Chromatography Forum

Hey, I am a student working in a research lab and I have run into a problem trying to install a new carbowax column in a Shimadzu GC2014. The instrument is throwing the codes CAR1 AFC leaks and CAR1 purge leaks. I have tried two different brands of ferrules and had no luck. I am running out of other ideas. Does anyone have any suggestions?

Is there anyone there who can show you how to do the installation and troubleshooting - trying to do it over the internet is a substantial challenge. Have you done column installation on this or other GCs before ?

Peter

Thanks for your reply! I have been able to install columns on this GC before. My research advisor is not sure what is going on with it either, he told me I have more experience with the instrument than any one else in the department. I have uninstalled/ reinstalled the column several times and tried enough new ferrules that now I am beginning to think it is something else causing the leak even though it seemed unlikely that something else would go out at the same time that I was switching columns. I have now also replaced the septum and the o ring and both leaks remain.

You need a leak seeker to find the leak - no GC lab should be without one.

What other symptoms are there ?, does the inlet pressure reach its set point ?. Do you have flow out of the split outlet and septum purge ? If you remove the column from the detector and dip it into some clean solvent do you see gas bubbles coming out. Are you sure that you have gas getting to the instrument ?

Do you have an operator's manual - what does it say about these two error codes ?

Peter

Sadly, we do not have leak detector. The pressure reading is 0/2.1 psi, the total flow is 87/87 mL/min, and the purge flow is .3/3 ml/min. What are your thoughts on using an isopropyl/ water mix to leak detect? We haven't tried dipping the column in solvent yet. Also, the gas cylinders are indicating they are putting out appropriate pressure, however we are unsure if gas is actually getting to the instrument. How could we check flow out of the split outlet? The operator's manual says for both of the codes that "the pressure cannot reach set value, check whether gas is supplied and whether gas is leaking from connections."

Remove the column completely. Plug the injector with your finger and check whether the pressure is reached, If so the problem is with the column connection. If not the injector is a problem.

Have you changed in the GCSolution that you installed a new column?

Marek2,
I have changed the column in GC solutions. Is your suggestion still applicable even though the inlet pressure is measuring at 0 psi? Where does the instrument measure inlet pressure at? I was thinking it was before the column, so my leak must be before the column...?

Yes, it is still applicable. The pressure is measured in the injector. So If the pressure will rise (after closing it with the finger) the problem is with column connection.

Sadly, we do not have leak detector. You really need to get one then, it will pay for itself with the first column that you do not destroy by having a leakThe pressure reading is 0/2.1 psi, the total flow is 87/87 mL/min, and the purge flow is .3/3 ml/min.You have either a major problem in the gas controls, or a massive leak in the inlet What are your thoughts on using an isopropyl/ water mix to leak detect?Avoid it if you can, if this gets into the gas plumbing you will have background contamination for a very long time We haven't tried dipping the column in solvent yetwith an inlet pressure of zero there will not be any flow . Also, the gas cylinders are indicating they are putting out appropriate pressure, however we are unsure if gas is actually getting to the instrument. How could we check flow out of the split outlet? find the split outltet form the GC, attach a piece of flexible tube and put the end of the tube into clean water - if there is flow you will see bubbles.To measure the flow you need a flow meter. The operator's manual says for both of the codes that "the pressure cannot reach set value, check whether gas is supplied and whether gas is leaking from connections."

Put in a new septum.

Peter

I did replace the septum already, but I went ahead and tried a third one. Still have both leaks. I have also now used a hose to check for flow out of the split and purge outlets. Neither of them blew any bubbles into my water beaker. I also put back on the column that had been working and have the same codes with it too. Any more suggestions of things to try?

Have you confirmed that you actually have a carrier gas supply to the instrument ? Just having a positive pressure reading at the cylinder does not confirm this.

How is you gas supply connected - do you have multiple instruments using the same gas ? Are you able to isolate instruments one by one by disconnecting gas lines or closing valves ?. If there is gas supply to the instrument than a leak large enough to give zero inlet pressure would empty a cylinder in a day or two.

There is very limited value to making the same changes over and over again.

Peter

The instrument's pressure gauge indicates gas is going to the instrument (and it drops to zero when the gas is shut off so it's not stuck that was). There is only the one instrument on the gas cylinder.

The instrument's pressure gauge indicates gas is going to the instrument (and it drops to zero when the gas is shut off so it's not stuck that was). There is only the one instrument on the gas cylinder.

Hi
If it drops to zero means that you have a leak somewhere. If there is no leak and the gas is shut down it should remain at the set value. you can check if you have flow on the column by detaching the column from injector and put it in a beaker with solvent. if you have bubbles in the solvent you have a flow on the column.
Irina

The instrument's pressure gauge indicates gas is going to the instrument (and it drops to zero when the gas is shut off so it's not stuck that was). There is only the one instrument on the gas cylinder.

Where is this pressure gauge located ? - the pressure readings you have been giving us are all extremely low - they indicate that (possibly) no gas is getting to the instrument. As Irina mentioned you must have a large leak for the line pressure to drop when you close the cylinder valve. This leak could be either in the instrument itself, or in the line going from the cylinder to the instrument. What happens if you shut the GC down completely, with power shut off, pressurize the gas line by opening the cylinder valve and then close the cylinder valve ?

What regulator do you have on your cylinder - I am guessing that it a two-stage with two gauges. Is there a shut off valve between the regulator and the gas line to the instrument ?

Peter