On 9/20/11 12:46 PM, J. Forster wrote:
Likely one of the Freons (TM) or Sulphur Hexafluoride.
Tektronix used a Freon in their 40 KV High Voltage probes. The Vapor
pressure of some of those compounds is low at 70F, but they do have to be
sealed.
Unfortunately, virtually all Freon useage has been banned by the EPA (they
are said to be "greenhouse gases") and the stuff in now almost unobtanium.
-John
===============
Long ago and far away, I recall a friend using a gas that had its
liquid/gaseous transition near room temperature and was inert (not an
inert gas) to pressurize a vessel having high impedance circuits in it.
I'm darned if I can remember what it was. Available in so-called "lab
bottles" ie not monster cylinders.
Would have to be sealed, though.
Don
All manner of refrigerants fit the bill. some form of halogenated
hydrocarbon for the most part, and while regulated, they're still
available. Just not dirt cheap.
SF6 fluctuates widely in price. It was really, really expensive 10-15
years ago (as flourination plants were used to make non CFC
refrigerants) but has come down a lot.
In lecture bottles (2 SCF) all gases cost about the same $100
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