We are using UHP O2 at 4.3 (99.993%) with no problems. Here in CA the cost
is $166/K size (249cu ft) orders of magnitude less exp then 5.0. It is
important to check with your supplier to see what the trace level gases are
in the tank. While it is true some suppliers are not consistant in the
naming (e.g., Zero vs UHP), most suppliers will supply a spec sheet on the
gas of interest.

Dave

At 08:23 AM 6/24/99 -0500, you wrote:
>Hi
>
>I'm using  research grade oxygen 99.999% min. and the cost is geting close
>to $ 400.oo /tank on my Carlo Erba elemental analyser.  Does anyone use a
>lower purity like ultra high purity 99.99 min. or is there any grades I can
>use?
>
>Thanks  Armand Krueger
>
>
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David A. Mucciarone
Laboratory Manager
Stanford University
Department of Geological and Environmental Sciences, 320
Stanford, CA 94305-2115
650-723-0817 (office) 650-725-0979 (fax)
Office - Green Earth Sciences Rm. 365
Stanford Stable Isotope Laboratory - Green Earth Sciences Rm. 332 & 334.
e-mail: [log in to unmask]
WWW: http://pangea.stanford.edu/isotope/dam
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