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Hi everyone, while doing some simulations with the decompression software I noticed a "strange behavior" of the algorithm. In this case I used the multideco software. Zh-l 16 c, gf 50/80 algorithm, last deco stage setting at 5 meters.
Starting from the assumption that the saturation and desaturation of a specific gas depends solely on the partial pressure gradient of that specific gas and is not influenced by the presence of other gases. For example the sat and desat. of helium depends solely on the partial pressure gradient of helium, the same thing obviously applies to nitrogen, in fact the half times of nitrogen and helium for a given compartment are completely independent of each other.
Open circuit diving.
Example: Dive in heliox 14/86 at 80 meters for a bottom time of 22 minutes. (don't pay too much attention to the first deco mixture being so high, it's just to give an example to give you an idea) First deco mixture at 70 and change at 12 metres. At this gas change the partial pressure of helium drops to zero so the desaturation gradient for helium is at its maximum so it is eliminated from the tissues with the greatest possible speed based on the desat gradient. At the gas change the partial pressure of the nitrogen breathed rises from 0 to 0.66 bar, a completely negligible increase given that the Partial pressure of the nitrogen is lower than that breathed on the surface when breathing air, therefore the saturation of the nitrogen passing to 'ean 70 is insignificant to further increase the decompression load. With this gas switch the total run time is 223 minutes. 6 meter stage lasting 7 minutes and 5 meter stage lasting 79 minutes. (stages in ean 70 at -12 for 12 minutes and stage at -9 for 17 minutes)
If in the same dive profile, in addition to EAN 70, oxygen is added as deco gas in the last two stages, the run time is lowered to 209 minutes, the 6 meter stage remains 7 minutes and the 5 meter stage decreases to 65 minutes. Why is it that by adding oxygen the deco time decreases even though the desaturation gradient for helium is at its maximum whether you are breathing ean 70 or oxygen? In fact, whether in ean 70 or in O2 the P.p of helium is always at 0.
The deco time remains the same whether you select the oxygen window effect or deselect the oxygen window effect (in the extended stages section). So for the algorithm, the indicated deco time, adding oxygen is not due to the oxygen window.
Do you have any idea why the deco time was decreased by adding oxygen starting from -6 meters?
Starting from the assumption that the saturation and desaturation of a specific gas depends solely on the partial pressure gradient of that specific gas and is not influenced by the presence of other gases. For example the sat and desat. of helium depends solely on the partial pressure gradient of helium, the same thing obviously applies to nitrogen, in fact the half times of nitrogen and helium for a given compartment are completely independent of each other.
Open circuit diving.
Example: Dive in heliox 14/86 at 80 meters for a bottom time of 22 minutes. (don't pay too much attention to the first deco mixture being so high, it's just to give an example to give you an idea) First deco mixture at 70 and change at 12 metres. At this gas change the partial pressure of helium drops to zero so the desaturation gradient for helium is at its maximum so it is eliminated from the tissues with the greatest possible speed based on the desat gradient. At the gas change the partial pressure of the nitrogen breathed rises from 0 to 0.66 bar, a completely negligible increase given that the Partial pressure of the nitrogen is lower than that breathed on the surface when breathing air, therefore the saturation of the nitrogen passing to 'ean 70 is insignificant to further increase the decompression load. With this gas switch the total run time is 223 minutes. 6 meter stage lasting 7 minutes and 5 meter stage lasting 79 minutes. (stages in ean 70 at -12 for 12 minutes and stage at -9 for 17 minutes)
If in the same dive profile, in addition to EAN 70, oxygen is added as deco gas in the last two stages, the run time is lowered to 209 minutes, the 6 meter stage remains 7 minutes and the 5 meter stage decreases to 65 minutes. Why is it that by adding oxygen the deco time decreases even though the desaturation gradient for helium is at its maximum whether you are breathing ean 70 or oxygen? In fact, whether in ean 70 or in O2 the P.p of helium is always at 0.
The deco time remains the same whether you select the oxygen window effect or deselect the oxygen window effect (in the extended stages section). So for the algorithm, the indicated deco time, adding oxygen is not due to the oxygen window.
Do you have any idea why the deco time was decreased by adding oxygen starting from -6 meters?
