Fasteners and Sealing
4 Hermetic sealing is crucial in preventing gas leakage in numerous operating environments and applications, especially those exposed to vacuums and high pressures. Christophe Boillat reports.
4 Des plafonds hermétiques sont essentiels pour prévenir les fuites de gaz dans de cadre de nombreux environnements et applications d’opération, en particulier ceux qui sont exposés aux conditions sous vide et aux hautes pressions. Rapport de Christophe Boillat.
4 Die hermetische Versiegelung ist bei der Verhinderung von Gaslecks in den verschiedensten Betriebsumgebungen und Anwendungen ausschlaggebend, vor allem wenn es um Vakuum und Hochdruck geht. Christophe Boillat berichtet.
Hermetically sealed connectors you can always rely on
S
evere conditions call for robust equipment you can depend upon at all times. In vacuum, pressurised or underwater conditions, there is a high risk of gas leakage into or out of
equipment via gaps, or diffusion through material. Leakage may lead to equipment failure or even bodily harm. High-quality airtight connectors and sealing barriers are thus prerequisites for reliable equipment performance and long-lasting protection. Fischer Connectors’ extensive range of
hermetically sealed connectors – like Fischer Core Series and Fischer UltiMate hermetic panel mounted connectors – are specially designed for vacuum applications and pressurised vessels, as well as for long-term immersion and exposure to strong jets. They all undergo a 100 per cent leak test to verify gas tightness, and their sealing is rated IP69K. Moreover, they have consistently demonstrated total reliability in even the most demanding environments.
Hermeticity in vacuum applications
A vacuum forms when gas molecules are removed from a given volume. Because air molecules act as barriers to other molecules or electrons, a vacuum has to be created in a chamber before
specific physical reactions can take place. A vacuum chamber is needed in, for example, equipment for analysing gas (mass spectrometers) or specimens (electron microscopes). Atmospheric’ pressure is equivalent to one bar, or 1000 millibars (1000mbar). Applications vary in their vacuum level requirements (10mbar for ‘low vacuum’, 1E-5mbar for ‘high vacuum’ or 1E-7mbar for ‘ultra-high vacuum’).
103 102 101 1
1000 Torr* - 0.1 Torr* 20 Torr - 0.1 Torr
10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 mbar Mass Spectrometer 1 Torr - 0.001 Torr 0.1 Torr - 0.0001 Torr 0.01 Torr - 10-10 760 Torr - 0.0001 Torr Low Vacuum * 1 Torr = 1. 33 mbar Medium Vacuum High Vacuum Ultra High Vacuum Torr Electron Microscope
Fig. 2. Vacuum levels (in mbar) required in low, medium, high and ultra-high vacuum applications. Mass spectrometers need 1E-4mbar to 1E-6mbar and electron microscopes 1E-6 mbar to 1E-8 mbar.
A minimal volume of gas will always pass through a connector on a vacuum chamber per unit of time. Hermeticity is vital to stop gas molecules entering the vacuum chamber, increasing the
Fig. 1. Connectors typically used in mass spectrometers need to be hermetic.
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