Convert to Super Chilled Alcohol
Its simple and easy, just cost a little more to get the extra equipment. Still tens of thousands cheaper than those Co2 systems that constantly break down!
Just take your closed loop system for butane and use super chilled alcohol as the solvent.
Super chilled means well below zero -40 to -60 degree C this requires a scientific chiller instead of your chilled LP tank. The chiller cools down the alcohol to -40c then you wash your material with it the same way you would for the butane solvent. The clear liquid and essential oil end up in your collection base as normal. Now you need a rotary-Evaporator or Rotovape for short to reclaim your alcohol similar to how your recovery pump worked on the butane.