Page 23 - 2021 High-Reliability, Harsh Environment Connectivity eBook

Case Study #2: Hermetic, Shielded Connectivity Solutions for Precision and Reliability at CERN
At the European Organization for Nuclear Research (CERN), physicists and engineers use the world’s largest and most complex scientific instruments to study the fundamental particles that make up the basic constituents of matter. These instruments include purpose-built particle accelerators and detectors that demand precision and reliability at every stage. CERN relies on Fischer Connectors for essential connectivity needs in measurement tools, vacuum pumps, and chambers for monitoring and safety devices. For instance, Fischer Core Series hermetic solutions serve vacuum environments; Fischer Ultimate Series connectors support operating temperatures extending from -55°C to +135°C and provide 360° shielding to avoid electromagnetic interference; and Fischer FiberOptic Series connectors, which are rated IP67 when unmated and IP68 mated, deliver faultless optical performance and fast, secure data transmission in all weather conditions. Tests performed at CERN’s cryogenic facility (SM18) at 1.9 Kelvin proved that the Fischer FiberOptic Series connector can also operate at cryogenic temperatures as low as -180°C.
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» CERN’s Mechanical Measurements Laboratory called for interconnects that can meet the highest requirements for ruggedness and reliability. (Photo courtesy of CERN.)
4. Which sealing criteria are most relevant?
There are two main types of sealing: environmental sealing against dust, water, and other minerals and hermetic sealing against gasses. With environmental sealing, an interfacial seal protects the junction between the two connectors, keeping harmful particles away from the connection area. Mounting panel seals, seals for protecting the contact areas, and cable sealing also protect the connector and the connection. Environmental sealing materials include Viton, a fluoropolymer with low permeation and excellent chemical resistance, and ethylene propylene rubber (EPDM), which is commonly used for interfacial O-rings designed to be mated and unmated in low temperatures. Hermetically sealed connectors, on the other hand, are traditionally sealed with glass, ceramic inserts, or epoxy.
Environmental sealing efficacy is measured by ingress protection (IP) ratings, which quantify the level of protection against dust, dirt, and water. Look for IP68 ratings or above for truly waterproof connectors. While most IP designations are defined by specific conditions, IP68 ratings are defined differently by each manufacturer, so it is important to check exactly what the IP rating means and whether the rating is for the connectors in a mated or unmated condition. Alternately, hermetic sealing efficacy is expressed by leak rates in terms of cubic centimeters atmosphere per second (e.g., 1E-9 atm-cc/sec or 0.000000001).
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