I don't think of a dil flush for hypoxia, despite what some instructors may try to teach. Here's my thinking on it and I really don't care if anyone agrees (I'm starting to sound like Don). If you dive mCCR, you are used to periodically hitting the O2 MAV to give a little squirt to bring pO2 up a bit. Same thing on eCCR if you happen to notice pO2 falling a bit and either you have setpoint low or maybe your solenoid is not working. So if your pO2 drops from 1.2 to 1.1, you are going to hit the O2 MAV. Or maybe if it drops to 1.0, same thing. Or 0.8 or 0.6. At what point do you suddenly switch to a dil flush instead of adding O2? No one is talking about an O2 flush here, just manually adding O2. And to me, muscle memory and keeping things simple is more important. If you look down and see your pO2 is at 0.18, you screwed the pooch somewhere along the line by not seeing it drop before then. In a true emergency setting, the last thing you want to do is to have to think about what to do. We train to make reactions automatic. So if your automatic reaction to any emergency is to do a dil flush, then that's fine. It will bring your pO2 up (assuming you're not a total dumbass using 10/50 while shallow). But if your automatic reaction to any hypoxic situation is to manually add O2, that's also fine.
You just have to draw the line somewhere between what is an emergency and what is not. Folks used to running manually (even on eCCR) might have a very different response than those who have always run pure eCCR.
Flame away, boys.
