| Gents,
It wasn't a CO2 that got me but O2. The scrubber was fine and I was diving it again after the break, but as I had turned off the gas in preparation to getting out the fO2 was probably about .21 before I partially drained the loop. Exhaling into the loop would have lowered it further when I went in to get my fins, and that is what caused the problem.
I gave myself both a CO2 and hypoxic O2 hit to see the difference. On the CO2 [all loop bits in place except scrubber material] my breathing rate went up, a bit of tunnel vision occoured, I started to sweat and the gas in the loop felt thick. The headache that kicked in later lasted a good while.
CO2 of 4-10% will cause the increase in respiration, which exacerbates the problem, and above 10% the breathing rate slows until you eventually die.
The O2 symptoms were different. Breathing stayed the same, I felt tired and thinking was an effort [more so than usual]. I didin't have the O2 meter on as I didn't ever want to be tempted into thinking 'I was alright on a loop pO2 of .16 on the surface, so I'm all right now'.
If you are going to try this at home, have someone else there with you because if you get immobilised by the hit you will be deaded and the newspaper reports into your death will make very interesting reading, right up there with a bin liner and orange.  |