FunTimes, If I don't have the oxygen on and the bag is not full of oxygen either and blow in to it, air does come out the outlet value but still have to use pressure, so when the oxygen is on, the oxygen is flowing toward my face and then there is even more pressure. Just is uncomfortable but..the value seems to be working but takes some effort to blow out. Definitely doesn't come out with a relaxed breathing or even slight effort, so when I breathe out hard, it does come out over the top of my nose.
I also have to mouth breath to get enough pressure and I've read that one should breathe oxygen through their nose, mouth breathing isn't good.