Just wondering how often it is recommended to change the gas line filters on a GC system.
that's a typical "it depends" answer. For the carrier gas line I assume you use at least a 5.5 or even 6.0 gas quality? Anyway depending on the gas quality there are different concentrations of impurities:
Now you need to know the capacity of the filter:
... and then it's just simple calculations.
As a rule of thumb we suggest one filter per one GC per year, that normally does it. And don't forget about the indicators in the Gas Clean Filters, they changes already at 0.2 ppm moisture or 0.1 ppm oxygen! It's not one of those cobaltnitrate indicators that change at 2%. The indicator itself has also some trapping capacity and when it starts changing you can change the filter without any column damage.
The hydrocarbon filter is a little trickier as the capacity depends on the components to trap and their break-through volumes on charcoal. As the filter is normally used in supply gas lines of the FID, maybe with a compressor for the air flow, it has to trap oil or oil fragments from the pump. Those are higher boiling hydrocarbons and are securely trapped on charcoal. We handle the same rule of thumb here, one filter per one GC per year. If you use synthetic air from a gas cylinder it's even better.
No indicator here as there are too many different components that could be trapped and all would need a specific indicator, if it even exists.
I shared your post with our consumable group for better visibility.
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