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Melissa,
I would expect it is ok. As the flow path is less restricted on the
"dillution on" side you may get a bit of change in the back pressure on the
line, Should not make much of an effect on chromatography, just be wary of
the jump timing from N2 to CO2.
Cheers
BJones

On Sat, Mar 29, 2008 at 7:36 PM, Melissa Bautista <
[log in to unmask]> wrote:

> Thanks William and Brian for your suggestions and advice. A check for flow
> from the stainless purge line indicated that this was blocked. I replaced
> this and also disassembled and cleaned the three-way valve, as described.
> I
> replaced the glass capillary from the EA to the open split, but the split
> itself is still quite clean.  Brian, you may remember that we cleaned it
> while you were here. I also baked and blew out the stainless transfer line
> from the EA to the conflo. After all was reassembled and the carrier flow
> turned back on (set at 100ml/min), the flow rate increases slightly from
> 100
> ml/min with dilution off to 107 ml/min with dilution on. Is this normal?
>
> Thanks,
>
> Melissa
>
> -------- Original Message --------
> Subject: Re: [ISOGEOCHEM] EA carrier flow
> Date: Fri, 28 Mar 2008 10:44:18 -0400
> From: B Jones <[log in to unmask]>
> Reply-To: Stable Isotope Geochemistry <[log in to unmask]>
> To: [log in to unmask]
> References: <004e01c89089$b1d673c0$2136820a@D3JMW62J>
>
>
>
> Melissa,
> There is most likely a problem with the pneumatic valve inside the
> Conflo interface. I would assume a blockage in the "dilution on" split
> section. If you remove the cover from the Conflo you will see a small
> pneumatic valve on the right. The Ea flow from the back of the interface
> connects to this valve. This valve switches from a split of the EA flow
> from 72ml/min with dilution off to 79.5ml/min with dilution on (flow
> rates based on 80ml/min EA flow; as in conflo manual pg 2-3). It does
> this by switching flow paths, one path being more restricted than the
> other.
> It would appear that the "dilution on" flow path is clogged and creates
> a back pressure on the EA slowing flow. I would suggest disassembly of
> the valve and both flow paths and cleaning both thoroughly with acetone
> followed by MeOH. Dry parts well in a oven at ~30C. I would also suggest
> replacement (or at very least cleaning as above) of the glass capillary
> associated with the EA flow to the open split. While it is open, you may
> want to clean the open split glass as well, but it can be a pain to
> remove and reset all capillaries. Noticeable brown stains in the open
> split would suggest a need to perform this extra work.
> Good Luck!
> Cheers,
> BJones
>
> On Fri, Mar 28, 2008 at 12:10 AM, Melissa Bautista
> <[log in to unmask] <mailto:[log in to unmask]>> wrote:
>
>    Dear Isogeochemists,
>
>    This is in regards to a change in carrier flow rate from our Flash
>    EA 1112
>    to a Conflo III.
>    The carrier flow is set at 100ml/min. However, when the He dilution
>    capillary is dropped in, the flow rate drops to c. 58ml/min. I have
>    checked
>    the heights of the capillaries in the open split and they are
> positioned
>    correctly according to the manual. Can anyone tell me why this happens?
>
>    Thank you
>
>    Melissa Bautista
>    Southern Cross University
>    Lismore NSW Australia
>



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