Talk:Vacuum flask

A good Thermos resource link
Thermosonline.com seems to cover a wide range of Thermos items and articles and would be a good link resource for readers.65.15.55.107 15:12, 27 March 2006 (UTC)

Perfect insulation?
I removed the following paragraph
 * In theory, a vacuum flask could therefore approach arbitrarily close to perfectly insulating fh, for example keeping a cup of coffee hot for a decade. In practice, however, the inside wall of the container must meet the outside wall, usually at the mouth of the container, at which point slight heat conduction does occur between the inside and outside walls (the vacuum being in between).

since I think it is misleading. While conduction is the primary route of heat loss for most materials, radiation is also important. I can't imagine decade-scale insulation, since heat would necessarily be lost through radiation. Thoughts? --TeaDrinker 19:53, 13 November 2006 (UTC)
 * Sounds like you were correct to remove it. 62.220.237.74 (talk) 21:19, 22 November 2007 (UTC)
 * Yes, it's always important to get "consensus" from anonymous sources. That's how science is done in the contemporary political climate. Phhhht! &mdash;QuicksilverT @ 16:11, 2 April 2009 (UTC

Radiation is a factor but is minuscule because of the shiny coatings. Decades, no, but it does transfer more heat from the conduction at the neck than anyway else.

Vacuum flask was invented by Adolf Ferdinand Weinhold
Already in 1881 Adolf Ferdinand Weinhold published a book in which he described a vacuum flask, similar to the "Dewar flask", for use in the laboratory. Only 10 years later did Dewar invent the flask for a second time. Should be mentioned. --129.13.186.4 (talk) 14:27, 26 January 2008 (UTC)

Surface Area
Should the low surface-area:volume ratio of the inner flask be mentioned? (i.e. that it minimizes heat transfer) —Preceding unsigned comment added by LaFoiblesse (talk • contribs) 20:49, 14 February 2008 (UTC)
 * No, surface-area:volume ratio is not relevant. The flask of any shape inside that has double walls with nearly vacuum in between will be therefore still a Dewar flask. There are different ways to reduce heat dissipation; one of them (double walls with vacuum in between) is the topic of this article. Other strategies (reducing of the surface-area:volume ratio, additional heating/cooling of the outer walls, etc.) can be used, but they are not the topic of this article. Adams13 (talk) 12:32, 23 January 2013 (UTC)

Could anyone please supply a photo for the domestic variant? :)
I can only see the industrial variant for liquid oxygen or nitrogen, which -- no doubt -- would not have much importance in everyday life. :) -andy


 * You mean like making liquid nitrogen ice cream?


 * I saw them "cook" with liquid nitrogen on Iron Chef. Perhaps a picture of that, if we can obtain the rights?


 * The most popular everyday domestic use of liquid nitrogen, I believe, is freezing random objects and smashing them.


 * Let me know what sort of photo of domestic use you want, and I'll take one when I get my dewar in a couple weeks. Minetruly (talk) 01:28, 10 August 2010 (UTC)

92.230.13.101 (talk) 22:24, 28 October 2008 (UTC)

Start-class
Not sure why this article is labelled start-class. I looked it up and found all the information I wanted (and more). --Martin Wyatt 20:16, 19 March 2011 (UTC) — Preceding unsigned comment added by MWLittleGuy (talk • contribs)

History is wrong in article
and German Reinhold Burger built then Vacuum flasks after the ideas of chemist Adolf Ferdinand Weinhold 188.96.181.140 (talk) 22:11, 7 May 2013 (UTC)
 * German chemist Adolf Ferdinand Weinhold invented Vacuum flask.
 * Physikalische Demonstrationen. Anleitung zum Experimentieren im Unterricht an Gymnasien, Realschulen und Gewerbschulen. Quandt & Händel, Leipzig 1881, S. 479, Abb. 362 (PDF-Datei auf Wikimedia Commons). 188.96.181.140 (talk) 21:47, 7 May 2013 (UTC)
 * welt.de:Deutsche Erfindungen, die die Welt veränderten (German) 188.96.181.140 (talk) 21:49, 7 May 2013 (UTC)
 * I looked at the German wikipedia article on Weinhold for a reference, instead they give an earlier date for Dewar, with reference: Dewar had used a vacuum vessel as an insulator in calorimetrical experiments in 1874, at the University of Edinburgh. This date came out after a claim of Louis Paul Cailletet who thought he antedated Dewar in this invention. . I don't know the significance of the 1892 date in this context, so I leave it to someone else to correct the article...Ssscienccce (talk) 22:14, 6 September 2013 (UTC)

Wrong Units in Eq. 3
It seems that the mass term has been dropped from Eq. 2 to 3. The units don't work out for Eq. 3. I think Eq. 2 should have had 1/m since both entrophy and enthalpy contain 1/m. Sameb112 (talk) 18:37, 4 October 2013 (UTC)

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How sure are we that this is all true?
There is something VERY odd going on here.

Check out this graph of thermal conductivity of air versus pressure: HERE

The generally accepted value for the thermal conductivity of air at 1 atmosphere (760 torr) is 0.026 - so the graph remains flat off to the right, as you'd expect.

So the conductivity of air only starts to decrease at around 10 torr.

So for conductivity to be what makes a vacuum flask work - the pressure would have to be pumped down to well below 1% of atmospheric pressure!! That's one hell of a good vacuum!

But if it is somehow evacuated to that degree - then that would mean that the flask is being acted on by at least 99% of 15psi. So pretty much there must be 15lbs on every square inch of that container - inside and out! It should be crushed flat!

It seems to me that it's more probable that the silvering on the inner vessel - combined with the elimination of convection currents by having a double-walled container is the only thing that has any effect - I bet that if you drilled a small hole in the outer container to even out the air pressure - then the flask would continue to work perfectly.

Sadly - I can't find data on the actual pressure they put these containers under - and I don't own a thermos flask to try it with.

But (admittedly on the basis of OR) I call bullshit!

SteveBaker (talk) 18:03, 1 February 2019 (UTC)

Requested move 20 November 2019

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion. 

The result of the move request was: Not moved (closed by non-admin page mover) Wug·a·po·des​ 03:31, 7 December 2019 (UTC)

Vacuum flask → Thermos – "Thermos" is a generic term, and Google Ngrams shows a significant amount more hits for "thermos", making it a WP:COMMONNAME. ZXCVBNM (TALK) 17:49, 20 November 2019 (UTC) —Relisting. Sceptre (talk) 21:17, 27 November 2019 (UTC)
 * Oppose The term "thermos" only seems to be in general use for food/beverage, whereas "Dewar" is more common for science (and also "vacuum flask" there). So I don't think "thermos" is the best name for the single article on all these things. Best to stay with the generic description of all of them than a genericized trademark for one subset. DMacks (talk) 06:32, 21 November 2019 (UTC)
 * Opposealso oppose, WPcommonname seems to be negated with WP:PRECISION, as thermos is 1: a brand and 2: a LLC, which makes "thermos" hugely ambiguous as a name. Also, the name violates neutrality, as(again), thermos is a brand/llc. Even if not legally protected.73.243.250.179 (talk) 05:16, 28 November 2019 (UTC) Additionally, a google search of "-flask 'thermos' -wikipedia" gives ~45.8million results and ~54.6 million for "-flask 'thermos' -wikipedia", which means that there is no real reason to switch for a less technical, be it more common, title.73.243.250.179 (talk) 05:25, 28 November 2019 (UTC) And when looking for n2 (l), ive never saw thermos, just dewar73.243.250.179 (talk) 05:31, 28 November 2019 (UTC)
 * Just noting we do have a separate Thermos L.L.C. article, so "thermos" is ambiguous, though I suspect that the object would be the WP:PRIMARYTOPIC vs the company meaning of this term. DMacks (talk) 06:04, 28 November 2019 (UTC)


 * Oppose Per above comments. I think thermos should really be a disambiguation page. Unlike other generalized trademarks, the originally company (Thermos LLC) is still very much active and is the main producer in the produce category. This would make it more like Zamboni (links to disambiguation) or even Kleenex (links to brand). Per DMacks's comment, the name thermos is only used for beverages and not in science or other fields. – Brandon XLF  (talk) 06:22, 29 November 2019 (UTC)
 * Oppose. This is absolutely not a generic term, even if some people don't know that and try to use it as one. It's a registered trademark in multiple jurisdictions. Something is not a genericized trademark until a court of competent jurisdiction declares it to be so, as happened with asprin but not Band-Aid or Kool-Aid, despite the frequency with which people try to genericize them.  — SMcCandlish ☏ ¢ 😼  18:07, 29 November 2019 (UTC)


 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Move discussion in progress
There is a move discussion in progress on Talk:Thermos (disambiguation) which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 20:00, 7 December 2019 (UTC)

Uno Vac
Does anyone have any information on Uno Vac bottles? TheMaggster (talk) 21:34, 10 June 2023 (UTC)