So what’s the perfect vacuum to run a 50l rotovap for maximum efficiency and put less on the chiller?
Probably 20 -in hg so that ur alcohol boils at 50C, set bath to 60 or 70C and chiller at 0C
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“deltas runs under NO vac and runs the water at 90c”
where did you get this info? I thought they use a liquid ring vacuum pump
Read the manual show me where the vacuum pump is, i uploaded it above.
Wow thanks for looking that up, i had no idea it affected vacuum i thought it was just things open to atmosphere. Im still kinda confused/baffled that u cant achieve good vac even with a turbo or diffusion in the himalayans or in the rockys
Im at 100ft, so ive never noticed or had troubles with vac.
What happens when u go below sea level? Lets say in a deep bunker by the sea?
You are getting very confused here. The vacuum you pull with that diffusion pump is actually the same, whether you’re in the himalayans or the mariana trench. The issue is you’re comparing gauge pressure to absolute pressure.
A closed system with a certain mass of air in it has the same absolute pressure no matter where it is. And ethanol, in that system, will boil at the same temperature. The boiling point is dictated by the absolute pressure of the system.
On the other hand, what your vacuum gauge reads will be quite different. The gauge measures relative to the pressure outside of the system. At sea level, the absolute atmospheric pressure is 29.92 inHg. A perfect vacuum thus reads -29.92 inHg on the gauge.
At 10,000 feat, the absolute atmospheric pressure is 20.64 inHg. A perfect vacuum with read as -20.64 inHg on the gauge. If you had a dial that goes up to -29.92, the dial will only go down 2/3rds. It will LOOK like your vacuum is bad – but it is not, it is perfect. And in each of these two systems, inside the rotavap, the ethanol will boil at the same temperature. The particles only see the absolute pressure inside your closed system. They don’t care what the gauge says.
Inversely, if you go under the sea and run your rotavap (bear with me on the fantasy here), your gauge might read -1000 inHg. Boy, that’s some great vacuum! But the actual absolute pressure inside the flask is once again the same. You won’t be observing any difference in the boiling point.
The confusion here came about because people were comparing two different things without specifying. There’s absolute pressure (what your ethanol cares about) and relative pressure (what your pressure gauge cares about). At sea level, the two are equivalent, because the gauges were designed for use at sea level. At any other place they start to diverge, and it becomes important to pay attention to that max vacuum chart to see what your gauge ought to be reading.
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Thats a vacuum pump motor, if there pulling vac before the condensers then how are they moving the vapor through the condensers? Theres no other pump. Im 99%sure this is the pump they use to apply pressure to reduce the boiling point. Its not a vacuum pump its a recovery pump, they’re just using a vacuum pump motor.
Ive never heard of a vacuum pump that can move solvent, and that’s what theyre using this for.
I can’t speak to exactly what Delta is doing without a callout for what model that Baldor is, but a liquid ring pump would put vacuum on the evaporation side and give it an extra boost towards the condensing side easily. There’s also a variety of other “dry” hazardous location rated pumps like the Blackmer, Haskel and CMEPs that have no problem pumping solvents and are capable of pulling vacuum if they are sized correctly for the vessels and heating/cooling power they are attached between.
There’s also the physical properties of vapors that moves them from hot areas to cold ones, a simple pot still at atmospheric pressure has no problem pushing hot vapor towards the condenser and recondensing those vapors as long as whatever condenser is of suitable size.
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Yup, thought so… thanks for explaining the confusion thats going on. 
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Ahhh, yea that was my understanding as well was it was just the gauge measuring against relative atmospheric pressure. On another note, inches of mercury seems to be the shittiest unit of measurement for measuring vacuum yet all these gauges on American equipment insist on using it. 
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Yeah there are way too many pressure units. I don’t think any of them are perfectly intuitive.
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I really like Millibars lately but i change my mind weekly.
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I use -28.5Hg @ 70°C or 80°C
Space is way deeper than 10-6Torr. We run 10-6 as a standard vac level on our mass spec. But its not a problem to get to 10-8. Not sure what tis has to do with distillation, but technically, atmospheric pressure is irrelevant inside a closed system.
“i think space is 10^-6 micron or deeper”
- Outer space 1x10^-4 to 3x10^-15 micron.
Yes space is deeper than 10^-6 like i stated before…
U hit 10^-6 micron or 10^-6 torr? Torr is easy. But if u read my measurement, 10^-6 (micron) is much harder to achieve.
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@Thetetraguy Itll be interesting to see what my new diff pump can do, breaking dabs is only a 200 liter a second. Mine is 2140 liters a second lol i wonder if this will allow me to pull deeper vac then him
My bad. Just so used to seeing units of Torr stated in that fashion.
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How did you find out that your PTFE gasket was leaking? I suspect maybe one of mine on my RE501 5L is leaking since my evaporation rate is slow