29 ms·
Under Pressure
- hmate9 11y agoFunniest story I've read in a while :)
- dijit 11y agothrilling 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.
- jsymolon 11y agoWhen I bought dry ice (last year) for the science fair, they do give out a safety brochure on handling. One of the top 5 points, no tightly closing containers. Styrofoam cooler is ok and dry ice will last 2-3 days like that.
- dsfsdfd 11y agoWhy 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
- maccam94 11y agoI agree that handling this was dangerous, but I wonder how much damage the explosion would have caused if he hadn't thrown it in the river...
- dntrkv 11y agoSeriously, 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.
- ohazi 11y agoIt'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...
- icebraining 11y agoLike 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.
- ohazi 11y agoYeah, 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.
- abakker 11y agoDrilling 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.
- rmc 11y agoAn explosion in a drain? Surefire way to cause a lot of shit....
- Wingman4l7 11y ago"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."
- leni536 11y agoWell 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.
- ablation 11y agoCurious: how much damage could this have done if it actually exploded? What kind of forces are we talking about here?
- x0x0 11y agoan aluminum scuba tank is filled to around 3k psi; they're quite energetic if they explode http://www.kirotv.com/news/news/dive-shop-explosion-sends-tank-shooting-through-pa/nbPfF/ http://www.kirotv.com/news/news/dive-shop-explosion-sends-ta... This guy died and damaged cars 100ft away from the center: http://abcnews.go.com/US/scuba-tank-explosion-kills-iraq-war-veteran-russell-vanhorn/story?id=14502395 http://abcnews.go.com/US/scuba-tank-explosion-kills-iraq-war... Now, the article says 100psi not 3k, but you'd still probably rather not be near it.
- noir_lord 11y ago100 atmospheres is approx 1500 psi. I inflate bike tyres to 110 and its nothing tbh, 1500psi is a different kettle of fish.
- smoyer 11y agoActually 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.
- abakker 11y agoIsn'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. My point is, speed of failure is important.
- angusb 11y agoThat 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.
- TisButMe 11y agoI'm not sure. The stream of bubbles could have been the remaining dry ice sublimating, couldn't it ?
- bengali3 11y agoThe 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.
- etaty 11y agoIn picture: https://www.youtube.com/watch?v=Ldgp3Ton7R4 https://www.youtube.com/watch?v=Ldgp3Ton7R4 experiment start at 3:00
- oxplot 11y agoCan someone explain how the entire bin went up? Does it mean that the explosion poked a hole at the bottom of the bin?
- troels 11y agoI think the shock wave travels through the bottom of the bin, bounces off the hard concrete floor and back to hit the bucket, thereby lifting it up.
- ColinWright 11y agoI 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.
- TheLoneWolfling 11y agoYou also have less pressure inside the bin than outside.
- TheLoneWolfling 11y agoAs 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.
- davidgerard 11y agoPete is the sort of guy who needs a Skippy's List. See his LJ icon? That's a burning NextCube case.
- sschueller 11y agoSo the solution was the place the "bomb" in the public canal where it could hurt some poor swimmer or small boat when it eventually ruptures. Seems very irresponsible to me.
- kranner 11y agoIt was the best solution he could think of at the time. That's not irresponsible, just human.
- thesteamboat 11y ago> That's not irresponsible, just human. The two aren't mutually exclusive.
- eru 11y agoI don't think anybody swims in the canal in Islington.
- anu_gupta 11y agoI've never seen anyone swimming in it - plenty of kayakers and narrow boats though.
- _anshulk 11y agoMy 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...
- emaniacs 11y agowow, i listening Under Pressure by Queen while writing this comment. :)
- teddyh 11y agoIce ice baby! (Sorry.) http://tailsteak.com/archive.php?num=25 http://tailsteak.com/archive.php?num=25
- Carlee 11y agoI 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.
- octatoan 11y agoSown?
- rtb 11y agoSewn, i.e. stiches in his arm.
- ryan-allen 11y agoI'm more curious about this animate college :)
- leni536 11y ago> 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.
- Lord_Zero 11y ago
- bandrami 11y agoWhy not just puncture the thermos?
- Peroni 11y agoHe 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.
- drostie 11y agoIf 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.
- jamesdelaneyie 11y agoFunny. 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.
- evan_ 11y agoBeing from a very rural area of the US my solution would've been to leave it in a field and shoot it.
- maho 11y agoA few calculations about the possible explosion: - 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. [1] http://en.wikipedia.org/wiki/Carbon_dioxide_data#Vapor_pressure_of_solid_and_liquid http://en.wikipedia.org/wiki/Carbon_dioxide_data#Vapor_press... [2] https://www.google.com/search?q=60+bar+*+1+liter&ie=utf-8&oe=utf-8 https://www.google.com/search?q=60+bar+*+1+liter&ie=utf-8&oe... [3] http://en.wikipedia.org/wiki/TNT_equivalent http://en.wikipedia.org/wiki/TNT_equivalent
- TheLoneWolfling 11y agoYour energy estimation makes no sense whatsoever. The figure you gave is for isobaric expansion, which is an entirely different beastie. Also, he mentions ~100bar, not ~60 bar. When I did a first approximation assuming adiabatic expansion, I got ~22KJ. See https://news.ycombinator.com/item?id=9449086 https://news.ycombinator.com/item?id=9449086
- maho 11y agoYou 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. [1]: http://en.wikipedia.org/wiki/Carbon_dioxide#Physical_properties http://en.wikipedia.org/wiki/Carbon_dioxide#Physical_propert...
- deleted 11y ago[deleted]
- erikb 11y agoPlease 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.
- cjbprime 11y agoSometimes people just write about their experiences, and it's your job to work out what lessons to take away from it, not theirs.
- erikb 11y agoSometimes you have to think about which articles you open to read and the title should tell you.
- aeze 11y agoOr you could spend a few seconds skimming through and see if it interests you. If you're that busy you probably shouldn't be on HN to begin with.
- erikb 11y agoYou 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.
- 11y ago
- secretdark 11y agoGreat 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.
- flarets 11y agoParaphrasing from that article: "So, realising I had created a bomb, I surrounded the bomb in shrapnel and took it to a crowded part of the city".
- mangeletti 11y agoAs soon as I read the bit about putting it in a bag packed with tile I was like, "this doesn't end well". That was a pretty cool read.
- toothbrush 11y agoYeah, 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" My god, man :/
- lvs 11y agoWhy? Nothing bad happened, so what is the point of punishing him? He learned something and went home. So did everyone else.
- greggyb 11y agoEndangerment 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] [0]http://en.wikipedia.org/wiki/Endangerment http://en.wikipedia.org/wiki/Endangerment [1]http://en.wikipedia.org/wiki/Attempted_murder http://en.wikipedia.org/wiki/Attempted_murder
- lvs 11y agoThe 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.
- JackFr 11y agoMy 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.
- arikrak 11y agoAs long as he didn't put aluminum and Drano in the bottle..
- JohnLen 11y agoThis seems to be crazy. Invasion of privacy.
- drc37 11y agoA 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.
- curlyquote 11y agoThe lesson of the story? Don't have kids.
- r00fus 11y agoCan 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.
- TheLoneWolfling 11y agoThe amount of energy in a thermos like that is high enough that I'm not sure that would be safe. Quick approximation, assuming adiabatic expansion: Gamma for CO2 is ~1.29. Pf*Vf^y = Pi*Vi^y Vf = (Pi / Pf) ^ (1/y) * Vi Vf = (100atm / 1atm) ^ (1/1.29) * 1L Vf = 35.51L W = (PfVf - PiVi) / (y - 1) W = (1atm*35.51L - 100atm*1L ) / (1.29 - 1) W = 22.31 KJ 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.
- lifeisstillgood 11y agoI have to ask - can you explain the equations please?
- TheLoneWolfling 11y agoThey all come from the equations of adiabatic processes of an ideal gas. Wikipedia explains better than me: https://en.wikipedia.org/wiki/Ideal_gas https://en.wikipedia.org/wiki/Ideal_gas https://en.wikipedia.org/wiki/Adiabatic_process https://en.wikipedia.org/wiki/Adiabatic_process (Especially the section "Derivation of discrete formula" in the latter) It's only a first approximation, but meh.
- r00fus 11y agoThe 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.