My experience with hypercapnic alarm (HCA):
I did a test run with my exit bag, no gas, just to see how long it took before my HCA kicked in. I didn't inflate the bag; it was just pulled on over my head and the elastic drawn snug (not tight) around my neck. It took a surprisingly long time for HCA to appear --several minutes of sitting in a chair getting bored, getting annoyed at the bag fogging up, then getting up to use the toilet, returning, sitting for a while longer. It then came on fairly gradually.
By contrast, when I was actually attempting to ctb (with 100% pure nitrogen) I was unable to keep my breathing deep or steady. My stress level was off the chart, my adrenaline levels must have been outrageous, and I did feel as though I was "gasping for air" even though I had a relaible 15LPM flow of gas.
I would not be surprised if what you're thinking is HCA may be something else. Perhaps a stress response? I don't know for certain, but from what I know was an HCA response, your situation sounds very different.
TiredHorse, thank you so much for replying.
So, in total I tried it 4 times, the first time my adrenaline was sky high and I basically had no idea what was going on, and breathing very fast heavy breaths. But after each attempt I prepared myself more. On the 4th time I'd calmed down an awful lot. In fact I would have kept trying probably to a 6th-7th attempt with that cylinder.
But on the 4th, I was calm enough to confidently observe that the argon gas itself was triggering some kind of panic response. I'd also pumped it up to 25lpm which helped. I was happy to go and relaxed and ready. The bag wasn't "in my face", breathing was calm - the most excitement I had was from sitting back down after turning on the gas!
So I decided to do a non-CTB test the next day, as I described, no bag over my head or anything - just something to see how inhaling that argon affected me. And after 3 breaths, inhaling from the gas and exhaling to the room (stitting somewhere safe), I was gasping for air as if I hadn't had held in a breath for 60 seconds - yet I had been having the 3 breaths quite naturally, over about 20-30 seconds. So loosely arguing, that's several times more of an HCA effect in that argon than in what effect holding my breath has.
So although I was obviously a little agitated even on the 4th attempt, by then it was minimal. I'd have thought I was about as calm as can be for someone about to CTB. I mean like, most poeple wouldn't have known anything was up.
So it's a real mystery because the only thing I can think is that it's the argon. This is so confusing and frustrating because everything made sense - or it would if I could detect CO2 in this argon! I'm wondering if there's a new gas they use to trigger the HCA in low doses without large quantities of CO2? I'm clutching at straws with that, it's all that I can think of but there's zero online I could find online about it.
