Setting up passive system

Just finished ordering everything to set up a new passive system. It will be wall mounted with bi directional flow capabilities and nitrogen assist. Here is a quick run down (does not include all valves, fittings etc):

4” shower head top cap w/ 2x npt ports
Compound gauge
4x48 spool with sleeve
4” Filter plate for stainless precut disc and paper
4” 5 micron sintered disc
4” 1 micron sintered disc
4-1.5 hemispherical Reducer w/ filter plate and paper filter
1.5” 5 micron sintered disc
Tri clamp- 1/2” mnpt adapter

For my collection pot I am using:
10” Hemispherical lid
Dual sight glasses
10”x10” spool
10”x12” bottom pot
Tri clamp- 1/2” mnpt adapter
Compound gauge

I am using a combination of tuff steel, ptfe envelope, and straight ptfe gaskets.

All vessels will have 150 prv’s.

I will be using bvv’s tri Gas blend. 50n/25iso/25prop

My solvent tank will be in plain dry ice during solvent injection and then move into dry ice & acetone during recovery. My sleeve will be filled up with dry ice & 99 iso. Collection pot will be in dry ice & acetone during collection and then Moved to hot water bath during recovery.

I am using 2 food grade barrels (1 medium sized and one large sized) cut in half. The large warm water reservoir will be preheated by 2 1500 watt bucket heaters will on thermostats and 1 submersible pump circulating water. Another pump attached to 1/2” hose will pump warm water to the collection vessels small warm water reservoir. In the small warm water reservoir I have a matched submersible pump attached to a 1/2” hose that pumps the water back to the large warm water reservoir.

My nitrogen tank will be plumbed to one of the vapor ports on my solvent recovery tank and directly to top of the spool. I plan to lightly pressurize headspace of solvent tank to Push chilled solvent to spool and then do a final push post soak (30 min)from the spools nitrogen port.

All parts should be here in the next week and a half. I will post photos as progress is made.


Everything looks good man. I recently quit using acetone in my baths because it’s just to aggressive on the ice. I find that 99.7 iso does the same thing temperature wise, but you’ll go through dry ice much slower


Thanks for the info, that’s the kind of input I’m looking for. I was only planning to use acetone because I had read that it will take the temp slightly lower than the 99.7.

Thanks again

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I wonder if one pump and gravity can t be used on your warm water reservoir
For finding two pumps with exactly the same volume displacement is hard

I second using one slurry solvent
Having more is complicating things

Are you planning on heating your blast tube ? If so how are you planing on dooing it

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I planned on just using two small submersible pumps that are used for hydroponics, but I bet you are correct when you factor in the lift and all other variables.

I will only heat my spool to recover residual solvent from material. I have a line running from the top of the spool to my recovery tank. Planned to just drain dry ice slurry out of drain port and fill with warm/hot water.


I meant to write my previous post in response to you.

The reason acetone burns ice faster is because it’s a better heat transfer fluid

Acetone will allow your bath to get colder because it transfers heat better than any alcohol


Makes total sense.

Thank you

They get to the same temperature though, do they not?


You’ll save money by using denatured alcohol and get same results. Gallons iso is expensive

And reuse ur slurry solvent guys! Throw lid on the cooler the next day and save it till next time


Eh I bought a 5 gallon jug of 99.7 for $115

There about 15 degree difference…balls cold is balls cold

Beside acetone requires pain in the ass gaskets


It’s not about the temperature it gets

It’s about how fast the heat transfers

Acetone transfers heat better

It’s like a glass cold trap compared to a steel one

The steel works better because it transfers heat better which allows a better temp


If you have 1 50 foot pre chilling injection coil, acetone will get the solvent colder quicker then iso will.


Ok that I can see. Dry ice is -78c and the bath just helps maintain that -78c.

I don’t think there’s a temp difference though like @StoneD said.


True, but if your solvent has time to get to temp in the bath, then it’s roughly the same, right?


I use 2 50 foot coils in an acetone dry ice bath

I do not chill my solvent tank

Even then I need more coil to get down passed -40

Our solvents move quickly through the coils most of the time

Which is why acetone would get it colder than iso would

Also ethanol doesnt get as cold as iso/acetone


You’re only getting to -40 with 2 injection coils?? You must be hauling ass through it.

I’m using 2- 50’ coils as well. Though I stage it. One is in 90/10 iso and the next is in 99.7

My extracts have only gotten better with the injection coils vs a fully submerged tank.

I need to get a temp gun now though, you’ve got me worried


Thanks for the pic, one c difference

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Excuse me 6 degrees even better! lol not worried about that I’ll stick w -72.