GC-MS saturation of gas filter


Can i check with you guys if it is normal. We just got  the GC-MS like 5 months ago. But i discovered that the moisture captured by the MSD shows a very high abundance level and our filter shows the filter has saturated. I have 2 type of gas filter attached to the carrier gas. A big universal trap and a combi Oxygen/moisture gas filter. 

I have done  a leak test using snoop liquid and no leak was detected. Column flow was able to achieve. So i can't understand why the moisture filter saturate within months. We don't have a leak detector equipment due to higher up decision

I have called the Agilent hotline and they said that there might be a high moisture due to the environment which cause condensation to occur in the pipe even if there is no leak. Is this true? If it is true how do i prevent this aside from purchasing filter every 5 months. 

Thank you

  • Under normal circumstances (standard GC flows, temperature and normal ambient moisture levels, we guarantee 1 year of lifetime). If something like what you described happened, normally something went wrong during the installation of the filter. When checking the indicator it should change colour from top to bottom, after installation mishaps or a tiny leakage at the gas inlet, the indicator would change colour from bottom to top.

    High ambient moisture levels would not change the indicator easily as even when diffusion through the housing occurs, the moisture would have to go through the packing material. We have seen filters from India where water droplets where on the inside and the filter still worked well.

    Checking the indicator color change regularly will show if it's the gas or the installation/leakage who is the culprit. From experience I would say leakage.



  • I see. i also suspect it was a leak but unable to determine where is the location of the leak as i have snoop the joints from gas source to filter.

    Also. Since this is a Combi gas filter of oxygen and moisture, if there is a leak, shouldn't the oxygen also saturate ? My oxygen indicator is still useable

  • The diffusion constants for water and oxygen are different, one of the reasons is molecular size - water is far smaller than oxygen. 

    BTW Snoop cannot detect leaks at very low flow rates.

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