind, it is not just the pressure difference between two mediums that affect the rate of change but surely also the area exposed relative to the volume of the medium that the gas is being dissolved into. Hence the evolution of alveoli.

Does a heavy breather expose more surface area in his lungs per volume off tissue than a slow/light breather?

 

[knotical]

Here’s a fairly recent thread on the topic:
http://www.scubaboard.com/forums/ad...3-larger-gas-capacity-increased-dcs-risk.html
Basically, since our alveoli are quite efficient at quickly transferring gases, the impact that breathing rate has on nitrogen absorption is quite small.

 

[AfterDark]

The reverse is true, exhalation does make a difference in off gassing. Decompression stops are not the place to practice skip breathing. Regular exhalation is integral to effective off gassing. Years ago I had to deco buddy breathing old school style we added 5 min. to the stop to be safe. It worked, I'm still here, never been bent.

 

[kasdeva]

Here’s a fairly recent thread on the topic:
http://www.scubaboard.com/forums/ad...3-larger-gas-capacity-increased-dcs-risk.html
Basically, since our alveoli are quite efficient at quickly transferring gases, the impact that breathing rate has on nitrogen absorption is quite small.

Thanks, that thread addresses my question nicely.