No yeah I just went with the inline over the floating ball type because the orientation of the flow meter doesn't matter and it just becomes a part of the system without having to mount it and make sure it's level so that it reads true. This one is FDA approved (probably accurate) and comes in...
I don't know if anyone else is using this to measure their oxygen flow rate but this product is pretty inexpensive and very easy to install. OXYVIEW® 203A is the one you want. The scale is from 1-3 L/M. You can get them for between $15-20. They fit snugly into the 1/4" ID tubing the all brass...