Pressure is critical. - critical in which way?

Regarding the "suction flask on tour"-theory: Maybe some more stable flasks will handle it no prob - but think about why submarines can't go deeper than their specified diving depth?

And, Hypo: how did you come to the thought Luminescent would've meant 30"Hg?? quote from Rhodium's post:

The weight of the earth's atmosphere pressing on each unit of surface constitutes atmospheric pressure, which is 14.7 psi (101,300 Pa or 0.1013 MPa) at sea level. This pressure is called one atmosphere. In other commonly used units, one atmosphere equals 29.92 inches of mercury (in. Hg), 760 mm Hg (or 760 torr), and 1.013 bar(1 bar=0.1 MPa)....according to this data, the 30 inches Hg you assumed would equal 1.00267 atmospheres (i.e. overpressure)? In a drying oven? (May I quote you: "think before posting, please!"

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And another thing that puzzles me:

I own an old vacuum gauge measuring from 0 to 1 "kp/cm2". Now the question: how to convert that to torr/psi/mbar/whatever? Hypo already clarified to me that this means kilopond/sq.cm (or kg/cm2) - can I assume that under normal atmosherical pressure (760 torr), the air puts pressure on a surface with the force of 1 kg per cm2? Or is bar=force/cm2 and 760torr therefore slightly more than 1kg/cm2 ?

TIA (thanks in advance) for any help!