Dry Ice

[dave6330]

OK - I'll admit I was no physics major back in my college days.

Is the vapor that comes off of dry ice (CO2?) heavier than air and does it pose a hazard in a sailboat?

The question is really whether or not it's safe to put dry ice in the galley ice box. The ice box has a drain that runs into the bilge but I don't want a build up of anything harmfull inside the cabin. Dry ice would definitely be handy at times, though...ice cream and such on weekend sails.

V/R

Dave

[TheFrog]

Yes it is denser. Density of Gases
What the danger level is I don't know, it would depend on the amount of dry ice, cabin volume, sublimation rate, ventilation, etc.

[Zanshin]

The Co2 is denser than air and YES, it poses a danger and risk in a sailboat. Not because CO2 is inherently dangerous, but because is displaces air and thus the oxygen required to breath.
CO2 is a by-product of fermentation, and even today one hears of vintners dying because they inadvertantly enter cellars during the wine season and either don't have their warning system (in the old days they would use a poor bird, just like the canaries in the coal mines) turned on. Even worse, occasionally rescuers succumb as well; not thinking of the speed with which unconsciousness can occur - one big breath can be enough to mess up your blood acidity and can cause unconsciousness.

But if you open up the ports and perhaps turn the fans to point to the bilges you should get enough movement to mix the relatively small amount of CO2 that sublimates.

p.s. A friend of mine had an incident years ago when his CO2 alarm system was faulty and he almost died, so I might be overly sensitive to the topic, so take my words with a grain of salt but realize that there is a potential danger.

[arbarnhart]

Another possibility to consider...

I have a little ice cream maker that has an insert that you freeze, then you add the ingredients into it and stir it every couple minutes to make ice cream. I have used it a couple of times to keep ice cream frozen for camping. I put the ice cream in it (it can be store bought prepackaged stuff still in wrapper) and put it in the deep freeze. I have a Styrofoam container for shipping frozen goods (we bought some frozen baby foods way back when) with very thick sides and a tight fitting lid that it fits in. I put it in there, tape the seam (just masking tape) and strap it closed. It is fine for a day or so, but this is a "transport and open once within a day or two" solution.

[Kakkerlak]

Hold your breath as you read this. Keep holding it until you feel that urge to exhale. That's your body reacting to the concentration of CO2 in your lungs.

That's one of the characteristic dangers of CO2, because it causes you to start breathing rapidly to attempt to expel it, which only increases the concentration. Your heart rate goes up, you burn more oxygen, and its a quick spiral into unconsciousness and asphyxiation and death.

Most industrial asphyxiations happen in sealed environments like boilers and sumps, that don't have open tops or ventilation ports. But I sure wouldn't take the risk on any boat.

Definitely do not attempt to use dry ice for cooling on a boat. Good old water ice is safe, plentiful, and a lot more fun to drop down your crew's shirts.

[sailingdog]

Don't generally recommend using dry ice without good ventilation.

[hellosailor]

Zanshin-
"p.s. A friend of mine had an incident years ago when his CO2 alarm system was faulty and he almost died" ARE YOU SURE ABOUT THAT?
It is extremely unlikely that your friend has or had a CO2 detector. Carbon Dioxide is very different from carbon MONoxide, which is what a "CO" detector picks up. CO, not CO2.
(If you'd had a decent cup of coffee this morning you'd have realized that.)

CO is toxic, because it binds to the hemoglobin in the blood--and binds very well--so there is no place for the blood to transport oxygen, and then you die. Cigarette smokers lose something like 5-10% of their hemoglobin capacity (blood oxygen levels) simply from lighting up and smoking, by the way. If you take someone out in the air, give them oxygen, it makes no difference after CO poisoning, because their blood cannot absorb the oxygen and they will either die or recover regardless.

CO2 is NOT TOXIC. It displaces oxygen, and is an INERT gas. Remove someone from a CO2 atmosphere, and they'll gasp and wheeze and start breathing and recovering immediately. If you are someplace where there is a lot of CO2, you'll motice it, and respond to it, and even wake up from it, giving you a chance to get out. Unlike CO, which makes you sleepy and keeps you asleep until you die.

Very very different gasses.

Back to the original question: A brick of dry ice in the icebox shouldn't be a problem, as long as there is normal ventilation in the boat and you're not sleeping in the bilges or on the floors with a huge chunk of it. I'd close off the icebox drain hose while using it--since the cold gas is still cold enough (I think) to keep regular ice frozen, and keep things cool. Any warm gas that comes out the top of the box, should mingle with the air and disspate without bothering anyone.

And of course, let everyone on board know, if they "feel funny" to let the captain know and get on deck at once--just in case.

[speciald]

There was an episode of CSI where a couple was killed while sleeping on the floor of a dorm room when dry ice was vented into the room from the adjacent room. The volume of gas released in a cabin from your fridge would probably be too smaal to have any affect, particurly if there is a breeze.

[arbarnhart]

This is the sort of thing I am talking about:

Cuisinart ICERFB Ice Cream Freezer Bowl - BizRate - Compare prices, reviews & buy - Price - Review

To make what I do work, I have the treats inside it, freeze it and the treats in our deep freeze and transfer it quickly into the "cooler" which fits it pretty snugly and I seal it. It sounds like more trouble than it is - I am just being explicit because every step is important. I tried it in a regular cooler. I tried adding the treats right before sealing up (they were just bought from the store, and not frozen rock hard). Those were both failures.

[hellosailor]

CSI, ROFL.

What's the saying? "The most convincing lies all have a grain of truth in them." Crime labs don't get DNA results while-you-wait, and McGyver aside, it is really really hard to mix toothpaste and mouthwash in the right proportions to blow anything up. Even if the TSA tells you otherwise.

Never take Hollywood too seriously.