Dry Ice + Beer

[ronbo 613]

I should have stuck around Chemistry class a little longer instead of cutting and going surfing.................

[Deer Slayer]

I saw this big chest freezer thing by the frozen food section in meijers today. It's full of little 5lb bags of dry ice, to keep your frozen goodies cold on the way home. They were only $.99 so I bought one. There wasn't much left of it by the time I got home, but it was enough to play with . The really funny part was you HAVE TO BE 18 TO BUY IT! I actually got carded buying a bag of dry ice (I was kinda mad because that meant more time that it evaporated)! I dunno what you could put it in that it would keep enough pressure that you could keep it from going to gas without the container exploding! I don't really want to experiment with it either, cause it could create a helluva bang! So, three questions, can dry ice be stored under pressure? If so how many PSI (assuming normal earth temperatures of a max of 150f and normal atmospheric pressure outside the container)? Does CO2 actually have to be chilled to make dry ice, or can it be done with pressure??? I really don't want to find out a rather thick metal container WASN'T ENOUGH to hold the pressure released by the dry ice!!!!! :eek:

I can feel darwin taking aim and squeezing the trigger!!!

[Fraoch]

The link on dry ice I supplied earlier wasn't as specific as the one on cryogenic distillation, but it's still done through pressurization and cooling. See here.

Sublimation is a rather weird process, but like boiling, it has to do with the material's vapour pressure. Any liquid and even most solids exert a small pressure on their surroundings. They are "slightly" boiling and a few molecules escape up into the surroundings. This vapour pressure varies with temperature as the molecules move around more and more. When the vapour pressure equals that of its surroundings, the liquid boils. So water at 100 C has a vapour pressure of 1 atmosphere, 14.7 psi.

If you can increase the pressure in the surroundings the liquid stops boiling - or more appropriately, its boiling point has been moved higher. Reduction does the opposite - on Mount Everest, water boils at 70 C because the pressure is so much lower, the vapour pressure equals atmospheric pressure at 70 C. A pressure cookier relies on this principle - it holds back some of the steam to increase the pressure. At an increased pressure, the liquid boils at a higher temperature, so you cook faster.

Sublimation is kind of a weird process. Soilds exert a vapour pressure too only it's much, much lower than liquids. Most solids don't "boil away" in front of your eyes. Usually a low vapour pressure implies a much higher boiling point, i.e. you're "far away" from the boiling point. However I'm not quite sure how this relates to dry ice, which pretty desperately wants to sublimate and doesn't even bother going through the liquid phase to do it!

So I'm kind of stumped on this one.

BTW one day someone brought in a block of dry ice to my high school chemistry class. She cut off a chunk with a cleaver and the steel "chattered" as it touched the dry ice. We weren't sure what it was at the time but I think it was little pockets of CO2 escaping around the steel.

[Shadow_419]

LO2(liquid oxygen) or LOX is used in life support systems on planes and millitary jets. At high altitude, wher else are you going to get enough O2 unless you bring it yourself.

[Fraoch]

Originally Posted by Shadow_419

LO2(liquid oxygen) or LOX is used in life support systems on planes and millitary jets. At high altitude, wher else are you going to get enough O2 unless you bring it yourself.

I've always wondered if what they said on Fight Club was true.

Tyler Durden: "Even wonder why they supply oxygen on aircraft when you're about to crash?"

Ed Norton's character: "It's so that you can breathe."

Tyler: "No. Oxygen is euphoric. It makes you high. Take a look at the safety card. See? Water landing, 600 miles per hour, everyone with faces like Hindu cows."

I don't think it's true - most people need oxygen on Everest, for example. But it's neat to think about. Along with "used motor oil can fertilize your lawn."

[Shadow_419]

Well I'll tell you one thing, if you ever have a hangover it'll definately clear your head. Can't help you being dehydrated, but it gets rid of headaches. go figure!

[sandman55]

Originally Posted by Fraoch

The procedure to remove the energy is a powerful refrigeration system. Yup, essentially the same thing as in your fridge or air conditioner, only on a much larger scale.

I wonder what they use for a refrigerant, it would have to boil at a lower temp than nitrogen.

[Fraoch]

Originally Posted by sandman55

I wonder what they use for a refrigerant, it would have to boil at a lower temp than nitrogen.

Hmm...I thought about that too. I can't remember my refrigerator theory (something about a "Carnot Cycle" IIRC) but I believe it has to do with the process itself rather than the material used.

It could be more of a pressure-reduction process rather than an atmospheric boiling process.

Hopefully someone fresh out of a thermodynamics course can enlighten us.

[Deer Slayer]

I'm glad I didn't try that, I have some tanks that will handle liquid oxygen! I dunno how they would have faired full of dry ice, but I don't think it would have been good to find out! Anyways, to make dry ice, CO2 is pressurized till it's liquid, then releived of some of the pressure with a special valve. This causes some of the CO2 to sublimate, and the rest to freeze solid in the form of snowflakes. Then they take a big press, and squish it into blocks. I dunno, seems like a PITA to me, and that means that dry ice is colder than liquid CO2 (DUH). Thus it would probably take a bunch more pressure than liquid CO2, if it's even possible to hold in a solid state with pressure.

Some of the dry ice safety things on that website were funny, it takes all the fun out of it! It said DO NOT put it directly in a drink! They also gave a bunch of warnings about not breaking it into pieces, and keeping it in closed containers.

[izibo]

Originally Posted by Shadow_419

LO2(liquid oxygen) or LOX is used in life support systems on planes and millitary jets. At high altitude, wher else are you going to get enough O2 unless you bring it yourself.

Correct, but you are not actually inhaling O2 in the liquid state. If you were inhaling it in the liquid form, you would destroy your lung tissue and that would somewhat defeat the purpose.

[Shadow_419]

Yeah, the have a heating system for the bottles.

[Bofinn]

Originally Posted by Deer Slayer

I saw this big chest freezer thing by the frozen food section in meijers today. It's full of little 5lb bags of dry ice, to keep your frozen goodies cold on the way home. They were only $.99 so I bought one. There wasn't much left of it by the time I got home, but it was enough to play with . I dunno what you could put it in that it would keep enough pressure that you could keep it from going to gas without the container exploding!

Here are some links to containers:

http://www.dryiceinfo.com/mfn.htm#STORAGE%20BOXES

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and this guy uses a tupperware bowl:
http://waltonfeed.com/self/upack/dryice.html

[Xtraneous]

Or just buy a few things of dry-ice and toss them into a styrofoam cooler... that's what all the chemical shipping companies use if they need to ship a frozen reagent.

Oh, and I am kinda sad, all my dry-ice sublimated away - no more fun...

until the next shipment!

[Deer Slayer]

Originally Posted by Bofinn

Here are some links to containers:

http://www.dryiceinfo.com/mfn.htm#STORAGE%20BOXES

------------
and this guy uses a tupperware bowl:
http://waltonfeed.com/self/upack/dryice.html

I was thinking about long term storage of dry ice under pressure. It wouldn't work, the dry ice would turn to liquid under pressure. I dunno how much pressure dry ice can exert on it's container, but I know it's more than enough to blow up a 40 oz beer bottle! That's gotta be well over 100 PSI, and probably over 300! I guess you can only use pressure to turn CO2 into liquid. I bet liquid CO2 is pretty cold though! If you put dry ice in something sealed that can't take the pressure, it could be VERY BAD! So, I'll just stick to the cooler idea. I do have a tank for a welder that can be filled with CO2, and a regulator for it.

[guiness]

We use liquid Nitrogen to freeze metal pins to create instant press fit. It is stored in a stainles "milk jug" with styrofoam for the cork cap. Store it in a fridge to reduce evaporation. To use we pour it in a styrofoam cooler and place the pins in it till it stops it's "boiling" then call it good and remove for "drop in press fit" That sucker AINT gonna come on out or work loose, assuming correct size for interference fit.