Amazon/Morrison's deliver frozen food with ice packs containing some fluid which doesn't stay frozen in my freezer.
What liquid are they using and do ice packs have any use once the frozen food has been delivered? Seems a shame to throw them away.
It is probably "Dry Ice". Frozen Carbon Dioxide. Your freeze°r would need to beta -78°C to keep it frozen ;-)
It isn't. Carbon dioxide solid sublimates, there is no liquid phase at normal temperature and pressure.
Perhaps Madame Pamela should try alt.morrisons.icepack.discussion.bollocks
Dry ice isn't a fluid.
Check your freezer temperature, it's probably faulty.
I would assume they use Sodium Polyacrylate to retain the water in a gel. It's the chemical they use in nappies to absorb water and is non-toxic if the pack is broken.
I would have thought they would be frozen at -18C or so. BICBW
I would be very tempted to get a thermometer to check. It's always good to have one.
Most obvious use would be as ice packs. We used to get them with frozen raw pet food, far more than I would ever normally want for domestic use (might I suppose be useful if organising a large barbecue at a remote site). I used to think they were the wrong sort of thing to go into landfill, after removing the packaging the contents can be flushed down the drain. (I'm sure they are non-toxic, otherwise they would not be used with foodstuffs).
Havn't seen them for a while, all we have had recently has been dry ice packets, but these are just empty polythene bags by the time they arrive.
I guess that's why it's called "dry ice".
You recharge freezer packs in the "chest freezer".
The regular refrigerator has to be set to a too aggressive setting, to do freezer packs.
Only a "new" fridge makes rock hard ice cream, with authority. When fridges get older, the chest freezer is a good place to store the ice cream instead. Or, to charge up a freezer pack.
You can store more energy in a freezer pack, if it goes through a phase change. The phase change of your particular freezer pack, is 3X better than water. The "flat section" of the diagram for your freezer pack, is three times wider than the plain-water diagram in this article. That means the freezer pack might "last twice as long" for some purpose.
Surely that would be rather dangerous to have around the place? Frostbite and co 2 release in a confined area?
Brian
Lot of it about near the poles of Mars and on other planets and moons further out of course.
Perhaps its antifreeze? Grin. Brian
No it could just be that the volume is far too large to freeze all in one lump. Brian
That is an interesting take on the issue. My fridge-freezer is now 13 years old, and the freezer compartment is still maintaining the set -19 degrees. Isn't that cold enough for you?
Chris
It's ok if you have a risk assessment and a hard hat.
The Federal Aviation Authority is perfectly happy with controlled dry ice quantities in aircraft.
Probably water and some sort of antifreeze
Because a refrigerator has adjustments, Uncle Vinny may have come over the house and randomly twisted the knobs.
The chest freeze is much less likely to be mis-adjusted that way. Leaving a lack of maintenance (frost buildup) as a potential source of malfunction. Some people have never seen the bottom of their chest freezer, since the day they bought it. And the bottom of it is lined with freezer-burned roasts :-) Chest freezers are like an archeology dig ("hey, this one says roast dinosaur!").
Paul
Apparently many freezer packs use a high MW polyacrylate to raise the viscosity of the water, and prevent it freezing.
This, from
The alternative explanation is that Pamela's freezer isn't working properly. As has been said elsewhere in this thread, she should check the temperature with a digital thermometer. If one isn't available, see if the ice pack goes solid in a friend's freezer.
Easy enough to do the sums. Breweries are potentially more dangerous places, my mate brought a Victorian one back to life and after a couple of decades the new factory inspector suggested he needed CO2 alarms. One of the rooms can reach a concentration that you can "taste" if you open a sliding door on the ground floor at certain stages in the process, but everyone there knows the fireman's rule for CO2 extinguishers. If you can taste it, get out. That space is a "special case", the door provides access to the "drain" from which casks are filled, it is only open at that stage and and with the door open the pooled gas rapidly flows out. For the rest of the building, a calc for max generation and very conservative assumptions about air changes showed there was no problem. The factory inspector accepted it without a quibble.
There aren't really a lot of "nice" cryogenic materials.
"Three die in dry-ice incident at Moscow pool party"
You don't really want the dry ice to change state, all at once. Every gas has some place it would prefer to be, and CO2 is heavier than air.
Paul
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