Discussion about Flask with Tea found in treasury sump.

[ZombieCake]

Whoever leaves teabags in the flask needs a lesson on how to make decent flask tea!

Suppose that could be the subject of a workshop at the next Hidden Earth.  Surely leaving the tea bag in the flask would render it rather stewy?  Would a more fuller flavour tea such as Assam be better than say a lighter green tea in an adverse environment?

 

[alastairgott]

technical

Suppose that could be the subject of a workshop at the next Hidden Earth.

Cracking idea, we'll have to write it up in the next journal for the Tea and Scone Group.

 

[pwhole]

There's probably a fat Cave Science research grant available too, if someone with too much time on their hands could write up a precis.

If you drew some big sad eyes on the flask, Pixar could make the movie...

 

[Maj]

Hi Pitlamp,
Yes fully aware of the difference between a vacuum and atmospheric pressure. But the point I was making was that since I would have expected a s/steel flask that had been subjected to severe pressure at depth, would have had its outer skin collapsed in towards the inner skin (particularly if the outer skin had lost some of its structural integrity by the odd dent or three). Suggesting therefore that regardless of whether the flask was full or not (with a non compressible fluid), the condition of the outer skin would perhaps be indicative of whether the flask had been subjected to a high pressure. And yes if the flask was empty (compressible medium at 1 bar) then the inner skin may also collapse too.

I've often taken flasks through sumps ........ But I always ensure it's brim full with tea on entry and I refill it to the brim with sump water before submerging again, to prevent collapse.

I'm now curious.
What then prevents the outer skin collapsing towards the inner skin when subjected to the pressure applied by the depth of the sump + 1 bar since there is a vacuum inside the outer skin?

Maj.

 

[Chocolate fireguard]

I think Maj has to be right.

The (partial but decent) vacuum between inner and outer means that the outer can receive no support from the inner, so it doesn't matter if the flask is empty, full of liquid or somewhere between.

 

[Nigelh]

This is a great topic!! One of the best in a while!

 

[alastairgott]

I'm now curious.
What then prevents the outer skin collapsing towards the inner skin when subjected to the pressure applied by the depth of the sump + 1 bar since there is a vacuum inside the outer skin?

Maj.

I think perhaps he puts it inside a daren drum with a bicycle valve in the top to increase Decrease(/stabilise) the pressure? (I think they pump it up before going through the sump?)

 

[RichardB1983]

A lot of thermos flasks have a layer of silvered glass either side of the vacuum as it's a poor conductor of heat - rather than metal. I'd guess that the glass would have to smash first before the surface shows any deformation - whereas a metal one could bend under the compression forces. The flask obviously must be designed to be strong enough to withstand the internal vacuum without the glass breaking - and no doubt will have a decent margin over that.

 

[alastairgott]

A lot of thermos flasks have a layer of silvered glass either side of the vacuum as it's a poor conductor of heat - rather than metal. I'd guess that the glass would have to smash first before the surface shows any deformation - whereas a metal one could bend under the compression forces. The flask obviously must be designed to be strong enough to withstand the internal vacuum without the glass breaking - and no doubt will have a decent margin over that.

That's it, we're going to need a circular saw to settle this one.

Then we'll have to ask the question can it be put in a blender?

 

[Roger W]

Flasks are usually cylindrical,making them pretty good at resisting pressure from the outside -think of a submarine's pressure hull.  The ends will be the weak points.

 

[Maj]

Flasks are usually cylindrical,making them pretty good at resisting pressure from the outside -think of a submarine's pressure hull.  The ends will be the weak points.

Agreed, provided they have no dents in them. My 20yr old s/steel flask has a couple of battle scars/dents in the outer skin and so I feel this would significantly reduce its structural integrity (of the outer skin) if subjected to a high external pressure. I am assuming that my s/steel flask's outer most surface is the outside skin of the vacuum envelope - and NO! I'm not cutting it open to find out  :ras:.

Obviously glass envelopes won't have dents in them, and might better withstand the pressures found in deep sumps ........ if you can get them to the deep sump without breaking the glass in the first place.

Maj.

 

[mikem]

I believe the outer skin is a separate protective layer to the vacuum layers (same as a "normal" flask).

Mike

 

[glyders]

There was a container of rubber ducks that fell off a ship years back and the dispersion of the ducks has yielded huge quantities of data on ocean currents. They were distributed most of the way round the world!

We should buy up a job lot of flasks and dump them in various sinks. Colour-coded of course - red for one sink, tartan for another, etc.

 

[alastairgott]

There was a container of rubber ducks that fell off a ship years back and the dispersion of the ducks has yielded huge quantities of data on ocean currents. They were distributed most of the way round the world!

I believe there's a sump in mendip which has had similar treatment, fortunately/unfortunately it's a static sump!

Perhaps the idea of a Goose making it out of Peak cavern with singed wings is not so ludicrous after all  :tease: :-\

 

[Benfool]

I heard a rumor that quite a lot of small foam footballs were dropped into the boulder choke at the bottom of the Rowter Hole Extensions to see if they would be found floating in the final airbell of Whirlpool Rising in Speedwell. They still haven't arrived and its been at least 6 months!

 

[ZombieCake]

Tea is mainly water, which doesn't compress. What about soup?  Would the chunky bits of carrot and potato which can be compressed under pressure reduce the structural integrity?

 

[alastairgott]

Excellent point, I like your thinking, I think that will require a name change! i'll take it at once to the next meeting, and we shall vote on a new name, The "Tea and Soup Group".

 

[Pitlamp]

Whoever leaves teabags in the flask needs a lesson on how to make decent flask tea!

Suppose that could be the subject of a workshop at the next Hidden Earth.  Surely leaving the tea bag in the flask would render it rather stewy?  Would a more fuller flavour tea such as Assam be better than say a lighter green tea in an adverse environment?

Correct, Zombiecake. It must be a good quality tea - and Assam is just about the best.

You don't get a prize - but well done! 

 

[Ian Ball]

Making tea in a flask is a skill I have yet to master.

 

[cavemanmike]

Making tea in a flask is a skill I have yet to master.

flask of boiling water and add a teabag/tea to the cup