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petrock
30-06-2012, 01:02 AM
Easy vacuum tester. Never needs calibration. Water temp down to -18 deg C
I wonder how much that is in microns..
http://www.youtube.com/watch?v=9h_lvNCDp6Y&feature=g-upl

xxargs
30-06-2012, 07:56 AM
we only see how vacuum freeze water for 0 degree C point - not how much below it.

0 degree C water (water/ice) = 6.1 mBar = 4570 micron
-10 degree C water (ice) = 2.599 mBar = 1950 micron
-18 degree C water (ice) = 1.27 mBar = 952 micron

(edit - missing multiply 1000 times on micron value in convension from mBar, this is corrected now)

petrock
30-06-2012, 12:13 PM
Heyyy.... Thanks for that.
Can you tell me the formula you use to get to this figure.? That would be handy for me to know..

Cheers mate

Peter

xxargs
01-07-2012, 11:01 PM
I take pressure value over water/ice from refprop, but possible source if you want formula, you can find here http://cires.colorado.edu/~voemel/vp.html - is not easy relation in simple formula and also many formula from different scientists author to select between - pick one you trust most :-)...

conversion between micron and mBar is easy

(micron/1000) * (1/0.75) = mBar

mBar * 0.75 * 1000 = micron

petrock
02-07-2012, 08:51 AM
Hi xxargs..
I clicked on that link and I think those formulas are very easy to understand. . . . . . . . . Not..... hehehe....

Thanks again mate... cheers

Peter