Change Gas Cylinders Early to Extend Purifier and Column Life

GC Performance Tip, Reporter Vol. 18.11

The tank pressure at which you decide to change your gas cylinders may affect the quality of your carrier gas. The lower the pressure, the greater the risk of causing problems with your chromatography system and your column due to higher levels of tank contaminants.

When the pressure in your gas cylinder drops below 500 psig, you risk drawing higher levels of contaminants from liquids that may be present in the bottom of the cylinder. You increase the chance of adding oxygen, moisture, and other contaminants to your carrier gas. These contaminants will shorten the lifetime of your purifiers and column.

Additionally, two-stage pressure regulators do not operate effectively at pressures less than 300psig. Below 300psig, your two-stage regulator begins to function more like a singlestage regulator, resulting in variable pressure. Without constant pressure, retention times will vary and irreproducible chromatography will be the result.

Supelco recommends that you change your gas cylinders when they drop to a pressure between 500 and 300psig. Avoid the risk of using impure carrier gas and causing more costly problems.

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