Bill:

We have been working on the same oxygen cylinder for almost two
years.  Our delta plus is configured in the same manner as yours.  I
would look hard for a leak somewhere.  Our experience has been that
the delta plus configured with the CE 2500 is very frugal in its
oxygen consumption.  We probably don't run as many samples as some of
the large labs but I think your oxygen usage is probably excessive.
Good luck.


Bill Griffis

*******************************************************
William L. Griffis
Chemist
Integrated Stable Isotope Research Facility (ISIRF)
Terrestrial Plant Ecology Branch
Western Ecology Division
National Health and Environmental Effects
Research Laboratory
US Environmental Protection Agency
200 SW 35th Street
Corvallis, Oregon 97333
Telephone:  541-754-4761   FAX:  541-754-4799
E-mail:  [log in to unmask]
*******************************************************

>>> Bill Showers <[log in to unmask]> - 4/28/99 9:18 AM >>>
Isogeochemists,

I have a question about the oxygen purge on our new CE 2500 EA hooked
up to
a F MAT Delta +.  The oxygen tank hooked up to the CE 2500 only lasts
about
6 months.  On our old EA, a CE 1108, the oxygen tank lasts over 1
year.
The difference between the 1108 and the 2500 is the autosampler on
the 1108
purges with He and on the 2500 the autosampler purges with O2.  What
are
the other folks experience with these new EA's, is the oxygen
consumed at
twice the rate as the old EA's or do we have a problem with our new
instrument that we need to fix?  The O2 blank size varies somewhat
with the
tank but is generally low, below 0.15 Vs.  We have installed the
smaller O2
loop on both EA's.

Bill Showers
----------------------------------------------------------
William J. Showers
Dept. of Marine, Earth, & Atm Sciences
North Carolina State University

(919) 515-7143 - voice
(919) 515-7802 - fax
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