Vacuum flask
A vacuum flask (also known as a Dewar flask, Dewar bottle or thermos) is an
Vacuum flasks are used domestically to keep contents inside hot or cold for extended periods of time. They are also used for thermal cooking. Vacuum flasks are also used for many purposes in industry.
History
The vacuum flask was designed and invented by Scottish scientist
Dewar's design was quickly transformed into a commercial item in 1904 as two German
The term "thermos" became a household name for vacuum flasks in general. As of 2023[update], Thermos and THERMOS remains a
Design
The vacuum flask consists of two vessels, one placed within the other and joined at the neck. The gap between the two vessels is partially evacuated of air, creating a partial-
Extremely large or long vacuum flasks sometimes cannot fully support the inner flask from the neck alone, so additional support is provided by spacers between the interior and exterior shell. These spacers act as a thermal bridge and partially reduce the insulating properties of the flask around the area where the spacer contacts the interior surface.
Several technological applications, such as
Other improvements to the vacuum flask include the vapour-cooled radiation shield and the vapour-cooled neck,[11] both of which help to reduce evaporation from the flask.
Research and industry
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
Vacuum flasks have been used to house standard cells and ovenized Zener diodes, 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.[12]
The design and shape of the Dewar flask was used as a model for
The industrial Dewar flask is the base for a device used to passively insulate medical shipments.[15][16] Most vaccines are sensitive to heat[17][18] 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 °C.[19]
In the oil and gas industry, Dewar flasks are used to insulate the electronic components in
Safety
Vacuum flasks are at risk of implosion hazard, and glass vessels under vacuum, in particular, may shatter unexpectedly. Chips, scratches or cracks can be a starting point for dangerous vessel failure, especially when the vessel temperature changes rapidly (when hot or cold liquid is added). Proper preparation of the Dewar vacuum flask by tempering prior to use is advised to maintain and optimize the functioning of the unit. Glass vacuum flasks are usually fitted into a metal base with the cylinder contained in or coated with mesh, aluminum or plastic to aid in handling, protect it from physical damage, and contain fragments should they break.[citation needed]
In addition, cryogenic storage dewars are usually pressurized, and they may explode if
Thermal expansion has to be taken into account when engineering a vacuum flask. The outer and inner walls are exposed to different temperatures and will expand at different rates. The vacuum flask can rupture due to the differential in thermal expansion between the outer and inner walls. Expansion joints are commonly used in tubular vacuum flasks to avoid rupture and maintain vacuum integrity.
See also
- Thermal cooking
- Hermetic seal
- James Webb Space Telescope sunshield (The layers of its thermal shield use a vacuum barrier to provide insulation.)
- Tervis Tumbler
- Yeti Holdings
References
- ^ doi:10.1063/1.881490.
- ^ a b "Our History". Thermos. 2011. Archived from the original on 28 May 2013. Retrieved 31 March 2013.
- ^ "James Dewar, the man who invented the thermos flask". BBC History. 2 April 2013. Archived from the original on 4 May 2014.
- ^ Frank A. J. L. James. "Dewar, James - BRITISH CHEMIST AND PHYSICIST". Advameg, Inc. Retrieved 30 December 2010.
- ^ "US Registration Number: 67002". Trademark Search, United States Patent and Trademark Office. Retrieved 2023-04-24.
"Thermos" LIVE For:DOUBLE-WALLED GLASS VESSELS WITH VACUUM BETWEEN THE WALLS
- ^ "US Registration Number: 176064". Trademark Search, United States Patent and Trademark Office. Retrieved 2023-04-24.
"THERMOS" LIVE For:Temperature-Retaining Vessels
- ^ "US Registration Number: 229816". Trademark Search, United States Patent and Trademark Office. Retrieved 2023-04-24.
"THERMOS" LIVE For:BOTTLES, JARS, DECANTERS, CARAFES, [ HIP FLASKS,] COFFEEPOTS, TEAPOTS, JUGS, LUNCH KITS, LUNCH BOXES, CARRYING CASES FOR BOTTLES [, AND DOUBLE-WALLED VACUUM FILLERS OF GLASS USED IN BOTTLES, JARS, CARAFES, JUGS, DECANTERS, COFFEEPOTS, AND TEA-POTS]
- JSTOR 795968.
- ^ King-Seeley Thermos Co. v. Aladdin Industries, Incorporated, 321 F.2nd 577 (United States Court of Appeals Second Circuit 1963-07-11).
- ^ King-Seeley Thermos Co. v. Aladdin Industries, Incorporated, 320 F.Supp 1156 (United States Court of Appeals Second Circuit 1970-12-30).
- ^ "History of Cryogenics: A Cryo Central resource from the CSA". Cryogenicsociety.org. 2008-04-18. Archived from the original on 2018-03-27. Retrieved 2012-11-29.
- ^ Cortright, Edgar. "Apollo Expeditions to the Moon." Official NASA publications. 1975.
- PMID 17791184.
- PMID 4984895.
- ^ Stinson, Liz (18 June 2013). "This Revolutionary Cooler Could Save Millions of Lives". WIRED.
- ^ "Gates-backed device extends cold chain to rural areas". FierceVaccines.
- PMID 24347729.
- PMID 17236617.
- ^ "Arktek Awarded Prequalified PQS Status by WHO" (Press release). ARKTEK. 2015-04-26. Archived from the original on 2016-03-11. Retrieved 2016-02-25.
- ^ "Thermal Management of Downhole Oil and Gas Logging Sensors for HTHP Applications Using Nanoporous Materials". ResearchGate. Retrieved 2021-02-11.
- ^ Baird, Tom, et al. "High-pressure, high-temperature well logging, perforating and testing." Oilfield Review 5.2/3 (1993): 15-32.
Further reading
- Burger, R., U.S. patent 872,795, "Double walled vessel with a space for a vacuum between the walls," December 3, 1907.
- Sella, Andrea (August 2008). "Dewar's Flask". Chemistry World: 75. Retrieved 2008-08-30.
External links
- Media related to Vacuum flasks at Wikimedia Commons