Spinlanders,
This is a summary of the messages and actions taken after my initial
query on 4 August for guidance for replacing the glass liner in a probe.
Initial Message:
> I'm looking for documentation for replacing the glass (quartz?) insert
> in a Varian 5mm 4-Num autoswitchable probe. I'm assuming that I can
> get a replacement from Varian or MRR. I'm hesitant to initiate the
> venture without some foreknowledge of the task.
>
> My major concerns are:
> -- Using the proper adhesive, if required ... as alluded in earlier
> ammrl messages
> -- Aligning the insert for perfect concentricity with the probe
> -- Possibly damaging other parts of the probe while attempting to
> correct this one thing
Andy Jensen replied:
> If my memory is correct, Varian probes have glued glass/quartz
> inserts, so
> removal may not be as easy as planned. Just a heads up. I do not
> have any
> literature regarding the replacement.
Paul Bruins replied:
> First of all don't count on Varian to supply you with any probe
> parts, that is my experience. If the inner coil insert is broken , I
> have been successful in removing the coil from the remaining insert in
> a ultrasonic bath, loosened coil from glass and managed to slip same
> back on new insert. Insert material was obtained from wilmad (
> precision diameter custom tubing ), your choice of pyrex or quartz (
> remember that nmr tubes are pyrex anyway.
> I soldered up the carbon coil leads a bit to increase stiffness and
> used no adhesive, I have heard people using minuscule amounts of super
> glue in strategic corners. ( I used single wrap of teflon tape to
> keep coil in place at bottom and top without affecting the probe
> back ground.
> The proton inserts can similarly be ordered from ****** and even
> though I have not done the procedure the H1 coil is sandwiched between
> glass inserts so requires no adhesive. Good luck and just be patient
> and careful. P.S. Make sure that you keep the C13 and H1 coils as
> orthogonal as possible
I've obliterated the name of the company above to protect the innocent.
I tried contacting that company to obtain an insert. The
representative said that they make the inserts, but they are under
contract not to sell them to end-users. He highly recommended against
attempting a local repair. I tried contacting some of the other usual
sources, but was still unable to find the liner.
Given the lack of a replacement liner and the lack specific
probe-repairing skills, we decided to return the probe to the
manufacturer for repair. We were initially caught in a "Catch-22".
Without an estimate for the repair, I could not get a purchase order
here at the College. Without a purchase order, I could not send the
probe to Varian to get an estimate. After another call to Varian, I
was able to get a rough estimate of $4700, which I rounded to $5000 for
a buffer. For the record, the entire cost was $5300.
Part of the reason for the high cost was our inability to supply an
MSDS for material spilled in the probe. The damage of the liner was
coincident with the breaking of a research-sample. Since the compound
is not commercially available, then no MSDS is available. Thus, the
compound is assumed to be toxic, rightly or wrongly.
We shipped the probe to arrive in Palo Alto on the morning of 19
August. We received the repaired probe on the morning of 3 September.
Varian had cleaned, repaired, tuned, and tested. By the way, the
old liner was quartz; the new liner is pyrex. We've been using the
probe heavily since then, and all seems to be well.
I expected an expensive repairing; I only wish that I could have
avoided seeing jaws dropping and subsequent hearing "It will cost how
much to replace a piece of glass?". I'll save the home-repair until
we are dirt poor or until the instrument is 20 years old.
Thanks to Andy and Paul for their wisdom and to Varian's probe shop for
the quality work.
----oooo-O-oooo----
Stephen Stanford Jones, jonesss_at_cofc.edu
Department of Chemistry and Biochemistry
Received on Fri Sep 19 2003 - 15:16:24 MST