"RCE" wrote in message
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"JoeSpareBedroom" wrote in message
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"RCE" wrote in message
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to reduce the pressure and it will suddenly freeze again and begin to
sublimate (goes from solid to vapor without becoming a solid).



All of this happens at what range of temperatures? When you're reducing
the air pressure, the temp is remaining fairly constant?


As the pressure is reduced, the only temperature left is that remaining in
the water, (aside from any radiant energy). As pressure is reduced, the
vapor pressure changes. Often, high intensity quartz lamps or UV emitters
are used to add energy to the remaining water molecules to excite them to
a state where they can be removed or captured by the vacuum pumps.
Otherwise they cling to the vacuum chamber walls and will slowly sublimate
for hours or days.

Think of your car's radiator. The pressure cap allows the cooling system
to operate at a higher barometric pressure than at atmosphere, raising the
boiling point of water. The opposite happens in the vacuum chambers. To
a less obvious degree, the normal barometric pressure variations at
atmosphere affects dew points, etc. for a given temperature.

BTW ... in my partial sentence quoted above about sublimation ... I meant
to say "goes from solid to vapor without becoming a liquid".

Eisboch



Well anyway, it appears I've gone beyond my streak of good luck with
windshield fluid. 35 years of driving in frigid climates, and never a
problem until now, when I get not just one, but two products in a row made
by idiots or liars. The stuff's frozen in the tank, at 14 degrees F.