On 05/10/2014 18:45, Robert C. Helling wrote:
On 05 Oct 2014, at 17:16, Willem Ferguson <[email protected]>
wrote:
Willem,
I am lupdating the user manual contents. There are two new additions to the UI
that I do not understand enough to generate appropriate text.
1) The "Shearwater-like" pressure information in the Info box on the dive
profile. Robert, please give some info in telegram style?
2) The pressure graph at the bottom of the profile. Please give a bit of
information? One can intuitively understand the green lines, but what are the
blue, grey and black lines?
the two are supposed to show the same information, in the info box for one
instant of time and the graph obviously shows it as a function of time. 1) is
meant to be a clone of what you see in this video:
https://www.youtube.com/watch?v=O81vX79X_mA
The info shown are the inert gas loadings of the separate tissues and even
though it is calculated it is meant as qualitative display.
In 1) the tissues are the grey bars moving up, the fastest on the left and the
slowest on the right. In 2) the faster tissues are greener while the slower
ones are bluer.
The scale of the y-axis is twofold (as partial pressure mbars don’t mean much
to people): If the partial pressure of the tissue is below the ambient
pressure, the scale is the ambient pressure (the ambient pressure being the end
of the green area in 1) and the grey line in 2). In 1), the inert gas pressure
of the current breathing gas is indicated by the lower black line (below
ambient pressure and thus in the green area). While you dive at constant depth,
all tissues approach that line exponentially in time.
For partial pressures above ambient pressure, the scale for the over pressure
is the maximally allowed overpressure according to vanilla Buehlmann (the
beginning of the red area in 1) and not explicitly shown in 2).
If you use gradient factors (other than 100/100), you only allow a depth dependent
fraction of the allowed overpressure compared to Buehlmann (that is the percentage
of the gradient factor). The applicable overpressure according to the gradient
factor at the current depth is the upper black line in 1) and the thick black line
in 2). If GFlow < GFhigh (as it is supposed to be) you will see this black line
going up as you ascend.
As said above, at constant depth the tissues approach the inert gas pressure of
the inhaled gas. As everything is plotted relative to ambient pressure (or
M-value respectively), the tissue loadings go up on ascent while they go down
on descent.
In deco (or when the planner takes care of the ascend), you ascend until the
first tissue touches the gradient factor line. Then you wait until that tissue
pressure has gone done so it is still below that line after ascending to the
next stop depth.
Does that help?
Best
Robert
Magic. Thank you.
Kind regards,
willem
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