JKX250
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quick question on vaccuum source
i bought a 1000ml distillation apparatus . i want to know a good general purpose electric vacuum pump to use with it . i have very low water pressure
so i cant use water pressure .
ive looked on ebay and craigslist , however the more i look the more confusing it is .
im just getting in distillation and want to get a all purpose quiet as possible vacuum pump that i would like to be able to make adjustable without
the pump burning up on me because of excessive load its under
thank you
jkx250
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radagast
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Vacuum Pump
What do you need to distill and what's your budget?
For distilling corrosive acids or organic solvents, I've had good luck with used Laboport diaphragm pumps from KNF. They start from ~$200 dollars on
Ebay, and are easy to rebuild.
I also really like the gel pumps manufactured by Savant, which are also designed to withstand harsh conditions without cold or base vapor traps. I
picked up an ancient Savant GP100 up at a University sale for $30, and it pulled ~7 torr without any issue.
Peach is a tireless proponent of using fridge pumps with gas wash bottles, so you may want to search for his old posts for more information.
Pumps are kind of like hotplates -- you use them so often that it's worth getting a good one.
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JKX250
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thank you for your reply , im just getting started so i dont know exactly what i will be distilling . i do know that i want to learn how to distill
and the distill under vacuum and also fractional distillation . ive been reading alot , however i know that there is no substitute for actual lab time
.
i really appreciate you taking the time to help me .
i want to get a good all around pump that i will do the best job as economical as possible ,
i was thinking around $150 to $200 price .
also are these vacuum pumps adjustable and do they need to be ?
thank you again
jkx250
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radagast
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At that price range ($150 to 200), I don't think you'll find a pump that automatically adjusts its pressure to what you want. But, so long as your
vacuum pump is strong enough, you can create a controlled leak to reach the pressure you want:
https://www.sciencemadness.org/whisper/viewthread.php?tid=21...
Generally, I'd say that you should aim for a vacuum pump that can get down to 20-30 torr. One of my prior pumps would only get down to 100 torr or
so, and while it worked, it took forever to rotovap off ethyl acetate and other higher-boiling solvents. This was particularly frustrating when I ran
fractional distillations to purify liquids with b.p. > 150 C , because with a weaker vacuum pump, it took much longer to equilibrate the
distillation column.
For your price range, I'd recommend grabbing a Laboport pump that can reach that pressure (check out KNF Neuberger's website for more info). The
prices on Ebay are sometimes outrageous, but sometimes you can snag a Laboport that pulls ~30 torrs for about $200. If you're near a university,
attend one of its property disposition or surplus sales -- you'll be astounded at how cheap the items are priced.
Oh, and one more thing: if you're testing the pump in person, the pump's loudness does not necessarily reflect its actual loudness during operation.
As the pump begins to pull a vacuum, the noise level goes down substantially. For instance, during vac distillation, my Savant GP100 gel pump is
quite loud for the first fifteen seconds or so, but then quickly quiets down to the point that I can't hear it over the noise of my fumehood fan.
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JKX250
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thank you for all your help . there are a few Savant GP100 gel pumps on ebay for 150.00 shipped to my door . i think im going to go with that .
i really appreciate your help . chemistry and doing actual experiments is really quite overwhelming to me . however with that said . i really enjoy
the reading . i hope i enjoy the actual lab work too.
thanks again
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