Improper GC-MS shutdowns...

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

9 posts Page 1 of 1
Okay, so in the GC-MS manual (Agilent 5975 N), it says : "Do not switch the MSD off unless it has completed the vent program. Incorrect
shutdown can seriously damage the MSD."

We come across the problem sometimes where ChemStation crashes, along with the computer. Upon rebooting, it can't detect the MS anymore because it's locked by ChemStation. I've called Agilent about this issue before and the procedure is to re-start the MS (obviously without venting), despite the fact that it's generally a bad idea.

Why exactly is it a bad idea? What kind of "serious damage" are we talking about...?

Obviously, the situation also occurs during an unexpected power shutdown (much less common).


Thanks.

With a 5973 (diffusion pump variety) we experienced oil contamination from years of repeated power outages. I think the final bill to clean the source, quad, detector and replace any damaged boards was 5-6k.

If you turn off an MSD without pumping down the instrument can suck oil back into the source chamber coating the quads, source and possibly destroying a board.

You need about 5 seconds of off time to re-boot an MS electronics. If you shut the switch off, count to five, and turn the switch back on and re-start chemstation you should be fine. Oil on quads comes from long shutdowns and should not be a factor with short re-boots.

Best regards.

Agilent have a publication ''how reboot MSD''
In this article, it is possible that the mechanical pump don't restart if you stop the instrument with the power button.....problem with diffusion pump

You can reinitialize the MSD with the chemstation in Vacuum control section or, you can reset the MSD with a little switch in the rear of the instrument.......so, i recommend to you to read this article on the Agilent web site.....but, i know, we are doing all the same thing, we push the power button, wait 5 second and restart :O)

Re:

Schmitty wrote:
With a 5973 (diffusion pump variety) we experienced oil contamination from years of repeated power outages. I think the final bill to clean the source, quad, detector and replace any damaged boards was 5-6k.


I have recently had an issue with our agilent GCMS that seems similar to what has been said in this forum. However, how did you know it was oil contamination from the pump?
I think it matters greatly if the forepump is connected directly to the MS power switch or can be operated separately.

If the forepump is left powered on and running and the vent valve remains closed during the momentary MSD shutdown, there is likely no backstreaming of diffusion pump oil or damage to turbopumps. Those problems usually arise from an unexpected forepump shutdown or admittance of air (as seen during a power outage).

Rebooting the MSD electronics separately from the MSD main power would be the best case. Agilent may have a undocumented remote command to be sent to the 5975 MSD to reset/reboot it while powered on.
atovar3 wrote:
Schmitty wrote:
With a 5973 (diffusion pump variety) we experienced oil contamination from years of repeated power outages. I think the final bill to clean the source, quad, detector and replace any damaged boards was 5-6k.


I have recently had an issue with our agilent GCMS that seems similar to what has been said in this forum. However, how did you know it was oil contamination from the pump?



Go into tune and vac control and start a manual tune scanning up to 500. Heat the oven to column isothermal max and the source and quads above normal operating temp. If you see a big ol 446 mass appear you've got oil hanging out in your analyzer chamber.

Re:

AICMM wrote:
You need about 5 seconds of off time to re-boot an MS electronics. If you shut the switch off, count to five, and turn the switch back on and re-start chemstation you should be fine. Oil on quads comes from long shutdowns and should not be a factor with short re-boots.

Best regards.


I second this. We have to routinely reboot computer, GC, and MSD on one system. We power off everything, then reboot everything. It seems to reset ok.
Regards,

Christian
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