Creating low temperatures

Dry ice solid carbon dioxide packed around a metal container. Liquid gas nitrogen?

Try a bath with some different proportions of dry ice and acetona. Methanol also works, but I'm not sure if it goes down to -60C. It normally works very well. Keep a conteiner with some dry ice around, and add it to the bath as required to control the temperature.

At last some one who knows a thing or two. Good post.

Having used dry ice and acetone, remember the carbon dioxide dissolves in the acetone and is a very effective freezing mixture, - 78C eqilibrium temp.

If you put a warm item into it you can get a huge surge of CO2 and acetone all over the bench and acetone burns very well. I can remember many small lab fires from this cause.

Here is a site about assorted freezing mixtures.

http://www.chemistry.ohio-state.edu/ehs/handbook/gases/coldtrap.htm

Mark

True. But I'd like to see a cautionary note also that one is dealing with highly flammable acetone, or toxic methanol, which is also flammable. We usually don't know the background of the people we send answers to, so please err on the side of safety.

"What additives can lower temperatures of a bath down to -20 to -60 deg C?"

Dry Ice and Cellusolve, will get you down to temperature of -78.5oF! Used as moisture traps in high vacuum systems at one time in distant past.

Baths with or without additives are one solution, but their use is consumptive; and in an open system, depending upon the solution to be cooled may be loss-inentsive or chemically counter-productive, requiring some means of enclosing the coolant or target item.

What are some ordinary/extraordinary mechanical means for generally accomplishing profound cooling? (i.e. quick, although not necessarily flash cooling of target items, conversion of volatile gases into liquid, etc.)

Mark

Does whatever you are cooling have substantial thermal mass?

A water chiller with an antifreeze mixture will get you -10C, vortex tubes will give -30 or 40C as will peltier devices. Liquid nitrogen is easy to use if you want to get much colder.

It all hangs around the mass you are cooling & the temperature gradient you want to achieve.

Sure, depends on your application. The original post claims for a solution for lab punctual problem. For steady state process, I'd go for a cryo chamber feed by liquid nytrogen (cheap and easy to handle with automatic devices), temperature adjusted by a PLC or a temp controller, with maybe the addition of a logger or data acquisition system to assure precision...

But I really don't think this is the problem.

Thanks. Is that the sum total of the set of devices in the field for accomplishing quick cooling?

Mark

Yes, this item to be frozen has a good (few grams) soild thermal mass.

I guess it all comes down to choice, and experience. Go carefully.