[crunch]

Hi,

We need to have dry ice on hand at all times for flash freezing brain tissue specimens.

We can get delivery once per week of 100 lbs which is way more than we need, but I am told the larger slabs will decrease evaporation.

We are wondering if storing the dry ice in a refrigerated coleman type cooler will help slow the loss of the dry ice.  The coolers are basically at fridge temp of about 40 degrees.

Any ideas?  Any tips greatly appreciated.

[Corribus]

Don't store it in an air-tight container unless you fancy working around a ticking time bomb.  In my graduate school days, we had a prankster in our lab who used to love putting dry ice pellets in rubber gloves, sealing the gloves closed with a knot, and then throwing them in the garbage can, whereupon they would burst several minutes later and scare the heck out of nearby workers.  One day he decided to try to do it with a Nalgene water bottle.

Yeah.

He didn't do that again.

[Arkcon]

There are dry ice coolers available.  Their lids are thick and insulated like typical coolers, but are held down with velcro, so the pressure can't build up to dangerous levels.  Unless summertime temperatures really cause your labs temperature to rise, the refrigeration, down to 2-8 C, really won't really be much different from a comfortable lab temperature 20-25 C, for dry ice at -78 C.

[Borek]

I would go the way Arkcon suggests - even building a makeshift Styrofoam box with thick walls kept in place by string should slow down the evaporation considerably (not to mention the fact it would be leaking CO₂, which is OK given circumstances).

I could build such a box here for under $3 (assuming they still sell single Styrofoam sheets, as they did 20 years ago).

[Corribus]

And buy bricks instead of pellets.  They evaporate much more slowly due to less surface area.

[STraxler]

I suggest you make your own, there are small dry ice makers where all you do is hook a CO₂ tank with a liquid draw off valve up to it.  We had one for years worked really slick for generating dry ice for pour point testing of power steering fluid.

[IsotopeBill]

If you have a walk-in freezer available, do NOT store the dry ice in there, due to dangerous buildup of CO2.  A few years ago there was an accident involving dry ice in the trailer of a large delivery van:  the driver went into the trailer and passed out, and nobody found him until it was too late