Kugelrohrs are awesome!



To be clear, Kugelrohrs are awesome!

Especially for a small producer, but also as an additional distillation apparatus.
For instance, if you have a small 2" WFMS as your only distillation equipment and you somehow break some glassware and it ends up in your beautiful distillate (or you even just think you might have! gotten it in there!!).

This is a big time-eater, right?

Now you probably have to put it back into solution so you can filter it, then you’ll need to remove the solvent, probably via rotovaping. Then you’ll need to either re-distill to remove residual solvents, or put the material into a vac oven. I’ll let you do the math on the amount of time thats going to eat up at your lab. Most likely using equipment that should be processing new material, not reprocessing material that may have glass in it.

Now, if you built yourself a little kugelrohr set up, say with an old Buchi RE-120 motor, and a modified large stainless say, wort brewing pot from the brew shop slipped over the heating bath (Now made into a air bath).

Now get yourself some old-spinning 2L Kugelrohr glassware (including a “flying saucer bump trap”, you may need this made for you. I recommend Adams & Chittenden in Berkeley, CA. They are thee scientific glassware pros for the western US and they have been for 30+years), two or three cold traps, a thermocouple probe and controller, hook it up to your vacuum system, and you’ve got an amazing set-up that can run material full of glass or whatever, no problem.

Plus when your not fixing your mistakes you can plumb it into a vacuum system and use it as a SPMS (short path molecular still) if you get a proper vac system that can pull below 10mTORR. The whole set up (minus the vacuum system) will probably cost you $2000-$3000.

I love having a Kugelrohr in my labs.

THC/CBD separation using short path

@Beaker does this but he uses a heating stirring mantle instead of a water bath.


Yes Sir, you’re looking for a heating element is all. Finding one thats already housed in something (like a old water-bath or a heating mantel) is all the better. You are creating an air-bath so anything that could heat water will usually be hot enough. The reason I like using the water-bath is 1) because its easy to slip a big stainless pot over and the walls of the water-bath provide a good ridged frame 2) you can usually get the motor and bath together on eBay for the same or just a few hundred more than the motor alone.


A windsheild wiper motor would work better than a rotovap motor because youll need to have less than 270 degrees of movement or else your collected distillate will feed past the collection flask as well as drip back into the boiling flask

Water wont get you hot enough to distill cannabinoids

Rotovap motor and vapor tube seals wont stand up to molecular distillation vacuum depths in my experience


kugel rohrs are super slow, while @Beaker has posted some interesting work with them, they are not suitable for commercial production, and a simple small short path can be set up for a similar price with better efficiency


Horizontal distillation is perfectly suited to micro scale stuff but as you said for a commercail operation would be a tough deal to scale up to. A fully rotating bulb set up was a problem for me owing to my idea which was to pull down and maintain very deep vacuum and initially my set goal was 20 microns or less. I now change the oil when it gets up past 10 and cannot pull down. Generally if given enough time the unit pulls down to one micron.

My solution was to simplify and keep the bulbs fixed. I use a cloth full sperical heating mantle and under that I have a stir bar mechanism. I use no bump trap but rather rely on the angle of incidence I adjust before and during the run to keep the splatters and such at bay. Temperature control is pretty important for this.

I agree with @Psilisophical that trying to scale up a kugelrohr unit is pretty tough and especially so if you plan to engage in rotating the bulbs whether by modified windshield wiper motors or some such similar lash up. Now if you had a serious R&D budget and commitment to figuring out a commercial horizontal unit then I think there is considerable potential. In fact I recently saw a picture of a unit that was on static display at a show that was in fact a horizontal distillation rig set up in high bypass mode so I do see at least the more vocal folks addressing this idea - but they are only leveraging the huge advantages of the horizontal configuration and dispense with the rotating bulb stuff too.

Spinning joints are the achilles heal of a traditional kugelrohr IF the goal is lowest possible boiling point from deep vacuum. :nerd_face: Truth is in all the industry I have helped with on an engineering level it is the spinning joints that need a seal that seemingly always introduce the problem areas of design.


No need for spinning joints, Pharmer Joe built a 5L kugelrohr with an old standalone jkem (basically wiper motor) stand alone and a big AI convection oven that we slapped a bearing onto. Tilting the bulbs to keep the path short helped immensely at that scale


Like I said I had no trouble maintaining molecular distillation pressures with Sasha’s old Sigma-Aldriech