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how hard would it be to liquefy air? Answered

Could someone with hardware store type parts be able to liquefy air. I read something about regenerative cooling...could this be used with a compressor to super cool the air to the point of liquefying it?

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WalterK (author)2012-07-04

Ok I only have a master of ME degree so I maybrave an advantage here. Usingg Home Depot and lowes materials I produce all the liquid air I want. Have to keep dumping the dewar due to nitrogen boil off. But the production is straightforward. Start with 100 psi air down a small central line. Expand through an orifice into a stainless insulated tank. The blow back air runs in a concentric jacket around the feed air . Now keep in mind, the feed air must be cooled to atmospheric say 90 f or below and the concentric section as long as possible, mine is 20 ft insulated. It takes a while to cool down. It chokes occasionally with ice but it works reasonably well. I'm looking for 50 lbs or so of thorium if anyone has any..... I have heavy water. Also would like to get a couple grams of radium.

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orksecurity (author)2009-07-31

Websearch on "liquify nitrogen" finds some related discussions, eg http://www.gizmology.net/liquid_air.htm. (There are also a number of badly uninformed flamages... but that's the net for ya.)

Note that liquid nitrogen is often available from the same places that supply tanks of gas and/or dry ice, and last tiime I looked (admittedly 30 years ago) the price per gallon was cheaper than milk. That's assuming you supply your own vacuum carafe -- an uncapped thermos bottle works. (It should be obvious why you don't want to seal the container tightly.)

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benthekahn (author)2009-02-04

Yes. Actually liquifying air is probably close to impossible with hardware store components.

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BeanGolem (author)2009-02-03

I know that the Space Shuttle Main Engine has provisions to avoid liquid air dripping off of the fuel ducts onto electrical components. But that's because the fuel is liquid hydrogen (second coldest boiling point to Helium) and much colder than anything you'll find in every-day life.

I don't think that hardware store parts could liquify air too readily. You would also want to be careful dealing with liquid oxygen, which has the potential for very spectacular explosions and various other extreme oxidation reactions.

Check out this site for some very helpful information on cryogens.

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UziMonkey (author)2009-02-03

I think that would be extremely difficult. Nitrogen (which is the primary gas in air) boils at something like -200 degrees Celsius. Liquid nitrogen is made by compressing and decompressing nitrogen repeatedly, until it condenses into a liquid. The type of compressors, coils and tanks needed may not be readily available.

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