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Restriction

Puffin

I have GC (8890) MS (5977B) with a PTV at the back inlet I am not seeing any peaks so I tried the troblershooter. Ran a leak & restriction test I got a result that I have a restriction.

I am only using the back inlet.


I have checked the back inlet isn't blocked, the liner is seated correctly, I get flow through the column, the only restriction I think could be at the cross piece to the FID? So, I have re connected that too. No leaks, but when I run diagnostics I get:

Back inlet diagnostic tests-

Method pressure check- ok

Split vent test - pass

Septum purge test-

Basic control OK

Basline with purge off - restriction (I took column out, and checked He flow through liner- He Detected)

Leak/restriction test
Basic control OK
Back inlet flow actual = restriction when test for leak & restriction

Any idea what I might try?

Thanks for any suggestions.

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  • 0

    The restriction test could mean that the split vent filter is clogged. When was it last replaced?  Is helium flowing out the split vent on top of the GC?  What inlet mode are you using? What flows? What configuration?

    No peaks.  It reads like you have a splitter installed to go to an FID and an MSD.  Do you have no peaks on both detectors?  What splitter - purged or non-purged?  What are the dimensions for the analytical column and the restrictors installed from the splitter to each detector?  Can you measure column flow out of the FID?   The simplest troubleshooting path for a splitter is to vent the MS and install the column directly from the inlet to the MSD and test it that way.

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  • 0

    The restriction test could mean that the split vent filter is clogged. When was it last replaced?  Is helium flowing out the split vent on top of the GC?  What inlet mode are you using? What flows? What configuration?

    No peaks.  It reads like you have a splitter installed to go to an FID and an MSD.  Do you have no peaks on both detectors?  What splitter - purged or non-purged?  What are the dimensions for the analytical column and the restrictors installed from the splitter to each detector?  Can you measure column flow out of the FID?   The simplest troubleshooting path for a splitter is to vent the MS and install the column directly from the inlet to the MSD and test it that way.

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