How to use old GC column Union

[MSCHemist]

I found an old 0.5mm/0.5mm Varian Column Union from 1994. I'd like to use it on my 5890 to create a retention gap/guard column. I have some .32mm fused silica tubing and a .32 DB-5 column.

The part has what appears to be two hexagonal nuts in the middle (though that is acutally the body) and two long nuts on each side with a hole for the column on each end. It looks to be made of aluminum. Anyways what type of ferrule do I need and how far in do I insert each column?

Thanks

[rb6banjo]

Can you provide a close-up photograph?

[MSCHemist]

It looks exactly like the one by the bottom in this webpage only there is a ridge in the very center that makes it look like two hex nuts rather than one.
http://www.sge.com/products/gc-supplies ... connectors

[rb6banjo]

I think that all of those types of fittings seal with the flat end of the ferrule toward the union. The nuts are such that the tapered end of the ferrule goes up inside so the flat side seats on the threaded (male) part of the union. You just need to get the ones with the right diameter for your column o.d. I think it goes 0.4 mm for the 0.25 mm columns, 0.5 mm for 0.32 mm and 0.8 for 0.53 mm.

The shape of ferrule you need is the same as Agilent 5062-3508. SGE, Restek, and Supelco make them too. I just don't have their part numbers handy.

I'd shoot for 1/2 way through the union for each piece of column. Cut an inlet septum in half (moon shaped) and run your tubing pieces through them. Use those to set the depth. You can also cut a slice in your half moons so that they'll stick to the tubing enough to seat the ferrules but you can remove them when you're done.

[James_Ball]

I have used those before, they should take a normal tall column ferrule, either graphite or vespel/graphite. The vespel/graphite is probably preferred. If the ends of the union and the inside of the nut are flat though, it will take a sealing ring which looks like a tiny piece of graphite/vespel tubing that compresses slightly to hold the column.

http://www.restek.com/catalog/view/965 this is what the sealing rings look like.

Usually the unions have a solid divider inside to keep the ends of the tubing from actually touching, you just but the ends up against that and be careful when tightening the nuts so as not to crush the ends of the tubing.

[MSCHemist]

I installed it and it works well. I used the standard graphite vespel ferrule (same as I would for the MSD transfer line).