Thermos Flasks
"Mildly" Eccentric Stardriver
Thread Starter
Thermos Flasks
Does anyone know the effect on a thermos of a depressurisation ? With the new security, the cabin crew are not allowed to bring drinks into the flightdeck. The idea of bringing my own thermos of coffee to work appeals (better coffee as well), but I'm a bit concerned that it may explode dramatically if the cabin loses pressure. This is a serious query, serious replies please.
Well it's not going to affect the vacuum, since you're only actually improving things. It's the actual contents that presumably are the problem.
Could I suggest (and no, I haven't tried this) that you could do worse than use one with a small-hole pouring spout in the lid. So long as you keep it upright - easy enough in one end of a flight bag I'd have thought, if you leave that open pressures should equalise without excessive loss of temperature. Certainly I've a Stainless steel one I use for hillwalking that would do that admirably.
Or use an old fashioned one with a cork in the top, worst case the cork pops off - but again you really do want to keep it upright ;-), and probably tie a string to the cork !
Just a thought from a simple Engineer who has nothing to do with airliners except sitting up the back with a glass of wine occasionally.
G
Could I suggest (and no, I haven't tried this) that you could do worse than use one with a small-hole pouring spout in the lid. So long as you keep it upright - easy enough in one end of a flight bag I'd have thought, if you leave that open pressures should equalise without excessive loss of temperature. Certainly I've a Stainless steel one I use for hillwalking that would do that admirably.
Or use an old fashioned one with a cork in the top, worst case the cork pops off - but again you really do want to keep it upright ;-), and probably tie a string to the cork !
Just a thought from a simple Engineer who has nothing to do with airliners except sitting up the back with a glass of wine occasionally.
G
The steel type would eliminate any shatter risk, though in my experience the plastic body of the ordinary ones contains the remains of a broken filler reasonably well. If you are unlucky enough to de-pressurise coffee soaked charts will be the least of your problems!!
Ghengis, I think, anticipates a second problem with the pressure inside the flask forcing out the contents through the stopper. Keeping upright, using a good quality flask with a rotational rather than a push button stopper will probably deal with this.
Ghengis, I think, anticipates a second problem with the pressure inside the flask forcing out the contents through the stopper. Keeping upright, using a good quality flask with a rotational rather than a push button stopper will probably deal with this.
Man of the Marsh
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I used a thermos on Twotters & Islanders, often up to FL100, without any problems. They're pretty sturdy items.
The problem now is that some over-zealous security screeners may confiscate it as a dangerous weapon
The problem now is that some over-zealous security screeners may confiscate it as a dangerous weapon
I use a steel one with a proper screw in plug (not those silly push button things. What happens when the internal plastic mechanism breaks?).
It works fine up to FL080 although the pressure equalisation is noticeable when I first unscrew the plug.
I'd expect it would be fine in a pressurised environment. To guard against depress. problems you could unscrew the plug slightly. The cup/lid doesn't seal very well but helps control accidental spills.
It works fine up to FL080 although the pressure equalisation is noticeable when I first unscrew the plug.
I'd expect it would be fine in a pressurised environment. To guard against depress. problems you could unscrew the plug slightly. The cup/lid doesn't seal very well but helps control accidental spills.
"Mildly" Eccentric Stardriver
Thread Starter
Thanks guys, I think I'll start taking one on board, but ease the top off before we get to any significant cabin diff. Ahh, decent coffee !!
To warn you before you get too dissapointed, the reduced cabin pressure compared to sea level tends to depress the taste buds. This is why the food is generally deliberately overspiced and the tea tastes incipid.
You may find it is in your interest to make your coffee slightly overstrong then at a typical cabin altitude of 8k.ft or so it may taste about right.
G
You may find it is in your interest to make your coffee slightly overstrong then at a typical cabin altitude of 8k.ft or so it may taste about right.
G
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Is the no cabin crew delivering drinks to flight deck a general rule now? If so, that is amazing. Presumably you guys are allowed out (with an armed guard), or does it mean that long haul pilots just 'hang on' until they land?
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Use Them all the time. Steel ones best, top tip is not to fill it all the way up, leave bout an inch for expansion otherwise you might scald yourself. Try not to use the FMS screen as a table for pouring the contents into a cup. I find the floor safest.
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I agree with HWEL, stainless steel with a screw lid. Do make sure you leave at least an inch of space as they do go with a bit of a hiss when you initially unscrew the lid. I do speak from experience of having scalded both my hands and lap whilst at FL100 unpressurised (both a/c and flask!) In fact, it happened a couple of times to fee paying pax and the Chief Pilot decided that he couldn't trust us pilots not to fill the flasks too full so therefore he removed all the rubber sealing rings from the lids!!! Solved the first problem but did lead to people burning themselves due to tipping a presumed 'sealed' flask! Strange that eh? He trusted us to go single crew in crap weather with low hours but couldn't trust us not to fill the flasks to much! My solution would have been to employ a particularly 'flask literate' and immensely attractive female 'flask operator' who would have been indespensible on those long nights ferrying organs around the country.....................ahhhhh.
PP
PP
They're fine when shut and will withstand the drop in pressure. Just be careful when opening - water at near sea-level boiling point temp will boil at a lower temp in reduced pressure. I know about one nasty incident (admittedly whilst flying unpressurised) when the water boiled instantaneously when the cap was opened.
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An interesting thread. I've had two of the Starbucks metal ones - they call 'em bullet flasks. I thought $28 each was ridiculous until I started using them. They'll keep your stuff not just warm, but HOT for hours. I have used them in an a/c, but only in a 182 unpressurised and low down (and no FMC to rest them on). 
I would have thought that whatever problems there might be would be alieviated by opening slowly.
BTW, good coffee on a trip does make all the difference.
I would have thought that whatever problems there might be would be alieviated by opening slowly.
BTW, good coffee on a trip does make all the difference.
"Mildly" Eccentric Stardriver
Thread Starter
Just to clarify my concern ref flasks; I'm not so worried about the liquid spurting out at a cabin alt. of 8,000', my concern is what would happen to a flask of say 50/50 air and coffee that has been closed at 8,000' if the cabin suddenly climbs to 25-35,000'. You have enough problems in that situation without a thermos blowing up in your briefcase. Fire extinguishers etc are designed to withstand the pressure drop, not so flasks.
Just bought a stainless steel 1litre flask for £8.99 from poundstretcher. It has a screw tap which gently releases contents to the air. I'm not sure how it would work in practice, I only fly a cessna !
Boyles law would suggest the air in the flask may increase in pressure as the ambient pressure drops, resulting in a nice hot spray.
I'm not sure about the vacuum in between the layers of the flask. Is it a true vacuum ?
Boyles law would suggest the air in the flask may increase in pressure as the ambient pressure drops, resulting in a nice hot spray.
I'm not sure about the vacuum in between the layers of the flask. Is it a true vacuum ?
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Ghengis!
the reduced cabin pressure compared to sea level tends to depress the taste buds
)(stands by to be ejected back to the SLF forum)
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but it's almost certainly a better vacuum than you are ever likely to come into direct contact with and survive the experience.
PP
