The difference in pressure between high and low  vacuum is very
small. The difference in high vacuum and ultrahigh vacuum is only a few
molecules that are attached to the walls of the chamber or trapped in
between spaces creating virtual leaks. Removing one atmosphere of pressure
or about 32 inches of mercury at sea level is all that can be attained.
        My understanding of the vacuum  in the drying process is that it is
used to move any moisture out of the chamber, followed by refilling it  with
dry air, thus creating an imbalance of moisture and pressure between the
chamber and the inside of the parts, which will leak out the moisture inside
of them through their porous  bodies. When this cycle is repeated over and
over, it speeds the drying of the components. The  temperature keeps the
water molecules volatile and the  vacuum  dries the chamber. It makes a lot
of sense. Even if the chamber has absence of gas pressure it will take some
time for the inside of the parts to reach the same low pressure.
        Regards,
        Ramon


> My understanding of the low temp moisture extraction process is that it's
> carried out under partial vacuum, not high vacuum, so that the moisture
> neither boils off rapidly, nor freezes - either of which would cause
> delamination if it were allowed to happen. My initial skepticism about the
> process was relieved after I spoke to Altos Engineering further about it,
> although I would want to see the process obtain industry approval or
> conduct my own tests with it before I considered adopting it as a process
> here.
>

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