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Best Method for Cleaning CO2 System

Some people say do a "dry run" with no material and run the machine as normal with fresh CO2. Others say add ethanol and let that run for a while. What do you think?


  • A dry run will solve the easy mess within your EV/SV1/SV2 areas. Like if your machine is running normally and you just want to have no carryover from one run to the next, you can do a quick dry run in between. You can set the pressure and temperature of the CO2 to be a solvent for the compounds trapped in your machine depending on what your parameters were in the runs you did previously. For example if I hypothetically normally run 1500 psi and 84F, I would want to dry run at something like 1800 psi and 130F to ensure that I have a denser solvent than the one I used in the previous run.

    I will use ethanol in my dry run if I know there are a lot of dense, heavy compounds trapped in my machine from a super critical run.

    Basically I use the dry run for cleaning between light runs, and the Ethanol for cleaning between heavy runs.

    I'm sure there is more to it than this, but that is my two cents. I would appreciate any further clarification!

  • That sounds about right. I would suggest a dry run or at least a passive fill and vent after an Ethanol flush to assure there is no residual ethanol in your next run.

  • For a clean run I like set the temp on the EV/SV1/SV2 to 175f and fill all 3 with some ethanol then close the vessels for an hour or so. This will wash the vessels fairly well. Then push the ethanol through the system by venting the valve at the bottom of SV2 and sending co2 from the bottle through the EV/SV1/SV2. This will wash out the piping between EV/SV1/SV2 with the hot ethanol. Then drain the remaining ethanol from the bottom of SV1. I will follow that up with a CO2/ethanol run at higher pressures and temperatures than I normally extract at. After the CO2/ethanol run, drain the system including EV/SV1/SV2 and the accumulator of CO2 and ethanol, replace all seals then flush the system with fresh co2 from the bottle making sure that you blow any residual ethanol out of the system.

  • Has anyone run into any issues when cleaning with ethanol, such as damaging the o-rings etc?

  • I only run cleaning cycles with ethanol, just ran one tonight and I always change that top extraction o-ring before every cleaning cycles just to ensure a clean run and I do notice a little bubbeling so I don't risk it. Ccycle 1-gallon 195 ethonol 1500 for 30 minutes, deco and collect solvent.
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