Metal Thermo Flasks: How Do They Keep Drinks Hot?

[sven56]

A question about metal thermo flasks, or metal vacuum flasks if you prefer.

I understand the principle of thermo/vacuum flasks.
Just to proofed that I read up before posting this question :-)
http://en.wikipedia.org/wiki/Vacuum_flask

But today I had a look at on of those new-isch thermo flask contraptions totally made out of stainless metal.

Its one stainless steel flask inside other with a vacuum between. But there is a stainless steel bridge connecting those two bottles at the opening. Since metal is such a good heat transfer medium – how can my drink stay boiling hot for hours?

 

[mgb_phys]

Stainless isn't a very good conductor and the neck is only joined by a very thin ring of metal. They aren't as good insulators as a glass flask but are better than nothing.
If you build cryogenic systems it is frustrating how poor some metals are as conductors of heat when you are trying to get that last 1degree temperature difference!

 

[sven56]

thanks for your prompt replay.

i was a bit worried that i missed some essential feature of this stainless steel thermo flasks- makes me feel better that i didn't. Other than that stainless steel is a bad conductor.

Thanks!