David Sparkes Posted February 1, 2010 Share Posted February 1, 2010 Can a query about a Vacuum Flask be considered a Land Rover topic? I hope so, but if not ... shrug! The 1 litre flask in question has a stainless steel outer and inner, presumably welded together near the neck, although the join is invisible. I found the flask in a field, together with several other discarded items, so I earned a brownie point for tidying them up. Naturally this action wasn't without some self-interest, but mutual aid is what makes us all rub along together. To the plot. Poured boiling water in, and discovered that within 30 seconds the outside was too hot to hold, so the 'thermal insulation by vacuum' wasn't working too well, and I assume the vacuum has disappeared. I checked, there is a significant difference in diameters between the ID and the OD :-) The base of the flask is a very tight push fit 'cup' shape, and has resisted a straightforward 'grip in the hands, twist and grunt' effort at removal. As I have nothing to lose by taking it apart I have wondered: How to get it apart (in such a manner that I can reassemble it). Whether filling the gap with spray on builders foam would be an effective insulator. I have tried standing the flask in a shallow tray of water, high enough to go over the join, then heated the flask with a 1800W electric heat gun. The steel goes a pretty colour, and gets uniformly 'too hot to carry', but there is no sign of air being expelled through the join (no bubbles in the water). Nor is water sucked in as the flask is left to cool. I have thought of drilling and threading a hole in the base, then screw + Loctite / Araldite a valve in, then blowing compressed air in to force the base off. I'd figure out a repair after 'foaming' the cavity. Of course, if I create some sort of valve, why not try re-creating a vacuum? Two snags, with the tools at my disposal I can't think how to create an effective vacuum, nor can I think how to seal it if I did create it. Anyone else at a loose end this afternoon, and would care to suggest a bright idea or two? :-) Quote Link to comment Share on other sites More sharing options...
BogMonster Posted February 1, 2010 Share Posted February 1, 2010 You have too much time on your hands I have an effective suggestion - dump it and buy a new one Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted February 1, 2010 Author Share Posted February 1, 2010 You have too much time on your hands Shucks, you guessed. Quote Link to comment Share on other sites More sharing options...
Lara Posted February 1, 2010 Share Posted February 1, 2010 Simple answer, 1.Drill a small hole somewhere that is out of the way, 2.Fit a Small one way valve to this hole, obviously going the right way so you can suck out and not blow in, 3.Boil a kettle full of hot water, 4.Get a piece of flexible tube strong enough to sustain full vacuum, 5.Fix one end of the hose to the valve and hold the other end in your mouth, 6.Take your shoes and socks off, 7.Get the wife to pour the boiling water onto your feet, and the resulting sharp intake of breath will create a very good vacuum inside the container. 8.Fill with coffee 9.Drink coffee in hospital waiting room while your burns are being totally ignored because you didn't go private Lara (Warning) This is a silly suggestion and no one should believe a word I say Quote Link to comment Share on other sites More sharing options...
SiWhite Posted February 1, 2010 Share Posted February 1, 2010 I wonder why a vacuum is such an effective insulator? Maybe no molecules to transfer heat between the two walls... Anyway, braze a small valve on and suck the air out! You can make about 5 - 10 psi just with your mouth IIRC. Have you got an old bicycle pump? If you took that apart and reversed the rubber scraper seal it would suck instead of blow. You'd also need to butcher a bicycle valve so it holds air out, not in. Anyway, you'd be left with a flask with a tyre valve sticking out of the side. Buy a new one! Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted February 1, 2010 Share Posted February 1, 2010 I wonder why a vacuum is such an effective insulator? Maybe no molecules to transfer heat between the two walls... Indeed, although there is still some heat transfer via radiation. Otherwise the sun would be pretty useless Quote Link to comment Share on other sites More sharing options...
GBMUD Posted February 1, 2010 Share Posted February 1, 2010 Useless stainless flask? Too much time on your hands? You need a project! Let us know how you get on. Chris Quote Link to comment Share on other sites More sharing options...
Bluemoon Posted February 1, 2010 Share Posted February 1, 2010 another project you could use it for is a wood gasification camp stove, with or without a fan, do a google | Brian Quote Link to comment Share on other sites More sharing options...
Turbocharger Posted February 1, 2010 Share Posted February 1, 2010 I've got a bottle of replacement vacuum in the shed - do you want me to tip it into a Jiffy bag for you? Quote Link to comment Share on other sites More sharing options...
Superpants Posted February 2, 2010 Share Posted February 2, 2010 It's clearly just forgotten that it should keep things hot- I usually find a firm talking to, and the threat of buying a new flask sorts the little blighters back into shape. ;o) Quote Link to comment Share on other sites More sharing options...
Happyoldgit Posted February 2, 2010 Share Posted February 2, 2010 This borders on fabrication so I'm moving it there ..if that appears wrong to some, well, shrugs Quote Link to comment Share on other sites More sharing options...
errol209 Posted February 2, 2010 Share Posted February 2, 2010 This borders on fabrication so I'm moving it there ..if that appears wrong to some, well, shrugs That's why my post failed Anyway, as I was saying - Aaargh - physics - must resist - can't - The best way of getting a half decent DIY vacuum is to seal the interstice and introduce a Nitrogen absorbing compound. It won't get you a really hard one, but not bad. Sorry? No, it's an expression of the residual pressure, not a comment on his level of excitement, behave! However, crazy foam will be an improvement over nothing, but a new flask would be the best and dullest method Quote Link to comment Share on other sites More sharing options...
mickeyw Posted February 2, 2010 Share Posted February 2, 2010 Hmmm, a twin wall stainless vessel. Sounds like you have the makings of a Kelly kettle. Light a fire under it and that'll keep the contents hot Quote Link to comment Share on other sites More sharing options...
Night Train Posted February 2, 2010 Share Posted February 2, 2010 Maybe it is one of those special flasks that keep hot things cold and cold things ho.... Or perhaps not. Put it on freecycle. Someone will use it. Quote Link to comment Share on other sites More sharing options...
Troddenmasses Posted February 2, 2010 Share Posted February 2, 2010 Dump it in a field.... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.