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Anonymous Modernist 347

Liquid nitrogen Dewars, etc

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Chef Rubber (www.chefrubber.com) has some reasonably priced liquid nitrogen Dewars, cryo-gloves and aprons, double-walled bowls and liquid separators, etc. A 6 liter Dewar is only $358, and a 10 L $410 -- a far cry from some of the ~$1000 prices I'd heard elsewhere. The holding time is about 109 days, and they include a dipper for removing the LN2 from the container.

Now the next question is whether it is safe to transport the LN2 in a car.

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A few things about buying liquid nitrogen dewars

1. Check around for deals - I found a set of 2 - 20L dewars for $500 on a lab auction site. You can sometimes find some deals on ebay although not as much.

2. Be careful if you are going to buy your dewars used, the principal behind a dewar is a double walled vacuum chamber which works as an insulator. Sometimes when buying a dewar the vacuum chamber has beencompromisedand thus you loose your liquid nitrogen a lot faster.

With all of that in mind, I checked out the chef rubber dewar and it seems like a pretty good deal for a new 10L. Although the item description states that the dipper is for removing the liquid nitrogen I would double check with them because anytime I've seen dippers, they were for submerging products in the liquid nitrogen (they areperforatedwith holes on the bottom of the wand).

When I transport my liquid nitrogen I wedge my dewar between the door of my hatchback and my backseat. It is also helpful to strap it down using some bungie cables or something similar. The biggest concerns with transporting it isaffixationdue to the release of the gas, so you solve this by riding with your windows down. The second biggest concern is having liquid nitrogen thrown about the car if you happen to stumble into a car accident, you can come close to solving this by securing the liquid nitrogen in a part of the car or truck that prevents it from coming near you should you be in an accident. Although both of those scenarios are unlikely, you still need to be vigilant when working with liquid nitrogen. Good luck and if you have any other questions, you know where to come.

Joe

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I bought the Dewar from Chef Rubber,but the dipper they shipped had holes in the bottom and was used to immerse samples, and not for extraction of the nitrogen. I called them, and they admitted that is was their error on the web site, and sent me a proper dipper.

Now that I have it, I guess I need to figure out something cool to do with it, other than smashing nasturtium leaves!

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Robert Jueneman said:

Now the next question is whether it is safe to transport the LN2 in a car.

The short answer is NO. If the Nitrogen should leak out - maybe the Dewar could fall over if you are involved in an accident the nitrogen will boil quickly to make nitrogen gas and this will displace the air in your car and you will suffocate - not a good idea. You can transport liquid nitrogen either in the boot (US trunk) of the car only if it has a separate sealed bulkhead - not in a car with fold down rear seats. It is best to use a van (US truck) with a sealed rear compartment or a trailer. You should inform your insurers that you will be transporting liquid nitrogen (otherwise you may find your insurance is invalidated) and you should display a cryogen in transit yellow warning sign.

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Now the next ques­tion is whether it is safe to trans­port the LN2in acar.

The short answer is NO. If the Nitrogen should leak out ' maybe the Dewar could fall over if you are involved in an acci­dent the nitro­gen will boil quickly to make nitro­gen gas and this will dis­place the air in your car and you will suf­fo­cate ' not agood idea. You can trans­port liq­uid nitro­gen either in the boot (US trunk) of the car only if it has asep­a­rate sealed bulk­head ' not in acar with fold down rear seats. It is best to use avan (US truck) with asealed rear com­part­ment or atrailer. You should inform your insur­ers that you will be trans­port­ing liq­uid nitro­gen (oth­er­wise you may find your insur­ance is inval­i­dated) and you should dis­play acryo­gen in tran­sit yel­low warn­ingsign.
Thanks, Peter. I was aware of the asphyxiation hazard, and had planned to drive with the windows open. Unfortunately, my SUV doesn't have a separate trunk, although I guess I could put it on the roof. But never in a million years would I have thought to talk to my insurance company, or display a HAZMAT sign. This was for a class in Modernist Cuisine I am planning to teach in Santa Fe, about 60 miles away, but all things considered, it just isn't worth it. Now a question for you and Joe Lipinski. Are you using liquid nitrogen as part of your modernist cuisine cooking, or are you just familiar with it from your occupation, e.g., a dermatologist of something? I've been thinking about starting a thread on liquid nitrogen techniques and recipes on eGullet, in part because the Cooks Forum doesn't seem to be very widely read. But if there is any interest, I suppose we could start one here.

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Judy, just so someone doesn't misunderstand you, you must NEVER, NEVER, EVER screw the lid on tight on a Dewar or other container of liquid nitrogen, e.g., a Thermos of it, whether you are transporting it or otherwise. A liter of liquid nitrogen will turn into 700 liters of gaseous nitrogen as it vaporizes, and that is enough to cause a very serious, concrete-busting, room destroying explosion. For this reason, Dewars may have a small lock on them to prevent misuse, but they do not have a tight screw-down lid. Instead, they are explicitly DESIGNED to leak, safely, albeit slowly.

For that reason, don't store the Dewar is a tightly closed room, and certainly not in something like a walk-in refrigerator. You might not be able to walk out again!

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Peter,

As Robert said, be careful when transporting Ln2 - I, myself never thought about letting my insurance company know that I am transporting Ln2 or also posting a sign on my vehicle indicating that I am transporting Ln2, so thanks Robert.

As for uses, the book lists some of the uses; You can also find some other techniques at cooking issues - http://www.cookingissues.com/primers/liquid-nitrogen-primer/ . Although the book and cooking issues covers most of the techniques you can find some new ones here and there... also don't forget to use your imagination.

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The Cooking Issues article by Dave Arnold cited by Joe is quite comprehensive. In particular, the Arizona State University PDF on cryogenic safety should be required reading for anything thinking about using LN2.Cf.http://ets.fulton.asu.edu/files/shared/CryogenHandling-FSE.pdf.

I recently had the tasting menu luncheon at the famous Eleven Madison Park in NYC, and during the meal they took me back into the kitchen where they fixed an "edible cocktail" made with LN2 ice cream, some diced apples, and some pomegranate juice (I think). While delicious and impressive, I was shuddering the entire time because their very casual attitude towards safety.

The woman who was preparing the "cocktail" was wearing a cotton chef's apron over her clothes, had no gloves or goggles, was handling the ice cream in what appeared to be an insulated Dewar with her bare hands, and was stirring the ingredients with a metal spoon, stll with her bare hands!

Good Grief, people!

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