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Where To Get Liquid Nitrogen?
I often get asked "Where can I get Liquid Nitrogen?", so here are some answers. It all depends on How Much liquid nitrogen you'd like to get.
If you'd like to get hundreds of gallons of liquid nitrogen every week, the best way is to have a machine to make it. It's made by compressing air and then removing the dry ice and oxygen. High-powered compressors are the way.
If you'd like tens of gallons a week, another alternative is to buy liquid nitrogen from some liquid gas suppliers. You can find these in the phone book. It's best to shop around! It has to be considered carefully, as some charge quite a lot for the delivery and/or containers. So get a variety of quotes from different companies. Remember that liquid nitrogen is considered as a by-product in some places and not others, so there is a wide range of pricing.
Some of the liquid gas companies operate like an emergency service, so if you want 250 litres right now, they can deliver. Expensive, but worth it.
However, most of the people who ask me about where to get liquid nitrogen are looking for a few litres to do their own experiments and to experience first-hand the strange cryogenic qualities of liquid nitrogen. So, the rest of this page is about this:
Where to get small quantities of liquid nitrogen:
The first thing to know about this is that you can't buy convenient small containers of liquid nitrogen off the shelf in shops and store them at home. It doesn't work like that. The problem is that nitrogen is much lighter than butane, which you can get in small aerosols. If you tried to squeeze nitrogen into a can you'd find it would need to be an extremely strong can! At room temperature, nitrogen is always a gas regardless of the pressure, and so the cylinders would have to be immensely strong, like oxygen cylinders. For this reason, it's generally best to avoid trying to keep nitrogen at pressure and much easier to just keep it in well-insulated cool flasks.
No flask is perfect, so the stuff is expected to evaporate slowly off. Don't try to stop it doing this. It will explode!
However, even though the industry standard for a liquid nitrogen flask is the five gallon (25 litre) Dewar, complete with loose cork, it's quite possible to store liquid nitrogen for a day or two in a Thermos flask of the type used for keeping tea warm! They're just as good at keeping the liquid nitrogen cold as they are at keeping the tea warm, and are usually made quite well, and won't often smash when the liquid at minus 196 degrees Celsius is poured in.
So, to get some liquid nitrogen, it's best to get some flasks and to look for places that already have huge quantities of liquid nitrogen being stored. The sorts of places that have liquid nitrogen are: hospitals, physics labs, mortuaries, strawberry freezing factories, cryonics facilities, and anywhere that's using superconducting magnets.
When you arrive at the place and ask nicely if they might spare some liquid nitrogen, your chances of being granted your request tend to be improved by:
1. Your reasons for requiring some liquid nitrogen.
2. The size of your flasks (bigger = better). (It's to do with Area versus Volume considerations, as well as the credibility of the proposed scientific purposes).
3. Your demonstrated safety-conscious knowledge.
Generally, if you've got some kind of personal scientific interest in the behaviour of liquid nitrogen and/or wish to put on a memorable educational demonstration, and you've got some reasonable flasks and the good sense not to screw the lids on, and you ask nicely, you're in with a good chance of winning yourself some liquid nitrogen.