Rotovap questions - Cannabis Concentrates - International Cannagraphic Magazine Forums

bunbun · 10-02-2017, 10:50 PM

Hi all,
New to extracts and have questions about rotovapping. Using a 5L rotovap with 29mm Hg of vacuum, which I thought should be plenty capable to extract ethanol at lower temps, like 40C or less, but it doesn’t seem to pull off ethanol as expected, or takes hours for small batches. Experimenting with higher temps, like 55-65C, and mixture will boil, but still seems little ethanol condenses off, and don’t want to degrade product. It does thicken, but even when it appears finished and nothing else comes off, I swear it still has the smell of ethanol. Even after hours of leaving it. Can rotovaps make final product or does there need to be a final finishing step?

blastfrompast · 10-02-2017, 10:56 PM

I believe most people just use the rotovap to recover the pricey ethanol then finish the purge in a vac oven...

fyi u will need to bump ur temps up a bit with ethanl vs butane when it comes to the finishing step...well at least imho.

BigJohnny · 10-03-2017, 12:56 AM

Set the vac regulator to 60 Torr, temp on the bath to 113F, start rotation to 100rpm and let the bath warm the flask while the vac pulls down.

Onc vac is achieved open the injection port and inject approx. 500ml of solution into the load flask. Once it starts condensing open the injection valve just enough to match the condensation rate. let it run and it should recover at a decent rate.

When it comes to the speed, I tend to try and have it at a speed that's enough to keep the puddle "chasing" the bottom of the flask, so essentially is always running down but never makes it to the bottom.

Gray Wolf · 10-03-2017, 11:40 AM

Here is our test of the Heidolph, which shows parameters:

https://skunkpharmresearch.com/evalu...ecision-ml-g3/

Phineas Freak · 10-03-2017, 11:58 AM

How do you get the final product out of the flask? Is it runny enough to just pour. Do you heat? Do you scrape it out?

Just observing.

Gray Wolf · 10-03-2017, 12:57 PM

Quote:

Originally Posted by Phineas Freak

How do you get the final product out of the flask? Is it runny enough to just pour. Do you heat? Do you scrape it out?

Just observing.

We either pour early and use the vacuum oven to finish it off, or chase it out of the boiling flask with a heat gun, leaving behind a thin film.

We use alcohol to remove that film and process that once we collect enough for a batch.

Old Gold · 10-03-2017, 07:39 PM

How are you guys dealing with pouring out of 20L and 50L flasks? Seems a little sketchy to pour from unless you have some kind of lab jack that grips the flask and has rotational degrees-of-freedom.

My plan for the 20L I'll be working on soon is to grab some PFA tubing, and literally suck the hot oil out of the flask and into the short path apparatus, using vacuum suction.

For our smaller 2L or 5L loads we are more able to just pour it out hot (100-120C) and dissolve that final film like GW mentioned above.

easystephen · 10-03-2017, 11:33 PM

Quote:

Originally Posted by Old Gold

How are you guys dealing with pouring out of 20L and 50L flasks? Seems a little sketchy to pour from unless you have some kind of lab jack that grips the flask and has rotational degrees-of-freedom.

My plan for the 20L I'll be working on soon is to grab some PFA tubing, and literally suck the hot oil out of the flask and into the short path apparatus, using vacuum suction.

For our smaller 2L or 5L loads we are more able to just pour it out hot (100-120C) and dissolve that final film like GW mentioned above.

I built a flask handling cart for pouring out of our 50L evaporating flask. It works quite well and we typically pour off 15kg of crude from the flask into a bucket in one shot. There's a frame on wheels and a square flat surface on top with a hole cut out into which the flask sits. There is a channel cut out to the from the circle to the front so the neck of the flask can fit through when rotating the flask for pouring.

bunbun · 10-04-2017, 12:49 AM

Quote:

Originally Posted by Gray Wolf

Here is our test of the Heidolph, which shows parameters:

https://skunkpharmresearch.com/evalu...ecision-ml-g3/

Thank you for the link. For some reason the figures and images don't appear, but the write-up was nice.

bunbun · 10-04-2017, 12:51 AM

Quote:

Originally Posted by BigJohnny

Set the vac regulator to 60 Torr, temp on the bath to 113F, start rotation to 100rpm and let the bath warm the flask while the vac pulls down.

Onc vac is achieved open the injection port and inject approx. 500ml of solution into the load flask. Once it starts condensing open the injection valve just enough to match the condensation rate. let it run and it should recover at a decent rate.

Will try, thank you. From other comments seems like there will still be residuals that need vac oven or other way to fully purge.

10-02-2017, 10:50 PM	#1
bunbun Newbie Join Date: Oct 2017 Posts: 3	Rotovap questions Hi all, New to extracts and have questions about rotovapping. Using a 5L rotovap with 29mm Hg of vacuum, which I thought should be plenty capable to extract ethanol at lower temps, like 40C or less, but it doesn’t seem to pull off ethanol as expected, or takes hours for small batches. Experimenting with higher temps, like 55-65C, and mixture will boil, but still seems little ethanol condenses off, and don’t want to degrade product. It does thicken, but even when it appears finished and nothing else comes off, I swear it still has the smell of ethanol. Even after hours of leaving it. Can rotovaps make final product or does there need to be a final finishing step?
	Quote

10-03-2017, 12:56 AM	#3
BigJohnny Member Join Date: Nov 2010 Posts: 841	Set the vac regulator to 60 Torr, temp on the bath to 113F, start rotation to 100rpm and let the bath warm the flask while the vac pulls down. Onc vac is achieved open the injection port and inject approx. 500ml of solution into the load flask. Once it starts condensing open the injection valve just enough to match the condensation rate. let it run and it should recover at a decent rate. When it comes to the speed, I tend to try and have it at a speed that's enough to keep the puddle "chasing" the bottom of the flask, so essentially is always running down but never makes it to the bottom.
	Quote 2 members found this post helpful.

10-03-2017, 11:40 AM	#4
Gray Wolf A Posse ad Esse. From Possibility to realization. Join Date: Apr 2009 Location: River City, USA Posts: 9,402	Here is our test of the Heidolph, which shows parameters: https://skunkpharmresearch.com/evalu...ecision-ml-g3/ __________________ An age is called Dark not because the light fails to shine, but because people refuse to see it. Believing is seeing and ignorance is bliss until it bites you in the ass! Fervor is the weapon of the impotent. The harder the sell, the poorer the product. Alas, my ignorance abounds; the more I've learned, the less I know that I know.......... Thou shalt seek and respect the opinions of operators, even unto the third helper, for theirs is a wisdom unknown to technicrats. Wise men learn more from fools, than fools from wise men. In my dotage I finally discovered that the secret to putting on pants both legs at a time is sitting down.
	Quote 1 members found this post helpful.

10-02-2017, 10:56 PM	#2
blastfrompast Senior Member Join Date: Apr 2013 Posts: 2,435	I believe most people just use the rotovap to recover the pricey ethanol then finish the purge in a vac oven... fyi u will need to bump ur temps up a bit with ethanl vs butane when it comes to the finishing step...well at least imho.
	Quote

10-03-2017, 11:58 AM	#5
Phineas Freak Member Join Date: Apr 2015 Location: floating Posts: 118	How do you get the final product out of the flask? Is it runny enough to just pour. Do you heat? Do you scrape it out? Just observing.
	Quote

10-03-2017, 07:39 PM	#7
Old Gold Member Join Date: Aug 2015 Location: N/A Posts: 743	How are you guys dealing with pouring out of 20L and 50L flasks? Seems a little sketchy to pour from unless you have some kind of lab jack that grips the flask and has rotational degrees-of-freedom. My plan for the 20L I'll be working on soon is to grab some PFA tubing, and literally suck the hot oil out of the flask and into the short path apparatus, using vacuum suction. For our smaller 2L or 5L loads we are more able to just pour it out hot (100-120C) and dissolve that final film like GW mentioned above.
	Quote