To those people who might want to produce their own counter-flow fitting,
the greatest problem is indeed to create a sealed connection between the
glassy carbon tube and a central tube - in most part because of the
variation in the internal diameter of glassy carbon tubes (this is the case
with the 9mm i.d. tubes anyway). We made one up to fit a randomly selected
tube using o-ring seals only to find that none of our other glassy carbon
tubes would fit. We then made one with threaded spigot on which to push the
g.c. tube, with three different-sized spigots to choose from.
Remember though that the pressure difference between the inside and outside
of the g.c. liner is barely 1 psi unless residue build up is extreme. So now
we simply use thread tape for the seal and push the liner firmly down over
it (not too firmly, you can crack the glassy carbon). This solution is not
tidy enough for a production model of course, eg IVA's, but once you get it
home, you can do what you like!
We have put nearly 300 solid samples into a 9 mm id tube in one run without
change in peak timing, although it's hard to get that much silver out when
cold. I cannot recommend these fittings more highly for tube-in-tube
pyrolysis. 
Good Luck
Robert Van Hale


> Apparently, they had A LOT of trouble getting a seal material 
> and configuration that worked properly for sealing the carbon 
> tube to the center metal tube. It took many months before 
> they determined it was ok, so it might not be worth trying to 
> re-invent the wheel yourself. 
> The fitting is probably cheaper than you could make yourself anyway.
> Jon
> 
> 
> At 02:04 PM 6/30/2006, you wrote:
> >The company is IVA. Here is the contact info:
> >
> >
> >IVA Analysentechnik e.K.
> >Breite Strasse 3
> >D - 40670 Meerbusch
> >
> >Phone   +49 (0) 21 59 / 69 42-0
> >Fax       +49 (0) 21 59 / 69 42-10
> >
> >[log in to unmask]
> >www.iva-analysentechnik.de