I do explosions with liquid nitrogen almost daily at my job as a science demonstrator. We've had one accident where a bottle exploded in the hands of a college of mine. He got a good scar up his arm, but nothing deadly. He had to get sewn, but that was about it.
Most often though, if you fill up the bottle with too much nitrogen, it won't explode. It'll just freeze up and slowly disperse through whatever cracks are present. If it didn't explode over night, it probably wouldn't have at all.
I suspect it might have started to fizzle due to air leaving the bag, or due to a small leak, which is pretty harmless. Nitrogen explosions of half-litre bottles are very large, and can shake the ground 20-30m away. I can test it later today if time permits and upload a video, but overall, it would've been much clearer if it went off.
Edit: to people saying the cap is the weak point: 9/10 times it's the bottom that gives in first.
I have some experience with dry ice in closed containers.
Every now and then some friends and I will get some dry ice, a bunch of plastic bottles and other containers with a screw-on lid and have a laugh making small explosions.
Basically you take a bottle, fill it 1/4 with water and 1/2 with dry ice and screw the cap on. You then have around a minute before it explodes.
A 1/2 liter coke bottle will make a nice whooompf and a 20 liter plastic gasoline can (the largest we have tried) will make a bang that can be heard maybe half a mile away. They very rarely sizzle out, and the ones that do probably have a defect, or we didn't get the cap screwed on properly. There's some time pressure, so you don't stand around checking before you throw the container. I would imagine that a metal container will make a pretty big bang (higher pressure before it ruptures) and may throw out some nasty debris.
Back when I did this a few times a year, 20oz soda bottles made the best boom. 2-liter bottles couldn't take as many PSI and water bottles... well, they're not designed to contain pressure. They'd fail at the cap, usually.
That may no longer hold, since 20oz bottles feel flimsier these days and all have low-profile caps. Haven't tried in a while.
Also, PVC pipe burried in ground, drop dry ice bomb in, drop another bottle with some water in it on top = dry ice mortar. Those little plastic bubble things that toys in vending machines come in? A little dry ice, a little water, close it, place lid down. POP, the bubble part flies a meter or so in the air.
I will note for anyone trying this that the parent's ratios are very different from what I used. Crushed dry ice to 1/10-1/8 full, about twice that much water. Unusually warm water (say, from near the surface of a pond or lake in late August) will greatly reduce time-to-boom, so beware. Too little water and it'll freeze before boom, greatly delaying or even preventing it. Very annoying. Attaching to something heavy (but NOT shrapnel-genrating) and sinking in ~5-10 feet of water is fun. Huge bubble, explosion can be felt on land nearby.
I used to do this too when I was a kid at my grandmom's house. They'd order steaks from TV commercials and receive them in the mail bundled with dry ice. It started as making foam messes with soap, water and dry ice... But soon I was filling up 2 litre bottles with ice and water and making bombs. It all ended when the police arrived because neighbors thought a gunfight was happening in their quiet residential neighborhood. Needless to say, they weren't very happy with me.
Big difference, I think, is that in your case you're mixing it with water, so it will warm up a lot more quickly. In the OP's case, he just had the dry ice in there with no water, so presumably it would melt more slowly, and there may be enough time for the carbon dioxide to escape through tiny gaps or cracks in the cap.
> to people saying the cap is the weak point: 9/10 times it's the bottom that gives in first.
It may be the case for a typical water bottle but thermoses have much larger caps. The maximal force that a cap can hold is proportional to its perimeter (~r), the force itself is proportional to the area of the cap (~r^2) and the pressure. So larger caps can blow off by lower pressure. I would bet that for a thermos the weak point is the cap.
Yeah, that guy should be arrested or at least given a heavy fine :/
"I had to keep zig-zagging to avoid pointing the bit which was going to explode at people coming up the street towards me" and "the canal is a crowded place on a Sunday morning"
Endangerment is legitimately considered a crime.[0]
Our go-to example in an Economics of Law course was firing a gun while in a crowd. Similarly, attempted murder is a crime even in the case where no harm befalls the victim.[1]
The value of endangerment laws to society, to the extent that there is any value, is to deter the offender and deter others as well. In the story here, I don't see how you can apply that ethic. I don't want to live in the society in which every low-probability danger is made into an offense. Life has some sharp edges.
Luckily there's a common sense rule to apply that an economic analysis of law makes clear.
Enforcement should occur up to the point where the marginal cost of extra enforcement is equal to the marginal cost of the activity we are seeking to deter.
I would agree with you that the particular circumstance described in the article does not warrant legal action, but your original post made no allowance for enforcement directed at anything other than purposeful and effective crime.
- Assuming the inside of the thermos is at room temperature (and that there was enough dry ice initially), the pressure should be around 60bar. This is the vapor pressure of carbon dioxide at room temperature [1].
- At 60 bar and with a volume of, say, 1 liter, the energy available for the explosion is roughly 60bar x 1liter = 6kJ [2]. This is a TNT-equivalent [3] of about 1.5g, or about 10-100 firecrackers. Enough to cause injuries, but not enough for structural damage to a balcony [citation needed].
In my personal opinion, the most dangerous thing was handling the thermos. I believe letting the thermos sit on the balcony for a few days and closing doors and curtains (to prevent glas shards flying in) would have been a much safer alternative.
You are absolutely right, I should have used the formula for adiabatic expansion.
However, I maintain that the pressure inside the thermos should only be 60atm, since this is the vapor pressure of CO2 at room temperature [1], where the liquid and the gas phase are in equilibrium. This is like the butane in a lighter: Butane evaporates at room temperature, but there is an equilibrium between liquid phase and gaseous phase when the pressure is higher.
Using 60bar and the adiabatic formula, I get 12.5kJ of energy.
Great read, but speaking as someone who lives on one of those houseboats (and passes through Islington occasionally), please don't consider a canal a safe place to 'ditch' potentially exploding things in future.
"I looked at the flask with that awful sinking feeling you get when you realise you have created something which is inevitably going to explode at some point in the future, and there's nothing you can do about it."
Probably the same feeling that when you lie to someone, see your lies being slowly exposed, and there's nothing you can do about it. Happens a lot when we are teenagers :)
Why not just put it outside on the balcony and leave it the hell alone? Fussing about it any more is just risking getting your hands blown off. Idiot. And all this faffing around with a time bomb while you have a kid to look after, totally irresponsible. Put a duvet over it and leave it alone. It's nearly Darwin award stuff
Seriously, why not just wrap it in blankets, put it all into some open lid container (trash bin, hamper, etc), and leave it on your balcony. There are so many better ways to handle this situation.
I expect that the floor of the bin is elastic in the technical sense - it returns to its resting form when no force is applied. When the BANG goes off the base of the bin is compressed into the floor, hard. This lowers its center of gravity. Then it returns to its previous shape, the CoG rising as it does so. Once it has returned to its original position it discovers, rather to its surprise, that it's now travelling upwards, and so it continues to do so.
As well as the shockwave mentioned elsewhere, you also have pressure effects.
The initial explosion drops the pressure in the bin below atmospheric pressure. Assuming there's enough kick to separate the bin from the floor, you've got a higher pressure pressing up on the bottom from below than down from inside the container, so the bin accelerates up.
I'm not sure if it'd be a significant effect, however.
A few years ago while on vacation with my extended family, all my brothers and I decided it would be fun to drop dime size chunks of dry ice into a water bottle with a few inches of water in them and then throw them into the pool. We did this and given a few minutes they would explode, harmlessly - not much more than a fire cracker.
Then we had the bright idea of tying a 5lb weight to the water bottle and let it sink. This was a bad idea on our part. When it exploded, it sent a shock wave through the ground. It was pretty intense make us brothers kinda freak out. People rushed from inside the house and asked what explosion was. We were afraid we had cracked the pool, the concussion wave was so strong. Luckily, we hadn't for my brother's sake. It just makes me think twice before containing dry ice.
Can anyone explain why putting a plastic ziplock or other bag around the thermos and hiding inside a cooler (or close-able container box) wouldn't be an adequate solution?
I imagine this isn't some pipe-bomb - the energy density simply isn't there - but you want to ensure that the thermos lid doesn't happen to injure some passer-by.
For comparison, a .50 cal round has ~15kJ of muzzle energy. Now, a lot of that energy won't be focused (if nothing else, the final temperature with adiabatic expansion is such that a large chunk should sublimate again), but still.
The 22 KJ seems widely varying form other estimates on this discussion (6KJ, 15KJ).
For example, is it clear that the pressure of 100 atm would actually be attained by a simple thermos and dry ice? What lead you to use that number?
Furthermore, the .50cal round is focused on a small area, the impulse and destructive force are multiplied by the shape of the bullet. Just like how shape-charges magnify the explosive force of munitions to bust armor.
The 6KJ number is flat-out wrong. You cannot multiply pressure * volume like that. It's not an isobaric expansion. I mentioned this in a reply to his comment.
As for the 15JK number, I cannot see any estimates in this thread saying 15JK. Could you link the comment?
The 100atm figure is assuming that the linked article's calculation of final pressure is correct, assuming the thermos doesn't burst beforehand. Although I fully agree that a standard thermos is unlikely to achieve that number.
And as I said a lot of the energy won't be focused. This is just a first approximation, to indicate that yes, potentially the energy is there.
Not much. At the student revue last year, we had filled a thermos with dry ice, closed it up, and forgot about it on stage overnight. At some point during the night, it blew off the plastic valve at the top, which was ruined, but the metal flask itself was fine. The people sleeping near the stage reported a loud bang, but nothing else.
Hypothesis: since the valve is only going to be propelled by the expanding gases for a relatively short time before it has cleared the flask opening, I don't even think it accelerates to that great a speed.
Clarification: a thermos is more or less a best-case scenario, since the valve at the top is going to be much weaker than the flask itself. A plastic bottle is worst-case, because it is going to shatter and eject plastic splinters.
Could have seriously damaged his hand if he was holding it. I have a permanent scar in my eyebrow from dry ice enclosed in a weak water bottle that exploded a few (4 or so?) feet from my face. There are YouTube videos of people ending up with severe hand damage from 2 liter bottles.
I was cringing reading this article. I would never ever have handled one of these things, based on my experience. I think I would've put it in the fridge, left the house for at least a day, and bought a new fridge based on the damage.
Wow. In the first example, it seems those weren't scuba tanks, but rather pressurized air containers that are used to fill the real scuba tanks - they are quite a bit larger. Never seen those before.
Actually the article says that people are also killed by exploding truck tires which are around 100 psi and further states that SCUBA tanks are pressurized at up to 3000 psi.
Isn't the pressure only part of the danger? In my non-scientific experience, it seems that the speed of failure is the important part. i.e a truck tire with a nail in it does no harm, but a 15-ply semi tire at 100psi having a catastrophic failure is a much different animal. All about the speed of release.
My own personal story:
some friends and I filled a 5 gallon bottle with a bit of isopropyl alcohol, shook it up, and lit the opening to make a "rocket flame". We had seen this done in class, and it went fine. BUT...we wanted to do it again. we had no more alcohol, so we used Acetone instead, but it wouldn't light. There wasn't enough air in the bottle, since we had just burned out the oxygen. Because we were 16, and lacking much foresight, we decided "why just put air in the bottle, when we could use pure oxygen from a welding tank?". We did that. The ensuing incandescent explosion lit up briefly like a lightbulb and then ruptured the bottle into about 100 pieces. the major one landed 2-3 seconds later, about 200 feet away.
Even though that was moronic, I pride myself for having worn welding gloves, a face shield, ear plugs, and used a 12 foot handle with a match on the end. The detonation left me feeling shaky and jittery for about 6 hours.
Well I personally know a physics teacher who does extreme physical experiments using dry ice and liquid nitrogen. One simple experiment is pouring really little amount of liquid nitrogen into a 0.5l coke bottle then wait. We stood away from the bottle (~10m) and let it explode. It is really loud when it bangs, otherwise it's a safe experiment (of course it's done outside and you really shouldn't hold it in your hand).
What's the weak point of a thermos? It's definitely the cap. I think leaving it alone would have just sent the cap flying, it could have been safely done in a park.
That there was a continuous stream of small bubbles (as opposed to one gigantic one) suggests that the failure mode was a leak, not an explosion. Still, I would have been scared.
The odd part is that submerging in a depth of water actually lessens the pressure differential making it less likely to explode, not more. So failure is less likely to occur as it's submerged further.
thrilling read; interesting that the device manufacturers explicitly warn you against putting dry-ice in a thermos. I had never heard that before.. I mean, thinking about it- it makes sense, but I would not have reached the conclusion without assistance.
My instinct would have been to cool it in some liquid nitrogen at the university and just safely let the dry ice out... Glad they had a canal nearby...
He was working on the assumption that there was significant pressure built up in the thermos. Puncturing it would release that pressure causing a potentially dangerous explosion. The same premise as puncturing a balloon except the balloon in this case is made of metal and glass and the amount of pressure is significantly higher.
If you're lucky then the top of the thermos is plastic.
Safe way to solve the situation with a metal thermos with a plastic cap: clamp thermos to workbench, pre-drill hole in large sheet of plywood, drill through pre-drilled hole into thermos. Depending on how complete the sublimation is, there may be a boom and you, the plywood, and your drill may potentially get kicked back a meter or two in the worst case, but your plywood shield would likely spare you from any high-velocity plastic fragments that would cause you injury. If you're lucky the pressure is still low enough that it just blows plastic out of the spiral of the drill bit and there is little other than the plastic shavings to work around.
You would definitely want to be wearing earmuffs though.
Funny. Being from a very rural area my solution would of been to walk outside and hoof the bloody thing as far as I could into the surrounding fields and have a cup of tae while waiting for the boom.
It's a good idea to own a few basic tools, including a handheld drill and maybe a hacksaw, even if you live in a small flat.
Although in this case, depending on how long the thermos had been shut, I'm not sure whether attempting to relieve the pressure would have been the smartest move.
Now I'm genuinely wondering what I would have done...
Like dsfsdfd said, leaving it on the balcony under a heavy blanket seems like the best option, though my first thought was just throwing it down the street sewers.
Yeah, thinking about it some more, "wondering what I would have done" quickly turned into "wondering whether I'd still have hands or a face right now." Scary stuff.
Drilling a hole is not a good option. If there is significant pressure inside then the hole will begin the explosion, not release the pressure. In an ideal world, the best option is to puncture it from far away, which is difficult out in a city. In the country, you might find someone to shoot the thermos with a small rifle.
My college roommate had a volumetric flask with water and dry ice explode in his hand as he held his thumb tightly over the top. No injuries, and we laughed at him for being an idiot.
Please add a more descriptive title. Is that some kind of autobiographic short story? Is it something that teaches how to be a better entrepreneur/developer/designer? What kind of people would be interested in reading that?
edit why is it so hard to say that there is a novel to read and not some specific information? It's okay to be a novel, but some people don't want to read novels.
That's good to know! I would interpret it differently, though.
The idea, as far as I see it, is that you don't use title changes to increase the attention, e.g., avoiding to use upper case. But you should certainly use the title to increase the information density, e.g. 'translate "10 Ways To Do X" to "How To Do X,"'.
You are right, and I basically do that and mostly write that kind of comment only to threads where I don't have an idea if I want to read it or not, even after skimming through (the first page) of that kind of article.
Look. No matter how wrong or stupid I act, If 10k people watch your link and everyone spends a second considering if they should click it or not, then that's a lot more time compared to choosing a title that says more about what to expect after the click, right? So even if I'm the biggest douche on the planet, we might still agree that it's worth for a link poster to spend some time about its title instead of just copy&pasting the article title.
Most often though, if you fill up the bottle with too much nitrogen, it won't explode. It'll just freeze up and slowly disperse through whatever cracks are present. If it didn't explode over night, it probably wouldn't have at all.
I suspect it might have started to fizzle due to air leaving the bag, or due to a small leak, which is pretty harmless. Nitrogen explosions of half-litre bottles are very large, and can shake the ground 20-30m away. I can test it later today if time permits and upload a video, but overall, it would've been much clearer if it went off.
Edit: to people saying the cap is the weak point: 9/10 times it's the bottom that gives in first.