nannah
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Vacuum pump on ebay suitable for a beginner?
Hi, i am thinking about getting a vacuum pump, and would like to ask your opinion about this one i found on ebay? I will use it for distillation,
filtration. Basic stuff.
What CFM's, psi's and stuff like that should i look for?
Will this one do? Probably not, but it is cheap, and the shipping is free. 
http://m.ebay.co.uk/itm/321441411736?nav=SEARCH
Thanks in advance. /Nannah.
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Burner
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You might want to consider a water aspirator - good to about 25mm Hg (http://www.ebay.co.uk/itm/Waterbed-Drain-Venturi-Pump-/29118...)
“There is a cult of ignorance in the United States, and there has always been. The strain of anti-intellectualism has been a constant thread winding
its way through our political and cultural life, nurtured by the false notion that democracy means that 'my ignorance is just as good as your
knowledge.”
- Isaac Asimov
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Magpie
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This looks like the typical Chinese made vacuum pump intended for use in air conditioner service. In the US they are commonly peddled by Harbor
Freight.
I have one rated at 2.5 cfm. I use it for vacuum distillations. Whatever you use it for you have to first consider what vapors might enter the pump
and contaminate your oil. If the vapors are going to mix more or less harmlessly with the oil then it's no big deal. But if they are NOx/HNO3 or
other such vapors then the metal pump wetted parts as well as the oil will likely incur severe contamination/corrosion. If this happens an immediate
oil flush/changeout would be required to save the pump.
If a cold trap is used ahead of the pump to condense out the noxious vapors then this will prevent or mitigate any pump/oil damage.
For Buchner filtrations and NOx I use my water driven aspirator instead of my vacuum pump.
In summary, it's a good choice as long as you understand its limitations.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Haber
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Is there any advantage to use an stage 2 rotary pump instead of an cheaper stage 1 when it comes to vacuum distillations?
How big might the difference in vacuum achieved be?
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Magpie
lab constructor
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Registered: 1-11-2003
Location: USA
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I get down to 2 mmHg absolute with my 1 stage $100 pump. For general chemical use this is more than sufficient.
The single most important condition for a successful synthesis is good mixing - Nicodem
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