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Author: Subject: Is this pump suitable for vacuum distillation?
fisma
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[*] posted on 31-5-2013 at 18:45
Is this pump suitable for vacuum distillation?


I currently use a water aspirator system and pump that I built. It works pretty well but i'm looking for something different. Let me know


http://www.harborfreight.com/25-cfm-vacuum-pump-98076.html
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CaptainOfSmug
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[*] posted on 31-5-2013 at 20:13


This should be fine. Granted I would really suggest going for the 2-stage pump from harbor freight just because of the fact that you should have a longer "shelf life with it". Regardless, always make sure you have some sort of trap from wherever your reaction is coming from into the pump and definately consider the possibility of suck back. If you don't have a relatively good ventilation source make sure you are also able to have a trap coming out of the vacuum to prevent excess fumes.
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Organikum
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[*] posted on 1-6-2013 at 14:12


Looks exactly like the asscheap chinese one I got off Ebay, I wouldnt be surprised this being the same. In this case you might get it cheaper under another name.

Its one stage without ballast, I am surprised the advertisement states its suited for removing moisture as thats exactly what rotary vane oil pump is not so very good for. A diaphragm pump would be better.
Without the ballast vapors might condense in the pump and damage it.
But serioously, the pump will not pull 10 torr and the main problem with vapors is they will contaminate the oil and reduce the possible vacuum.

You really must use a cold trap with ice or better when distilling solvents or similar.

But actually I am rather satisfied with my chinese baby. It pulls to 1 or 2 mbar (100/200 torr) alone and would go further with an aspirator as forepump.
As a forepump is very much recommended when you have no ballast valve but the aspirator is to water consuming I got me a asscheap airpump (14 €) for in and de-flating rubberboats and such. Mounted it sloped upside down (motor up, suck-in down, outlet downwards) and wonders over wonders now I really would be able to get to 10 torr if needed, the effect is almost the same as with the aspirator which pulls 22mbar alone.
and literature tells that your pump wont suffer with forepump.

So in short:
I suppose you are on a limited budget so get this kind of pump from the chinese at Ebay it wil be the same but cheaper and for the saved bucks get the airpump and a coldtrap and you will be fine. Change oil often, better use cheaper oil and more changes.

/ORG

PS: The airpump is of course connected to the outlet of the rotary vane, if you have a Roots-blower or a liquid ring pump around you can use those for the purpose... ;)

[Edited on 1-6-2013 by Organikum]
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turd
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[*] posted on 2-6-2013 at 04:21


Quote: Originally posted by Organikum  
But serioously, the pump will not pull 10 torr [...]

It pulls to 1 or 2 mbar (100/200 torr) alone and would go further with an aspirator as forepump.

??
1 mbar is 0.75 torr (= mmHg). Do you maybe mean "microns" as in μmHg ?
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Organikum
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[*] posted on 2-6-2013 at 04:35


Pascal. I meant Pascal and hope it is correct then. If yes it was a slip, if not I blame it on climate change and society.

regards
/ORG
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Furboffle
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[*] posted on 4-6-2013 at 15:43


I have that one. I got it in November, it crapped out last month. I didn't use a cold trap so solvent vapor got sucked into the oil reservoir over the months, I tried changing the oil a few times but even after draining it and putting new clean oil the oil would seem thicker than normal and cloudy immediately after adding the new oil. Now in the window it just all looks corroded and if you flip it on it just sounds like a jammed pencil sharpener.
But I'll be honest while it worked it was great, very strong vacuum. I checked with a gauge and was getting down to about 0.25 torr. Just make sure you prevent solvent from being sucked into the motor. I'm now in need of a new one, I may go exchange it for the same one but I'd kinda like to invest in an oil-free pump like I couldn't afford last time around....
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