Chris Townsend <
[email protected]> writes:
>In message <
[email protected]>, John Laird <nospam@laird-
>towers.org.uk> writes
>>On Sat, 28 Feb 2004 17:37:10 +0000, Gordon <
[email protected]> wrote:
>>>Harry Newton <
[email protected]> wrote
>>>>'Trail' did a review of SS flasks a few months back, and based on that I got a Vango 1 litre.
>>>>This is far better than the Aladdin I used before this.
>>>>
>>>>I think the main problem is that some (all ?) of the 'click to pour' lids let out heat quickly.
>>>>The new flash has a better design: one of the 'half unscrew to pour' stoppers.
>>>That's the type of top which leaks on mine, and doesn't pour very well. No name on it - so it
>>>could be a cheap one I suppose.
>>I have a "Tatonka" (bought for me, I hasten to add) 1l flask and a genuine Thermos 0.5l one. The
>>larger one pours copiously when the cap is partly unscrewed, the smaller has a tab that levers up
>>a seal underneath, allowing a dribble from the top. Mind you, the cup size on a 0.5l flask is so
>>small that a dribble is quite adequate - it reminds me of my daughter's toy tea sets. I bought
>>the small flask because I quite like carrying a modicum of hot drink in addition to a Sigg bottle
>>of squash.
>>
>>I don't find keeping either upright all that difficult, but I don't think they leak easily anyway.
>I did a test for TGO a couple of years ago, checking contents temperature after 4, 8, 12 and 24
>hours. There was no discernible difference between flasks after 4 hours but there was after 8
>though even after 12 the water was still pretty hot (highest 91C, lowest 74C). The best results
>came from the 1 litre Salewa Thermo Star. Of the half-litre flasks the Zojirushi Tuffslim Compact
>and Aladdin Stanley were pretty good. I found, unsurprisingly, that smaller flasks cooled down
>slightly faster than large ones.
>When choosing a flask I think weight and type of lid matter more than heat retention, as they are
>all pretty good at the latter. The heaviest 1 litre flask I tested weighed 770 grams, the lightest
>585 grams. Some of the flasks were hard to pour from without removing the cap, which of course
>leads to the contents cooling more quickly.
I tested half a dozen a few years ago, just random samples picked from campers who were starting off
from our house, some glass, some steel, and found that the largest difference between them was the
efficiency of the stopper in heat retention. Some were very good, some were terrible, and the rate
at which they lost heat seemed to correlate well with the conductivity of the stopper. Easily tested
-- fill flask with boiling water, seal, leave for half an hour, take of cap, leaving stopper in,
measure temperature of top of stopper. The worst were those where the stopper was simply a hollow
plastic plug, with free air circulating inside, no attempt at internal insulation. So stupid.
Slicing the top off, stuffing it with cotton wool, and gluing the top back, made a big difference to
the performance of one of the worst offenders, which happened to be mine.
--
Chris Malcolm
[email protected] +44 (0)131 651 3445 DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[
http://www.dai.ed.ac.uk/homes/cam/]