Hi. I just bought a CPS 2 stage 10cfm 10 micron pump for my 2L… I am new to this and am constantly researching. However; I am really struggling to wrap my brain around how to go about choosing the correct vacuum pump. So my question is this, do you think that I have chosen correctly and that this pump will work properly and efficiently with my 2L or should I return it and look for something different? Also, if anyone could please direct me towards good basic information to assist me in gaining a basic grasp on this subject I would so appreciate it!!!
I would say return it and find one of the adixen pumps for cheap on ebay. Hold on, I’ll grab a link and update my comment.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F303027418912
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I feel dense here but if I can’t get past 100000 or 25 hg what’s the parameters at this altitude?
25hg doesn’t matter. That’s just altitude. What micron guage do you have
I have an hg gauge. I will order a micron gauge today I printed off a chart going down to 0 micron and sliding across full vacuum is between 29 and 30 if I was at sea level. Do you need to be more accurate for fractions or…?
Thank you! Would you please help me understand why?
It’s been widely discussed on this forum that you really don’t want to use under a 14cfm pump for any of this. And the bigger on the short path you go. The bigger pump that is needed.
Much appreciated! I just contacted the seller and am going with one of those. I noticed infinite posted about altitude and micron rating. I am close to 5,000 ft, what should I expect full vacuum to be at my altitude?
Micron will still be fine. But a vac guage at that elevation will only read to -25hg or so. I have several ovens and they all have different readings at vac.
So your saying a micron gauge will read correctly even though I’m at 5000’ ? But an hg gauge will not?
The hg guage works off pressure and being at elevation, you’re already at pressure. Your micron guage doesn’t care about elevation. If you are reading microns, you are at vacuum.
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Altitude has a negligible effect on the ultimate vacuum level. The dial gauges which use atmospheric pressure for reference will not read correctly with changes in altitude but any standard thermocouple gauge or similar will not be affected.
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To my understanding, you can view micron as reading the moisture in your apparatus. The lower the micron the less moisture there is in your vessel. If you’re pulling a deep vacuum and your microns are low I assume that means your vapors are recondensing at a consistent rate, because as the material boils off vapors are created and thus add moisture and atmosphere to the vessel.
I have not personally run a short path before this is just my basic understanding of the process. Please correct me if I’m wrong.
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Substitute “vapor pressure” for “moisture” and you’re right on track.
“Moisture” implies water vapor explicitly.
In our flask, we haz vapor…
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Ok so last advise
Rule of thumb for every liter of boiling flask a minimum of 8 cfm is good
If on a filled rig with cold trap working And heat at 100C a vacuum below 100 microns You are good to go
If At this stage there is a higher vacuum then 100 microns
You haven t decarbed Well small bubbels apear in boiling flask
You have a leak in system boiling flask is at temp and oil is silent and stil
You still have water in system or Many volitille terps that want to boil of
Oil in flask is boiling
A micron meter after the cold trap at this
Point should be Reading below 100 microns once iT does get started
Remember that a vacuum pump needs time to heat up
IT can take up to 30 min before iT reaches iT s ultimate vacuum
Because of the viscosity off the pump oil
The hotter iT is the better iT pulls a vacuum
Wich ever pump You use try to have as wide as possible vacuum lines 1/2 " internal diameter as the minimum
Try working with transparant tubing so You can see If there is Any condensation in the lines
Place all lines i such order that by means of gravity Any condensate in the lines Will flow towards cold trap glaswear
And at last have a valve on the pump or lines to keep vapors or oil from the pump beeing sucked back in your glaswear When shoting down your pump
O yea and two pumps are better then one
And for your terp fractions a singel stage high cfm pump Will do
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