What is meant by Cryogenic for control valves?

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THINKTANK control valves are used in many cryogenic application, what is meant by Cryogenic? General for used in liquefied gases, such as liquid nitrogen and liquid helium, the condition temperature usually achive minus 196 degrees Celcius(-320 degrees Fahrenheit). 

The cryogenic valves are kept in a natural closed position to keep cryogenic gasses or other medium secure and safely contained. A cryogenic valve is generally designed to react to high pressure which pushes the valve into the open position to allow the gas or other media to flow readily through. Such open flow will continue until the pressure again decreases, at which point it will swing back and become seal with a special metal seat bubble-tight shutoff to prevent any leaking. 

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