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#pressure#lid#thermos#release#before#food#cap#valve#enough#design

Discussion (47 Comments)Read Original on HackerNews

x______________•about 3 hours ago
Initially assumed it was due to some sort of contamination or production defect.

Turns out people leave perishable and fermenting foods in the thermos, and after a while when opened, the pressure lifts the lid of the thermos at quasi-unimaginable speeds, striking the curiously unsuspecting humans straight in the face, with some instances causing permanent damage to vision.

Coffee is hot, but a pressure release system is cool too..

jofzar•about 2 hours ago
I really hope we get a video out of this to see how bad it actually is and how much "pressure" is needed for this.

> Incidents/Injuries: Thermos has received 27 reports of consumers who were struck by a stopper that forcefully ejected from these containers upon opening, including complaints of impact and laceration injuries requiring medical attention. Three consumers suffered permanent vision loss after being struck in the eye.

That's an awefully large amount of reports about this. I wonder what about the design makes it a rocket compared to what I would assume is a pretty standard design?

> The Stainless King™ 470ml Vacuum Insulated Food Jar is the ultimate day to day companion to keep your food at optimal temperatures. Keep fruit fresh and vegetables cool for up to 14 hours while you take on the day. For your favourite soups, pastas or stir fry, they’ll stay warm for up to 9 hours – ideal for taking last nights left overs. You can be sure that your food will be perfect for consumption at lunchtime after you pack it in the morning. The wide mouth makes it easy to fill and clean, and comes crowned with a stainless steel lid that doubles as a serving bowl. Plus, it comes with a handy stainless steel spoon that fits neatly into the lid compartment.

It's meant for storing food, for anyone who is confused why someone would be.

baq•about 1 hour ago
> I wonder what about the design makes it a rocket compared to what I would assume is a pretty standard design?

Injuries nonwithstanding, the quality of the seal means it was an exceptionally well designed item for the purpose of storing 99% water.

side note: there's a reason you get a visit from the FBI if you buy ten pressure cookers (e.g. if you find a great Black Friday deal and have a large family and plan Christmas gifts...)

numpad0•29 minutes ago
Thermos jars have interior threads for an inner plug and an exterior thread(singular) for the cosmetic cap that doubles as a drinking cup. Maybe there's a condition where the external cup would be holding the inner plug from releasing, and then upon removing the cap, the entire lip starts tapering outward and lets go of the plug without gradually relieving pressure.

(to be fair, I don't think an externally threaded cap will solve this problem. If the thread held to a higher pressure, then the core part of the plug will eventually blow out even more energetically. An overpressure vent port is still necessary)

2muchcoffeeman•about 1 hour ago
The pressure build up can be quite a lot from fermentation. I’ve accidentally fermented drinks in glass swing top bottles. And upon attempting to open the bottle the pressure ripped the stopper and the metal parts right off the bottle at high speed.

If you were purposely fermenting something, you could build enough pressure to pop the bottle.

jmalicki•about 3 hours ago
I'm a little surprised it's a recall - is there some expectation that it should have pressure release? Can you not sell simpler products legally?
alentred•about 2 hours ago
Yes, the article seems to be not detailed enough. They show the pictures, and it is evident what the pressure release valve is, but I agree that by this logic any container or any steel water bottle is dangerous. Maybe there is some other additional feature that makes it particularly dangerous compared to other models (like, the new seal keeps higher pressure, or the lid needs fewer rotations to disengage, etc.) that is not explained here and makes all the difference. Older models didn't even have a pressure relief valve, did they?
Someone•about 2 hours ago
I guess the amount of rotation needed between “airtight seal gets broken” and “lid can come off” is fairly short for these thermos.

If the difference is, say, a full 360° turn, pressure will get relieved before the lid can come off.

See also https://news.ycombinator.com/item?id=48006887. Apparently, many bottles have discontinuities in the threading to allow for that.

traceroute66•about 3 hours ago
> is there some expectation that it should have pressure release?

Scroll down in that article to the section with photographs of "recalled" and "not recalled" lids side by side.

jmalicki•about 3 hours ago
Why is there an expectation that it should be a required feature?
globular-toast•about 3 hours ago
The whole point of Thermos is to keep things warm for a long time. That means pressure. It's a basic safety feature.
mschuster91•about 2 hours ago
> The whole point of Thermos is to keep things warm for a long time. That means pressure.

That by far is not enough to forcefully yeet out the cap, probably not even if you take it to an Antarctic research base in -40 °C outdoor weather.

People forgetting about content that ferments however? Kaboom.

iammjm•about 2 hours ago
Isn't the point of a thermos to put "perishable and fermenting foods" in it, like coffee or tea? Like this could totally have been me, like make a thermos-full of coffee one day, then forget about it only to come back to in some weeks just to open it and have one of my eyes blown off
rimliu•about 1 hour ago
good luck of anything fermenting after dousing with boiling water..
nirava•about 1 hour ago
Any (sealed) container designed to hold hot things should have a pressure release system.

It can be seals that buckle before the lid. It can be a tiny hole with a soft rubber stopper. It can be one of many things that cost a couple of cents extra and a bit more engineering and testing effort.

The cheapest disposable coffee cups I've used have a tiny hole for the express purpose of not pressurizing and spilling hot liquid everywhere.

There's a lot of conversation in the comments about "was there was an expectation that the pressure release valve would be there" There absolutely is a safety expectation that a sealed container of hot food is designed with a pressure release system.

BTW the fermented food thing is a misdirection. The pressure release system should have released pressure way before it even reached ballistic territory.

odie5533•about 1 hour ago
My steam cleaner recently was recalled and sent me a new cap with a built-in pressure-locking valve. People were opening it too early and getting burns. Heat and pressure can be very dangerous.
roel_v•about 1 hour ago
That sucks. I have both and the ones with the pressure relieve valve are a pain in the ass to clean. You have to pull out the rubber inner thingy, you can't get a towel inside the hole that thingy goes into, and in general the rubber thing gets lost easily. I wish Thermos would send me a few of those 8 million stoppers, I'll promise I won't be a dumbass with them :(
edwcross•about 1 hour ago
> I promise I won't be a dumbass with them

That's not very empathic of fellow people who might just have mistakenly forgotten food in the container.

It's not like they were intentionally using this for brewing some illegal substance or misusing it in a way specifically forbidden in the manual or obviously unsafe (e.g. removing a magnetron and all of its protections from a microwave to make pretty wood carvings).

brazzy•about 1 hour ago
> I'll promise I won't be a dumbass with them :(

Can you also guarantee with absolute certainty that you'll never forget them anywhere another person who's unaware of the contents or the danger could find them?

_trampeltier•about 2 hours ago
There is a well known solution. Look at most PET bottles. The thread (mostly on the cap) is not continuous. That's for the pressure to relieve before the cap is off, and that could happen from a coke bottle or so to you.
thomascountz•about 2 hours ago

   The malfunction is due to multiple models of containers missing a pressure relief function in the center of the stopper.
They have a well-known solution, but it was not implemented.
_trampeltier•about 1 hour ago
You have to activate it manually?
pizza234•about 3 hours ago
Happened to me once. I was emptying one of my child’s thermoses in the bathroom when it suddenly "exploded" and sprayed the contents all over the bathroom walls. Quite a remarkable day :)

I didn't consider it a defect, though. I can hardly imagine cheap products adopting this solution.

ludicrousdispla•about 3 hours ago
I would have thought they could design the screwtop so that it would relase pressure before fully disengaging the lid from the flask.
teruakohatu•about 2 hours ago
That is what I was wondering. I would have thought it would need to be opened at eye level for the contents to hit the eye before being depressurised.
altacc•about 2 hours ago
If it's a forceful opening and you're not holding the top tightly, then I imagine the top could launch upwards. I know from experience this can also happen if you put just a bit of boiling water in and seal it. The air expands under heat and will push the top out whilst you're unscrewing. A version of this top comes with a metal spoon & raised holder built in, providing some edges to hit you with and an extra projectile.
jofzar•about 2 hours ago
Nah I think most people would open it at waist level standing with the lid facing up (towards you face as you are looking down), and twisting to open.

I can totally see how that would fly straight up at your face.

kjuulh•about 2 hours ago
Had this happen to me once, though totally my own fault. Was brewing kombucha, and left it out in the bottles a little too long before burping.

Me standing there, kombucha and peach slices pulverized against the cap, kombucha leaving a large mark on the ceiling it all happened so fast, glad I was wearing my glasses.

No injuries except my pride, but it did take some hours to clean up.

I wouldn't do it in a thermos, but I guess those are mostly accidents?

ErroneousBosh•about 2 hours ago
It was bramble beer for me. Put a load of lovely ripe brambles in a batch of homebrew beer, one of the little pithy bits on the inside wedged up against the bottom of the airlock, and overnight the pressure built up enough to pop the cork out and spray the ceiling with brambly splats and beer.

Tasted okay though.

My mate brewed his bramble beer by putting his brambles through a juicer and only adding the juice and pulp, because he's cleverer than me and has a certain amount of foresight.

traceroute66•about 3 hours ago
I too from the headline assumed it was some sort of chemical contamination during manufacturing.

But then I read the words "The malfunction is due to multiple models of containers missing a pressure relief function in the center of the stopper."

How non-existent does your quality assurance have to be in order to miss such a critical, obvious and easy to identify flaw ?

Looking at the published photographs, you don't even need training to identify that manufacturing defect. A five year old could spot the difference between "lid has a hole" and "lid does not have a hole".

Aachen•about 2 hours ago
I've never seen a thermos bottle with a relief valve. Not sure if all manufacturers in Europe have nonexistent QA or if it's just not a thing that's commonly needed since you can't heat the contents up in there anyway (it's not like an insulated water boiler, which does have a release valve). Never considered that someone might leave food in there long enough to build up explosive pressure. Feels a bit like saying a missing cat detector function in microwave ovens points at them having no quality control
gcr•about 1 hour ago
I bet you’ve been using these your whole life without knowing it: in non-USA thermoses, the lid releases pressure before becoming mechanically free. You’d hear a “pop” and then the lid has to be twisted slightly further before it can be removed.

Not all safety features have to be obvious/obtrusive.

Aachen•about 1 hour ago
I see no hole in the metal anywhere on the inside. The only non-metal part that touches the inside is a rubber(?) gasket/ring thingy that sits above the thread and is squeezed by the lid, which I take out to clean and there's only metal under there as well. How would this work? Did I get the exceptional model that doesn't have one and just didn't look at other models closely enough?
_ink_•about 3 hours ago
I would assume that it was some cost optimization that led to the removal of the pressure relief.
bilekas•about 2 hours ago
This is wild.. It looks like they changed their lid to be a bit cheaper ?

Looking at the version that's not recalled, I would guess it costs more to make.

roel_v•about 1 hour ago
The one without the relieve valve is nicer to use because it's (much) easier to clean. Source: I've cleaned these things pretty much every weekday for the last 2 or 3 years.
jofzar•about 2 hours ago
The one that's not recalled has a pressure release button
ZpJuUuNaQ5•about 1 hour ago
I hate life a little bit more every time I stumble upon stories like this. Anything and everything can happen to you, suddenly, without warning, without planning, not necessarily because of any obvious fault of your own (from your perspective, at least). "Oh, you thought you already had enough problems and worries as it is? Congratulations, now you are blind in one eye, forever, because you wanted to keep your coffee warmer for a little longer."
globular-toast•about 3 hours ago
So who decided to cut costs by "simplifying" the lid design? A case of Chesterton's fence perhaps?

My partner has one of these so just checked it. It does have the pressure relief feature, but it turns out it's also missing all the seals anyway so never would have been a problem!