Compressed air question (chemistry related)

THEPAIN73

Odd question: Someone at work was playing with some compressed air and got the bright idea to turn it upside down and spray the fluid into a plastic baggy.

Well it was like a boiling liquid that was super cold.

Would that be liquid nitrogen then?

RUNN1NGMAN

Was this actual compressed air, or was it a can of "compressed air" for cleaning keyboards and such? Canned air for cleaning is actually a flourocarbon refrigerant (a highly compressible gas).

Captain Vash

similair but different.

It is cold because it's super compressed, and when compressed gases expand they consume energy(read heat) from their enviroment.

bowen

It's not Nitrogen.

bowen

That liquid will probably also boil itself away eventually, it's a typical fluorocarbon though.

TetraNitroCubane

The liquid you're seeing is very likely 1,1,1,2-Tetrafluorethane, which I've seen used in the compressed air cans that I buy regularly. It only has a boiling point of ~-26 C, as opposed to nitrogen's boiling point of ~-195 C. If it had been liquid nitrogen, that plastic bag would have become brittle and stiff.

bowen

Liquid Nitrogen is awesome.

THEPAIN73

Yeah it was the compressed air that you clean a keyboard with.

Interesting guys, we use the same type of liquid (R-134a) for fixing air conditioning.

Thanks a lot.

Killgrimage

bowen wrote: »

Liquid Nitrogen is awesome.

I work with it every day, and I love my job.

Raekreu

TetraNitroCubane wrote: »

The liquid you're seeing is very likely 1,1,1,2-Tetrafluorethane, which I've seen used in the compressed air cans that I buy regularly. It only has a boiling point of ~-26 C, as opposed to nitrogen's boiling point of ~-195 C. If it had been liquid nitrogen, that plastic bag would have become brittle and stiff.

More than that, the can would have exploded due to the pressure at some point. Liquid nitrogen would only stay in liquid form if it were kept under amazingly high pressure, iirc it's something like 9 billion PSI as opposed to the R-134 being somewhere close to 10-15 PSI.

shadydentist

Raekreu wrote: »

TetraNitroCubane wrote: »

The liquid you're seeing is very likely 1,1,1,2-Tetrafluorethane, which I've seen used in the compressed air cans that I buy regularly. It only has a boiling point of ~-26 C, as opposed to nitrogen's boiling point of ~-195 C. If it had been liquid nitrogen, that plastic bag would have become brittle and stiff.

More than that, the can would have exploded due to the pressure at some point. Liquid nitrogen would only stay in liquid form if it were kept under amazingly high pressure, iirc it's something like 9 billion PSI as opposed to the R-134 being somewhere close to 10-15 PSI.

Not exactly related, but you know those giant industrial tanks of liquid N2? They're designed to vent the nitrogen as it boils off, so basically keeping the LN2 cool through evaporation. You hear stories about people who hear the tanks venting N2, and thinking its a leak, and welding the vents shut. That rarely ends well.

TetraNitroCubane

shadydentist wrote: »

Raekreu wrote: »

TetraNitroCubane wrote: »

The liquid you're seeing is very likely 1,1,1,2-Tetrafluorethane, which I've seen used in the compressed air cans that I buy regularly. It only has a boiling point of ~-26 C, as opposed to nitrogen's boiling point of ~-195 C. If it had been liquid nitrogen, that plastic bag would have become brittle and stiff.

More than that, the can would have exploded due to the pressure at some point. Liquid nitrogen would only stay in liquid form if it were kept under amazingly high pressure, iirc it's something like 9 billion PSI as opposed to the R-134 being somewhere close to 10-15 PSI.

Not exactly related, but you know those giant industrial tanks of liquid N2? They're designed to vent the nitrogen as it boils off, so basically keeping the LN2 cool through evaporation. You hear stories about people who hear the tanks venting N2, and thinking its a leak, and welding the vents shut. That rarely ends well.

Where I currently work, the halls in the building are filled with several these upright liquid nitrogen dewars (vacuum insulated tanks). They're old, and very often they vent gas in loud, startling way. It's frightening, but terribly necessary. Every year at safety training they scare the bejeebus out of all of us with the horror story about what happened a few years ago at Texas A&M when one of these tanks built up too much pressure and detonated, because the vents were sealed off.

In the Pipeline wrote:

The cylinder had been standing at one end of a ~20' x 40' laboratory on the second floor of the chemistry building. It was on a tile covered 4-6" thick concrete floor, directly over a reinforced concrete beam. The explosion blew all of the tile off of the floor for a 5' radius around the tank turning the tile into quarter sized pieces of shrapnel that embedded themselves in the walls and doors of the lab. The blast cracked the floor but due to the presence of the supporting beam, which shattered, the floor held. Since the floor held the force of the explosion was directed upward and propelled the cylinder, sans bottom, through the concrete ceiling of the lab into the mechanical room above. It struck two 3 inch water mains and drove them and the electrical wiring above them into the concrete roof of the building, cracking it. The cylinder came to rest on the third floor leaving a neat 20" diameter hole in its wake. The entrance door and wall of the lab were blown out into the hallway, all of the remaining walls of the lab were blown 4-8" off of their foundations. All of the windows, save one that was open, were blown out into the courtyard.

So, yeah. Sorry for the slightly off-topic post, but that story still gives me the willies when I walk through the halls.

RUNN1NGMAN

shadydentist wrote: »

Raekreu wrote: »

TetraNitroCubane wrote: »

The liquid you're seeing is very likely 1,1,1,2-Tetrafluorethane, which I've seen used in the compressed air cans that I buy regularly. It only has a boiling point of ~-26 C, as opposed to nitrogen's boiling point of ~-195 C. If it had been liquid nitrogen, that plastic bag would have become brittle and stiff.

More than that, the can would have exploded due to the pressure at some point. Liquid nitrogen would only stay in liquid form if it were kept under amazingly high pressure, iirc it's something like 9 billion PSI as opposed to the R-134 being somewhere close to 10-15 PSI.

Not exactly related, but you know those giant industrial tanks of liquid N2? They're designed to vent the nitrogen as it boils off, so basically keeping the LN2 cool through evaporation. You hear stories about people who hear the tanks venting N2, and thinking its a leak, and welding the vents shut. That rarely ends well.

And liquefied natural gas is shipped and stored in a boiling state. Pretty cool when you think about it. Whenever you see a big natural gas storage tank somewhere (like the ones in Boston) they're filled with boiling liquid.