GC-FID - CTC CombiPal Flush Gas Regulator

[wan]

Our laboratory has a GC-FID with a CTC CombiPal autosampler.

The flush gas regulator of the CTC is set at 0.5 bar. However, the pressure kept dropping and remains at 0 bar.

I checked the pressure of the helium gas that leads to it and can't find anything wrong with the pressure.

I am not too familiar with the hardware, but is there anywhere else I should check at the GC?

Thanks!

[ingochrist]

If you have a leak on the other side of the regulator or the valve (on the inside of the PAL) is open, the pressure will drop to near 0. Please make sure that you have no leak before and after the regulator and it would be best to turn off the PAL autosampler so that the internal valve is closed. Then regulate the pressure to about 0.5 - 1 bar. Turn the PAL back on and check that the pressure stays at that level. Lastly, when you flush the syringe (during the headspace cycle), you will see the pressure drop to near 0.

If you require new o-rings or regulator, feel free to contact us. The o-ring is P/N: ORing 3.68x1.78GA-65, the fitting on the regulator MM 09-01 and the entire regulator with fittings MM 03-01.

Best Regards,
Ingo Christ
Autosampler Guys LLC
+1-703-780-1500

[Peter Apps]

Why on earth are you using helium to flush the syringe ?

Peter

[wan]

Hi Ingo, thank you. I will check for leaks at the regulator. Realised I checked elsewhere, but not there. Thanks for the reminder.

Hi Peter, may I know what gas should I be using then? Our system has been set to use helium to flush the syringe since I started working there, so I thought that is the norm (never use GC before that). Would appreciate your advice. Thanks.

Wan

[ingochrist]

Just in case Peter doesn't respond quickly, Helium is very expensive and it serves no purpose other than cleaning the syringe. N2 would do just fine.

Regards,
Ingo

[wan]

Hi Ingo, thank you for your quick reply. We do have a N2 supply, given that the GC is also coupled to an ECD. I will talk to my supervisor about a switch. Thanks again.

Wan

[Peter Apps]

Just in case Peter doesn't respond quickly, Helium is very expensive and it serves no purpose other than cleaning the syringe. N2 would do just fine.

Regards,
Ingo

Thanks Ingo - that was exactly my thinking.

Peter

[north90ty]

We had trouble before with the gas lines that run from the regulator in the PAL to the syringe. Because the syringe moves around these lines bend and move around within the frame of the PAL.
In our case these lines got stuck in the mechanism of the PAL causing the PAL to give errors on the x-axis motor stalling.
In your case i would check if helium (or now maybe N2) actually reaches the syringe. If the lines are broken it is not weird that the regulator can't keep it's pressure.