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Hi Karine,

Anther potential problem with your MOVPT valve could be a leaking seal.  I have repaired my HS valve on GC/C system by replacing a small seal inside of a valve body.  A seal kit is normally included with a new valve or you can probably purchase it separately from SGE (p/n 6990004).

See www.sge.com) and search for PNEUMATIC ON/OFF VALVES
 
You will see file MN-0078-A_rev05.pdf (the seals I am talking about are p/n 8 and 8a on the Figure shown).

Regards,
Anna  

-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Karine Charlier
Sent: May 6, 2011 09:04
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Problem with a MOVPT valve

Hi Rodrigo,

This is the way I built this part of the valve :
I put a GFV003-004 ferrule in the T of the valve, with the silica 
capillary inside it. The capillary can't protrude the ferrule, because 
of the 003 end, which is placed on the "plunger side" of the T.

Karine

Le 06/05/2011 11:47, Rodrigo Maia a écrit :
> Hi Karine,
>
> It seems that something is wrong in the way the vg-gvf003 ferrule is
> assembled; it seems CO2 is leaking across the plunger seat.
> Are you sure that the capillary is not protruding the ferrule? If the
> plunger damaged the end of the capillary, that can be enough for a leak
> across the seat. As the pressure of the CO2 is higher than that of the He,
> it will backflow on the He line due to the resistance imposed by the
> stainless steel capillary.
>
> Also, are you sure the ferrule is not the wrong way around?
>
> Hope this helps,
>
> Rodrigo
>
> Rodrigo Nascimento Maia
>
> http://sites.google.com/site/siiafcba/
>
> Laboratory Technical Supervisor
> SIIAF - Stable Isotopes and Instrumental Analysis Facility
> Fundação da Faculdade de Ciências de Lisboa
> Universidade de Lisboa
>
> T: +351 21 7500619 (direct) ; internal: 22119
>
> Address:
>
> SIIAF - Stable Isotopes and Instrumental Analysis Facility
> Faculdade de Ciências de Lisboa - Departamento de Biologia Vegetal
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> 1749 016 Lisboa Portugal
>
>
>
> -----Mensagem original-----
> De: Stable Isotope Geochemistry [mailto:[log in to unmask]] Em nome de
> Karine Charlier
> Enviada: sexta-feira, 6 de Maio de 2011 10:20
> Para: [log in to unmask]
> Assunto: [ISOGEOCHEM] Problem with a MOVPT valve
>
> Dear Isotopists,
>
> I work with a Carlo Erba EA linked to an Isoprime IRMS.
>
> I thought one of the MOVPT valves of the reference gas injector (the CO2
> valve) was leaking, so I re-built and tested it for atmosphere and
> internal leaks.
> There is no atmosphere leak, but when I open the CO2 valve, Helium
> pressure in the reference gas injector increases considerably (several
> psi). When I open the N2 valve which works prefectly, Helium pressure
> doesn't increase...
>
> When I rebuilt the valve, I changed all the ferrules according to both
> the manufacturer (SGE) and Isoprime schematics. But these schematics are
> either different of the configuration I have, or not complete, so I'm
> not sure if I used the correct ferrules.
>
> Has anybody ever encountered this problem, or can explain what's
> happening in the valve ?
>
> Thanks for your help,
> Best regards,
> Karine
>

-- 
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Karine CHARLIER
Environnements et Paleoenvironnements OCeaniques
UMR CNRS 5805 EPOC
Universite Bordeaux I
Avenue des Facultes
33405 TALENCE Cedex
FRANCE

Tel : 0 (33) 5 40 00 83 62
Fax : 0 (33) 5 56 84 08 48
E-mail : [log in to unmask]
Web : http://www.epoc.u-bordeaux.fr/

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