Chromatography Forum

GC flows He H2 Air
Tank psi 2400 2300 2200
reg. psi 50 20 55
Set mL/min 30 30 350
"actual per GC" 19.6 not noted
soap flow meter sec to 5mL 8 24 17
5/sec*60sec/min 37.5 12.5 17.6

Anyone else seen something like this?
I'm told that the GC was just PM'd by a third party provider and worked fine shortly thereafter. Now, the FID will not stay lit and after checking these flows 1 line at a time, I understand why.

Time for a service call??

Thanks in advance,
DR

The line pressure for the hydrogen is too low surely. Other than that a dud EPC module looks likely, but it might just be sulking because it can't have the hydrogen it wants.

Peter

The line pressure for the hydrogen is too low surely.

Peter - that's exactly what jumped out at me too, from original post.

Even w/ a 60M 0.025mm capillary column in place?

Our intrepid end user is hearing that going w/ 80-100psi He (carrier), 80psi air and 60psi for H2 would be detrimental to the epc... Bad info?

DR - either the instrument manual or stickers on the rear of the GC should specify the pressure range required for each gas.

If that's too much trouble, post what make and model and maybe somebody will do that homework for you.

We have the line pressure set at 60psi for the entire building for H2, and He and no regulators at the individual instruments and all work fine, even the oldest 6890s(non network models). Standard pressure EPC modules usually have 60psi as a max pressure and ours do fine, because by the time it gets from the Hydrogen generator to the instrument you get a little drop below 60psi. Unless you have something really strange in the setup it should work. 60-100psi normally is only for the high pressure inlet EPC controller, that one you will want to check the tags on to make sure it can handle that much.

Our air is regulated down to 60psi at the bench because we have 120psi on the line to feed the N2 generator.