Hi Guy,

I ran an experiment last year to test out the theory.  What I failed to
consider was the thermodynamics of lowering the pressure.  (it was too
obvious in the formulas to notice).  When you lower the pressure, gas
expands, sucking up heat in the process.  If you don't take special
precautions, it will cool enough to freeze.  There are special ovens you can
buy that lower the air pressure, but notice the key word 'oven'.  You still
require 'heat' to get the moisture out of your parts.

Kind Regards

Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]


> -----Original Message-----
> From: Guy Ramsey [SMTP:[log in to unmask]]
> Sent: Thursday, May 24, 2001 12:44 PM
> To:   [log in to unmask]
> Subject:      [TN] Moisture Sensitive Components
>
> Anyone out there ever considered dring moisture sensitive devices by
> lowering the pressure in a storage vessle?
>
> It is difficult to achieve 40?C and less than 5%RH when ambient RH is
> 50-60
> percent. So, someone called and asked how long he would need to keep the
> parts at a pressure equivelent of 80,000 ft above sea level, temperature
> at
> room ambient to dry out parts.
>
> No one here had considered it before. The physics made me feel like I was
> at
> altitude.
>
> Guy Ramsey
> Senior Lab Technician / Instructor
>
>
> E-Mail: [log in to unmask] <mailto:[log in to unmask]>
> Ph: (610) 362-1200 x107
> Fax: (610) 362-1290
>
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