Half dump freeze method questions

Hello all and thank you for welcoming me to this incredible community! way to go Future!

I am relatively new to extractions and have never had much of a mentor or any other info other than what I can dig up online or learn through trial and error.
I have the 5lb Bogart extraction system with a desiccant chamber and heat exchanger.
I live at 6000 ft above sea level so when reading the psi that is why its low.

I have been putting out good color ( but can always be better ) and maintaining my terps well. However, I think that my method is preventing me from getting the highest yield.

Im going to break down my process now and hopefully someone can have some insight and advice.

  1. Vac system (21-22psi), wait 5 min for leak.
  2. Close collection valve and desiccant valve to where the column and top of desicant chamber is shut of completely from catch
  3. Open stem port then slowly release 70/30 into column
  4. Once my psi is no longer rising (usually reaches about 35 psi) and i can’t feel the gas moving through my hose I shut my stem port
  5. I then open my top valve to my dual port and the valve on the side of my desiccant column creating a loop from the top of my column to my recovery port.
  6. After opening this loop I turn on my cep-ol and run it watching my column freeze colder and colder.
  7. I have found that I typically reach 0F at the same time that i get back down to 0 psi. That is when I stop my recovery (or freeze)
  8. I then once again open my stem port and slowly allow my mix into the system (35-40psi)
  9. Once gas has stopped moving I open the collection and desiccant main valves allowing for my final dump. From this process I have found that i get about 3 inches of liquid from my initial dump into my 12" collection pot. Which is about where my max is I would say without risking pulling liquid gas into my cep-ol.
  10. From that I recover until i feel like I’m ready, gas off, pour and put into the oven.

So here are some questions and i am open to any and all critique.

  1. Would using dry ice/ isopropyl in my cryo-sleeve be better than the half dump freeze method?
  2. Thoughts on 0F? Should i go colder?
  3. I keep the temp around my collection pot at 80F. Would going higher cause any problems?
  4. Would changing my blend increase my yield? But i don’t want to lose color.

I use a very similar type of method, it works well when you dont have a column that is jacketed.

Would probably work even better with a vacuum jacketed column now that i think about it.

We recover to 0°C/0 psi and stop there. The cmep-ol does not like to pull a vacuum it is hard on it so to pull it lower for a lower temp. Might cause hardware problems down the road. We use trs21’s in series atm for the reliability we have seen and they are ok pulling a bit of a vac.

The evaporator temp is kind of personal preference and what type of product you are after. If its crude/trim run we push the temps higher. If its shatter your after, keep it cooler as to not decarb your material. Ive seen nicer color oil turn more orange because the water was too hot on the evaporation. Ran it again and evaporated the butane at a lower temp and there was definately a difference in color.


Without discounting the importance of material prep and the butane evaporation rate mentioned above; may I ask:

How much solvent per lb/kg are you using on your material? I have found that anything higher than 4:1 can be overkill, but that can vary with material and if whether or not you soak it.

When I did side-by-side tests with more or less solvent,
dialing this in got me the higher yield I was looking for.

1 Like

I am having trouble visualizing what loop exactly you have open? This loop bypasses your collection vessel and essentially pulls a vacuum from the top of the column straight to the recovery pump? or through the desiccant dryer first? May you define what your dual port is and how it is used? I have a hot air reloop from the collection vessel to the top of the column that remains closed until full recovery as described in an old Summit Research article.

1 Like

Thanks Aurion!

I actually don’t currently use a specific amount of solvent for my runs. I simply bump it until my color changes or the level gets too high. However, I will start now.Thanks Exact!

Yes from the top of the column to under the vesicant chamber going through the desiccant and then to my recovery port.
I am unfamiliar with this hot air reloop. I’ll have to look into it.