Pat,

If I remember correctly, according to Dawn Merritt's Thesis (Indiana), using
a liquid filled CO2 tank can result in fractionation of 1-2 ppt over the
life of the tank.  We purchase "gas filled" tanks (which as I understand it,
means pressure less than about 800 psi) in larger cylinders.  They won't
last as long, but they cost less and seem to avoid the problem.

Louis Elrod

>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
>
>


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis W. Elrod
Research Scientist
Geotechnology Research Institute
Houston Advanced Research Center
4800 Research Forest Drive
The Woodlands, TX  77381

Phone:     281-364-6061
FAX:       281-364-6052
E-mail:    [log in to unmask]
WebSite:   http://gtri.harc.edu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~