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Evacuation time, vacuum pump sizing |

Pascal (Pa)
Pa=N/m² : The Pascal (Pa) is the SI unit, 1 Bar = 10E5.Pa = 101 kPa = 0.1 MPa
A pressure of 1 Pa applied on a surface A=1m² generates a force F=1N (1N=1 kg.m.s-²). 1 Torr = 4/3 mbar, =133.3 Pa 1 standard atmosphere, 1 atm. = 760 Torr = 1013 mbar
1 technical atmosphere, 1 At = 1kp/cm² = 981 mbar
more about vacuum units (Pascal, Bar) in Wikipedia Relative vacuum in %:
Vac% = (Po-P)/Po 300 mbarA => (1013-300)/1013= 70% vacuum or P = Po-(Po.V%), 30% of vacuum in Torr => 760-(760 x 0.3) = 532 Torr |
atm. pressure (1 Atm.)
= 1.013 bar = 1013 millibars (mbar) = 101325 Pascal (Pa) = 101 kPa = 760 Millimeter Quecksilbersäule (mmHgA) = 760 Torr (1 Torr = 1 mm HgA) = 29.92 inches of mercury absolute (inHgA), = 14.7 pounds per square inch absolute (lb/in², PSIA) Atmospheric pressure is often measured with a mercury barometer, and a height of approximately 760 millimetres (30 in) of mercury is often used to illustrate (and measure) atmospheric pressure. However, since mercury is not a substance that humans commonly come in contact with, water often provides a more intuitive way to visualize the pressure of one atmosphere: One atmosphere (101 kPa or 14.7 psi) is the amount of pressure that can lift water approximately 10.3 m (34 ft). 10.3 m (34 ft) is also the maximum height to which a column of water can be drawn up by suction with a vacuum. |