I am runing continuous flow system with a Carlo Erba EA, ConfloII, and Delta S. I am setting up a new tank of CO2 reference gas and am not clear on the concept of, or need to worry about fractionation in a tank of CO2 at 800 psi. Should I reduce the pressure so that all the CO2 is in the gas phase( what pressure would that be ). Or is combination gas/liquid phase not a problem. Thanks in advance for input. Pat Anderson Great Lakes WATER Institute