Dear Isogeochemists,
        At the University of Baja California (Mexico) we are trying to make
a few modifications to our Optima-Isocarb system in order to make more
efficient use (and simultaneously get an uninterrupted supply) of liquid
nitrogen (for cold-fingers in the dual-inlet) during a carrousel run. Our
system is set in such a way that we have to fill a 32-liter dewar with
Liquid Nitrogen at the begining of the batch run. This liquid nitrogen is is
pumped into the cold fingers by means of two independently controlled (by
software) Charles Austen Pumps.
        The drawback of this system is that we have to re-fill the 32-L
dewar in the middle of the batch run. Instead, we would either like to: (1)
connect the bigger ~160 Lt thermic containers (in which liquid nitrogen is
supplied) to the cold finger tube-lines or (2), somehow connect the bigger
container (~160 lt) to the smaller one (32 lt) by means of any sort of
liquid nitrogen automatic refiller.
        These options may sound easy to many of you, but at these latitudes
we do not know of many suppliers for this type of equipment and accesories;
most of them are abroad. Option-1 could probably be achieved by using
electrically-driven selenoid valves, but I have no idea what kind of (so
they would be Ok for operating at LN temp's). Option-2 could probably be
simple but we do not know the model or company that sells this kind of
cryogenic accessories.
        Could anyone of you please suggest alternatives or provide relevant
information for this case? Your help will be greatly appreciated.

Regards,

Jose Carriquiry




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Dr Jose Carriquiry                          . USA MAILING ADDRESS:
Instituto de Investigaciones Oceanologicas  . 1125 Loma Ave. #144-E099
Universidad Autonoma de Baja California     . Coronado, CA 92118
Apdo. Postal # 453                          . USA
Ensenada, Baja California, c.p. 22,800      .
Mexico                                      .
Tel (61) 74-46-01, ext 123                  .
Fax (61) 74-53-03                           .
http://www.ens.uabc.mx/iio/iio.htm
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