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A vacuum is a volume of space that is substansively empty of matter, so that gaseous pressure is much less than standard atmospheric pressure. The root of the word vacuum is the Latin adjective vacuus which means "empty," but space can never be perfectly empty. A perfect vacuum, known as "free space", with a gaseous pressure of absolute zero is a philosophical concept with no physical reality, not least because quantum theory predicts that no volume of space is perfectly empty in this way. Physicists often use the term "vacuum" slightly differently. They discuss ideal test results that would occur in a perfect vacuum, which they simply call "vacuum" in this context, and use the term partial vacuum to refer to the imperfect vacua realized in practice.
The quality of a vacuum is measured by how closely it approaches a perfect vacuum. The residual gas pressure is the primary indicator of quality, and it is most commonly measured in units of torr, even in metric contexts. Lower pressures indicate higher quality, although other variables must also be taken into account. Quantum mechanics sets limits on the best possible quality of vacuum. Outer space is a natural high quality vacuum, mostly of much higher quality than what can be created artificially with current technology. Low quality artificial vacuums have been used for suction for millenia.
Vacuum has been a common topic of philosophical debate since Ancient Greek times, but it was not studied empirically until the 17th century. Experimental techniques were developed following Evangelista Torricelli's theories of atmospheric pressure. Vacuum became a valuable industrial tool in the 20th century with the introduction of the light bulb and vacuum tube, and a wide array of vacuum technology has since become available. The recent development of human spaceflight has raised interest in the impact of vacuum on human health, and life forms in general.
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American Vacuum Society - Includes descriptions of the society's aims, online access to publications, administrative information, related news and information on conferences.
British Vacuum Council - The representative for Great Britain on the International Union for Vacuum Science, Technique and Application. As such it has a role to stimulate international collaboration in the fields of vacuum science, techniques and applications and related multi-disciplinary topics including solid-vacuum and other interfaces.
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Building your own Vacuum pump - How to build your own Vacuum pump
Meta Description: [ Step by Step instruction to build your own Vacuum pump system. ]
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Graphic Symbols for Vacuum Components - A handy indexed reference for examples of graphic symbols for components used in vacuum technology. Useful when constructing vacuum system schematics.
Meta Description: [ A handy indexed reference for examples of the Graphic Symbols for Important Components Used in Vacuum Technology. ]
How Thermoses (Vacuum Flasks) Work - For inquisitive people howstuffworks.com tells about how thermoses work. You can find there other vacuum-based devices as vacuum cleaner and television.
Meta Description: [ How can the same device keep hot things hot and cold things cold? Find out what goes on inside a Thermos! ]
International Union for Vacuum Science, Technique, and Applications - International meetings, conferences and workshops, educational opportunities, international awards and prizes.
Introduction to Vacuum Technology - Some basic principles for beginners.
Mc Nally Institute - An excellent resource with enormous amount of information for advanced vacuum users about pumps and seals (troubleshooting, specifications etc.)
Oxford Vacuum Science - Oxford Vacuum Science Ltd promotes good vacuum practice and understanding through the provision of training, design and consultancy services, and supply of bench-top thin film deposition research equipment.
Meta Description: [ Oxford Vacuum Science - the vacuum technology training and consultancy service
promoting good practice and understanding within the vacuum industry ]
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Pumps - The Engineering ToolBox - Different information on pumps and piping systems.
The Bell Jar - Site of vacuum technology and techniques for students and amateur scientists. Articles; links; experiments.
The Society of Vacuum Coaters - Education and information about vacuum coating. Technical conferences, educational programs, publications.
Meta Description: [ Society of Vacuum Coaters (SVC) covers industrial vacuum coating applications using physical vapor deposition (PVD) processes - evaporation, sputtering and ion plating through a conference, short courses & equipment exhibit. ]
Thermo Vacuum Generators - One of the worlds leading manufacturers of UHV components. On this web-site you will also find a lot of reference data on vacuum components (e.g. pumps, gauges, valves, flanges etc.) including their principles of operation.
Meta Description: [ VG Scienta, supplying vacuum components including, chambers and Fabrication, HV and UHV valves, feedthroughs, HV and UHV Fittings, HV and UHV Flanges, Gaskets, Viewports, Manipulation including Omniax, Linear and Rotary Drives, Pressure Measurement and gauges, Pumps and Traps, Bakeout heaters an... ]
Ultra High Vacuum - Describes what ultra high vacuum (UHV) is, why we need in it, how to get UHV.
Vacuüm Specials, The Netherlands - Specialised in the implementation, construction, manufacturing of components and subsystems and the realisation of complex projects on a turnkey basis regarding vacuum technology and cryogenic applications.
Meta Description: [ Vacuüm Specials B.V. - Vacuumtechniek - Cryotechniek ]
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Vacuum Technology and Vacuum Coating Forum - Discuss subjects about vacuum physics, vacuum and coating systems, evaporation coating and sputtering technology.
Meta Description: [ Information exchange on all phases of Vacuum Processing and Equipment including systems, evaporation, sputtering, measurement, melting, and related technologies. ]
Vacuum Technology Guide - Links to buyers guides, organizations, research, eZines and journals world-wide.
Meta Description: [ Webguide for Process, chemical engineering, measurement and control, microelectronics, vacuum, thin films, surfaces and material technology, physics, research, patents and standards. Associations, journals, eZines, marketplaces, buyers guides, and suppliers directories. ]
Vacuum Technology Lessons - Lessons and practical exercises on Vacuum Technology.
What is vacuum? - Nice web-site for beginners who want to know what vacuum is
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