Hello all, I have an oxygen tank that is 10 L in volume, pressurized at 500 barr (pressure can be adjusted down to 1 barr out of the tube), and I want to 'bubble' the oxygen into a beaker of water. I will simply use a tube (diameter is around 0.5 cm) connected from the tank and with the other end placed in a beaker. I want to know how long it will take for the oxygen tank to run out. I thought this was a very trivial problem at first but now I see that it's not so. The flow rate is not constant with time because the pressure in the tank will change and the flow is compressible so I can't use Bernoulli's eqn. I would really appreciate some insight into how I can calculate the time, or at least the flow rate due to the pressure drop. Thank you!