Editing Vacuum flask (section)

== Research and industry ==
{{see also|Cryogenic storage dewar}}
[[File:Dewargefäß Deutsches Museum.jpg|thumb|upright|Laboratory Dewar flask, [[Deutsches Museum]], Munich]]
[[File:Liquid nitrogen tank.JPG|thumb|upright|left|A [[cryogenic storage dewar]] of [[liquid nitrogen]], used to supply a [[Cryopreservation|cryogenic freezer]]]]

In laboratories and industry, vacuum flasks are often used to hold liquefied gases (commonly liquid nitrogen with a boiling point of 77 K) for flash freezing, sample preparation and other processes where creating or maintaining an extreme low temperature is desired.  Larger vacuum flasks store liquids that become gaseous at well below ambient temperature, such as [[oxygen]] and [[nitrogen]]; in this case the leakage of heat into the extremely cold interior of the bottle results in a slow boiling-off of the liquid so that a narrow unstoppered opening, or a stoppered opening protected by a [[pressure relief valve]], is necessary to prevent [[pressure]] from building up and eventually shattering the flask. The insulation of the vacuum flask results in a very slow "boil" and thus the contents remain liquid for long periods without [[refrigeration]] equipment.

Vacuum flasks have been used to house [[Weston cell|standard cell]]s and ovenized [[Zener diode]]s, along with their printed circuit board, in precision voltage-regulating devices used as electrical standards. The flask helped with controlling the Zener temperature over a long time span and was used to reduce variations of the output voltage of the Zener standard owing to temperature fluctuation to within a few parts per million.

One notable use was by Guildline Instruments, of Canada, in their Transvolt, model 9154B, saturated standard cell, which is an electrical voltage standard. Here a silvered vacuum flask was encased in foam insulation and, using a large glass vacuum plug, held the saturated cell. The output of the device was 1.018 volts and was held to within a few parts per million.

The principle of the vacuum flask makes it ideal for storing certain types of rocket fuel, and [[NASA]] used it extensively in the propellant tanks of the Saturn launch vehicles in the 1960s and 1970s.<ref>Cortright, Edgar. "Apollo Expeditions to the Moon." Official NASA publications. 1975.</ref>

The design and shape of the Dewar flask was used as a model for [[optical]] experiments based on the idea that the shape of the two compartments with the space in between is similar to the way the light hits the eye.<ref>{{cite journal | last1 = Haynes | first1 = John | last2 = Scott | first2 = Jesse | year = 1948 | title = A Method for Silvering a Dewar Flask for Optical Experiments | journal = Science | volume = 107 | issue = 2777| page = 301 | doi=10.1126/science.107.2777.301| pmid = 17791184 | bibcode = 1948Sci...107..301H }}</ref> The vacuum flask has also been part of experiments using it as the capacitor of different chemicals in order to keep them at a consistent temperature.<ref>{{cite journal | last1 = Elliot | first1 = Willard | year = 1970 | title = A Spectrophotometric Dewar Flask with Integral Light Shield | journal = Public Health Reports | volume = 85 | issue = 3| pages = 276–279 | doi=10.2307/4593845| pmc = 2031665 | pmid=4984895| jstor = 4593845 }}</ref>

The industrial Dewar flask is the base for a device used to passively insulate medical shipments.<ref>{{cite magazine|url=https://www.wired.com/2013/06/how-to-design-a-life-saving-device|title=This Revolutionary Cooler Could Save Millions of Lives|date=18 June 2013|magazine=WIRED|last1=Stinson|first1=Liz}}</ref><ref>{{cite web|url=http://www.fiercevaccines.com/story/gates-backed-device-extends-cold-chain-rural-areas/2013-07-18|archive-url=https://web.archive.org/web/20130721200830/http://www.fiercevaccines.com/story/gates-backed-device-extends-cold-chain-rural-areas/2013-07-18|url-status=usurped|archive-date=July 21, 2013|title=Gates-backed device extends cold chain to rural areas|work=FierceVaccines}}</ref> Most vaccines are sensitive to heat<ref>{{cite journal|title=Frequent exposure to suboptimal temperatures in vaccine cold-chain system in India: results of temperature monitoring in 10 states| pmc=3845272 | pmid=24347729|doi=10.2471/BLT.13.119974|volume=91| issue=12 |year=2013|pages=906–13|vauthors= Murhekar MV, Dutta S, Kapoor AN, Bitragunta S, Dodum R, Ghosh P, Swamy KK, Mukhopadhyay K, Ningombam S, Parmar K, Ravishankar D, Singh B, Singh V, Sisodiya R, Subramanian R, Takum T|journal=Bulletin of the World Health Organization}}</ref><ref>{{cite journal|title=Evaluation of the Cold-Chain for Oral Polio Vaccine in a Rural District of India|pmc=1802111| pmid=17236617|volume=122|issue=1|year=2007|pages=112–21|vauthors= Samant Y, Lanjewar H, Parker D, Block L, Tomar GS, Stein B|doi=10.1177/003335490712200116|journal=Public Health Reports}}</ref> and require a [[cold chain]] system to keep them at stable, near freezing temperatures. The Arktek device uses eight one-litre ice blocks to hold vaccines at under 10 [[Celsius|°C]].<ref>{{cite press release|url=http://arktek.org/news-detail.html|title=Arktek Awarded Prequalified PQS Status by WHO|date=2015-04-26|publisher=ARKTEK|access-date=2016-02-25|archive-date=2016-03-11|archive-url=https://web.archive.org/web/20160311052133/http://arktek.org/news-detail.html|url-status=dead}}</ref>

In the oil and gas industry, Dewar flasks are used to insulate the electronic components in [[Wireline Logging|wireline logging]] tools.<ref>{{Cite web|title=Thermal Management of Downhole Oil and Gas Logging Sensors for HTHP Applications Using Nanoporous Materials|url=https://www.researchgate.net/publication/267492247|access-date=2021-02-11|website=ResearchGate|language=en}}</ref> Conventional logging tools (rated to 350&nbsp;°F) are upgraded to high-temperature specifications by installing all sensitive electronic components in a Dewar flask.<ref>Baird, Tom, et al. "High-pressure, high-temperature well logging, perforating and testing." ''Oilfield Review'' 5.2/3 (1993): 15-32.</ref>