We've been having a disscusion on gas swithching on rebreathers. Heres the question.(bear with me). On a trimix dive ccr let say I'm diving heliox as my dilutent and I keep that as my dilutent throughout deco. I am penalized quite abit over the guys who switch to air. (pro-planner). Now according to Navy dive tables for a given depth on ccr with a po2 of .7 a heliox 21/79 mix requires more deco than air.
I assume this is because the He is absorbed quicker than the N2 thus the amount of gas being removed is greater?
Now I'm way rusty on the models, but does'nt the addition of a heavy gas like N2 result in a time of supersaturation as well as slower desat of the He?
or am I incorrect and N2 has no bearing on He desat. This would collaborate my planners diffs. If N2 does not affect He desat then the "lighter" He would continue its speedy exit while the uptake of the N2 would be slower. So by removing He from the loop and adding the Heavier N2 we can offgas the He quickly while not absorbing a high volume of N2. I deffinately dont believe this is the case..But it would explain some of the figures...
Help! The more I think the stuppider I become, Like I said its been awhile.
thanks
I assume this is because the He is absorbed quicker than the N2 thus the amount of gas being removed is greater?
Now I'm way rusty on the models, but does'nt the addition of a heavy gas like N2 result in a time of supersaturation as well as slower desat of the He?
or am I incorrect and N2 has no bearing on He desat. This would collaborate my planners diffs. If N2 does not affect He desat then the "lighter" He would continue its speedy exit while the uptake of the N2 would be slower. So by removing He from the loop and adding the Heavier N2 we can offgas the He quickly while not absorbing a high volume of N2. I deffinately dont believe this is the case..But it would explain some of the figures...
Help! The more I think the stuppider I become, Like I said its been awhile.
thanks
