Tissue load question

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kos
Posts: 11
Joined: Wednesday 27. September 2017, 18:10

Tissue load question

Post by kos »

It has been 5 days since the last dive, but the tissue are still shown as loaded upto the green mark. The complete desaturation time had long passed already.

Dont the tissues suppose to be completely desaturated ?

[attachment=0]photo_2023-03-02_09-17-05.jpg[/attachment]
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gr3yw0lf
Posts: 106
Joined: Thursday 28. November 2019, 22:18

Re: Tissue load question

Post by gr3yw0lf »

hm...

the saturation of your tissues at the surface is never "0" - the ppN² will always be round about 0,78 and your ppO² round about 0,21. got it?
but it is below the green line - everything ok for me ;)
life is better in fins

OSTC Plus #18168
kos
Posts: 11
Joined: Wednesday 27. September 2017, 18:10

Re: Tissue load question

Post by kos »

well, of course the tissues would be saturated at the surface to the level of the natural O2 + N presence in the air. I just wasn't sure whether the computer shows the extra increase in the tissue saturation over the normal level. As the during the dive, there are lines underneath "CNS: %" as well, that appear and then are completely gone. So here is the confusion.

Just quickly looked at the latest manual, and I don't think this point is well explained.
What do the lines above "CNS: %" represent (16 tissues), what do the lines below "CNS: %" represent (16 tissues again)
and what does the number on the right, just above red line, means?
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gr3yw0lf
Posts: 106
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Re: Tissue load question

Post by gr3yw0lf »

hm...

I think Ralph posted it somewhere here in the forum (couldn't find it fast) but lets try....

the horicontal lines above "CNS %" are showing the tissues (from top to bottom the fastest on top, the slowes at the bottom)

"CNS XX%" gives you the O² "charge" of your CentralNerveSystem

and the vertical lines under "CNS%"

should show (if I remember it right) the left (blue) one saturation of "0", the next (green) your GF low, the next (yellow) your GF high and the right (red) one 100% saturation. (you see how close a GF low 30 is to the saturation at the surface?)
life is better in fins

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Ralph
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Joined: Saturday 24. June 2017, 11:31

Re: Tissue load question

Post by Ralph »

As had been said before, the tissue graphics has three sections: the upper bars, the lower bars and the CNS percentage number in the middle. The meaning of the bars depends on the "Graphics" setting in the "Display Settings" menu: "N2+He" or "Pres+Sat".

If "N2+He" is selected, the upper bars show the ppN2 tissue pressures and the lower bars show the ppHe tissue pressures. These are continuously updated, so after a dive one can see the bars usually becoming shorter as the tissues release pressure. The upper bars will stop shortening when the body tissues have equalized with the ppN2 in the ambient breathing air. In case an O2 deco was made, one can see that the upper bars, representing the fast tissues, are shorter than in surface-equalized state. This is because during O2 breathing the body can theoratically release all N2 dissolved in the tissues, as there is no ppN2 in the inhaled gas that stopps off-gassing at some point. After complete off-gassing, one will occasionally see small differences in the length of the bars - these are caused by changes of the surface pressure, which the tissues are following (ppN2 = Fraction N2 x total Pressure), As there is no Helium in ambient air, the lower bars will completely disappear over time, leaving only a 1-pixel long line behind which is for pure reference of where the zero-point is.

If in the "Pres+Sat" mode, the upper bars show the combined N2 + He total pressures of the tissues, that will behave as written above. The lower bars will show the same total pressure, but tissue-by-tissue scaled by the respective M-value of the tissue, with the M-values calculated for the current surface pressure or diving depth. So the resulting bars depict the relative supersaturation of the tissues, from left end = 0% via the red line at 100% (M-value limit reached) and a bit above M-value limit at the right end (the not good section...). In case gradient factors are enabled, there will be additional green and yellow lines, the green one corresponds to the GF low supersaturation % value, the yellow one to the GF high one. As the M-values decrease when ambient pressure decreases, it comes that during the ascent the upper total pressure bars shrink while the lower supersaturation bars become longer. The same will happen after a dive, when the surface pressure changes, especially when driving up a mountain or in a plane. If there is a no-fly time displayed, this time it will take for the lower bars to just not exceed the red 100% line when in a plane at cruise cabin pressure or at the set mountain hight. During a dive, the small number that is displayed at the right end of the bars section is the number of the leading tissue, that is the tissue that will have the highest relative supersaturation at the next stop. Without GF enabled, this tissue will hit the 100% M-value, with GF enabled this tissue will hit the GF low line at the 1st stop, the GF high line on reaching the surface, and some points between GF low and GF high on the stops after the 1st and before surface.

BR
Ralph
kos
Posts: 11
Joined: Wednesday 27. September 2017, 18:10

Re: Tissue load question

Post by kos »

Ralph,

thanks for a very comprehensive explanation. I would really hope this would finds its way into the manual somehow.

On my OSTC Plus I don't have Display settings menu to choose between N2+He, so I assume it is always "Pres + Sat"

Also when you say 'If in the "Pres+Sat" mode, the upper bars show the combined N2 + He total pressures of the tissues'
In non trimix computers, it would simply show N2, right?

thanks again.
Ralph
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Joined: Saturday 24. June 2017, 11:31

Re: Tissue load question

Post by Ralph »

Thanks!

> I would really hope this would finds its way into the manual somehow.

Problem is, if everything that would be worth putting into the manual would actually go in, it would be 300++ pages...

> On my OSTC Plus I don't have Display settings menu to choose between N2+He, so I assume it is always "Pres + Sat"

You should have: Main Menu -> Settings -> Display Settings -> more -> Graphics

> Also when you say 'If in the "Pres+Sat" mode, the upper bars show the combined N2 + He total pressures of the tissues'
> In non trimix computers, it would simply show N2, right?

Yep!
kos
Posts: 11
Joined: Wednesday 27. September 2017, 18:10

Re: Tissue load question

Post by kos »

>Problem is, if everything that would be worth putting into the manual would actually go in, it would be 300++ pages...

True, but some things are pretty easy to work out, while others, like the tissue graph, are prone to speculations


>> On my OSTC Plus I don't have Display settings menu to choose between N2+He, so I assume it is always "Pres + Sat"

>You should have: Main Menu -> Settings -> Display Settings -> more -> Graphics

Interestingly, I checked, and I don't have this option. See the pic attached.
[attachment=0]photo_2023-03-03_10-21-15.jpg[/attachment]
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Ralph
Posts: 708
Joined: Saturday 24. June 2017, 11:31

Re: Tissue load question

Post by Ralph »

Do you have the sport firmware? If yes, the setting may indeed been removed from the menu as with no He the N2+He view does not make any sense and there is no loss of information with only the press+sat view then.

PS: a lot of information on what the tissue do and how the OSTC handles & displays this can be found here:

https://www.heinrichsweikamp.net/downlo ... web_en.pdf
kos
Posts: 11
Joined: Wednesday 27. September 2017, 18:10

Re: Tissue load question

Post by kos »

Yes, the sports firmware.
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