Pressure drop in the GSV inlet

Discussions about GC and other "gas phase" separation techniques.

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Hi,

I am trying to familiarise myself with a GC 7890B and gas chromatography in general. The device is used to analyse gas samples and a gas sampling valve is used at the inlet. Before we run the analysis, we inject pure helium at the inlet and we run the method a couple of times to make sure that no peaks are detected prior to the analysis of the actual gas sample we are interested at. It is some sort of "flushing" the device. I observed that when I connect the helium sample at the inlet (at round 2 bar abs), and before running the method, suddenly the pressure drops to atmospheric levels (~1 bar abs) in around 15-20 seconds. The connections up to the GSV are checked and they seem to be tight.

Has anyone experienced something similar? Any advice would be appreciated.

Thanks!
Hey, I don't have your method conditions but I would assume that the maximum operating pressure for your GSV has been reached, maybe have a look at the manual for your online see if that's the case.
99 problems and chromatography is every one !
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