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- Posts: 115
- Joined: Fri Oct 22, 2010 8:53 pm
- Location: San Francisco Bay Area, United States
We're having an issue with our Agilent 7890B's FID occasionally extinguishing. We bought this new several years ago, and it currently has 62,900 injections. It's single channel (on back channel), MMI, and of course FID. Hydrogen carrier and fuel provided by a Parker H2-1300 hydrogen generator, with a drier in line as an added precaution. This generator supplies hydrogen to two additional GCs. Air is provided by an oil-less compressor through a Parker HPZA-7000 Zero air generator which feeds a total of six GCs. Each GC has a Restek moisture/hydrocarbon trap (yes, overkill) for the air line feeding it. Nitrogen is used as make-up and provided from a tank. So a total of 6 Agilent GCs in the lab, with all but one functioning as usual without issue. Until recently, we haven't had any issues with the lab configuration or the specific GC. A few weeks ago, at the beginning of a weekend run, the FID flame started going out during runs. It would immediately automatically re-ignite without issue. At first it appeared to be happening at the beginning of runs, but then it became clear it was random. Here's what we've done so far on the specific GC, basically trying any- and everything regarding the detector:
1) Remove air moisture/hydrocarbon trap on problem GC.
2) Replace jet
3) Cut/reinstall column.
This looked like it helped, but about 3 days later, same problem
4) Replace entire collector, carefully inspected all detector components
We went about a week before the issue returned.
5) Now we're feeding that specific GC only with a zero air line directly from a tank.
No issue yet, but it's only been through the weekend. Again, no problems with the other GCs, which share the gas sources, run the same samples, etc.
When it first started happening, I could have sworn I saw something along the lines of "detector temp. not stable," but I can't find that in any of the logs. I thought there could be an intermittent problem with the detector's temp. sensor, but I don't know anything about how that works.
Thanks for reading.