Another Deco profile post.

[boulderjohn]

To my understanding there is On-gassing at the begin of the dive, once your tissues are saturated and you go up to your stops you are OFF-gassing, it go by differential pressure or not ?? if not it will be a never ending story that you will never be able to decompress the way I maybe misunderstood it, not saying I'm right.

As I understand what you are saying, your mistake is that you think all tissues are the same. Some tissues both ongas faster than others and offgas faster than others. The faster tissues will saturate during a dive and begin offgassing as you ascend. The slower tissues, however, will not be saturated and will continue to ongas as you ascend until they, too, are saturated and can begin to offgas.

 

[Remy B.]

Not sure if your talking about the relationship between tissue tension and inert inspired gas pressure as it relates to ambient pressure ?
switching to a higher o2 reduces inspired inert gas pressure thus creating a steeper gradient without exceeding ambient pressure
or
are you talking about the rate of exchange controlled by bubble size ( i.e. your conveyor belt picture) I see it more like a reducing funnel rather than a conveyor belt so off gassing can occur from both slow and fast tissues at the same time rather than "waiting in line"

deco for divers has a good section on page 101

actually a combination of both, yes a reducing funnel better represented of what I'm trying to understand, there for I see it that the smaller bubbles will be exchanged first, maybe a Doctor can put some light in this, and see if it is so or like you mention.

 

[Patoux01]

You should go back and read the basics of deco. It'd be a lot easier for you to understand. Something like Deco for Divers would probably do the trick.

 

[Remy B.]

As I understand what you are saying, your mistake is that you think all tissues are the same. Some tissues both ongas faster than others and offgas faster than others. The faster tissues will saturate during a dive and begin offgassing as you ascend. The slower tissues, however, will not be saturated and will continue to ongas as you ascend until they, too, are saturated and can begin to offgas.

No, I understand that tissues are different and they on-gas and off-gas at different rates. ( how much and how fast I don't know )

But will you not reach a pressure equilibrium on the slow tissues at shallower depth where they need a greater pressure to be significant ?, or you still On-gassing dangerously ?

if the Tissue have a determined pressure due to the pressure of atmospheric weight then it will have a greater saturation pressure in the tissue and the only way to Off-gas is by differential pressure, Tissue gas pressure been higher and escaping due to the fact that at that point the ambient pressure have a lower pressure, if it is not like that gas doesn't flow, you need to have gas differential pressure in order for flow to occur or not ?

 

[Remy B.]

You should go back and read the basics of deco. It'd be a lot easier for you to understand. Something like Deco for Divers would probably do the trick.

Yes that is a book in the Bucket list, maybe birthday gift

 

[KevinNM]

You will on-gas on all tissues until they saturate. Doesn't matter if you are a 3 meters or 300 meters. However the implications for Deco are pretty different.

 

[Remy B.]

what about the permeability of the compartments/tissues ?

Is speed on-gas not the reason of why slower tissues saturate slower, as deeper you go more pressure is outside the compartment there for it will saturate faster, and I can see it when you pass 2 atmospheres or more than 10m deep, but what I'm after is the control speed and size of the bubbles that exchange in your lungs. only from 12 to 6m re-distributing the time between them kind of in the stair or inverted pyramid profile.

Remember this is not about Deep stops, for me deep stops are everything deeper than 12m or 2.2bar absolute, we know that the NEDU study shows that those deep stops will create more quantity and bigger bubbles.

I'm actually curios of the answer from Elmo, on the Heat bar questions regarding the yellow area heat signal.

 

[PfcAJ]

Remember this is not about Deep stops, for me deep stops are everything deeper than 12m or 2.2bar absolute, we know that the NEDU study shows that those deep stops will create more quantity and bigger bubbles.

???

 

[tbone1004]

???

i was scratching my head on that too.... Last I checked deep stops were a function of your depth, not an absolute depth. I.e. 75% of your max depth, vs 50%, vs 25% or whatever

 

[Remy B.]

Go ahead, test it yourself: Subsurface is free

Just downloaded Subsurface but it doesn't do anything, can't open any icon on the task bar, I clic on new file or log file, but that doesn't take me anywhere.