I don't think you can do that satisfactorily. Under pressure, CO2 liquefies, and although you are drawing gas off, the pressure in the cylinder remains constant as long as there is some liquid left. O2 does not behave in that manner, it does not liquify under pressure, and as you draw gas off, the pressure in the cylinder continually drops.
Posted on Jun 23, 2004, 9:11 PM from IP address 80.58.44.109