Cool it, man.
I never arranged cooling for a stuffy office one hot summer by pumping liquid nitrogen slowly onto the floor. I didn't get through 200 litres of the stuff per day for a two week heatwave. And I certainly didn't make sure that this waste of expensive cryogen was booked to the metallurgy department next to the engineering department for which I worked.
(ubergeekian, Tue 20 Sep 2011, 9:11, 59 replies)

that's right, you never did.
because you are a liar on the internet.
( janet aylia y'all motherfuckers need jesus, Tue 20 Sep 2011, 13:01, closed)

Is that how you got your superpowers?

( Edd: The Unfunny Try-Hard Edgelord, Tue 20 Sep 2011, 13:21, closed)

please explain this...
or risk looking like a lying cunt
(likeajackhammer, Tue 20 Sep 2011, 13:22, closed)

So, assuming you only worked a 5-day week that's 2,000 litres.
Of course it happened.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 13:23, closed)

I ONCE PUMPED LIQUID NITROGEN IN A PROZZIE'S CUNT TILL I CUMMED ICICLES.

( mark morrisons prison shoes I love Willie, Tue 20 Sep 2011, 13:27, closed)

This is more likely

( Two Hats I saw someone eating M&M's with a spoon, Tue 20 Sep 2011, 13:34, closed)

I once beat up Chuck Norris and Bruce Lee for calling my pint a puff

( Two Hats I saw someone eating M&M's with a spoon, Tue 20 Sep 2011, 13:34, closed)

In 1972, I was in a crack commando unit and we were sent to prison by a military court for a crime we didn't commit. We promptly escaped from a maximum security stockade to the Los Angeles underground. Today, still wanted by the government, we survive as soldiers of fortune. If you have a problem Two hats, if no one else can help, and if you can find us, maybe you can hire... The QOTW-Team.
( mark morrisons prison shoes I love Willie, Tue 20 Sep 2011, 13:41, closed)

"Face" drives a Honda Accord

(likeajackhammer, Tue 20 Sep 2011, 13:51, closed)

I BET IT SPLUFFED

( mark morrisons prison shoes I love Willie, Tue 20 Sep 2011, 13:58, closed)

Well, someone's done the math for doing this at least
Science bits
( monkeyboyalpha jumping on the bandwagon since, Tue 20 Sep 2011, 13:37, closed)

Meh, it's vaguely possible
It's not as though that stuff is really expensive. As one of my professors put it "It costs about the same as milk".
( MatJ LOOK, Tue 20 Sep 2011, 13:59, closed)

I guess it depends on the quantities you're talking about...
www.intermedicaldirect.com/products/Minor+Surgery/Cryosurgery/Liquid+Nitrogen+Storage+Dewar,+20+litre/992051844

And also purity etc.?
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 14:04, closed)

This is for the container, not the liquid
Liquid nitrogen itself is pretty cheap.
(Imaginary Ed was dreamed up on, Tue 20 Sep 2011, 14:07, closed)

A mong AND a cunt!
I've achieved quite a lot there...
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 14:11, closed)

it's vaguely possible.
provided, of course, you've got someone to take away the asphixiated bodies of everyone in the room afterwards.
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 20 Sep 2011, 15:29, closed)

You're breathing 78% nitrogen right now

(moon monkey is busy making memories worth repressing, Tue 20 Sep 2011, 15:35, closed)

Yup, indeed we are.
However it wouldn't take much effort or poor ventilation to bollocks that % right up.
The ventilation's the thing.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 15:37, closed)

ooh, I'd never have know that. Cheers for the info.
200L of liquid nitrogen is 200 cubic metres of gas, more or less. That's enough to completely displace all the air in a fairly large room. And you pass out at around 12% oxygen and you die around 8-10%, so you'd only need to displace just over half of it to kill everyone.

To put it into context, knocking over a dewar (liquid content a couple of litres) can and has proved fatal in small enough research labs, particularly basement ones. Which is why all mine have low 02 alarms. 200 L in a day? not unless it was in a hangar.
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 20 Sep 2011, 15:46, closed)

Seeing as you seem to know about this sort of thing...
How much would 2,000 litres of liquid nitrogen set one back?
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 15:49, closed)

I dunno, invoices for filling my dewars go to a different Uni department
for some obscure reason. It's not expensive, though. Cost certainly isn't the restraining factor in the likelihood of the above story being true.
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 20 Sep 2011, 15:52, closed)

Since you're interested
I just called my facilities manager. BOC charge around 30 pence a litre for liquid N2. Although there's a fairly sizable minimum order.
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 20 Sep 2011, 15:55, closed)

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, closed)

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)

Not all at once.
If it had been done, the 200l would have been pumped out over seven or eight hours.
(ubergeekian, Tue 20 Sep 2011, 23:04, closed)

This story has generated quite a number of serious, technical responses.
Me? I'm just disappointed that the result of your antics wasn't everyone's feet shearing off at the ankles, like they do in films.
( monster munch person, man, woman... camera... TV?, Tue 20 Sep 2011, 19:25, closed)

Fantastic!
At least someone round here is keeping their eye on the big picture.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 19:40, closed)

OK, since you all ask ...
I was working as a research assistant at a Large University doing low temperature tensile testing of various composite materials. Each test involved submerging an entire tensile test rig in a big bucket of LN2, and since the university was too bloody mean to buy me the LN2 recycling pump I wanted, I would typically use around 40 - 50 litres of the stuff per test. To ferry that around I had a great big dewar, about as tall as I was, which carried 200 litres at a time.

So when the hot weather struck it was^H^Hould have been easy to take the dewar to the main LN2 store fill it up and then leave it pumping slowly out over the office floor. It didn't break our ankles off because it boiled instantly, providing a pleasantly cool layer of gas near the floor. It didn't asphyxiate us because as has been pointed out, air is mostly LN2 anyway and we kept the place well ventilated. It didn't bankrupt the university because LN2 isn't that expensive - about the same price per litre as milk.

All happy now?

I must say that being called a lying fantasist by Blaireau is an interesting experience. I presume the late Cyril Smith will be along in due course to call me fat ...
(ubergeekian, Tue 20 Sep 2011, 23:02, closed)

I called you no such thing, you cheeky, lying cunt.
In fact I didn't call you anything at all.
But I presume that you, in a backhanded way are calling me that?
If that's the case then fuck you.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 23:21, closed)

(Kazza , loathing myself so you don't have to, Tue 20 Sep 2011, 23:31, closed)

Strong words.
And if you are stating that opinion as fact then it's even funnier, cos that makes you one instead.
Edit: If it's nothing more than an opinion then that makes you a bandwagon jumping fool.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 23:33, closed)

(Kazza , loathing myself so you don't have to, Tue 20 Sep 2011, 23:43, closed)

Well it shows a complete lack of imagination and/or intelligence.
So yeah, I do consider bandwagon jumping a bad thing.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 23:47, closed)

(Kazza , loathing myself so you don't have to, Tue 20 Sep 2011, 23:52, closed)

LOL so funny. I'm not getting wrapped up in anything, just making a valid point.
And I certainly don't need you to remind me what I called some people on Saturday. It wasn't everybody, just a few of your fellow bj's.
You didn't imply that I'm a liar, you said it straight out. At least what you lack in other areas you make up for with bluntness. Or directness, if you'd rather.
( blaireau69 , the Cumbrian Travis Bickle., Tue 20 Sep 2011, 23:59, closed)

(Kazza , loathing myself so you don't have to, Wed 21 Sep 2011, 0:09, closed)

Yeah, LOL I called you a bj!
BjLOLs
( blaireau69 , the Cumbrian Travis Bickle., Wed 21 Sep 2011, 0:25, closed)

I'm terrified
Leave my radiators alone, you maniac.
(ubergeekian, Wed 21 Sep 2011, 12:09, closed)

That's veeeeeery interesting.
SO if you worked at Large University one summer you must have worked with my friend Hugh Jass. You did, you say?

PSYCH! Hugh Jass never worked there. I made him up MoFo!

Caught you out
(Kazza , loathing myself so you don't have to, Tue 20 Sep 2011, 23:29, closed)

Whilst I might accept that your improved explanation makes it more plausible
since I forgot to factor in the 200L/8 hours thing, you most certainly did not fail to asphixiate people because "air is mostly nitrogen". That's irrelevant. You still can't respire nitrogen. You failed to asphixiate people because you were extremely fucking lucky.

However, I'm confused about this still. Dewars don't pump liquid out. They allow a tiny proportion of the internal liquid to vapourise, then vent this gas slowly to allow themselves to self-cool because the latent heat necessary for vapourisation needs to be sucked from the surroundings. Leaving a dewar to stand around in your office might cool the office (although we'd be getting into a bit of a 1st/2nd law of thermo situation so it's probably not that simple) and will produce a cool gas layer on the floor, as cool gas sinks, but it's demonstrably not pumping LN2 anywhere. And it's still really dangerous unless your office is the size of a hanger.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 9:06, closed)

I think word dewar is often interchangeable (even though it shouldn't be)
Some of our lot call the 200L storage tanks dewars, when they're not. Our magnetism lab wasn't much bigger than an average sitting room, but with the windows open, we'd pump ~120 litres through the SQUID when cooling it down over 6 hours, all of which came pissing out the exhaust port. Still didn't manage to set the O2 alarm off.

Still, not as much fun as the time the techie was a lazy shit and forgot to fill the N2 dewar in the SQUID. When it boiled off, the vacuum jacket decided to desorb all of its contents and create a heat sink for the helium dewar, which resulted in a screaming jet of helium boiing off through the safety valve. Fun times.
( Colonel Boris "...a desperate Buzzfeed imitation...", Wed 21 Sep 2011, 10:55, closed)

Helium's a different matter
I used to use a lot of helium too - in fact "helium evaporator" was more or less my job title for a bit. Any significant disparity between the liquid I collected and the metered gas I returned brought a furious technician to my lab door with forthright suggestions about my gas seals and my parentage.
(ubergeekian, Wed 21 Sep 2011, 12:07, closed)

This reminds me
of helping fill a superconducting electromagnet with liquid helium.

I was on work experience (back when I was 16) at a university and they let me play with high intensity lasers, cray computers, superconductors, extreme vacuums and liquid helium.

Not at the same time, unfortunately, that WOULD have been fun...
(Imaginary Ed was dreamed up on, Wed 21 Sep 2011, 13:50, closed)

There's a 1 kW unshielded laser lying around in one of my labs
it's aimed at the door. as you do. Fun times.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 14:06, closed)

Liquid helium
is an awful good way of making high (if not very extreme) vacuums. Cryopumping, it's called. ah, happy days and great fun.
(ubergeekian, Wed 21 Sep 2011, 16:35, closed)

Dewars
There are lots of different designs. For fast filling of the test rig I had a small centrifugal LN2 pump which was lowered through the neck. We tried (sorry, would have tried) that for the air conditioning experiment, but it was (would have been) a bit noisy. So we tried (hell, I can't be bothered pretending) method two. You seal the neck with a rubber bung containing a dip tube which goes to the bottom of the flask. As heat leaks in the thing self-pressurises and drives liquid out, just like the LPG tank on a car. That's how LHe dewars work, by the way, though you sometimes have to encourage things with a bit of work on a gas-filled bladder.

Whether this works for LN2 depends on how good your dewar is. Too good and it doesn't push enough out: too bad and it empties too quickly.

You are quite right about the physiology. We weren't poisoned because nitrogen is not (at those pressures) poisonous, which is where the air-is-mostly-nitrogen comes in. We weren't asphyxiated because the room was well ventilated, we weren't putting that much more nitrogen into it, and because the nitrogen rich area would have been at the floor. Touch shit for the mice, possibly.
(ubergeekian, Wed 21 Sep 2011, 12:05, closed)

Interesting.
you'd need to watch it, though, - the N2 rich air is only at the floor because it's cooler. N2 is marginally less dense than air, all else being equal, so it's really the room vents that matter.

I'm surprised by the amount in both yours and Boris's posts though - I can trigger a full 02 alarm just by mis-filling a small storage dewar, although all our labs run odd sealed air handling systems to be fair.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 14:05, closed)

Sure
It was the coolth what done it. It was just a normal office, so no alarms of any sort. None in the helium labs either - you knew something was leaking when your voice went funny. Seriously.
(ubergeekian, Wed 21 Sep 2011, 16:36, closed)

(McChinaman banned, Wed 21 Sep 2011, 0:54, closed)

If this isn't what happened,
then someone needs to take science out the back, for a serious talking to.
( monster munch person, man, woman... camera... TV?, Wed 21 Sep 2011, 9:02, closed)

it really doesn't work.
I've tried it with liquid oxygen and liquid nitrogen and rubber hoses.

Science regularly gives itself a good talking to, and then we go out and make fluorescent cats. It's all about the LOLZ.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 9:08, closed)

Takes a bit of time.
But we freeze rubber tubing and fruit for 1st-year demonstrations, usually ending in smashing them with hammers.
( Colonel Boris "...a desperate Buzzfeed imitation...", Wed 21 Sep 2011, 10:56, closed)

Yeah, you're right - it works if you dip them in it for ages
it doesn't if you pour it on, because the constant vapourisation at the surface means a layer of gas between the tube and the liquid for the duration and vapour is a rubbish conductor. I've poured the stuff onto my bare hand before for the same reason. Although I wouldn't recommend it, kids.
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 13:58, closed)

Good tricks with LN2
#341: Fill a foam polystyrene bucket with the stuff, drop a rubber bung in and then reach in and pick it out with your bare hand. Note: long arm hairs can penetrate the vapour barrier, let the liquid through and sting like hell.
(ubergeekian, Wed 21 Sep 2011, 16:38, closed)

Since my research group is more biology than anything else these days
it's the dry ice for the pranks. You'd have thought, with my supposed maturity and seniority, I'd have stopped putting dry ice in other people's tea, wouldn't you?
( the mighty badger Aphrodite, on a bar stool, by your side, Wed 21 Sep 2011, 17:26, closed)

I read this as 'rubber horses'
I want to dip a rubber horse in LN2 now.

Edit: Or oxygen, or helium...
(Imaginary Ed was dreamed up on, Wed 21 Sep 2011, 13:46, closed)

Oh happy memories
Staedler pens explode in LN2 but BIC ones don't. Mars Bars disintegrate but Marathon (shows my age) remain intact.
(ubergeekian, Wed 21 Sep 2011, 12:08, closed)

I rather like this.
Is there a peanut stability matrix?
( monster munch person, man, woman... camera... TV?, Thu 22 Sep 2011, 9:07, closed)