If I may add a few comments to this discussion. We have a MultiPrep here
in Lyon and I can only agree with what Georges, Li and Steve said.
The acid delivery line is an absolute key parameter to good carbonate
numbers. Although it may look as a simple piece of design, I know for
the MultiPrep there has been a few iteration to find the right way to
make those double needles suitable for small carbonate analyses. The
welding is important but the welding material can be as well, as some of
them may interfere with the phosphoric acid reaction. Plus this may not
appear right away but slowly with time. Trying to make your own is
always a possibility, but you have to thoroughly test it if you're
interested in high quality carbonate data. It doesn't take much to
contaminate 20 micrograms of calcite.
Leak checking the needle when you install it is definitely a good practice.
We have been using ours for over a year now with no problem so it is
worth taking a bit of extra time to check it when you install it.
Now there may be alternative options to IRMS manufacturers, but you have
to be very careful as if 100US$ may sound expensive for a needle, having
a whole IRMS-carbonate system stopped because of a 100US$ needle may not
be ideal. Especially when a needle may last a year or more. But that is
a personal opinion.
The acid quality is also a key parameter but that is anothoer discussion.
Hope this helps,
--
François FOUREL
UMR CNRS 5125 PEPS
Université Claude Bernard Lyon 1
2 rue Raphaël Dubois - Bât. Géode
F-69622 VILLEURBANNE Cedex - FRANCE
Tél : +33 (0) 4 72 44 62 42
FAX : +33 (0) 4 72 43 16 88
Email : [log in to unmask]
Joel Savarino a écrit :
> Hello,
>
> don't order expensive double holed needles, make your own one. Go to
> Hamilton website
> (http://www.hamiltoncompany.com/newdev/syringes/needles-tubing.asp) and
> you will find
> all kind of different SST needle gauges.
>
> To do the side hole, ask you machine shop (they have excellent tools to
> do very small
> hole with "wire cutting machine")
>
> To weld, use new SST solder wires that can be used just with a soldering
> iron (very precise
> and no overheat compared to welding)
>
> When your side hole and solder is done, slip into a guitar type string
> to clean the inside needle
> then slip into our silica tubing, flow He through it, add a small drop
> of glue (araldite -two components glue)
> at the tip and retract the silica so it stays inside the tip of the
> needle. At the top glue your second silica
> tubing.
>
> Done ! you can make 10 needles for $100 and choose the level of your
> second hole.
>
>
>
> joel
>
>
> A 15:07 08/02/2006 -0500, Stephen S. Howe a écrit :
>
>> Toti:
>>
>> Both Georges and Li have replied to your message before I had a chance
>> to, but I concur with their comments. These are the needles that we
>> have been using with our prototype MultiPrep (one of the first
>> manufactured) for the past 9 years and we have had good success with
>> them. The length from the tip to the upper weld is indeed about 9.0
>> cm, and the needles come with an extra length of the inner, smaller
>> diameter tubing above the upper weld to a length of 14.5 cm. For our
>> setup, I cut the upper inner needle portion so that it extends about
>> 1.5 cm above the upper weld, for a total length from tip to tip of
>> 10.5 cm. It is important to cut the inner tubing gently with a file.
>> It is too easy to collapse the thin walls of the inner needle by using
>> wire cutters, and its diameter is too small for most stainless steel
>> tubing cutters. Otherwise, you will have difficulty inserting the
>> silica capillary used to transfer the acid from reservoir to needle tip.
>>
>> I prefer to check the welds in the fashion that Georges mentioned,
>> rather than submerging the tip of the needle in water like Li does. I
>> put a rubber septum over the side port closest to the tip of the
>> needle, evacuate the needle under high vacuum for a few minutes, then
>> close the vacuum valve and open the line connecting the needle to the
>> pressure transducer section of our dual inlet. If the weld is good,
>> there is no rise on the transducer. If the weld is starting to break
>> down, the transducer will slow increase over several minutes. If the
>> weld is really bad, you won't be able to evacuate the needle.
>>
>> Hope this helps!
>>
>> Steve
>>
>>
>>> Hi Toti,
>>>
>>> Our Multiprep uses different kind of double hole needle from that of
>>> gasbench. I got double hole needles (part # M69-4072CD1, tel
>>> 603-880-3233 ) for our multiprep from GV US for US$ 99.57. They are
>>> very good in quality as I had some bad ones before from else where.
>>> The length from the tip to the welding part at the top is about 9 cm.
>>>
>>> For any new double hole needles, do check to see if there is any hole
>>> at the tip with microscope as it will affect your 18O eventually. I
>>> also do a leak check by sealing the side hole with a tape, flush some
>>> He through the transfer line while the tip is in water (surface is
>>> lower than the side hole). If you see bubbles don't use it.
>>>
>>> Good luck,
>>> li
>>>
>>>
>>> ----- Original Message -----
>>> From: Toti Larson
>>> Date: Wednesday, February 8, 2006 1:18 pm
>>> Subject: [ISOGEOCHEM] two holed needles
>>> To: [log in to unmask]
>>>
>>>> Does anyone know a supplier for two-holed needles that are used
>>>> on the
>>>> Multiflow (and maybe also the Gasbench?). The one I have right
>>>> now (that is
>>>> beat-up) is stainless steel 1.45mm OD and 9.5cm length. The
>>>> inner tube is
>>>> 0.7mm OD and is welded at the top and bottom
>>>>
>>>> Thanks,
>>>> Toti.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>> Li Huang
>>>
>>> Laboratory for Stable Isotope Science
>>> University of Western Ontario
>>> London, Ontario
>>> Canada
>>> Phone: 1-519-661-3881
>>
>>
>> --
>> ---------------------------------------------------------------------------
>> Stephen S. Howe Office: (518) 442-5053
>> Dept. of Earth & Atmos. Sciences Stable Isotope Lab: (518)
>> 442-4471
>> Earth Science 352B FAX: (518) 442-5825
>> University at Albany E-mail: [log in to unmask]
>> 1400 Washington Avenue
>> http://www.albany.edu/geosciences/sshowe.html
>> Albany, NY 12222-0001
>> http://www.albany.edu/geosciences/sirmslab.html
>> ---------------------------------------------------------------------------
>
> *************************************************************************
> Joel Savarino
> Laboratoire de Glaciologie et Géophysique de l'Environnement/CNRS/UJF
> 54 rue Moliere, BP 96
> 38 402 St Martin d'Hères Cedex
> France
> tel: + 33 476 82 42 51
> fax: + 33 476 82 42 01
> Email: [log in to unmask]
> Web: http://www-lgge.obs.ujf-grenoble.fr
> <http://www-lgge.obs.ujf-grenoble.fr/>
> **************************************************************************
>
>
|
