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The Mk IA & automated Mk II Terpenator BHO Extractor

The Terpenator Essential Oil Extractor

Our main project and the one closest to completion is our volatile gas (butane) essential oil extraction apparatus. This project started when we realized how expensive large quantities of butane are and how environmentally damaging it is to volatilize that butane into the atmosphere. We began to think of a passive recovery device that anyone could DIY with a little help from a local machine shop.

While that was in the brainstorming phase we learned of a DIY active recovery unit designed and built by FOAF, that made use of a refrigerant recovery pump. He posted it on Overgrow, and subsequently on IC Mag in 2006.

Alas, our first pump had a misclocked valve operator from the factory, and though oil less, some how butane still got to the bearings and washed out some oil into the extract.

We discovered the oil in the  essential oil extract using a black light, and by the time we figured why the recovery was so ghastly slow, the seals were toast from running dry.

We were back on the hunt for an oil-less refrigerant recovery pump that was suitable for R-600 (Butane). We found a large scale compressor that is used for liquid to liquid extraction of propane from train cars; which would not be suitable for our needs.

From a fellow researcher who had similar problems with pumps, we learned of the Appion unit that ultimately proved successful. He had about 80 hours on his unit at that point without issue.

After choking a few days over the cost, we purchased the same G-5 model Appion, and we have put a several hundred testing hours on it, with one upper end rebuild.  Primarily caused by running the pump under hard vacuum too much of the cycle.

After increasing our systems bottom heat and adding column heat in the final recovery, we have noted little loss of performance on the new rebuild.

We were also able to cut the process time in about half, by having our collection pot sitting in boiling water, while we kept our butane recovery and storage vessel in an ice bath.

Presently the test sled is running  ten flood and soak cycles over a 30 minute period, using about 10 column volumes of butane, with full recovery in about 15 minutes.  The unit has extracted in excess of 25%  essential oil extract Absolute by weight, and averages in excess of 20%.  A full cycle has a sample floor to floor time of 45 minutes.

With the 24" column in place, it holds about 240 grams of material, which provides an average production rate of about 80 grams per hour plus raw  essential oil extract.

During testing, we noted how boring it was to watch a vacuum gauge and proved that with every new step in a manual process, there is an exponential increase for human error, so our next all stainless steel unit will use explosion proof automatic valves and microprocessor controls. Our new unit will be simple to use even for the most non technical user; load the column, push start and then clean out the collection container and column.

As we have no desire to build more than prototype test sleds ourselves, we sent the conceptual CAD prints out for competitive bid by CNC water jet cutting and machining vendors, as well as an aerospace pressure vessel shop, with ASTME certifications.

Alas, we discovered that with negotiating as an OEM, we can buy the ASTME pressure vessel lower end, cheaper than we can have one made, and even buy columns off the shelf at retail for less than we can have them made using local resources.

As our survival as a company, is more important to us than supporting the local economy in the style to which they have become accustomed, we will modify our designs to reflect that and then start posting the DIY details.

Now that the pressure vessel is a buy out, there is nothing else that isn't buildable in a garage workshop, equipped with a drill press and TIG welder.

We have taken a deposit from the vender whom has our original test sled leased out, for a fully automated unit, and have ordered the pressure vessel and identified explosion proof automatic Asco valves that will work, but are still reviewing alternatives before placing that order.

The controls is the open question at this point.  Our original plan was a PLC micro processor, but after looking at the price for an industrial unit, we are  reviewing using simple timers and pressure switches with solid state relays to accomplish the same thing, using a hobbyist microprocessor, or building our own dedicated solid state electronics at about 25% the cost of a PLC with software.

Our mostly retired electronics genius, is pondering the issue on his current vacation in warmer climes, and will begin looking at it seriously on his return.  If we end up building our own, we will post an electronics design as well.

We are building this first G-2 prototype ourselves, and I will take pictures as we progress, starting with the modifications of the pressure pot when it arrives.

The unit is designed, so that it can also be fitted with manual valves, and forgo the automation.  The current manual test sled works extremely well, so the only advantage to automation, is less stand by labor, and more precise timing of process steps.

We will of course also be trying to beat old process records, whose records continue to improve, and to make loading easier and faster.

Here is a schematic of how the system operates, as well as a picture of the test sled after shakedown. Follow us to stay up on our latest development’s.

collection vessel

The Terpenator Essential Oil Extractor

 Hi ya'll!

I picked up a 2.8 gallon Bink's Model 183S stainless steel ASTME paint pot, rated at 110 psi and am excited to try out some 1 1/2" X 24" stainless tri-clamp columns that I discovered at

Our target operating pressure is -29.9" Hg vacuum, to +60 psi and according to Glacier, the sanitary pipe spools are capable of several times that pressure.  If it works out in field beta testing, I will adapt the Mk I test sled, to the new column, so the lessee has a common column.

The paint pot has a central opening for an agitator, which had a plug with an o-ring seal filling the hole, on my cheaper non agitated model.  I dropped that plug off at a machine shop yesterday, along with the loading port lid, for modifications, which will allow me to more or less just screw the whole thing together out of available parts from this point on.

I'll share pictures of those, after I pick them up, but here are some pictures of  what we have so far:


Progress is being made. I developed the process logic and then met with Bob, to discuss controls.  My logic assumes three pressure switches and three timers, but we looked at using a single pressure transducer, with a 4 to 20 miliamp output, in concert with three voltage comparitors, but just the transducer was $540, as opposed to $38 each for the double pole adjustable pressure switches.

For timers, we found some premade count down timers which we will modify, and we will have two LCD timer readouts. One adjustable total process timer, 5 minute hard vacuum purge soak time, and one 20 second flood timer.

I also dropped by Paramount Plumbing Supply and looked at the ball valves with operators, which I will need to automate this unit.  For both size, cost, and explosion proof qualities, I have elected to go with pneumatics, and the operators are still so big and heavy that I will have to build a metal frame to support them.  Hopefully I have enough structural aluminum in my haunted garage to do so without adding much weight.

Here is the logic sheet.

Butane Recycle System Logic














Event driver











Turn on power










1.1 Momentary start button O X X X


1.2 Vacuum pump valve NC O X O O   O X O O
1.3 Ref. recovery valve NC O X X X   X O O O
1.4 Lower isolation valve NC O X O O   X X X O
1.5 Upper vent valve NC O X X O   X X X O
1.6 Butane control valve NC O O X O   O O O O
1.7 Vacuum pump on/off O X O O   O X O O
1.8 Ref pump on/off O O X X   X O O O
1.9 Hot water pot on/off X X X X   X X X X
1.10 Column heat on/off O O O O   X X X O
1.11 Vacuum switch -29.2Hg O X O O   O X O O
1.12 Vacuum switch -22" Hg O O O O   X O O O
1.13 Vacuum switch -10" Hg O O X X   O O O O
1.14 15 minute timer O X X X X O O O O
1.15 20 second flood timer O O X O   O O O O
1.16 5 minute timer O O O O O O O X O

 *Once in the 2/3 loop, 1.13 becomes the driver, instead of 1.11, as on the first cycle. 

To initiate, turn on power and push momentary start button.

X in a column is ON

O in a column is Off

X in a column is the event that ends the cycle and initiates the next.


More progress!  The lessee who is operating my pumped test sled, and who ordered a full blown automated system, has continued to refine the process and has not only bumped the record yield to over 25% Absolute, but has determined that four flood cycles are all that is required.

She now has the total floor to floor cycle time down to about 28 minutes.  That processes about 480 grams of material an hour, for a yield of around 120 grams of BHO Absolute.  That would compare to around 130 grams of raw BHO oleoresin, before winterization.

She also no longer tries to recover 100% of the butane, but instead stops the recovery when the recovery vessel reaches -22 mm/hg, and turns on the hard vacuum pump to pump 29.9 mm/hg, which pumps off about 57 cu/in/.00095m3 of gaseous butane to atmosphere per cycle, or about $0.076 worth.

Electrical costs are about 3.3 KW per hour, at $0.09, or $0.045 per cycle.

Total operating cost, less labor and periodic pump maintenance, is $0.18/hr, or about $0.0015 gram.

We have noticed that our recycled butane is starting to pick up water, so I will add a dryer.  Fortuitously, I was able to pick up a R-12 Robaire refrigerant recovery and recycle system off E-Bay cheeep, and will rob the filtration and dryer system off of it.

That includes a circulation pump, a dryer, and a water detector, which can be circulating the butane in the recovery tank through the dryer and returning it, while we are doing other things.  It has been used to recover automotive refrigerant, so I will completely rebuild it and replace the hoses and dryer element to avoid cross contamination.


Well, progress is going slower than planned, with illness rearing its ugly head amongst usn's cadre of graying, hoary moss covered retired machinists.

Here is the only two pieces in the basic system, that require machining or welding, and you can see how easy they are to make.  They still need to be cleaned and polished, but the attached pictures show what they look like immediately after fabrication.

The center plug in the pressure pot lid was bored for an easy slip fit on a 3/4" 1.050" OD  Schedule 40 316SS pipe, with 10.5" sticking out the bottom of the plug and 3.5" sticking out the top.  This is where the valves and column attach.

The paint port lid was also modified by cutting off the wrench boss and boring for the same 3/4" pipe.  This will be for the control valves and pressure switches. We decided on pneumatic operators on full port stainless ball valves.  All are air to open or close, except the butane supply valve, which is a normally closed, spring return valve for safety. The three and four way Asco solenoid valves for the air, will allow us to separate the electrical functions from the extraction area, for explosion proof protection. Here is a picture of the valves that I've ordered and the prices.  Keep in mind that manual valves can be used at significantly less cost. 4-11-12 Lu lu lu lu lu lu lu lu lu lu lu!!!!!!!!!!!!!!!  The pneumatic operated valves arrived and I installed them.  Here is the Mk II assembled and ready to roll. The electronics are scheduled for smoke test this week end, so we are close to beta testing.  Here is a list of additional parts:

Progress on controls! 

For ya'll that have been waiting with baity breath for what our resident electronics genius came up with, Bob picked a Panasonic FP -X C30-TD PLC (~$300) for the task. Because of some of the loads involved, Bob also built a relay panel, using an existing standard PSI elevator PC board, and a cycle timer display built from a count down timer kit.  The heavier 2 hp and 1/2 hp motor loads, as well as the 1200 watt soup pot loads will be controlled using Crydom solid state relays. Here are some pictures of it being smoke tested before installing it in the 12" X 12" Hoffman enclosure.

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  1. Williamsr

    Hi. So, if i'm not mistake, it was your topic on forum about "XEvil + XRumer 16.0"? Seems it' really fantastic program, that review video is amazing! Solve Facebook captcha just in 0.01 second without any mistake at most... Incredible. Do you know where I can download XEvil OCR? Maybe you can share? Thank you! :)

    Reply       Edit
  2. Marc Maza

    Great article Dr. Kate, I can't say, "thank you," enough from all medical and non medical folks. Skunkpharm, you are such great and wonderful people, much love and keep up the great work! Woot Woot

    Reply       Edit
    1. skunkpharmresearch

      Thanks for the good thoughts brother MM! I agree wholeheartedly and continue to be impressed with the masterful quality of her work! We at Skunk Pharm Research feel privileged to have enjoyed her professional insight on many of our own projects, as well as to be able to post her work! GW

  3. peter

    GW, I love this site. Best place on the Web to receive a free education. One thing I can not seem to understand is the use of a recovery pump such as the appion g5. These pumps and lines are not food grade and have been shown to contaminate. Am I missing something? I'm looking for a suitable recovery pump for the rask...rated for flammable gases and using food grade parts. Any thoughts?

    Reply       Edit
  4. skunkpharmresearch

    Sorry to take so long to get back to you bro, but we had to take the extra step of discussing it with our business attorney. Yes, we will take care of all of you. For the mechanically handy, I will publish the complete details of the current Mk II as I put it together, and am available to hold your hand and field any questions you might have as you build and learn to use your own DIY unit. For those who want to purchase a unit or critical component kits for a unit,Skunk PharmResearch, LLC's bylaws proscribe doing retail sales, or business outside the state ofOregon. However, due to the number of inquiries, after discussing it with our attorney and a couple of the businesses that we lease equipment to, we are going to license our technology to a company who does do retail sales nationally and internationally. More on that, after they have had an opportunity to get set up. In the interim, please enjoy this resource site, which will remain free to all and uncluttered with advertisements, because retail sales are outside our core purpose.

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