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Stable Isotope Geochemistry

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Subject:
From:
Julia Cox <[log in to unmask]>
Reply To:
Stable Isotope Geochemistry <[log in to unmask]>
Date:
Tue, 5 Jul 2005 17:39:26 -0400
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BrF5 users:

We have 2 vacuum lines that see bromine pentafluoride - a laser
fluorination line plus a line used to distill and load BrF5 into a Kel-F
container.  The fluorination line has Hg diffusion pumps for trapping
residual BrF5 and protecting the mechanical pump downstream.  On the
distillation line we were planning to use an in-line trap filled with
granular soda lime.   However, I have been questioning how well the soda
lime will work.  When we first put the trap in place, we could not pump
the line down.  After taking the trap out and looking at the 60 micron
filter on the downstream side, we saw the filter was at least partially
clogged with tiny purple crystals.  Fluorite?  If so, that is surprising
since the line had seen very little BrF5 so far.  After re-installing
with a clean filter, we observe that the line is pumping down, but very
slowly.  The soda lime is taking days (almost a week now) to degas.

I'm interested in recommendations you have for protecting vac pumps from
BrF5, and whether using soda lime is a practical solution.

Thanks for any suggestions!
Julie

--
Julia Cox
Dept. of Geology
University of Georgia
Athens, GA  30602
706-542-1005

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