Adams, Colin Center for Space and Engineering Research, Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.
Last reviewed:July 2016
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- McLeod gage
- Mechanical devices
- Pirani gage
- Ionization gages
- Knudsen gage
- Residual gas analyzer
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The assessment of gas pressures of lesser magnitude than standard sea-level atmospheric pressure. Vacuum measurement is important in many industries, including electronics manufacturing, metallurgy, and the pharmaceutical industry, and in the physical and life sciences. The most common unit of pressure in vacuum measurement is the torr, which is defined to be 1/760 of standard atmospheric pressure, and is approximately the pressure differential between two points separated vertically by 1 mm in a column of mercury (1 mmHg). Other units include the pascal (Pa; 1 pascal is equal to 1 newton per square meter, and 1 torr = 133.322 Pa), the atmosphere (1 atmosphere = 101,325 Pa), the bar (1 bar = 100,000 Pa), and the pound per square inch (psi; 14.696 psi = 1 atmosphere).
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