Are you sure the nitrogen is liquid in the bottle? I very much doubt it. I tend to believe it is in gaseous form compressed to a gazillion PSI +/- 5%. There is no way to keep nitrogen liquid at “room” temperature. The gas cools as it expands but I believe the bottle is at ambient temperature until that moment.
Well… it’s a replacement. I miss Britannica, too.
If you’re referring to LN in the street tanks, Oh Yes it’s liquid. Those are dewars. Not scotch, but basically giant thermos bottles, and you can get them designed to deliver the liquid from the bottom of the tank, too. There’s always a space at the top of the tank to hold some vapor, ullage, insulating the liquid from the place at the top where the inner and outer walls must meet so that you can access the contents.
In fact, you can’t top off a cryogenic liquid in a dewar, because the top will immediately boil off, spill out, and create an ullage layer.
If you’re referring to the high pressure anaesthesia tanks, then yes and no. The Nitrogen and Oxygen are gases, but the Nitrous Oxide liquifies under about 40 psi [don’t have a reference handy].
Nitrous Oxide is almost a perfect oxidizer for this very reason. It liquifies in the tank handily, allowing you to pack a lot in a tank at low pressures, and its self pressurizing at a convenient relative pressure to ambient. The only drawback is that you need to already have a combustion going in order to split the O from the N in order for it to act as an oxidizer.
Since I’m bored, I’ll report some results from informal experiments I performed as an undergrad one summer afternoon at my job at a nuclear physics lab that had lots of LN around to cool solid state detectors.
Abstract:
We determined the tolerance of common insects to immersion in liquid Nitrogen sufficient to achieve steady state temperature. Tests of chitin’s brittleness at cryogenic temperatures were also performed.
Apparatus:
[li] One (1) 8 gallon dewar of LN[/li][li] One (1) 8 oz styrofoam coffee cup, used and rinsed[/li][li] One (1) pair of forceps[/li][li] Assorted creepy crawlies[/li]
Procedure:
We captured an assortment of arthropods and arachnids found in and around the laboratory. As the experiment progressed, we ranged farther and farther outside the lab to capture specimens for the experiment. Despite their availability, we elected not to capture other local fauna, such as groundhogs and doves, primarily due to the limited volume of our apparatus, but also because we had little faith in these specimens’ ability to tolerate the exposure to cryogenic temperatures.
(Note: this is not the origin of this investigator’s alias. Any perceived correlations are strictly coincidental.)
Once the subjects were procured, we grasped them gently with forceps and immersed them in the LN, waiting for boiling to subside as an indication that steady state temperatures were achieved. We then removed the subject from the LN and placed them on the laboratory bench to witness any recovery from this exposure. Some redundant specimens were thrown forcefully (“bounced”) against the bench to test the brittleness of chitin at cryogenic temperatures.
Results:
Ants, silverfish, spiders, and pillbugs all succumbed to exposure to the LN. No signs of viability ever returned to these specimens after immersion. However, to our combined elation and horror, common German cockroaches did revive after returning to ambient temperature, although only temporarily. Immersed cockroaches failed to survive for more than 20 minutes after reviving.
None of the “bounced” specimens showed any evidence of shattered exoskeletons, although limbs did repeatedly detach.
Conclusions:
This experiment adds evidence to support the widely held hypothesis that cockroaches will one day inherit the earth.
No measurements or estimates were made of the forces or impulses delivered to the bounced specimens, so no conclusions can be drawn regarding the mechanical properties of chitin at cryogenic temperatures.
Further Research:
A quantitative investigation into the mechanical properties of chitin at cryogenic temperaturs may yield potentially useful results.
Also, a control for the effects of residual coffee, non-dairy creamer, and sucrose in the apparatus may yield contradictory results.
Well, the label says liquid nitrogen. It also says nonflammable gas. There are a lot of labels on the canisters. Another says extremely cold liquid and gas under pressure.
The top is securely attached, so I don’t think I open it to check if I tried. But I’m not going to try; I don’t want to get ullage all over me. That sounds messy.
bughunter, you are to be commended for your work fighting ignorance. Excellent work!
So, I wonder how they keep it liquid. Even if the bottle is insulated, some heat will seep in over time. I suspect there is probably a pressure relief valve which would vent some nitrogen out which, in turn, would refrigerate the one left inside. With nitrogen you can do this as it is quite inert. I dunno what they would do with a gs which could not be vented… it would have to be refrigerated…
bughunter:
[NITPICK]
We captured an assortment of arthropods and arachnids found in and around the laboratory.
[/NITPICK]
Arachnids are arthropods. Maybe you meant to say “insects and arachnids”, then decided to switch to arthropods, and got mixed up in the posting.
I’m currently sitting one foot away from one of these liquid nitrogen canisters. My lab has a -150? freezer that uses LN[sub]2[/sub] as a back up in case of power failure. 240 liters of liquid fun.
Here are the technical specs of the XL-240 that I’m sitting next to.
They are definitely filled with liquid although there is a vent line, too. And I dont think heat seepage is a tremendous problem. The specs say 1% loss per day. But I bet they tear thru the N[sub]2[/sub] enough that it’s not a major issue.
Alphagene, I saw those specs and I don’t understand how the pressure can be so low (100psi). Can someone explain to me at what temperature and pressure the nitrogen is to be liquid? I expected some thousand psi. Can you have liquid nitrogen at atmospheric pressure?
The canister is essentially a big ol’ pressurized thermos bottle. If you look at the schematic, you’ll see that the nitrogen is in a vessel that is well insulated from the external portion of the dewar thingy.
My WAG is that by keeping the inner most container cold (i.e. insulating it very well) you don’t need extreme pressure to keep the nitrogen in liquid form.
You sure can. I used to grind up plant tissue with liquid nitrogen. The lab had a what was essentially a big metal thermos about 3 feet high that wasn’t pressurized at all. The stopper didn’t even fit very well and just sat on top of the mouth. If no one was using it, the N[sub]2[/sub] could last for at least a couple of weeks.
I was thinking about a vague recollection I have about certain gases not liquifying above a certain critical temperature no matter how high the pressure…
::slapping forehead::
Ok, never mind, call me stupid… carry on… just ignore me