[TheForge] Power hammer questions/Frosty

[Mike Linn]

It depends on your reference.  0 psia (absolute) is a perfect 
vaccuum.  psig (gage or gauge) is referenced to standard atmosphere at sea 
level.  Typically when describing vacuum one uses the units mmHg.  Normal 
atmosphere is about 30 mmHg, I sometimes calibrate vacuum instruments down 
to about 10-7 torr ( 1 torr = 1mHg) the lowest I've ever heard of is 10-9 torr.

mike





At 09:03 AM 04/11/2003 +0930, you wrote:
> >I've left it out
> >simply because I have no idea what kind of partial vacuum to expect but for
> >my own guestimating I've been using -10psi
>
>Did you mean negative 10psi? or 10 psi, 0psi would be a perfect vacuum
>wouldnt it, or did you mean -10 psi from atmospheric so 5 psi? or when
>talking about vacuums on earth with its atmosphere do we use negatives if
>under 14.6???
>
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         Michael Linn
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