Quote: (Originally Posted by
finbar.taylor)
Mike
I'll agree it should be and there's no point in conflict get's people no where and wastes every one's time.
It also was not on my mod2 course but I think that's more the circumstances I did the course in than any thing else
what is the chance of a quick synopsis on how you'd calculate it?
My understanding is it'd be calculating a % mix below your dil but how to calculate that eludes me.
Fin
I posted something on that in previous post. I know there are others on here with way more experience and skill than me but until they come along ill just have to fill in (if thats Ok with steve)
Quote: (Originally Posted by Drmike)
Switch vr3 to OC mode and knock back the FO2 a tad. How much to knock it back depends largely on freq of venting you use and can be determined experimentally with a working ppo2 display
At const depth I run semiclosed with O2 turned off/isolated whatever and look at what the ppo2 stabalises at for a give number of breaths/vent. From this displayed ppo2 I calculate the effective FO2 in the loop and thats what Id use in my deco calcs in the future for the same vent rate if I bailed with that same dil/off board OC FO2 gas. Of course its not possible to determine the effective FO2 drop at all depths and all fFO2 eed gases but you dont have to - you just do enough tests to build up a general idea as to roughly how much an fo2 drop you can expect then apply a more conservative drop when you do deco calcs.
So when you switch VR3 to OC bail mode you make sure the comps FO2 bail gas/dil is reduced by the amount you decide is typical fo2 drop. You can reduce more than you need to to make it more conservative/cover any inaccuracys in assumed FO2 drop
Hope that helps
FWIW I did this on my Mod1, 2 and 3 courses - but as you say maybe thats not typical