In article , Keith G
wrote:


From what little Physics I do remember, I thought it was quite the
opposite of "At very cold temperatures (below -312°F), the molecules
will align in a more uniform, compact structure through the removal of
kinetic energy." - I thought the only way molecules could move in solid
objects was if you *heated* them up! (Which is why blacksmiths ring the
anvil when bashing red-hot metal about - to 'jiggle' the molecules!)

In essence, you are correct and the quote is either incorrect or
misleading. :-)

If you wish materials to 'crystallise' then in general you may find it
useful to cool them slowly *through the range around their melting or
softening point*. I'd suspect that the materials used for the electrodes in
'valves' would be well below this at normal room temperature. Hence it
isn't clear cooling them to very low temperatures will do what is claimed.

Hard to see that if will affect the 'structure' of the vacuum, either...
:-)

Hence IIUC you'd have to first heat the valve to the point where the
materials were starting to melt, then slowly cool it *if* you wanted any
serious recrystallisation. But simply using it and then allowing it to cool
to room temperature would probably do much the same.

Also, FWIW, if someone flogged me 'Cryo' valves I wouldn't even
*believe* they had been so treated anyway - how many fridges go down to
-312°F...??? (Oh, OK - most valve dealers have got a cryo plant out in
the back somewhere then?)

I'm trying to work out what "-312 deg F' actually means as a real
temperature... :-) I'd thought that science and engineering moved on to
Kelvins some decades ago. Certainly, I stopped even thinking with F units
many years ago. Do they charge in pounds, shillings, and pence? :-)

Sounds to me like they just dunk the things in a bucket of liquid nitrogen
(77K). You can buy that by the bucketfull from your friendly local 'liquid
air' supplier. (Someone like BOC, Air Liquide, or a local uni)

(WTF is "CYROGENTIC" [sic] anyway - a proprietory name or one which
*implies* the real thing without being the real thing - like 'Mapleen
Syrup'....?? :-)

As distinct from Potcheen Syrup... :-)

Slainte,

Jim

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