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Homemade Liquid Nitrogen Generator
- idlewords 6y agoI don't see this mentioned elsewhere, so I'll mention it here. Liquid N2 is benign and hard to harm yourself with, apart from frostbite. But it is colder than the boiling point of oxygen, and if you leave open containers of it around, or chill empty glassware, you can condense O2 out of the air. One dangerous scenario is where you chill an empty flask that has organic residue in it, and liquid oxygen condenses onto that. It can go boom. It's not easy to hurt yourself this way, but something to think about (while running at top speed in the opposite direction) if you see pale blue liquid in an N2-cooled apparatus. On the bright side, you can make fantastic ice cream by pouring liquid N2 into a bowl of heavy cream with walnuts and sugar added. The crystals are super tiny so the ice cream has a fantastic texture.
- totetsu 6y agoHandy for when you need to ice some tear gas canisters on the DL
- totetsu 6y agoAfter some research. It seems it might have been mud that they were using in HK for this.
- 082349872349872 6y agoDespite the attempts at monetisation very nice content, containing both theoretical and engineering exposition. Also has descriptions of dead ends on the way to the final working design. (how much revenue can a niche subject like this generate anyway? a dinner per month?[1] at least now the ad-trackers have all incremented the geek bucket for my profile. hope they use saturating addition; I'd hate to see what ads I'll get if my geek score ever wraps around.) [1] this is a serious question. Edit: based on "web site value" sites (as if those are trustworthy), I was way too optimistic with that estimate; it's more like the NPV of the whole domain is a dinner.
- shmerl 6y agoIt's better to use Celsius for such articles and in general too. Metrication process in US is really way too slow.
- deleted 6y ago[deleted]
- cesis 6y agoOr even better - SI Kelvin scale
- mschaef 6y ago> Metrication process in US is really way too slow. I've thought that too, but wonder about what metrification would mean for things like screw thread pitch (which is measured in TPI, and I assume would change if the units changed).
- caf 6y agoIn Australia, where metrication is 50 years old, hardware stores typically stock both imperial and metric fasteners. It's not an issue in practice.
- kstenerud 6y agoSame in Canada. My parents weren't very adept at metric, my generation could handle either one, and the following generations don't know much about imperial other than the few things still stubbornly hanging on (mostly in construction).
- rfrey 6y agoConstruction is the one place where imperial measurements are superior, because they're base 12. Easy division of any measurement into thirds, quarters, half.
- 6y ago
- itronitron 6y agoNeat article, the picture makes me think he refrigerated his entire neighborhood.
- jojobas 6y agoA piston detander should work reasonably well for a small scale liquifier. Last time I ran the numbers it was reasonably possible to liquify air with 2 relatively cheap compressors.
- tim333 6y agoInteresting to see how it works. I've sometimes pondered if you could do cheaper cryosuspension awaiting the singularity.
- throwaw4y-plate 6y agoThis wouldn't seem to be the sort of thing to cut corners on! Five nines and all that.
- tim333 6y agoThough given the chances of it working at all are questionable you could argue that's not such a big deal.
- raducu 6y agoDoes the article/tutorial talk about how you remove water and oxygen from the liquefied air?
- ColinWright 6y agoThere was a chap here in the UK who used to go around giving STEM demonstrations, and in particular would do some wonderful lights, smells, and bangs with simple chemistry. Then the company supplying him with lox found out what he was doing and deemed it too dangerous, so they stopped selling it to him. So he bought liquid nitrogen and distilled his own lox instead. He said it was a great demonstration, and cheaper to boot. He just made sure the supplier never found out. But with this rig he could have done the lot for himself ... I wonder why he never did ...
- MaxBarraclough 6y agoI think I saw one of these demonstrations! I recall him mentioning the tiny temperature difference being enough, as liquid nitrogen is a few degrees colder than liquid oxygen. Wasn't sure at the time if he was kidding about his supplier refusing to sell him oxygen; now I know he wasn't. Assuming I have my memories straight, I must have been about 12 at the time. I had the honour of being handed some candy from his stash [0]. Seemed like a nice gesture. Of course, his next demonstration was some kind of sugar-fuelled pyrotechnics. Evidently, he made a lasting impression. It seems unfair that chemistry has fire and explosions as such a universal and compelling demonstration. I suppose computer science has graphics. [0] Of course, this being in England, I was in truth handed sweets, but one makes accommodations for our American cousins.
- michaelmcdonald 6y agoFear not! I am a ~heathen~ American cousin and would have perfectly understood the reference to sweets. Though I can't speak for all my brethren, I would think most could at least infer what you were talking about.
- MaxBarraclough 6y agoAlmost the Queen's English, too. Purists discourage the ending of a sentence with a preposition.
- rootusrootus 6y ago
- visarga 6y ago> Celcius ಠ_ಠ
- brandmeyer 6y ago(deleted - misinformation)
- kmm 6y agoExpansion into a vacuum, also called free expansion or Joule expansion, is not the same as an adiabatic process, there is no piston and no work is done. For an ideal gas the internal energy does not depend on the volume, so conversely such an expansion does not change the temperature. And of course it's not isentropic either, since the same amount of gas with same amount of kinetic energy now can spread itself over a larger volume.
- brandmeyer 6y agoI stand corrected.
- stevespang 6y agoat $150 I'm onboard as a buyer . . .
- altcognito 6y agoSomething that struck me as pretty amazing was that if you can get liquid nitrogen, you're already cold enough to get liquid oxygen (in fact separating the two may be part of the process here, I don't know) Anyway, liquid oxygen is pretty crazy blue and amazing in its own right.
- HPsquared 6y agoDefinitely a hazard to be aware of - liquid oxygen can be a lot more dangerous than liquid nitrogen, especially if you're not expecting it!
- m4rtink 6y agoYeah - talk with a couple scientists after a liquid nitrogen experiments demonstration. They mentioned even just liquid air is dangerous, as the liquid oxygen in it makes many hydrocarbon materials flamable and even explosive in some cases.
- Gatsky 6y agoHomemade yes, DIY not really.
- jsjohnst 6y agoI’ve read over the plans, doesn’t look to be that hard assuming you already know how to weld decently.
- dylan604 6y agoWhat plans? The sped up video of his hand made sketches? The video was so poorly done, it's hard to even see what is occurring. He spent more time on fucking with his cat with liquid nitrogen than he did on the actual concept/plan/build.
- c22 6y agoThere's a whole website there that includes images of the sketches, lots of photos, and large blocks of explanatory text. If you only watched the video you're missing out.
- dylan604 6y agoi saw the links at the bottom to his about the heater, but totally glossed over the "next" link. i honestly thought it was just a simple write up and was disappointed. thanks for letting me know there was more to be read
- yomly 6y agoWhat kinds of safety risks are there in storing liquid nitrogen in a DIY context? If your container is well sealed and sufficiently strong (define sufficiently...) can you store it in a room temperature garage? What happens if it's a freakishly hot summer one year? Do you have a ticking time bomb in your garage?
- AlexCoventry 6y agoI would be more worried about asphyxiation due to accidental release.
- jedimastert 6y agoThis is why a garage-type situation would probably be better. At least in my garage there's a not-great enough seal that any leaks would go outside before they'd go in the house.
- dylan604 6y ago>can you store it in a room temperature garage? I'm from texas, and that's just a strange use of words in a sentence to read. The air temp outside is 95+ (in the shade) this time of year, and lately >50% humidity. It's stifling hot. Step into the garage, and it is even hotter. Most garages have zero air flow, and rarely are they insulated. It's the least friendly "room" of my house. >What happens if it's a freakishly hot summer one year? We call that a Tuesday.
- mint2 6y agoI’ve never seen a fully sealed LN2 tank. Granted I’ve only worked with the ones for university labs, but all of them have a pressure release valve that’s goes off periodically, with a secondary back up valve. Is this what you consider sealed? If not, you’ll most likely be creating a bomb. Okay I’ve read a story about a fully sealed tank: https://corante.com/how-not-to-do-it/how-not-to-do-it-liquid-nitrogen-tanks/ https://corante.com/how-not-to-do-it/how-not-to-do-it-liquid...
- tptacek 6y agoThere is no danger in storing LN in your garage. Your container won't be tightly sealed (a tightly sealed container full of LN likely is a bomb); gaseous LN will continually leak from your dewar. It's nitrogen, who cares? The major risk with LN is storing it in enclosed spaces, as it can quickly asphyxiate you. So, like, don't take it in an elevator. I'm not sure I understand what the ambient temperature has to do with LN safety.
- jmount 6y agoOne of my favorite chemistry memories: "what is that dripping out the back of the crystallography setup?" (ans: "okay would be a liquid nitrogen leak, explosive risk oxygen condensing out of the atmosphere.")
- tgflynn 6y ago> okay would be a liquid nitrogen leak, explosive risk oxygen condensing out of the atmosphere I don't think that's very likely. I used to work in cryogenic labs and a simple LN2 leak would not have been considered a danger (except in a confined space). The only concern we had related to LO2 condensation was to never let a cryostat warm up or cool down while full of air.
- avmich 6y agoA really good description for how to do it. I've only found one instruction for self-making liquid nitrogen before this site, the one by Ben Krasnow, but that one cheats and uses helium cryocooler. I don't really understand why separation of nitrogen from the air is so essential. I'd also like to see a Kapitza liquifier, where in addition to Joule-Thomson effect you use a turbine for cooling and you need less than 8 atm pressure from the compressor, that would be cool :) .
- lasermike026 6y agoMaybe he shouldn't have poured liquid nitrogen next to the cat.
- nabilhat 6y agoNeeds more safety! Commercial full pressure handling tubing starts at 0.049 to accomodate stress at fittings and thermal cycling. Don't think I'd be comfortable next to 1/4" / 0.035 at full pressure after forming like that! Fittings deserve a mention, they're specialized. LN storage needs more than a mention. An all-stainless thermos can work, but if you've made it this far you can afford $150-200 for a real LN dewar. Source: Dad worked at an air liquefaction plant and is full of usually hilarious stories about gas handling done wrong.
- wglb 6y agoWould love to hear them.