That’s subjective
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You use ice water For your condenser coil res? You don’t have problem with creating pressure in your tank? Or are you chilling your tank too?
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i’ve seen no advantage in running acetone over alcohol, but to each there own.
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Are you running 99% iso?
yes sir
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Acetone and 99% iso will both get to the same temp in the dry ice bath. I use 99% iso because it’s not as aggressive on the dry ice, and I’ve got a 50’ coil… the benefit to acetone vs iso comes down to heat transferability.
Acetone transfers heat better, so with a shorter coil like above, seems like acetone would work better.
At least that’s my rationale
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I use two coils, first uses cold water the second uses dry ice slurry. My tank is not chilled, but it is insulated very well.
Ive got a couple reasons why i like to do this, the main one being that its just more efficient.
The first coil at 25-30F is able to condense most of the vapor before it e reaches the dry ice coil. This means that when the solvent does make it to the dry ice coil less cooling power is taken away from the dry ice slurry because that fluid no longer has the job of condensing vapor, it only acts a chiller. This ensures my temperatures on my low temp coil stay LOW.
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whatever works best for you 
totally unnecessary. how much dry ice does that save you a day? 2 scoops?
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If your running with acetone you need to be sure your gaskets can handle acetone. The reason acetone works better for a chilling fluid is due to the fact that its got a lower viscosity at those temps than isopropyl alcohol does. When the fluid starts to get syrupy you start to lose cooling efficiency.
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whatever works best for you
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have you done comparisons to how much better that is then just using 1 coil? i’m just saying i highly doubt that extra effort is worth another coil and another set of hoses
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You and I are on the same page…
heat transferability
@J12 could be right. I’m currently using 2 coils back to back. One in 90/10 iso the other in 99% iso.
I’m not here to split hairs though, to each his own
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not knocking you guys. just saying i think the extra coil is just an unnecessary extra to save a little on dry ice especially if your running a coil that cold to begin with. more parts more hoses more connections for not very much extra in the end.
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how do you guys recover with a coil without chilling your tank?
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The incoming gas is cold enough to chill the tank
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But wouldn’t the warmer tank create back pressure against the gas in the coil, preventing it from entering?
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Maybe a little at first, burp the collection tank. I have to burp a little nitrogen from mine at first anyways.
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set up a purge line off your solvent tank and open it up before you recover. Once you get a good flow going into the tank you can close your purge line and it should start to pull more vacuum as more cold solvent flows in. You can get very good recovery using this method
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I have the lines insulated so the losses are somewhat mitigated. The reason i do it is because i like to use a smaller volume of chilling fluid, it allows me to get to lower temperatures.
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