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nathanm

Cooking with Liquid Nitrogen

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A thermos, glass or not, would not keep it at room temperature. It would keep it much colder than that since it is in fact an insulated container.

Insulation only buys you time. No matter how well insulated the container, the LN2 is going to pick up heat from outside, and a certain amount will boil off. A cryogenic dewar (the only thing liquid gasses should be stored or transported in) is basically a thermos that can't be fully sealed. The better ones are spill proof, but still vent to the outside. A fully sealed thermos is 100% guaranteed to explode ... eventually.

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Does this mean the English-language media will correct all the "dangerous chemical" references and ridiculous assertions that liquid nitrogen and molecular gastronomy are inherently unsafe?

...of course not.

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It is making more sense now.

Looks like he brought it home in an ISI Siphon or the like (sealed). He then proceeded to try to open said (pressurized) siphon with a screwdriver in the bathroom (why) of his girlfriend's apartment. I'm guessing he had the siphon between his knees at the time since the explosion blew a chunk out of one of his calves and also did significant damage to his naughty bits. Talk about adding insult to injury the local police also will be pressing charges against him.

If not a darwin award winner certainly a runner up.

Well, if he successfully blew off his naughty bits - then he should qualify for a Darwin award! Don't think you have to kill yourself, just remove yourself from the gene pool.


Edited by Kerry Beal (log)

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It is making more sense now.

Looks like he brought it home in an ISI Siphon or the like (sealed). He then proceeded to try to open said (pressurized) siphon with a screwdriver in the bathroom (why) of his girlfriend's apartment. I'm guessing he had the siphon between his knees at the time since the explosion blew a chunk out of one of his calves and also did significant damage to his naughty bits. Talk about adding insult to injury the local police also will be pressing charges against him.

If not a darwin award winner certainly a runner up.

...Währenddessen wurden neue Details zum Hergang des Unglücks bekannt... Martin E. soll sie in einem Sahnesiphon – einem druckfest verschließbaren Gefäß – in die Wohnung seiner Freundin gebracht haben, für einen solchen Transport ist der Siphon ungeeignet.

Im Badezimmer habe der Koch dann versucht, den Stickstoff umzufüllen, das Gefäß stand wahrscheinlich bereits unter hohem Druck. „Offenbar hatte er versucht, den verschlossenen Siphon mit einem Schraubenzieher aufzuhebeln“, so Laurisch. Dabei kam es zur Detonation, das Badezimmer brannte völlig aus. Gegen den Koch werde nun strafrechtlich ermittelt, sagte Laurisch. „Wenn die körperlichen Schäden über das hinausgehen, was er angerichtet hat, werden solche Verfahren aber gemeinhin eingestellt.“

full article

More on the extent of his injuries

Full Article Translated (Thanks to Babelfish.yahoo)

English Translated Page-Injuries (thanks to babelfish.yahoo)


Edited by RAHiggins1 (log)

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For years, I used LN2 in the lab. It was kept in large thermos bottles. Yes, the stuff is dangerous if not handled correctly. Protective eyewear is necessary as mentioned above. You don't wear flipflops or go barefooted – that is asking for trouble. The chances of t going into a shoe are small and it provides sufficient protection. As for playing around with it.... You keep your hands away, only using non conductors such as gloves when putting things in, taking them out or manipulating them. I have seen chefs spinning things in LN2 without gloves. That is asking for trouble. The stuff boils at -196C (-321F). In less than a second your fingers will freeze solid.

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Mikels is right. LN2 is used all over as a source of cold. (I've used it in various kinds of laboratories for many years.) It's fairly benign stuff if you follow the simple precautions, which are second-nature for people who work with it. Note that anything that builds pressure can cause an explosion if you put it in a closed container (I've seen it happen with "dry ice" -- LN2's solid cousin -- and even beer). Actually there are even other, rare dangers with LN2 because some solid objects, if they freeze in it, form internal stresses (rather like Prince Rupert's tears, or Bologna bottles -- both made from molten glass suddenly chilled). In LN2, pink rubber erasers, for use with pencils, become like little ceramic bricks, but when taken out and left to warm up, they can fly apart from the internal tension. A favorite prank of graduate students. (Or so I hear.) I've been wondering if the same thing will happen from someone freezing solid food in LN2, who doesn't know about that effect.

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Another hazard that I don't think has been mentioned is that liquid nitrogen will condense oxygen from the air. Liquid oxygen is very reactive and can cause explosions when in contact with organic matter.

Hey, if you want to play with the stuff, great. But invest in training - the chemical companies offer it all over, as do universities. I'm not saying it's any more dangerous than the stuff cooks deal with every day, just that different precautions are needed.

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The main lesson here for kitchen people is REALLY simple.

Don't ever, EVER, EVER close any liquid Nitrogen container. Ever.

Simple enough?

Not ever.

Never.

The stronger your closed container is, then the more damage that will be caused by the eventual, inevitable, explosion when it bursts.

If you don't know that, then all other advice would be wasted. Except the advice that if you don't know that, then you should not have anything to do with the stuff ...

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The main lesson here for kitchen people is REALLY simple.

Don't ever, EVER, EVER close any liquid Nitrogen container. Ever.

Well ... a liquid nitrogen dewar is designed to be closed. They close without creating an airtight seal. Except for the pressurized ones, which have a pair of relief valves.

So don't ever close a container of LN2 unless it's designed to be closed.

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The chances of it going into a shoe are small and it provides sufficient protection.

Yes, the chances of it going into a shoe are small.

But does a regular shoe provide sufficient protection? Debateable at best.

I'll challenge anyone to this: I will happily, with witnesses or on video, pour a fluid ounce of LN2 onto my bare foot.

Will anyone here volunteer to pour the same amount onto the opening at the top of their shoe? I sincerely hope not.

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I'll challenge anyone to this: I will happily, with witnesses or on video, pour a fluid ounce of LN2 onto my bare foot.

The context is cooking in kitchens, full of hazards for foot injuries.

Unless you're prepared to expand the offer to things like boiling sauces, or knives and forks falling from table height, I think the point is moot and not worth belaboring. (I've always worn closed shoes when working with LN2, btw, in labs with safety standards. Flip-flops would not be allowed or sensible, for the same reasons as kitchens.)

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How are the splash-related hazards of liquid nitrogen any more dangerous than they are for boiling oil in, e.g., a deep fryer?

If people in the kitchen simply think of LN2 as the "cold equivalent" of boiling oil, a lot of problems would be solved. Splashing boiling oil on your foot or in your eye is not such a great thing either, and yet every fast food restaurant in American has a fat fryer.

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The context is cooking in kitchens, full of hazards for foot injuries.

Yes, and as I said earlier, bare feet or the equivalent are not an apropriate solution for a commercial kitchen. If I ran a kitchen that used LN2, I wouldn't necessarily follow all the oficial lab saftey recommendations (gauntleted gloves, neoprene-type boots and aprons, etc.) but I'd want employees that handled it to wear high topped boots like blundstones, with their pant legs over the tops of them.

How are the splash-related hazards of liquid nitrogen any more dangerous than they are for boiling oil in, e.g., a deep fryer?

The dangers are similar, but in many cases less intuitive. For example, you can freely pour LN2 over your bare skin and watch it roll off ... something you probably wouldn't do with hot fryer oil. This can lead to complacency.

Also, LN2 often gets handled in more awkward ways than typical hot liquids in the kitchen. Pouring it into the bowl of a stand mixer from a 4 liter dewar, while the whole counter is enshrouded in white mist, opens up some unique potential for splashes.

In addition, there are dangers unrelated to splashing that people need to be educated on ... like the exploding container potential that started this thread, or the suffocation potential from spilling a bunch of it in a closed space.


Edited by paulraphael (log)

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I think that I'm going to try to score some liquid nitrogen. My use of the verb "score" should indicate the level of thrill-seeking risk I imagine. Whatever those pleasures, I also don't want to be silly about something potentially dangerous.

I know that the Modernist Cuisine book, which I haven't got handy at the moment, has a section on this, but I can also imagine that others here have experience, techniques, cautions, and the like.

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My first and best advice: pay attention. It's not as dangerous as it's made out to be, but there are some real risks associated with it. Use it in a well-ventilated area, don't let it touch your skin for long periods of time, don't use metal utensils in it and let them touch your skin for very long (I gave myself frostbite that way once, because I wasn't paying attention.) Obviously, don't put it in a sealed container. Overall, pay attention!

Oh, and have fun with it! Be sure to take a drop of it and roll it across a flat surface to enjoy the Leidenfrost effect, freeze things solid and shatter them, and make spooky vampire voices over all the "smoke." :biggrin:

Edit: Having offered that advice, I have a question of my own for all the other LN2 users out there: A local hardware store carries liquid nitrogen, but specifies that it's not food safe. I think it's cool that they felt the need to specify that, but it made me wonder: how can it not be food safe? Is this something I actually need to worry about, or are they just covering themselves legally?


Edited by mkayahara (log)

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I wonder if the container it is stored in was not cleaned to food-safety standards? Perhaps it has oil residue or the like? The same may apply to other equipment that was used to handle it. I don't know for sure, obviously, just guessing here.

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The big big thing with LN2 is to NEVER put in a tightly sealed container. It will explode. Get a thermos and drill a hole through the cap so it can vent off pressure. A thermos is a good idea to slow evaporation of the LN2 and it is cheaper than the Dewar flask somebody will try to sell you.

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Just one liter of liquid produces around 700 liters of gas at atmospheric pressure, displacing significant quantities of breathable air if the gas is released in a confined space.

You can kill (suffocate) many people inside an elevator cab if your nitrogen container is broken inside an elevator.

The lack of oxygen in a confined space with a fire burning can also create CO.

dcarch

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I have not used liquid nitrogen myself, but the cooking issues primer seemed pretty good (as their stuff usually is):

http://www.cookingissues.com/primers/liquid-nitrogen-primer/

Yes, I second that! VERY informative, and leans toward the cautionary side of things. I too am looking to score a dewar of liquid nitro, but will probably find a local chef that has experience walk me thru the paces first.

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Great and timely topic!

I've been curious about this as well, and have frankly been a little too scared to bring some home, especially with a three year old around the house. That said, I'm completely ignorant as to the real vs. imagined hazards of liquid nitrogen. For example, I fry stuff all the time, and a hot oil spill is probably more dangerous than a liquid nitrogen spill. Then again, I had no idea about the sealed container issue! There's so much I don't know about this stuff.

I guess my big question is what are people doing to store it and what quantities are practical for purchase and storage at home. Also, how long does it last? Given that a proper container must incorporate some ventilation to release pressure, it seems like you would also have significant loss from evaporation.

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Airgas Corporation has a plant several miles from my house and one of my neighbor’s works there. On occasion he has brought some home to play with. Not culinary uses. Just for laughs. He is very safety conscious with it. The container he transports it in looks like a heavily insulated five gallon gas can. He always tells me that most people understand that it can cause serious freezer burns, but most have no idea of the dangers of oxygen replacement. In the industrial enviorment he tells me the oxygen replacement danger is of a greater concern than the thermal one. I've seen him freeze all sorts of things and shatter them for effect. But he does this outside.

I have no advice on how it works in a culinary fashion, but I also urge caution with it as I have seen what it can do.

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I guess my big question is what are people doing to store it and what quantities are practical for purchase and storage at home. Also, how long does it last? Given that a proper container must incorporate some ventilation to release pressure, it seems like you would also have significant loss from evaporation.

Personally, I would never store or transport it in anything but a purpose-built Dewar. I'm not sure what the evaporation rates are like, but there is certainly some loss over time, so I'd buy it in small quantities and use it promptly.

Edit: Heard back from a friend, who says his supplier told him that 10 litres would take 40 days to dissipate from a Dewar.


Edited by mkayahara (log)

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I used to use LN for my graduate research (characterising semiconductor materials at low temp). There used to be a big pressurised tank of it in the basement of the building. Every so often I would trundle down with a large spherical dewar (polystyrene stopper) in a wheeled mount that allowed it to be transported and allowed tipping out. This was my "stash" - can't remember how long it lasted - maybe a week or two.

On a "per experiment" basis, I would fill a big polystyrene bucket with as much LN as I needed to fill a small cryostat. I was aware of the oxygen/air displacing properties but the lab was sufficiently ventilated.


Edited by CFT (log)

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