Editing Cryogenics (section)

== Industrial applications ==
[[File:Liquid Nitrogen Tank.JPG|thumb|A medium-sized [[Cryogenic storage dewar|dewar]] is being filled with liquid nitrogen by a larger cryogenic storage tank.]]
{{Multiple image
| total_width       = 330px
| image1            = Cryogenic carbon steel socket weld globe valve.jpg
| caption1          = Catalogue image of a cryogenic valve
| image2            = Iced nitrogen valves.jpg
| caption2          = Cryogenic valves in situ, heavily frozen from [[Deposition (phase transition)|condensed]] atmospheric [[humidity]]
}}
{{Further|Low-temperature technology timeline}}
[[Liquefied gas]]es, such as [[liquid nitrogen]] and [[liquid helium]], are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the [[boiling point|lowest attainable temperatures]] to be reached.

These liquids may be stored in [[Dewar flask]]s, which are double-walled containers with a high vacuum between the walls to reduce heat transfer into the liquid. Typical laboratory Dewar flasks are spherical, made of glass and protected in a metal outer container. Dewar flasks for extremely cold liquids such as liquid helium have another double-walled container filled with liquid nitrogen. Dewar flasks are named after their inventor, [[James Dewar]], the man who first liquefied [[hydrogen]]. [[Thermos]] bottles are smaller [[vacuum flask]]s fitted in a protective casing.

Cryogenic barcode labels are used to mark Dewar flasks containing these liquids, and will not frost over down to −195 degrees Celsius.<ref>{{cite web|last1=Thermal|first1=Timmy|title=Cryogenic Labels|url=http://www.midcomdata.com/cryogenic-labels/|website=MidcomData|access-date=11 August 2014}}</ref>

Cryogenic transfer pumps are the pumps used on [[LNG pier]]s to transfer [[liquefied natural gas]] from [[LNG carrier]]s to [[LNG storage tank|LNG storage tanks]], as are cryogenic valves.

=== Cryogenic processing ===
The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Based on this theory of [[cryogenic hardening]], the commercial [[cryogenic processor|cryogenic processing]] industry was founded in 1966 by Bill and Ed Busch. With a background in the [[heat treating]] industry, the Busch brothers founded a company in [[Detroit]] called CryoTech in 1966.<ref>{{cite book|last1=Gantz|first1=Carroll|title=Refrigeration: A History|date=2015|publisher=McFarland & Company, Inc.|location=Jefferson, North Carolina|isbn=978-0-7864-7687-9|page=227|url=https://books.google.com/books?id=0UgjCgAAQBAJ&q=ed+busch+cryotech&pg=PA227}}</ref> Busch originally experimented with the possibility of increasing the life of metal tools to anywhere between 200% and 400% of the original life expectancy using [[cryogenic tempering]] instead of [[heat treating]].<ref>{{Cite book |last=Zohuri |first=Bahman |title=Physics of Cryogenics: An Ultralow Temperature Phenomenon |publisher=Elsevier |year=2018 |isbn=978-0-12-814519-7 |pages=34 |chapter=Chapter 1 - Cryogenic Technologies |doi=10.1016/C2017-0-01796-2}}</ref> This evolved in the late 1990s into the treatment of other parts.

Cryogens, such as liquid [[nitrogen]], are further used for specialty chilling and freezing applications. Some chemical reactions, like those used to produce the active ingredients for the popular [[statin]] drugs, must occur at low temperatures of approximately {{convert|−100|°C|°F}}. Special cryogenic [[chemical reactor]]s are used to remove reaction heat and provide a low temperature environment. The freezing of foods and biotechnology products, like [[vaccine]]s, requires nitrogen in blast freezing or immersion freezing systems. Certain soft or elastic materials become hard and [[brittle]] at very low temperatures, which makes cryogenic [[mill (grinding)|milling]] ([[cryomilling]]) an option for some materials that cannot easily be milled at higher temperatures.

Cryogenic processing is not a substitute for heat treatment, but rather an extension of the heating–quenching–tempering cycle. Normally, when an item is quenched, the final temperature is ambient. The only reason for this is that most heat treaters do not have cooling equipment. There is nothing metallurgically significant about ambient temperature. The cryogenic process continues this action from ambient temperature down to {{convert|-320|°F|°R K °C|0}}.
In most instances the cryogenic cycle is followed by a heat tempering procedure. As all alloys do not have the same chemical constituents, the tempering procedure varies according to the material's chemical composition, thermal history and/or a tool's particular service application.

The entire process takes 3–4 days.

=== Fuels ===
Another use of cryogenics is [[cryogenic fuel]]s for rockets with [[liquid hydrogen]] as the most widely used example, with [[liquid methane]] starting to become more prevalent in recent years. [[Liquid oxygen]] (LOX) is even more widely used but as an [[oxidizer]], not a fuel. [[NASA]]'s workhorse [[Space Shuttle]] used cryogenic hydrogen/oxygen propellant as its primary means of getting into [[orbit]]. LOX is also widely used with [[RP-1]] kerosene, a non-cryogenic hydrocarbon, such as in the rockets built for the [[Soviet space program]] by [[Sergei Korolev]].

Russian aircraft manufacturer [[Tupolev]] developed a version of its popular design [[Tu-154]] with a cryogenic fuel system, known as the [[Tu-155]]. The plane uses a fuel referred to as [[liquefied natural gas]] or LNG, and made its first flight in 1989.<ref>{{Cite web |title=Tu-155 / Tu-156 |url=https://www.globalsecurity.org/military/world/russia/tu-155.htm |access-date=2023-11-27 |website=www.globalsecurity.org}}</ref>