In my experience, most facilities that have oxigen flow also have compressed air flow with cheap controllable fluxometers, but a blender is often lacking or too

In my experience, most facilities that have oxigen flow also have compressed air flow with cheap controllable fluxometers, but a blender is often lacking or too expensive. In those cases we use a Y piece connecting air and oxigen flows to the inspirarory limb. The role of the blender is to control the percentage of oxigen offered. With the Y piece we can control that by the equation: %O2 = (O2flow + Airflow * 0.21) / Total flow If you can use Total flow of 8L/min (reasonable in most cases) the approximations table below is of easy memorization and precise enough: O2 flow - Air flow - %O2 8 - 0 - 100% 7 - 1 - 90% 6 - 2 - 80% 5 - 3 - 70% 4 - 4 - 60% 3 - 5 - 50% 2 - 6 - 40% 1 - 7 - 30% 0 - 8 - 21% Edited:formatting