Here's my 1.5 cents worth!
I would have grave safety considerations about putting an oil diffusion
pump on a fluorination line. One major release of fluorine into an oil
based diff pump and you'd have an explosion in a (probably) glass diff
pump. I do agree though that coating the inside of glass lines gradually
with Hg fluoride is a pain, even if a mercury trap is used.
Of course a major release of fluorine into an oil lubed rotary would also
be less than satisfactory. Perhaps cynically I have always regarded the
rotary as where the traces of fluorine and mercury end up ....
I have also seen soda-lime used by fluorine-noble gas chemists as a trap
and their pump oil stayed beautifully clean.
Final thought - bromine and steel (even stainless) are highly
incompatible, even in a vacuum line. Steel probably survives in the
fluorinated parts of BrF5 lines due to a fluoride coating. How does a
steel diff pump do in the non-fluorinated part of the line?
Hilary Le Q. Stuart-Williams Ph.D.
(Climate, behaviour study and ecology using stable isotopes)
Research Officer - Stable Isotope Laboratory
School of Environmental Sciences, University of East Anglia
Norwich NR4 7TJ, England
Telephone 01603 593837 (Work), 01603 507719 (Fax)
01603 503430 (Home)
More data at : www.uea.ac.uk/~sil/