Wait so would I be correct in assuming since the diaphragm that runs in this unit is PTFE doesn’t that mean I wouldn’t need a cold trap at all for rotovaping ?
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also next time read the whole thread at least before asking the same person the same question i already asked him 
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Deterministically, running a full flask vs a nearly empty flask is going to be worse for the motor, but I’ve never met someone that’s burned out a motor on a 2L. Those things are typically overbuilt, even the cheap BVV chinese ones.
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well i just got my first 2L roto, so if anyone can burn out the motor itll be me
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You’re sucking too hard.
Get yourself a controlled leak.
Either a needle valve, or just use the feed port as others have suggested.
Even with an aspirator, the above helps get the vac level “right”
A diaphragm pump is fine ingesting ethanol, however, it spits anything it Ingests back into the room. So a cold trap is still the right response.
I haven’t set a rotary vane pump on fire yet, but I can verify the oil is essentially swapped out for ethanol, and pump gets HOT
The auto ignition temp for ethanol is pretty high, but there are lots of other ways to achieve ignition.
Edit: not my “leak”, but a decent implementation. Uses an LP gas needle valve.
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Thanks il try that. I cant get dry ice for my cold trap all the time. Do you guys recommend any substitute? I just have about 3 gallons of etoh crude i need to do
Aspirator…
Condenser on rotovap is too restrictive to get decent flow through that AND the aspirator.
Was hoping for an AC hack that sucked…
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Anyone else using a bump trap?
Not sure if it’s helping…makes spraying into an almost empty evaporator pretty much impossible…
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i ran my roto vap 4 times before this a no problems. but i was using a thinner hose that used to collapse basically as i turned my vac on and it didnt pull ethanol and it didnt bump. but i switched to a non collapsible hose and then the problems happened.
Co2 tank with syphon tube. Put a sock over the end of the bottle valve opening and fill with dry ice.
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Remember the four variables you control are pressure/temperature and flow/level.
Pressure increases so does temperature and vice versus. The same thing applies to flow/level.
The best thing for this process is manipulating Pressure. As stated above a needle valve is best Bc this type of valve is made for precision vapor/air flow. If you are not able to acquire this than you will need to adjust your temperature.
When i run the roto i bring up the speed to max (sometimes not applicable due to the viscosity of the mixture) and bring my temperature up to designated temp. I wait a bit till my water temps are steady go know my sloution is the same temp as my water bath. I’ll start introducing vacuum. Once i see the bubbles starting to come out i will continue vacuum for another second and wait a bit. Than keep adding vacuum once the bubbles die down
My suggestion. vacuum down and max out your rotater. Slowly work your temperatures up. Try to avoid introducing outside air in the process but def relive the vacuum if you’re over bubbling. you can bring down the speed of the rotation to slow slow down the reaction.
Second problem. Your solution is instantly bubbling Bc your introducing a liquid that isn’t close to the same temperature of what’s in your flask. Preheat the liquid for batch.
I use to run a a Buchi-220 pro
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Semi found the solution and fixed my problem
i swapped out my hose for a much lighter hose (10 ft in length)
As soon i turned my vacuum on the hose collapsed making the pull much more weaker and im pretty sure it made it much harder for the ethanol to reach my pump. I turned on my pump for about 15 seconds then turned it off when i saw my etoh bubbling … it maintained a vacuum and all of my ethanol was captured into my collection flask
i didnt use a cold trap, my pump ran for maybe 3-4 times at 15second intervals through the entire process. The oil doesn’t look contaminated in my pump and it didnt run long enough to even get warm.
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Hey if it works… it works… even if it’s a bunch of things that don’t work… this is like adding a whole bunch of negative numbers together and then getting a positive result- abstract to most but to the scientist 
it’s all about the results- which will be very inconsistent if you keep this up.
still makes every part of my ass itch please just get an $8 vacuum relief valve off of amazon and some proper hosing.
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Haha yeah man… it wasnt a permanent solution just so i could finish the crude i had .
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i will be! Thanks!
Use the continuous feed line like Plague says, If you add a bunch of new ethanol to a hot solute that’s in the boiling flask it will boil over every time. Let it drip in at the same rate that your are precipitating ethanol from the column. I like my solute feed to not shoot into the middle of the boiling flask, but hit the neck and run down the side of the glass into the sample thats in the boiling flask. There should be no sudden changes when running your roto, do everything in small increments, keep everything smooth, so you don’t boil over, or crack any glass, or get ethanol in your vac pump. Cold trap (or even two) is a must.
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And the pharmacy guys looking to take over this field are laughing like hell at you. if you are looking to have others consume and you don’t control all the controllable inputs you are going to be inconsistent in the outputs. I would recommmend a real vacuum hose, needle valve vacuum vent then as soon as you can a water aspiration vacuum. No oil, very rugged, forgiving, and consistent. I believe greenbuggy on here has some for sale around $300. Then you can start the long fun journey learning how to process your product. Rotavac alone may take a year or more to master. But man you are a chemist.
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