HI Ben--

Yeah, not that uncommon...

The capillary tube (from the mass spec) lowers through the constriction 
of that
lower tube (which is a fused silica union, but the capillary is too small to
seal--which is a good thing).  You'd like it to be just above the capillary
tube coming up from the bottom.  Sometimes the capillary will catch on the
fused silica union--sometimes it'll "stick" to the He capillary line in the
tube and do a curly-q instead of dropping.

Alignment issues...

Sometimes playing with the relative position of the He capillary helps.  There
is some wiggle room with the connector on the piston.  You can gently undo the
set screw holding the lower capillary in place (you'll see the hole on the
front edge of the block holding things in place).  And you can try holding off
to one side and re-tightening--and/or move it a little up or down.  A little
trickier is loosening the screw on the top that holds the center glass
capillary tube in place, and try moving that around a bit and re-tightening.

You also may need to wipe off the capillary lines if there's sticking.

Probably not needed, but...
To be on the safe side, better order more capillary tubing,ferrules, two-hole
ferrules (for mass spec side), some similarly sized micro-cap (tm) glass
capillary tubes and fused silica unions.  If you do end up needing to remake
it, you'll probably have to re-set the positions of the He line in (make your
own can have different flow patterns--so you need to find a position 
that keeps
the air out)

good luck...

take care

gerry



Quoting "Harlow, Benjamin" <[log in to unmask]>:

> Hi all,
>
> On our Thermo GC-III interface, the capillary that goes to the IRMS
> inlet recently broke just below the actuator arm at the movable open
> split.
>
> It appears that it broke because it could not line up properly to the
> lower glass tube in the split.  This glass tube I am talking of has
> larger diameter fused silica glued in it, coming from the nafion trap
> and N2 trap if installed.
>
> I'm wondering if my open split itself dropped and what else may be out
> of sorts.
>
> 1) Does the IRMS capillary actually go into the lower tube of the open
> split when actuated?  If so how far?
>
> 2) How far is the top alignment tube (where IRMS sniffer and He
> capillary enter) from the lower, main open split?  Mine was almost level
> with the aluminum block with a set screw loosely holding it.
>
> Thanks,
>
> Ben
>
>
> Benjamin Harlow
> Manager, Stable Isotope Core Laboratory
> Washington State University
> School of Biological Sciences
> G-81 Eastlick
> Pullman, WA  99164-4236
>
> Office:  509-335-6161
> Lab:     509-335-6154
> Fax:     509-335-3184
>
> Laboratory for Biotechnology and Bioanalysis (LBB2) Stable Isotope Core
> http://www.isotopes.wsu.edu
>
>
>