Terp Strip Problems

So our team received our KDL-5 system from Chemtech not too long ago. The company (Helderpad) had some issues with the glass feed tanks, which was letting our heating solution (marlotherm) into our product. (We have since been in contact with the company and the tech that came out is working with us and others to ensure that the problems will be fixed).

After we fixed the feed tank issue, we ran a few liters through it to make sure everything is working properly. We pushed out about 2-3 liters of D9 to make sure it was all good. So yesterday, I was working late, and I noticed that the terp strip was hella dark and some distillate was being stripped off the main body into the terp fraction. Thinking quickly, I cooled the evaporator temp from 130C to 120C and slowed my feed pump to 30 from 35. Waited… no action to stop the flow of distillate or dark color… So I cooled the evaporator temp from 120C to 110C, and it was still pulling distillate into the terp fraction. I just stopped there and called it a night.

First time this issue is bothering us. BTW, on a side note, we carbon scrubbed and used carbon chemistry’s Silica Gel (which, using the gel seems to be giving us problems… we PIG Filtered the hell out of all our solution and then hochstrom filtered with 1micron filter papers and it still didn’t get all the silica gel out of it).

If anyone has had similar issues with wiped film evaporation, please help us out. Thanks

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Can you post a pic? You’re not distilling thc or CBD at that temp, however you could be experiencing “bumping” from a volatile gas sweeping across the system (terps, high BP solvent?) .

Are you sure it’s your desired compound and not something else that is viscous?

Unless I’m hella confused, he’s talking about a wiped film, so bumping shouldn’t be an issue.

That’s pretty hot for terp strip, try 95C instead. If your vac is even decent you’ll get cannabinoids at 110C.

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My feed tank and residue was set to 95C, I had my evaporator set at 110C the last time I tried, and the condenser for the fraction of terps was set at 20C. Would you recommend leaving my feed tank and residue at the same 95C and just set my evaporator to 95C?

Feed @ 115c
Residue @ 115c
Evaporator @ 158c
Cold trap @ -40c
Condensor @ 50c

This is the vta SOP posted here and I’m pretty sure its posted as a good life gang sop

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Yes, I have the pic I took from last night. the right side is the terp fraction, though the hella darkness would fool ya.

To be fair I’ve never run a VTA, I know if I do a true first pass on my Pope at 158C I distill a vast majority of my cannabinoids with the terps.

The temp at which the target compounds distill is relative to the vacuum depth, so, if my vac is at 100 mTorr and evap is 110C, I get cannabinoids, I’ve tested it.


Right on that’s killer vac! in my experience in a terp strip you wont have a deep vac and you should be using a roughing pump anyways

I was doing R&D to see if acidic cannabinoids could be distilled so I fooled around with it a fair bit.

It is very much possible with a WF btw.


What was your vac depth?

Forgot to mention, we our getting pretty decent vacs with the system. We opted for the upgraded stainless still. Our vac is around 1.15E-01Torr, when our feed pump is set to 30. If we set it around 25, our vac is 3.85E-02Torr. But at the feed rate of 25, our terp fraction is taking hours and hours just for one liter to be terp fractioned… We’re about to start if up and I’ll see if the 95C will have a significant change. Our tech said with such good vacuums, the temps need to be lowered. I’ll run a couple liters and keep the progress updated with pictures. Thanks

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So you think the simultaneous decarb could propel the cannabinoids across?

We decarbed on a hot plate (induction cooktop nuwave) over 210F (~100C) with an overhead stirrer til the coke fizzles were non existent. Afterwards, we poured it over another filter (5 microns) before we put it into our feed tank. We’re up to temp now, about to run and see what it does. I’ll post pictures and videos during run to show the rate and quality. Thanks


If you’re using chemtec gear Ill ask a couple of questions.

  1. For feed, are you reffering to RPM? Like on a gear pump? They usually are fitted with a gear pump for dosing.

  2. Are you pulling vacuum/degassing your feedstock in the feedtank?

  3. What is your vacuum system, rough and a booster?

A few comments,

Do you run solvent through your silica gel prior to adding your material? A lot of silica gel will come with fine particle “dust” which must be rinsed from the media before adding your material. If you’re not then I would highly recommend running solvent through the gel until you see the solvent run clear.

You most certainly can distill cannabinoids at 125-130*c. Infact I had an SOP that ran at these exact temps, however it was extremely low throughput, and I was usually in the range of 5mTorr. However I dont think its totally far fetched for you to have some cannabinoids in your fractions at your described vacuum

Like @Apothecary36 was saying you would want to use only a roughing pump for terpene strips. You would want your vac to be in the mTorr range but not too deep, most terpenes are fairly volatile and do not require ultra high vacuum.

I would surely recommend running these strips at a lower evaporator temp (say 90-100C) and with just a roughing pump. Also, if you can with your chillers and transfer fluids, try running your condenser much hotter. I usually run condensers on WFE at 90C

Edit: formatting

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I don’t believe the decarb is propelling it. Because the residence time is so short, the molecules are able to distill without decarbing. Certainly some decarb happens, I didn’t work on fine tuning the process to minimize it.

It seems decarb is predominantly affected by temperature and time, so keeping those factors to a minimum of exposure while maximizing possible vacuum depths allows the cannabinoid to distill without breaking off the carboxyl group.


Try 250-500 microns and you should be able to raise the evaporator temperature.

Interesting note regarding cannabinoid-acids: I had about 0.4% CBDa show up from a batch SPD run (~800g hemp crude in a 12L boiling flask). Total run time was 2 hours, including initial temperature ramp and decarb.

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I apologize for not posting sooner. Been pretty busy over here. So we did some studies and came up with this: terp strip was too hot and our feed rate was too slow. We literally doubled down on the feed rate and cut down our evaporator temp to 135C and it started to run as expected again. Another thing we didnt do correct was using the silica gel. We didnt create the bed good enough on our PIG filter and didnt wash beforehand to get the small dust particles out. So when we did our first THC pass, evaporator temp being 150C, the small silica gel particles heated up and glued themselves to the wall of the still. So it created our rollers to not have good smooth contact. (I’ll post photos below with the first being the THC pass and us getting dark, shitty distillate… the next photo will be after we cleaned the whole system and ran again to “fix” the problem). What a mess and long ordeal but worth the knowledge. We cleaned the system by first passing 500ml vegetable oil at a slow feed rate and at evaporator temp 130C, condenser temp at 30C, and residue & feed tank at 70C. After all that ran through, we changed our parameters to evaporator temp of 50C, condenser temp to 10C, and feed/residue to 50C, and ran Xylene 1000ml through. And third, we kept the parameters the same and just changed the feed rate to fast and ran 1000ml of IPA through. It worked great! We took the system apart to check and it was hella clean. (Photos) and the catch hopper did show a lining of silica. so happy and we will never make that mistake again. Haha cheers

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We are having the same problem with More residue than distillate coming out on our KD-10 from chem tech. Does anyone know what temperatures and what speeds the motors should be for CBD.

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Did you degum?

I did, I got the terpene strip figured out. Now the cannabinoid strip is doing the same. It looks like our product is very viscous once we run it through. Completely different viscosity than before I put it in. Could temperatures be too high? Our vacuum is at 2.75E-02 What’s supposed to be our distillate looks more like terpenes.