User manual: Explanations for new UI additions

Robert Helling helling at
Mon Oct 6 12:29:35 PDT 2014

On 06 Oct 2014, at 11:13, Willem Ferguson <willemferguson at> wrote:


> The current position of the black line suggest that it perhaps indicates the equilibrium partial pressure for all inert gases (He + N2) combined?? Similarly, the dark green portion of the bar graph seems to indicate the present combined partial pressures for He + N2.

Indeed, everything is for N2 and He combined.

> But the bar graph surely only pertains to the nitrogen fraction because offgassing for nitrogen and for He follow different patterns, He requiring much longer offgassing times??

Still, it shows N2 plus He as this is what is relevant for Buehlmann-like algorithms.

> I suspect the gradient factors apply only to the nitrogen partial pressure?

Again, they apply for the sum. To compute the M-values, you are supposed to take the (weighted by the percentage of the gases) average of the a- and b-parameters. Have a look at the code in deco.c which I hope explains it, see the function tissue_tolerance_calc specifically.

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