It's cheap because it's a waste product. The boiling point of nitrogen is fairly high as far as cryogenics go, where all the rare expensive gases such as argon are much lower. They basically obtain shit loads of liquid nitrogen in the pursuit of obtaining the rarer gases from air which they sell at a massive premium.

Hence LN2 is as cheap as frozen chips. But the storage cylinders aren't cheap. They are stainless pressure vessels that vent in order to keep a low temperature.

But 200L is about 140 cubic metres of gas at ambient conditions and sounds like a supiciously dangerous way to air condition an office. With nitrogen asphyixiation you don't get any warning, you just pass out and die.

He might have got away with it if it's a large well ventilated office with no midgets working in it.
( Draconacticus Reject shampoo. Demand real poo!, Tue 20 Sep 2011, 16:02, 1 reply)

yeah, I know, I've bought a few dewars in my time.
I don't use the stuff in large quantities though, top-ups to the dewars with my cell banks in once a week really.
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 20 Sep 2011, 16:09, closed)

We used it in an experiment in power generation from it. We had a 950 litre high pressure dewar with a 4kW ambient evaporator attached to it and ran the nitrogen through an expander to generate power.

We vented the nitrogen outside because it's an asphyxiant despite the apparent air conditioning advantages. But we still managed to fill a huge warehouse with an eerie 2 foot deep fog that formed from air passing over the evaporator.

Fun day that :)
( Draconacticus Reject shampoo. Demand real poo!, Tue 20 Sep 2011, 16:14, closed)