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Carbon Dioxide CO2 Grades Required for Critical Point Drying

Generally speaking, the grade Quorum Technologies "recommend" is the "normal" grade, that is the one most commonly offered by industrial gas suppliers.

In most parts of the world "normal" grade of CO2, from the suppliers, is specified as "N4.5" or 99.995% minimum purity with a maximum level of 50 ppm of impurities.

There are however, two other grades available, and from most gas suppliers it would be available by special order. One is "N4.0" or 99.99% (less pure than "normal" grade) the other is "N5.5" or 99.9995% minimum purity. The N5.5 purity is easier to find in those parts of the world where there is high level of activity in electronics, since these customers often demand gases with higher purities.

We are not aware of anyone who has ever reported either superior results using N5.5 purity (vs. N4.5) or inferior results using N4.5 vs. N5.5. However, we do want our customers to have the benefit of such detail about gas procurement in the event they should ever find reason to believe that their particular samples might benefit from the higher purity gas.

Remember the requirement is for LIQUID carbon dioxide and NOT gaseous carbon dioxide. For this reason a cylinder should be an internal "syphon" must be specified. A syphon (siphon) cylinder is normally denoted by a white stripe painted along its length.