Just another note about Optima versus Delta-S. We have had the Delta-S at
Michigan for about six years and I have to conclude that it is a very
robust machine that is fairly easy to work on. In the six years we had
some trouble with the magnet current supply and the high voltage source.
Both problems, with a little technical knowhow were relatively
inexpensive to repair ($12 and $2.50!!). It took a little while to trace
the problem though since both went down more or less simultaneously and
the Delta-S has little display features to indicate the status of the
electronic equipment (voltage stability, magnet current display, etc. -
just like the new 252 sadly!). Since the software is also awkward, it
does not help very much. The machine worked great for CO2 but has a very
high H3-factor, which gets even worse with the software (correction may
not be correctly applied). While this can be corrected for, if you are
out of the calibration range of the standards, there may be trouble.
Other minor problems were transmitting valves (largely on the multiport
which is based on a cracker-system and provides ample glass-shards) and a
mechanical problem with the sample-side bellows - gear linkage broke but
could be repaired with spares from the local hardware.
In short - good, robust machine for CO2, but not recommended for H2.
That is it for now,
Department of Geological Sciences
University of Michigan
Ann Arbor MI 48109.