After looking at this threadon dry ice, it got me thinking. I’ve been cooking up some food for Burning Man and I was sort of hoping to have it last for a reasonably long time. I’ve got an ice chest that’s maybe 36 quarts. If I was to toss a couple pounds of dry ice into it, what kind of pressure will be building up in it? What sort of valve could I retrofit into the drain plug that will vent the carbon dioxide without letting a ton of heat in.
depending on where and what kind of storage place you are keeping your chest in you could probably just put something kind of heavy on top of the chest instead of using the latch/lock thats on the chest, something that wont fall off if there is a burp of pressure being released. that way the pressure goes out the top but the lid stays closed and the cold stays in.
that seems like the simple way to go about it.
Does the ice chest really seal well enough to build pressure? For instance, if you filled it with water and set it on its side, would none leak out?
I think most refrigerator door designs with nice gaskets would flex a little and let the building vapor fart out a bit at the seams, or be even less able to seal. It’s hard to imagine a scenario where it would blow. If your ice chest has heavy gaskets and multiple bolts to clamp its opening together, then maybe it could, but I can’t think of any ice chest or refrigerator I’ve seen that could build up enough pressure to even open in startling fashion when unclasped, let alone explode.
According to Wikipedia’s CO2 data page, the vapor pressure over solid carbon dioxide varies widely depending on what temperature you’re trying to keep it at. If you keep the dry ice below -78.2C, the vapor pressure will be less than atmospheric pressure, and it won’t sublimate at all.
Of course it won’t stay that cold. The temperature in the cooler is being driven toward room temp by ambient condtions; if you heat a block of dry ice to room temp, you need to supply a crushing 870 psi to prevent sublimation.
Thing is, you don’t want to keep that pressure in there. That would stop the sublimation process, which would end the cooling effect you so desire. Let the pressure out; let the dry ice sublimate and keep your beer cold. You just need to keep the heat out as best you can. Keep your cooler out of the sun, and wrap it in whatever blankets/sleeping bags you have.
Even if you wanted to keep the pressure in, you couldn’t. The lid on your cooler is, what, maybe 12" x 12" = 144 square inches? At 1 psi interior gauge pressure, that’s 144 pounds pushing out on the lid. The cheap plastic hinges/latches can’t take anything close to that; the lid will bow out at the least supported corners and relieve the pressure as needed. And that’s assuming that your cooler happens to achieve a perfect pneumatic seal to begin with, which is unlikely.
Yeah, you’re not going to contain the pressure, and you don’t want to either. Just close the lid as normal, without latching it closed in any way and it will relieve the pressure itself. Do take caution to make sure you don’t leave the cooler in a closed up area where the CO2 gas can displace all the oxygen and kill you though. Don’t leave it in a closed up car, or possibly even in a tent overnight. Vent the car, or leave it outside the tent to be safe.
I have two Coleman Xtremes and they seal pretty well. When I put dry ice in it pops the lid every time. If you want to vent the pressure just leave the drain plug slightly open. That’ll let the pressure out but keep the cold in.
Unlike carbon monoxide, carbon dioxide is easily detectable before it reaches dangerous levels. Example: the discomfort you feel when holding your breath for an extended period is due to buildup of CO2 in the lungs. Likewise with the discomfort of a beer/soda burp that exits through your nose. You won’t die if you climb into a car (or sleep in a tent) that’s full of CO2 gas, but you will feel compelled - long before you pass out - to find fresh air.
I can’t give you a scientist’s answer, but I can give you a camper’s.
It’ll be fine. The only time anything weird happened to one of our campsite’s coolers with dry ice, it was in one of those older coolers with an actual metal latch, not just a top that pressed into place. And all that happened there was that the fruit inside ended up carbonated. It was actually really cool! The cooler wasn’t damaged, nor did it explode.
Dry ice is awesome in coolers. It can keep meat frozen up to a week in 95°+ weather, so I’d bet you’ll get a few days out of it at Burning Man temps.
I realize this is a bit off topic, but figured I’d chime in since I used dry ice for a multi-day music fest recently and it worked great. You’ll need more than “a couple pounds,” though. More like 20-30 depending on how hot it is and how long you need it. I put a 30 lb block in my cooler and it lasted from Wednesday afternoon through Monday night. I’d recommend bringing two coolers and put the stuff you’ll be using each day into the non-dry ice cooler along with some regular ice. That way you’re not constantly opening and closing the cooler with the dry ice in it and it will last longer. I froze some gallon water jugs and smaller water bottles the night before and kept those with the dry ice and then transferred them over to the second cooler as needed. When those melted I used them as my drinking water.
True. But IIRC moderately elevated but not outright noticeable levels CAN still make you feel like crap/nauseous/give you a pretty good headache. And I imagine your body might not wake you up for that until its too late.
So, you still dont want to be in a well enclosed space sleeping with a significant CO2 source.
Seconded in all respects.
Thanks for the answers. I’ve got 2 ice chests. One is humongous. The smaller one I’ll use for dry ice and mount it on the outside of the car so that it won’t vent too much carbon dioxide on the inside of the car. I’ll keep that one for my frozen food and see how long it lasts. It’s actually missing the cap on the drain plug and I’ll try to retrofit some sort of pressure release valve into it.
I think that might be pointless. We use CO2 when offroading in the place of air tanks. The CO2 tank can be used to fill tires, run air tools etc and it lasts a long time. Once the CO2 is put in the tank, it turns to gas until it reaches a high enough pressure to stop the conversion (over 800psi at room temp, something like 1100psi outside in the summer sun).
Once you use a little bit of it, the pressure drops and more CO2 is converted to gas, bringing the pressure back up. I’m not sure how fast it builds pressure, but I’ve always assumed it’s more or less instant. I know that using a 150 psi regulator, I can run an air tool or fill tires constantly until it runs out of gas and there’s no hint of any change in pressure. So, if I had a 150 psi pressure release valve, it would constantly stay open and I’d just save money and use a hole instead of a valve.
I actually had something along these lines happen. We were traveling with frozen samples stored in coolers with dry ice. We left the car in the hold of a ferry, then after the ferry ride, got back in to the car to await disembarking. After about 15 minutes in the car with the windows rolled up to avoid the other cars’ exhaust, we noticed we were all hyperventilating, breathing away with short fast pants. Eventually we realized it was CO2 buildup from the dry ice in the closed car. We rolled down the window and all was fine, but it was a peculiar and uncomfortable experience.
I have been using dry ice in my ice chests for quite a while, in most cases the ice chest would self vent itself. The lid would slowly raise up enough to release any pressure then settle back down. The only problem I had was anything that came in contact with the dry ice package would freeze solid. Potato salad does not taste too good after it freezes solid. I made a wire cage type device to hold the dry ice and keep the food a few inches away.
So that’s why my steak tasted like freezer burn. Well, that’s the last time I store beef in an acetone/dry ice bath. (Not really.)
I do second rigging up a way to get some air space between the dry ice and the food. Things will freeze surprisingly fast when in contact with dry ice. Nothing worse than wanting your breakfast cereal and having to wait for the milk to thaw out.