So this is for any of you who have some medical training dealing with O2. Were you taught to fully open the tank, fully open then a quarter turn back, just one turn, something else? I've always been taught to fully open then a little twist back. I did a quick yahoo search and I only found evidence to support that.(I just did a quick search so I'm not saying it's not out there) I just had to go through a DAN O2 class which was quite possible the biggest waste of time, it was everything I already knew dumbed down about 100X. Some of the things they taught I don't agree with, one of them being just to open the O2 tank one full turn.