Hello Dave,
Here's my 2 cents....To my knowledge there should not be a problem
with hydrogen and Kel-F seats, but metal to metal might be safer.
We've been using the standard lecture flasks (~300 cc Swaglok 316
stainless steel cylinders) equipped with Whitey Bonnet metering
valves (31 series, metal to metal shut-off). The only down side is
the cylinders have NPT pipe thread ends, which require Teflon tape to
seal, and are always a poor choice for a good seal. I have always
wanted to weld the valves on to the ends instead, but even with the
NPT fittings, we've had no problems.
Electropolishing is always nice, but depending upon your needs, may
or may not be necessary. Perhaps if you plan to use the cylinder as
an absolute standard, that you count on not drifting, it would
certainly be worthwhile paying attention to such details of the
container. For our money, all of our analyses do not rely on the
reference gas as an absolute, but instead rely on standard reference
materials (ie. calibrated internal lab standards of waters, whole
air, carbonates, etc.) run along with the samples. That way the
consistency of the value of the running gas from run-to-run becomes
less important, and drops out of the equation.
Hope this helps.
Cheers,
Bruce
------------------------------
Date: Tue, 9 Nov 2004 12:00:18 -0800
From: Dave Winter <[log in to unmask]>
Subject: cylinder for hydrogen gas
We are putting together a small commercially available sample
cylinder for holding reference hydrogen gas for our new mass
spectrometer. We are planning on having the inside of the cylinder
electropolished also.
Anyone have experience with different types of valves to use in
dosing aliquots of hydrogen? For instance, is there any
incompatibility with hydrogen gas and kel-f or any other common valve
seats? What can you recommend as the best valves to use in this
application?
Thanks,
Dave
--
DAVID WINTER e-mail: [log in to unmask]
Department of Geology Office: (530) 752-9225
(Rm 282 Geology/Physics) Lab: (530) 752-3311
University of California FAX: (530) 752-0951
Davis CA 95616-8605 USA
--
_________________________________________________________
Bruce H. Vaughn Shipping:
Institute of Arctic and Alpine Research Attn: B. H. Vaughn
UCB 450 INSTAAR
University of Colorado 1560 30th Street
Boulder, CO 80309 Boulder, CO 80303
http://instaar.colorado.edu/
http://instaar.colorado.edu/sil/
303-492-7985 voice 303-492-6388 fax
303-492-5495 lab email: [log in to unmask]
_________________________________________________________
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