Vacuum pressure

Testing my new WFE this is the vacuum pressure would this indicate a leak or do you think good to run with this?

Regards Bryn

Definitely got a leak, 5 torr is 5000 microns

Ideally you want to be under 300 microns when you distill


You don’t think 300 microns is a bit high? I mean wouldn’t you want to get how much lower micron reading? While I don’t have any real experience with wf those numbers seem a bit high. Also if you have a significant leak then depending on where the leak is you can end up pulling in a bunch of “undesirable”.

OP, What kind of vacuum are you pulling right at the pump?

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This is just a general rule of thumb, yes lower is better but ive made plenty of high testing distillate on a wf at 300 microns

Your main problem at high vacuum with a leak is oxidation

You really dont want oxygen coming in from somewhere and oxidizing your disty while its hot


I know my system well enough to were I haven’t used a vacuum gauge 7 or 8 years. I can tell by the temperature of boiling flask and head and by the consistency and somewhat by the color pretty much what I’m dealing with at the time but recently I had the conversation on a different thread over here about using vacuum gauges so I decided to go ahead and connect the vacuum gauge to my system and start paying attention to see how everything correlates together.
I’m running at about 35 to 40 microns. On the first pass I start collecting mains roughly at about 184°c in the boiling flask (but as I mentioned earlier, I start collecting at other indicates not necessarily at temperature or vacuum). Second pass I start collecting mains at roughly 180° to 182°c (and just as I’ve mentioned earlier it is not dependent on temperature or vacuum). Now having said all of that, at 190 microns my mains come off at about 194° to 195°c if I remember correctly, leading me to believe at 300 microns you’re going to be running burning hot. But that’s on a regular SPD not on a WF. Is that the same temperature as you are running at on the WF?

At 300 microns even at 180c youll still be distilling it just wont be as fast. Youll have a higher BP than if you had lower vacuum but that doesnt mean evaporation wont be happening. There is a difference between boiling something and evaporating it. Boiling happens from the bottom of the solution, where as evaporation happen from the top usually. Water that gets spilled on the floor will still evaporate even on a cold day when its no where near its boiling point. Obviously the warmer it is the faster that happens, the point is you dont have to necessarily hit a solutions boiling point to distill it or evaporate it

At 50 microns thc boils at 152c, at 10 microns thc boils at 132c. im not sure what the boiling point is at 300 microns i could use a nomograph and check but I’m busy rn ill do it later. Ive noticed once your vacuum gets below 300 microns the system (wf or spd) really starts to rip which makes sense as the lower the vacuum the lower the boiling point and less energy you have to waste heating the solution to its boiling point. You definitely will notice a speed difference between 300 and 200 microns and lower, that doesnt mean you can’t distill at higher vacuum levels itll just take more time.

Uploading: IMG_1961.jpeg… hi this is what I can pull as pump I will get troubleshoot and find the culprit leak thankyou I have 140l/h roto vane pump

this is what my pump can pull at the pump

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If I’m reading your Gage correctly you are running 630 microns at the pump and 5,000 microns in your system. Your vacuum pump is not good and you have some vacuum leaks in your system.

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Forgive me if I’m being stupid but if 5.124 is 5000microns 0.0630 would be 63microns or does it not work like that ?

It looks like you’re reading in Torr (little light is on right next to the word Torr). 1Torr for all practical purposes equals 1,000 microns.
Sorry it’s 3:30 a.m. and I’m not as sharp as I should be

No problem buddy different time zones only 17:32 here appreciate the response I’m glad the pumps good I’ll just shoot the leaks now. Many thanks

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Might want to verify your pumps ultimate pressure against what you’re seeing on your display. Some pumps 63 microns is great but some are rated to go as low as 5 microns or lower. Don’t want to be chasing a phantom vacuum leak when a flush of the pump oil might be the ticket! Also I don’t know what size system you’re running on but if you have the budget I’d say consider upgrading to a dry scroll backing pump. Other than that seems like you’re on the right path. Please let us know how it turns out!