# Liquid nitrogen

1. Sep 9, 2006

### Mk

Liquid nitrogen!!

No, I don't have any, but I WANT SOME. I have no idea how to proceed. How much does it cost, flask included, and where can I get it? Do I have to use all of it right away, or can I store it for more than a few days? What kind of saftey should be taken into consideration besides the obvious?

2. Sep 9, 2006

### Staff: Mentor

Well, one should probably enroll in a university physics program.

One could get liquid nitrogen from a company like "Liquid Air (Air Liquide)", or BOC. One needs a Dewar Flask.

Precautions - Do not drink it! Do not pour it on your skin.

3. Sep 9, 2006

### Mk

:rofl: :rofl: :rofl:

Actually I guess there are some people that actually did that.

Then again people involved are usually smart enough not to think about it.

Last edited: Sep 9, 2006
4. Sep 9, 2006

### franznietzsche

Incidently you can make perfect ice cream with it. Just milk, sugar, whatever frui ingredients you want, stir while pouring in the nitro. Keep stirring. Works wonderfully. Thanks for the tip on where to get it.

5. Sep 9, 2006

### Bystander

Hit the "Jello Pages" for "welding supply;" used to be around 10-20 cents a liter, probably gone up; dewar rental ain't that bad, cheaper than buying one and having it go "soft." Storage "life" in a "hard" dewar is around a week for 50 liter, don't count on more than two to three weeks for a 200.

6. Sep 9, 2006

### Staff: Mentor

My dad used to bring some home every now and then when he worked for an industrial gas company. The big, insulated thermos bottle he had held 5 or 10 gallons or so and kept for a few days.

And if you can get it, it can be cheaper than bottled water.

7. Sep 9, 2006

### Mk

Oh man, I was going to use 200 L! :rofl:

8. Sep 9, 2006

### Gokul43201

Staff Emeritus
How much do you need? Any big school that uses LN2 on a regular basis will let you have some - it's real cheap when you buy it bulk. Much less so if you want small quantities. Some places like welding supply stores or maybe even medical suppliers will sell maybe by the gallon or so. If you're buying small amounts - a gallon or less - the typical cost is somewhere between $15 -$30 per liter, but if you want several tens of liter, you can get it for a buck a liter or thereabouts.

How long you can store LN2 depends on how you're storing it. If you can borrow a 5/10/20L dewar from a friendly neighborhood physics or chemistry lab, that will typically boil off no more than half a liter a day. If you're going to use a thermos flask, you won't likely be able to store any amount for more than a day (two, if you're real lucky).

Safety: there are several good links on the web that teach you the basics of LN2 safety. The most important thing to keep in mind is to not store in an airtight container - that makes a bomb.

http://webs.wichita.edu/facsme/nitro/safe.htm
http://www.chemistry.ohio-state.edu/ehs/handbook/gases/cryosafe.htm

Probably the neatest LN2 site on the web:
http://www.physik.uni-augsburg.de/~ubws/nitrogen.html

Last edited: Sep 9, 2006
9. Sep 9, 2006

### Mk

About 50L sounds like the right amount for me right now.

Thanks for that last site, I haven't seen it for a while!

What kind of thermos flask are you talking about? Surely not a normal THERMOS?

10. Sep 9, 2006

### Gokul43201

Staff Emeritus
Yup, a stainless steel (as opposed to a fiberglass) thermos flask with a vent hole in the cap will work for short durations. But I don't think you get these in anything bigger than a couple liters.

11. Sep 9, 2006

### Manchot

Honestly, I wouldn't even bother. Up until a few months ago, I thought that liquid nitrogen was really cool (no pun intended). Finally, I got to play with some in the lab in which I work, and I was, quite frankly, pretty disappointed. Once you get the initial fun out of the way, it becomes quite boring.

12. Sep 9, 2006

### franznietzsche

ICE CREAM!!!!

13. Sep 9, 2006

### zoobyshoe

I've read that if you drive a Stirling Cycle engine with an external motor of any kind it will cause the hot end to become extremely hot and the cold end to become cold enough to liquify the air that comes in contact with it. The liquid air was described as just dripping off the cold end. This would be a mix of O2 and N2, but should serve for all the same fun and experiments, including ice cream. I've always wanted to try it.

14. Sep 9, 2006

### Rach3

No, it's quite different. Liquified air, and LOX, is a very dangerous oxidizer.

15. Sep 9, 2006

### Mk

16. Sep 9, 2006

### Tomsk

Actually... you can, if you're careful, as it boils before it touches your skin, creating a pocket of air to sit on. Thing is, you have to have your hand pointed down so it runs straight off. I wouldn't do it if you have hairy arms, and roll your sleeves up, it'll get into fabric and freeze it, which would probably then freeze your skin.

I did hear a story about a student getting mixed up with that, and he thought you could put it on your tongue, or even swallow it. He was wrong. Ouch.

17. Sep 9, 2006

### Mk

But you better not pour too much on yourself, drips are ok, but not a liter.

18. Sep 9, 2006

### Rach3

A labmate once accidentally spashed a bit of LN2 from an open flask he was carrying, onto his arm. Says it burned and was very painful. No lasting injury though.

19. Sep 9, 2006

### Gokul43201

Staff Emeritus
I've SEEN a professor swallow about a handful of LN2.

20. Sep 9, 2006

### Tomsk

I saw a professor poor quite a lot over his hand, but it was at a steep angle. I've dipped my finger in some quickly, but apparently this student had to go to hospital, which must have been horrible.