Hi Georges,
In an attempt to avoid leaks we will be replacing
the seats, as well as the diaphrams and buttons,
but not the valve blocks because, as you noted,
they are welded together. I'm keeping my fingers
crossed because I don't want to have to rebuild
the entire thing at the moment. So many samples
.... so little time. However, putting together a
new valve assembly will probably happen sometime
in the near future because Swagelok no longer
sells our type of valves and getting replacement
seats/diaphrams will eventually be impossible.
So if you could send me your part list that would
be great.
I normally blow a bit of N2 gas through the
needle after every batch of samples. If acid
comes out it is time to clean. However, it would
be ideal to do this after every sample. I think
it is time to contact the software guys at GV and
have the multicarb method tweaked a bit. They
have made similar small modifications to Masslynx
for us in the past. Its a great service.
Free filters! Who could say no to such an
offer...especially after spending $500 on valve
repair kits. My postal address is below.
Thanks again for the help.
Jennifer
>Hi Jennifer,
>
>Yes. The solder connection at both ends of the
>needle are a weak link. Apparently many users
>have had success with these solder connection
>needles for years, but of late, the quality is
>unpredictable. GVI developed the new laser
>welded needle (four hole). There must be a
>reason for this, even though it's hard to get
>anyone to come clean at GVI regarding this issue.
>
>There are two ways acid gets into the prep line
>and beyond. The first is from the solder
>connection cracking, which can result in a large
>amount of acid moving quickly. The resulting
>droplets can cause partial physical blockage
>which results in fractionation and incomplete
>transfer of the gas to the cold finger. The
>other mechanism is accumulation of acid droplets
>from routine use. There are users blowing N2
>gas through the needle after every sample. This
>has resulted in keeping the prep line and needle
>free of acid blockage.
>
>Good luck cleaning out your multiprep valve
>block. These valves are not servicable, meaning
>that to replace the seat, you must replace the
>valve block in addition to replacing the
>diaphram. When we cleaned out our multiprep
>valve block after needle failure, we did the
>same as you by replacing the diaphrams only.
>Cross seat leaks developed on these cleaned
>valves. This can mess things up, especially
>valves FC and FH that have one atmosphere on the
>other side. Since the multiprep valve block is
>a pre-welded assembly, replacing valves is
>problematic. We have since replaced the
>multiprep valve block with individual valves
>connected using VCR fittings. Any future
>servicing will be one valve at a time. Let me
>know and I can shoot you a parts list.
>
>I recommend using the filters in the 1/4" to
>1/16" union. GVI part #T3602810. I just
>realized that I have extra filters because they
>don't fit in my VCR to 1/16" swage union. I need
>a different filter. If your interested, I'll
>send you a few.
>
>Happy cleaning,
>Georges
>
>
>
>
>----- Original Message ----- From: "Jennifer
>McKay" <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Friday, April 21, 2006 3:27 PM
>Subject: Re: [ISOGEOCHEM] Multicarb problem
>
>>Hello Georges,
>>
>>Thanks for the advice.
>>
>>I did check the 1/4 to 1/16 union for acid as
>>part of my needle and stainless (ss) tubing.
>>It looked OK. However, there is no filter in
>>the union. If the missing filter is designed
>>to keep acid from reaching the dual inlet
>>valves I could have bigger problems. That
>>said, we are now in the process of taking apart
>>and cleaning the valves and replacing the valve
>>diaphrams.
>>
>>Now, I've noticed that acid gets into the
>>system (i.e., needle side hole and ss tubing)
>>when there is a leaky vial or leaky needle.
>>Have you observed the same?
>>
>>Jennifer
>>
>>>Hi Jennifer,
>>>
>>>Although you mentioned that the needle and
>>>prep line don't have acid blockage, it may be
>>>worth pulling the 1/4" to 1/16" union that
>>>attaches the prep line to the multiprep valve
>>>block. We've had acid migrate to the filter in
>>>the union. This resulted in very strange
>>>performance, including no gas getting to the
>>>cold finger. Swab the inside of the 1/4"
>>>tubing with a kimwipe and inspect for acid.
>>>Also look closely at the filter in the union.
>>>A quick boiling in DI followed by a good bake
>>>will clean the union (filter).
>>>
>>>I'm glad to hear you installed the new four
>>>holed laser welded needle. Maybe GVI would
>>>consider a recall of the old design needle, or
>>>possibly offer a reasonable trade-in.
>>>
>>>I've observed that the laser welded needles
>>>don't seal as well to the blue septa/kel-f
>>>disk combo. I was wondering if anyone had any
>>>experience with the new laser welded needles
>>>running small carbonate samples. This extra
>>>leaking may affect small samples.
>>>
>>>Good luck,
>>>Georges
>>>
>>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>Georges L. Paradis
>>>ICPMS Lab Manager
>>>Department of Earth Science, Marine Science Institute
>>>University of California Santa Barbara
>>>Santa Barbara, CA 93106
>>>805-893-7182
>>>[log in to unmask]
>>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>>
>>>----- Original Message ----- From: "Jennifer
>>>McKay" <[log in to unmask]>
>>>To: <[log in to unmask]>
>>>Sent: Friday, April 21, 2006 9:25 AM
>>>Subject: [ISOGEOCHEM] Multicarb problem
>>>
>>>>Hello Everyone,
>>>>
>>>>I have a rather interesting/annoying problem
>>>>with my Isoprime-Multicarb system.
>>>>Essentially, during a run no gas is getting
>>>>from the reaction vial to the first
>>>>coldfinger (CF2). At first we thought it was
>>>>a problem with CF2 (e.g., either it was
>>>>plugged or not cooling properly) but the
>>>>problem still persisted after changing to a
>>>>new coldfinger. If we simply inject CO2 into
>>>>the vial (bypassing the calcite-phosphoric
>>>>acid reaction) we are able to get CO2 from
>>>>the vial to CF2 and trap it correctly.
>>>>However, this works only if we are using a
>>>>lot of CO2 gas. If we use only a small amount
>>>>(as if we reacted 100 ug calcite) it does not
>>>>work. I have confirmed that CO2 gas is being
>>>>produced (i.e., no problem with the addition
>>>>of acid to the vial). So essentially, it
>>>>appears that CF2 does not have the ability to
>>>>"pull" the CO2 from the reaction vial or the
>>>>CO2 gas is being trapped / lost somewhere
>>>>along the way. I have considered the
>>>>possibility that the water trap is too cold
>>>>(and that the thermocouple is reading
>>>>incorrectly) and will check this today.
>>>>
>>>>Here are a few more details. I've checked
>>>>the system for leaks with Argon and
>>>>everything looks OK. The needle and
>>>>stainless steel tubing leading from the
>>>>needle to the inlet system are not plugged
>>>>with acid (...those of you with the multicarb
>>>>know this is a common problem). We have
>>>>confirmed that the heated rack is at about
>>>>90°C. We are using a new batch of acid, but
>>>>it worked fine for a few runs so I don't
>>>>think this is the problem. We also have the
>>>>re-designed multicarb needle, but again we
>>>>used this for a few runs without problem.
>>>>
>>>>Any suggestions would be greatly appreciated.
>>>>
>>>>Jennifer
>>>>
>>>>
>>>>--
>>>>Post-doctoral Researcher
>>>>Centre GEOTOP, Universite du Quebec a Montreal
>>>>C.P. 8888, succursale Centre-Ville
>>>>Montreal, Quebec, Canada
>>>>H3C 3P8
>>>>
>>>>GEOTOP: 514-987-4080
>>>>Office: 514-987-3000 (1718)
>>>>Lab: 514-987-3000 (7028)
>>>>Fax: 514-987-3635
>>>>
>>>>E-mail: [log in to unmask] (or [log in to unmask])
>>
>>
>>--
>>Post-doctoral Researcher
>>Centre GEOTOP, Universite du Quebec a Montreal
>>C.P. 8888, succursale Centre-Ville
>>Montreal, Quebec, Canada
>>H3C 3P8
>>
>>GEOTOP: 514-987-4080
>>Office: 514-987-3000 (1718)
>>Lab: 514-987-3000 (7028)
>>Fax: 514-987-3635
>>
>>E-mail: [log in to unmask] (or [log in to unmask])
--
Post-doctoral Researcher
Centre GEOTOP, Universite du Quebec a Montreal
C.P. 8888, succursale Centre-Ville
Montreal, Quebec, Canada
H3C 3P8
GEOTOP: 514-987-4080
Office: 514-987-3000 (1718)
Lab: 514-987-3000 (7028)
Fax: 514-987-3635
E-mail: [log in to unmask] (or [log in to unmask])
|
