Guest guest Posted November 10, 2004 Share Posted November 10, 2004 The other day, I discovered that the boiling hot drink in my stainless thermos had gone cold in just 3 hours.I have 3 of these stainless thermos. I poured boiling water in all 3; then 2 of them became very hot on the exterior and soon the water cooled inside. The newest one stayed cold on the outside and hot inside.The 2 failed thermos have no leaks between the inner and outer shells. They have all been exposed to the cargo area of a plane, but people carry them on their person to over 20,000 feet anyway. The 2 failed ones are the ones I've used for sea kayaking.Do these things just go bad after a while. I guess I've always lost them or bent them before they could go bad. Quote Link to comment Share on other sites More sharing options...
jeffcasey Posted November 10, 2004 Share Posted November 10, 2004 they lost vacuum. lousy welds or rough handling.get over it, get a new one.if you want a good vacuum seal, you need glass...but then the failure mode on rough handling is worse than cold tea.... Quote Link to comment Share on other sites More sharing options...
scamlin Posted November 10, 2004 Share Posted November 10, 2004 The only place where there is metal to metal contact is at the neck. I've found that if the flask is stored upright, it stays hot longer. If on its side, conduction bleeds heat to the outside of the flask, warming it to the touch while cooling its contents.Beyond this, I've found that FULL stainless thermos flasks stay hot for over 24 hours, but partially full ones get cold within a few hours. Hmmmm, a case of Liliputian physics? Or something else?Scott Quote Link to comment Share on other sites More sharing options...
djlewis Posted November 10, 2004 Share Posted November 10, 2004 >Beyond this, I've found that FULL stainless thermos flasks >stay hot for over 24 hours, but partially full ones get cold >within a few hours. Hmmmm, a case of Liliputian physics? >Or something else? Hypothesis...Partially full ==> sloshing ==> more circulation ==> bringing more hot liquid into contact with colder parts of flask (at the neck) ==> more efficient cooling (higher temperature differential at the neck) ==> cold beverage ???Totally full ==> no circulation ==> the liquid develops an even gradient of temperature from the neck down ==> less efficient cooling ==> beverage stays hotter, except at the top.How to test this? Fill a flask to the brim; leave it for a few hours; open and pour it carefully; see if the liquid at the top is noticably cooler than the liquid at the bottom, with a relatively steady gradient all the way down.--David. Quote Link to comment Share on other sites More sharing options...
Richard N Posted November 11, 2004 Share Posted November 11, 2004 >>Beyond this, I've found that FULL stainless thermos flasks >>stay hot for over 24 hours, but partially full ones get cold >>within a few hours. Hmmmm, a case of Liliputian physics? >>Or something else? >>Hypothesis... >>Partially full ==> sloshing ==> more circulation ==> >bringing more hot liquid into contact with colder parts of >flask (at the neck) ==> more efficient cooling (higher >temperature differential at the neck) ==> cold beverage ??? >>Totally full ==> no circulation ==> the liquid develops an >even gradient of temperature from the neck down ==> less >efficient cooling ==> beverage stays hotter, except at the >top. >>How to test this? Fill a flask to the brim; leave it for a >few hours; open and pour it carefully; see if the liquid at >the top is noticably cooler than the liquid at the bottom, >with a relatively steady gradient all the way down. Final answer????After you try the above, try the experiment below.You have a small ice cube (1"x1"x1") and a block of ice (one cubic foot).Both are at the same temperature when you place them on a (your) counter. For 1 point: Which one will reach room temperature first?For 10 points: Why?Hint: Hot or cold, the basic reason is the same.Another puzzler:A Thermos is really a very intelligent piece of apparatus that always performs correctly.Without switches or settings, it automatically keeps the contents hot or cold!When you put hot water in a Thermos it keeps the water hot.With cold water it keeps the water cold.How does it know?Richard NLiving to learn.Romany, White with Blue trim Quote Link to comment Share on other sites More sharing options...
Bill Gwynn Posted November 11, 2004 Share Posted November 11, 2004 On the same subject. Is there any difference between a $13.00 S.S. Vacuum Flask from Walmart and a $35.00 one from REI? I need to get one. Quote Link to comment Share on other sites More sharing options...
bob budd Posted November 11, 2004 Share Posted November 11, 2004 >On the same subject. Is there any difference between a >$13.00 S.S. Vacuum Flask from Walmart and a $35.00 one from >REI? I need to get one. One is sold by a company that forces employees to work overtime and pays regular wage as well as using illegal immigrants to clean their stores at substandard wages. The other is sold by a company that donates a part of its profits to causes in defense of the environment. Check Campmor, REI Outlet(.com), etc. to find a better price and help me put Walmart out of business. Quote Link to comment Share on other sites More sharing options...
bethany Posted November 11, 2004 Share Posted November 11, 2004 see if it has that feature where you can unscrew the stopper partway and pour -- keeps it warmer and the *&%^ stopper doesn't roll away somewhere. The Nissan ones at Target do have that feature. Quote Link to comment Share on other sites More sharing options...
scamlin Posted November 11, 2004 Share Posted November 11, 2004 You like your coffee hot. But you also like milk in your coffee. Problem is that after you buy your coffee, it's a 10 minute walk to the put in where you'll be drinking the coffee.The question is: do you put the milk in the coffee at the store, or do you put the milk in a separate container and add it to the coffee at the put in? Which method gives you the hottest coffee?Scott Quote Link to comment Share on other sites More sharing options...
rick stoehrer Posted November 11, 2004 Share Posted November 11, 2004 "...and help me put Walmart out of business."earth to bob. earth to bob....come in bob. bob, that windmill you are tilting at? let it go bob, let it go. earth out. over.all i can hear in my head is richard kiley singing to dream the impossible dream! Quote Link to comment Share on other sites More sharing options...
Brian Nystrom Posted November 11, 2004 Share Posted November 11, 2004 >How to test this? Fill a flask to the brim; leave it for a >few hours; open and pour it carefully; see if the liquid at >the top is noticably cooler than the liquid at the bottom, >with a relatively steady gradient all the way down. That won't work due to the natural circulation caused by temperature changes. As the liquid cools, it will naturally settle to the bottom and warmer liquid will rise to the top. Quote Link to comment Share on other sites More sharing options...
Brian Nystrom Posted November 11, 2004 Share Posted November 11, 2004 >The other day, I discovered that the boiling hot drink in my >stainless thermos had gone cold in just 3 hours. >>I have 3 of these stainless thermos. I poured boiling water >in all 3; then 2 of them became very hot on the exterior and >soon the water cooled inside. The newest one stayed cold on >the outside and hot inside. That indicates that either:A) Two of them have lost vacuum and now have air between the walls, which conducts heat to the outside.or The inner an outer walls are not separated by enough space and heat is being radiated to the outer shell.If the two bad bottles used to work OK, A is the obvious answer. If they always cooled rapidly, B is probably the culprit. I've never seen this problem with the small, .5 liter bottles (~2.75" by 11.75", tapered), but I've seen it with a couple of the larger (.8 liter?) bottles that come with a black vinyl cover. I've even drawn a new vacuum in one of them in an effort to get it to work properly (yes, it's possible) and it didn't make any difference. Quote Link to comment Share on other sites More sharing options...
djlewis Posted November 11, 2004 Share Posted November 11, 2004 Good point. OK, forget that test. But it still might be that circulation by sloshing is a lot more efficient than by temperature differential, and that's why a partially full container cools more rapidly. Ah, there is still a test. Leave the partially full flask upright and quiet, and compare it to an equivalent partially full one that's subjected to acceleration forces of various kinds in the hatch of a moving kayak, and when handled. Or, just pick up the second flask every few minutes and shake it enought to cause sloshing.--David. Quote Link to comment Share on other sites More sharing options...
Richard N Posted November 11, 2004 Share Posted November 11, 2004 Another KISS test:Three same size Thermos containers in good working order.Heat some water to boiling.Fill each Thermos half full of water.Tightly seal one.Lightly seal the second.No cap on the third.Let them stand undisturbed on the counter.In 3 hours record the temperature of the water in each Thermos.Any difference in the temp.?Additional Info:FYI: All brand name vacuum flask manufacturers (Zojirushi,Thermos, Nissan), have a 5 year warranty on the seal. Personally, although they may cost a few dollars more, I would only purchase a flask made by one of the above companies.Richard NLiving to learn.Romany, White with Blue trim Quote Link to comment Share on other sites More sharing options...
christopherG Posted November 11, 2004 Share Posted November 11, 2004 ken, i have had similar experience in the last year -- actually with two different symptoms (one same as yours; one a matter of a leak in the stopper, allowing what i take to be contamination of the hot contents by the now-decaying liquid inside the stopper)unfortunately the person best equipped to answer the question is not paddling with us anymore (ken condon, whose business is stainless medical instruments and appliances, etc). i remember discussing just this problem with him and ken telling me that the rim-weld between inner and outer steel barrels is a highly-technical and complicated manufacturing procedure, requiring great precision. this weld is the likely culprit: it needs only open up in however microscopic manner to release the vacuum and...bob's yer uncle: no more hot tea for your lunch on whatever remote island -- when you needed warming up!i suggest a return to the store where you bought them: they are supposed to have a lifetime guarantee, no? i just changed one of mine with no questions asked... Quote Link to comment Share on other sites More sharing options...
markstephens Posted November 12, 2004 Share Posted November 12, 2004 This is one of the silliest threads yet, but...If you are not using low-fat milk, I would add the milk (or cream) in the store. The fat in the milk/cream forms an insulating layer on the top of the coffee, keeping it warmer in transit to the put-in. Quote Link to comment Share on other sites More sharing options...
Richard N Posted November 12, 2004 Share Posted November 12, 2004 >This is one of the silliest threads yet, but... Mark, 10 points for the right answer.5 points for the reason.Believe it or not.......someone has done research on the subject and has "brewed" up a very impressive "final answer".Keeping Coffee HotAn age-old question is finally resolved. Should cream be added to coffee upon purchase or right before consumption? The difference between these two thermodynamic alternatives could mean hotter coffee.Jonathan AfilaloRichard NLiving to learn.Romany, White with Blue trim Quote Link to comment Share on other sites More sharing options...
scamlin Posted November 12, 2004 Share Posted November 12, 2004 Richard:It ain't a brain teaser if you google the answer. You're supposed to think!!!! (Or maybe you already figured it out and were just citing the research).Scott Quote Link to comment Share on other sites More sharing options...
mskulick Posted November 13, 2004 Share Posted November 13, 2004 Bob, I'm with you. If enough of us tilt at these"windmills", then maybe we CAN make a difference.I hate "Wally-World" too. What a place. I bet Samis spinning in his grave.Mike. Quote Link to comment Share on other sites More sharing options...
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