Re: EA troubles: NA1500
A couple of (long-shot) suggestions:
1. have you independently checked the temperature of your
2. what reactor packing are you using? Are you using the
WO3 & Cu packing, or the Cu-only packing? A long time ago I
used to use the WO3 & Cu packing, but it would sometimes give me
SO2 chromatography problems that drove me to distraction
(IPA-distraction, not lolly-distraction, in my case). Since
switching to the Cu-only configuration, and adding V2O5 to each
sample, I've generally had good SO2 chromatography.
Dept. of Geological Sciences & Engineering MS-172
University of Nevada - Reno
1664 N. Virginia St.
Reno, NV 89557-0138. USA
Fax: (775) 784-1833
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Questions for NA1500 users.
I am still battling my EA which is
smearing my sulfur peak over 200 seconds instead of the usual 50.
I have tried all the usual things to no avail.
BUT I have now determined that I have a
compressed air leak where the line feeds into the EA. The culprit is
the little double block of aluminium which the compressed air and
oxygen and He lines immediately feed into once entering the EA.
The manual labels the blocks as a 'safety line' which consists of
a single effect microcylinder and two, 2 way single effect
microvalves. The manual does not mention them at all in
the spares list. The air is coming out of the little hole at the top
of the block and also where both the blocks join together, which leads
me to ask.
1. Is it
normal for the aluminium blocks of the safety line to leak compressed
air at all times?
2. Is this
likely to cause enough of a problem to prevent the bimatic valve
operating properly? Given that the compressed air gauge at the front
of the EA reads as it should and is Teed in before the safety
3. I have
measured the oxygen flow at the oxygen vent at the front of the EA and
it is ALWAYS 25ml/min, even when doing an oxygen injection.
Should the flow from the oxygen vent slow down or stop when the
bimatic valve is actuated?
4. Could my
poor peak be a result of the oxygen regulator not working properly?
I notice that the pressure gauge gives a dramatic jump when the
bimatic valve is closed although this may have always happened. J
There is also a small leak in the
micro-solenoid valve that powers the sample carousel but this does not
appear to cause any problems.
If anyone has any insights they would be
greatly appreciated. Because of this I have become a highly
valued customer at the lolly shop and I don't think that that is
good for my sugar levels J
Stable Isotope Geochemistry Laboratory, Earth Sciences
The University of Queensland, 4072
Ph +61 7 3365 1131
Fax +61 7 3365 1277