With the same frivolity as "Has anyone ever built a dalek", I wonder if any of you have thought about making liquid nitrogen at home.
I always liked cryogenics as a kid :-)
Of course anything is possible - it's just a matter of cost! :-)
M
It's very, very difficult to do on any kind of DIY budget :-)
However, the good news is it's very easy to buy, and quite cheap too. You'll need a reasonable sized dewar, maybe 20-25l, and an account with BOC. I pay ~£40 per fillup.
Or in a farming area, talk to the local AI man. (And no, I don't mean Artificial Intelligence.)
And what do you use it for Grunff? Surely not just for party tricks? :-)
M.
Sadly it is just for messing around. I have a nitrogen laser which I run off it sometimes, but that's about the most useful thing I do with it!
What happened was I missed it too much after my time in the lab, so had to sort out a private supply.
What sort of requirements are there on getting an account? How much is a dewar?
Hydrogen peroxide vacuum distillation to make HTP for rockets is annoying, and I was wondering if O2 might be more usable.
(messing around in garage making rockets - eventual goal is a 4 stage orbital one with a kilo to orbit.)
This varies a lot depending on who you talk to. There is supposed to be a minimum annual spend, but I've never had this enforced. I buy 2-3 loads a year.
New a 25l dewar is about £300, but you can get second hand ones for around £100.
Liquid O2 is a lot less readily available, but you can still get it if you try.
Excellent!
Ice cream, of course!
I'm half-seriously thinking about doing it as a finale for one of our barbeques this summer.
I remember going to a Royal Institution (?) science lecture whilst at school and the lecturer put a sausage in a flask of liquid gas. When he took it out it was of course supercold: he dropped it and it shattered into fragments. Ever since I've wondered what those fragments would be when thawed out: a sort of mince? I'm not asking you to repeat the experiment
Agree with the "Excellent"; but I somehow hope I live up-range from Ian!!
Andrew
Depending upon the sausage probably some mixture of rusk, hoof, nose, lips and whatever else... Nice and easy way of chopping liver I suppose!
The fun lectures were the ones at University periodically held by the resident pyromaniac of the Chemistry dept across the road from us. Digestive biscuits dipped in liquid O2 & then ignited make rather good catherine wheels. Don't know whether Rich Teas are any good but at least at that temperature you wouldn't have the "one dunk disintegration" problem a la Peter Kay.
Small, squishy lumps of sausage meat.
One great thing you can use it for is freezing herbs. I haven't done this in years (been too busy with house project), but the quick freezing really preserves the flavour.
I saw a similar thing at the Smithsonian, only he used a squash ball and chucked it pretty high. When it hit the floor some unsuspecting passers-by had a bit of a shock - it made quite a bang and there was shrapnel flying around. Afterwards I picked up a few pieces; the fractured surfaces looked like broken glass.
Thanks.
HTP H2O2 is even less available. IIRC, 70-90% may be available if you're willing to buy a train load, but otherwise you've pretty much got to distill it yourself.
Well, I can always get you on reentry :)
Actually, the stage weights are fairly modest, somewhere around 5Kg, 25Kg,
125Kg, 625Kg (fueled), so on launch it's well under a ton. And the first stage is meant to come back on a parasail.The second stage, which bits may reenter intact of, has a dry weight of only 25Kg.
I was initially considering a launch from around John-o-groats (sp?) over the pole.
I would think you would need at least a scuba bottle compressor. You then need a longish length of very very small gauge metal tube (probably less than 0.5mm ID). This you coil so it fits into a very very small thermos flask.
The output of the scuba receiver (already cooled to ambient) compressed at about 200 bar goes into the fine tube the air escaping from the open end of the is cool this pre-cools the compressed air coming down the fine tube until the stuff coming out is so cold it's liquid.
I've done this at college with a 200 bar bottle of nitrogen as the source. This made about a thimble full in 5 minutes. The flask part being the size of a thimble so it might only work on that scale. 8-(
I expect there are some nasty gotchas like having to get rid of all the water and CO2 from the air before compression? 8-(
Why 4 stage ? I've always thought the helium weather balloon (also from BOC) then a single stage (fired in the correct direction and not through the balloon aka "the difficult bit") was the most elegant approach. (this is about to go sooooo OT)
No, many people have built LN2 refrigerators. It's hard to do it efficiently, but refrigeration to this temperature isn't much harder than making your own gas turbine.
Don't forget that Ohnes liquified helium in 1911 and discovered superconductivity almost immediately afterwards. Nitrogen was back in the 1880's. Now how much technology did any lab have back then that you can't reproduce in a half-decent modern home workshop ?
Even more fun - damaged Dewars are free and the TIG welding course is about £200. If it's not aluminium and the damage is minor, you might just be able to silver solder it.
Well the availability of whatever ore the Curies purified radium from is presumably a little harder to get now :-)
That'll cost you in orbital velocity: you won't pick up anything from the earth's rotation in that direction. I assume you've done the calculations :-). I've been down to the ESA launch site at Kourou, French Guiana, and it's there for a good reason, unobstructed launch path east over the atlantic and only 5 degrees north. You'd better talk to the folks in the Orkneys, they're due north of John O'Groats!
Andy.
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