Re: [CAD_CAM_EDM_DRO] Re: gm-cm to oz/inches conversion?

e.heritage@... wrote:

> Seeing as we're on this metric / imperial debate I have to ask, how do I
> convert inches of mercury or water into microns of vacuum?
>
> John

John, et al
I may be all wet but think of this as a reverse system. i.e a perfect vacuum would be draw a column of Hg equivalent to the
atmospheric pressure. Vacuum then is expressed (?) as the difference between this and what you achieve. (in mm of Hg or microns
(micrometers) of Hg. multiply by the sp. gr. of Hg to get the measurement in H2O.
In the real world, as you pump down, you watch the gage go from 980 mm or so to a mm or so. You turn on the diffusion pump, wait a
little bit, turn on the ionization gage and go on down. Been 40 years since I've done this so it is a little fuzzy.

Did I obfuscate the issue sucessfully?

Dave


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