Agilent 7890A - Self Tightening Column Nut

[Lulux7]

Hello!

Our lab purchased Self Tightening Column Nut (Inlet or Detector) due to some leak issues. We have reviewed the videos and guides on how to install it, however, for some reason the column is loose at the inlet/detector opening and slides down if it is gently pulled (even after tightening the nut). Any suggestions on why this is occurring or if this is supposed to be happening? We also installed a Self Tightening Column for the MS Interface and that one is completely secured and not loose when it is gently pulled. We are using the correct type of ferrules (listed as compatible on the installation guide) and have installed it exactly as the guide states, so I'm not exactly sure why the column is loose :S Any help is appreciated!

[Rndirk]

Are you using graphite, vespel, or graphite/vespel ferrules? Can you give your column diameter and the diameter listed on the ferrules?

We started with graphite ferrules but switched to graphite/vespel for the inlet after a visit by an Agilent expert.

If the column slides then clearly it is not tightened enough. In my experience, you need to apply quite a bit of force on it (more than just hand-tight!). After a couple of column heat/cool cycles it's best to tighten again. After that, it's OK until next maintenance.

What can help is to condition your ferrules: put a couple of them in a beaker in the GC-oven during your analyses.

[Lulux7]

Hi! Thanks for your reply. The ferrule used is 0.4 mm 15% graphite/85% Vespel, 0.1 to 0.25 mm column, short (P/N 5181-3323). And the column is DB-5MS UI, 30 m in length, 0.250mm diameter and 0.25um film (P/N 122-5532UI). The ferrules are the ones recommended to use with the self-tightening nuts

[aldehyde]

That ferrule and column combination sounds correct to me. You don't need to use a wrench with the self tightening column nut, but may want to hand tighten it a bit harder. Make sure you have the right column insertion depth and then tighten a quarter turn further than you're been going, and gently tug on the column. It should be nice and snug.

I much prefer the self tightening nuts, and the quality control is pretty good so I doubt the nut itself is bad.

[Bigbear]

Not to be insulting, but are you using the proper self tightening nut? Agilent makes 2, one for MS interfaces, and one for inlets.