Thermos advice

[AdamW]

Bit of an odd one, but being manly types who enjoy hot beverages I'm sure someone can supply an answer:

How long does a thermos keep stuff hot for? For instance, if I poured some piping hot homemade soup into one at say, 7am, would it still be nicely hot 5 hours later at 12?

I have a very nice insulated mug that keeps coffee hot for a good 2 hours or so, but I've never had a full-on thermos flask. Just thinking about whether or not it is worth buying one to eat homemade soup out of, with my lunch.

Assume I pour it into the flask at a good simmer.

EDIT: I was thinking carrot and coriander by the way, so not very much fat in it (presumably cream soups keep their heat much longer... Erm... BEER! STEAK! MORE POWER UGH UGH UGH! (sorry, was sounding a bit girly)

 

[oilman]

I found Asds's stainless flasks work well, you'll still burn your tongue at lunch time.

I should think watery soup keeps hotter longer, as the specific heat is higher

 

[Richardp]

Its going to be affected by outside temperature, humidity, altitude, phase of the moon etc

 

[johnny_t]

When I was at junior school my Mum used to do me a Thermos flask full of Ravioli in the morning, and it was still piping hot at lunchtime.

I think your hot soup will stay that way for about 24 hours, though have nothing to back it up.

 

[Thermo]

thought we were talking about me for a second! How do they know to keep hot things hot and cold things cold?????????????

 

[andy]

thought we were talking about me for a second!

so did i. confusing titles.

 

[Richardp]

Well! if Thermo dosnt know what chance the rest of us

 

[petewood]

I take a stainless steel thermos to work most days during the winter with homemade soup and it's still very hot at lunchtime.

 

[securespark]

How do they know to keep hot things hot and cold things cold?

Well, Thermo, it's like this. The insulation allows a minimum of heat transfer, regardless of whether the substance is hot or cold to start with. This means that cold things stay cold, and hot things hot.

 

[AdamW]

That settles it then. I'll be buying a thermos flask next time I'm in the supermarket/millets.

I shall be the envy of all the other engineers as I sup my piping hot soup whilst they nibble their room-temperature sandwiches.

 

[oilman]

You will be, until you spill it over your desk, and dribble it down your shirt, then you will be a joke.

Our bread maker gets used all the time, sandwiches are great, even have them for Sunday lunch (really).

 

[securespark]

sandwiches are great, even have them for Sunday lunch (really).

I suppose you could have the Sunday equivalent of a breakfast barm......roast cow, spuds, veg, yorks, gravy and horsesauce in a butty!!

 

[TexMex]

I have a Stanley Stainless steel flask that I bought when they were first brought out. Recently my wife made up a flask of coffee for me. As the job got called off I didn't need it after all. A couple of days later, upon opening it, the coffee was still too hot to drink, and didn't taste bad either.

Apparently the secret is to fill with boiling water first and allow to stand for five minutes. This heats up all the metal that would otherwise conduct some energy out of your beverage.

Also fill the flask right up. As the liquid cools, it will contract. This will cause a vaccum to be developed at the top (the poorest insulated part of the system). The vacuum then reduces any further heat loss through this path. If, however, you have air in the system, this vacuum will be less perfect.

Finally, for absolute optimal results, keep the flask upright. Otherwise the afore mentioned vacuum will not be against the conductive stopper. If all you're after is about 5 hours though, you needn't worry about this last point.

 

[Thermo]

Well, Thermo, it's like this. The insulation allows a minimum of heat transfer, regardless of whether the substance is hot or cold to start with. This means that cold things stay cold, and hot things hot.

oh so its not got a little computer inside then?

 

[securespark]

Thort of, yeth.