How do y’all feel about a roto evap speed test using only ethanol?

Personally I believe that’s an Inaccurate test.

If your using tincture, the more oil that builds up the slower you recover. Also you have to take the time to empty the ball, and if your supposedly recovery 70LPH you’d have to empty your 50L ball every like 45 mins? Which would cut into your per hour quota. On top of the fact that tincture vs pure ethanol is going to evaporate slower depending on ratio of resin to ethanol especially as your ratios drop as you recover your ethanol. Just a thought

What’s yalls thoughts?


I absolutely agree, the first half of the ethanol comes off significantly quicker than the second half of it. Seems within reason that as more of the oil gets in the way, the ethanol needs more time or energy to separate from the solution.


I agree with both of you, however a run with ethanol only could be used as some type of standard comparison, even if it doesn’t accurately reflect real life usage. At least it would eliminate variables due to differing tincture compositions.


The boiling point of a solvent raises when it has things dissolved in it. This is called colligative properties. So they’re very different.


The scientific terminology for “this shits slowing down I think cause of all that oil”


So then the next argument is, is this a fair metric to state their capacity ? I think this is severely misleading.

Like my 20L rotos maxing out at like 15-16 LPH with oil


If you ran a typical oleoresin and timed it. And then ran a equal volume of pure ethanol and timed it. You could probably get a time ratio that would be scalable. Something like oleoresin takes 1.25 times longer than pure etho. Not 100% on that but it seems like it could work in my head. Lol


Maybe one of our resident chem wizards could come up with a formula for a testing standard that could be easily formulated for in house testing. Preferably non cannabinoid, maybe a blend of natural oils in ethanol, something like coconut oil. That would allow testing in non legal areas.

Definitely doesn’t reflect real-world performance, but is much easier to standardize on.

As the tincture gets more concentrated, the difference between “real-world” and “pure solvent” is going to grow wider, I’m not convinced it does so in a manner that we can deconvolute reliably (seems more complicated than a simple multiplier).

Would I like to see real world numbers? Absolutely!!

Would I believe them?

Nope. I don’t tend to believe anything I haven’t replicated. Especially if uttered by a sales engineer…

Want me to believe that’s ethanol you’re recovering at 100liters an hr not pentane? Let’s see a swig from the recovery flask…


I think it’s meaningful but only if comparing apples to apples. So (let’s just assume Summit’s number is true for this argument), getting 80 L/h of pure ethanol on a summit vs 16 L/h of oily ethanol on an AI, is not a quantitative comparison. However, getting 80 L/h of pure ethanol on a summit vs 20 L/h of pure ethanol on an AI is meaningful.

This setting aside the question of accounting for the emptying of the flask, which like you said is important. For that reason I also hate the use of L/h for SPD without further qualification. L/h on SPD is usually only considering mains, not the ramp up. While L/h for wiped film actually reflects the entirety of the process from the moment it turns on.


It would only be possible if every single roto was exactly the same besides the advertised volume. Voltage, KW, volume, pump, dual coil or single, evaporation area, condensing area altitude test is conducted at. Way to many variables from manufactures.


Personally Speed is speed. Price determines how fancy or how many KW etc.

Like we compare cars 0-60 time. They all have different engines different transmissions different turbos etc. but it’s still the same metric of measurement regardless of price or technology.

So a set real world metric would be more ideal. Like magister said about SPD LPH is dumb dumb. Unless they start a timer from the second you turn on your mantle to the second the last drip comes out and then average that speed out over the time it took to get your LPH then that would be accurate but that then reflects a lot on skill of operator.

But if every single roto based their speed on just pure ethanol in the system for 60 mins flat running as fast as they could possibly run, I guess that would give a rough idea. But still have to take into consideration the emptying of the recieving balls at the minimum

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Yes and no because a test done in Cali will have different results from one done in Denver. It’s the same when it comes to our cars as the same car will have different 1/4mi times at different tracks. Altitude, temp and DA all come into play. I think you will agree that a dual condenser 50L is not going to perform like a single and the same can be said for single/dual turbo cars. To many variables to say every 20L roto will recover X in 1hr.

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If you guys want to turbo charge your Roto. We added a coil in a bucket of dry ice between the chiller and the top of the collection column. It eats up a lot of ice, but also saves us a lot of time. Almost double in collection rates. You can run the bath hotter with this configuration.

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This gives me a fabulous video idea. Thanks.

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Wouldn’t this also somewhat depend on chillers, cold traps, pump, mantle/water bath and boiling point?

My 50L rotary evaporator keeps running pretty good while I drain the recovery globe. Pumping the globe down again stops production if I let the pump running the roto do it, so I use an extra vacuum pump to suck down the recovery globe after I drain it. Keeps everything going real well. It helps dramatically with a big unit and only takes a minute or two.