"Peter Wells" wrote in message
...
On Wed, 20 Dec 2006 01:00:17 -0500, Bill in Detroit
wrote:

How can I correlate mbars, as in :

Ultimate vacuum mbar 1.10-4

with inches of mercury so as to make a comparison between various makes
of vacuum pumps. I'm not in the market today but I'm reasonably
confident that I eventually will be ... so I'm trying to understand the
lingo.

Just asking wikipedia about millibars (mbars) brought me to a nice chart
comparing them to hectoPascals. On this side of the pond, that's still
apples & oranges.

Not sure I understand you: a hectopascal IS a millibar. Shipping
forecasts and reports here (in France) now use the hectopascal as
standard for all atmospheric pressures.
For medical purposes (the only area where it is still used in Europe,
apparently), 1 mm mercury = 133.322 pascal, or 1.33322 hectopascal.

As 1"=25.4 mm, my calculation makes that 1" mercury = 33.864
hectopascal.

Unless I've screwed up somewhere...


Millibar. One thousandth, right? Nope. BTW, 29.92" or 760 mm is assumed
standard sea level pressure in Hg . Mystery is why there are 1014 one
thousandths of a bar in a standard atmosphere.