9.4.7.2 Subzero Extraction
For ya’ll brothers and sisters looking to process larger quantities at a time, we recommend that you consider the Subzero Ethanol process, by which either fresh cut or dry material is packed in bags, which are subsequently placed in a stainless vessel at ambient temperature, through which ethanol at >-50C or lower, is pumped in a circle through it, as it is being agitated, dissolving and removing the essential oils.
Temperatures that low are typically achieved by adding dry ice to the bath of ethanol.
A pump is required that can operate at those temperatures, and due to low seal elasticity at those temperatures, typically a mag drive pump without seals is required.
At those temperatures, full extraction of 25 to 30 pounds of material takes about 10 to 15 minutes, before being passed through a 0.5 micron PTFE coated polyester felt sock filter, available from places like Duda Diesel.
![](https://i0.wp.com/graywolfslair.com/wp-content/uploads/2023/04/Subzero-Extractor-jpg.webp?resize=640%2C548&ssl=1)
Subzero system using cryogenic mag drive pump
Here is a conceptual of a system that uses either nitrogen or air pressure to transfer the liquid from the storage tank through the shower head into the second tank of plant material, and then a gain to blow it from the process tank back to the storage tank. Pneumatic pressure can also be used to transport it to the next next process.
![](https://i0.wp.com/graywolfslair.com/wp-content/uploads/2023/04/Subzero-extractor2-jpg.webp?resize=640%2C498&ssl=1)
Subzero extractor using Nitrogen pressure to cycle