Octavian
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n00b Vacuum pump setup questions.
For the last couple of months I've been tinkering with the idea of picking up a cheap vacuum pump since some recent experiments have brought me to the
point that regular atmospheric distillations and my 200torr aspirator can't handle.
I have searched a bit on here, as well as google, and of course the chem lab survival manual & Vogels but haven't come across a clear answer - or
I have, it's just that the clear answer has been strung out over 20 pages and by that time I was getting the fried feeling and having trouble piecing
things together into a whole picture.
If it matters any, my current setup consists of a full standard distillation kit with GG joints and single neck, round bottom, flasks from 50ml -
1000ml (Soon to be added a fractioning column, hopefully atleast a couple of 3-neck RB flasks, and maybe a cow or pig vac adapter). To this I also
have made a magnetic stirring oil bath using a household electric frying pan dished out in the center to be deep enough to half submerge a 1Lt RB in
oil and a 5" PC fan with neodymium magnets attached for the stirring - Not the best, but beats the $300 - $400 for a stirring hotplate and from
initial testing, seems to work well up to around 210C...for now :p
My question is, I'm looking at picking up a cheap single stage pump for under $100 new. Aside from buying the thing and connecting the vac hose from
the pump to my vac adapter - What do I need? Dry ice seems to be surprisingly hard to come by here so I'm doubting if the dry ice/acetone trap I have
constantly read about will be an option. I've figured that I will definitely need some kind of trap even if i'm careful with what i distill (acids and
corrosives will be handled by my aspirator) so I'm wondering if one or maybe even two vacuum E-flasks filled with whatever I need to neutralize the
fumes from what I'm distilling using rubber stoppers and 6mm glass tubing in the line would take care of most of the pump wrecking nasties? How do I
regulate the vacuum in the system if i need to? I'm assuming some kind of vacuum gauge is needed in-line to know how many torr I'm pulling to know
what is coming over and when, what would be the most cost effective way of doing this?
Sorry in advance for the poorly structured post, it tends to only be late at night and after much reading that I have the need to post here and by
that time I feel like 50 points has been knocked off my I.Q as I'm sure many people here can relate to after long study sessions 
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battoussai114
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I'm assuming you're thinking of a diffusion pump. People usually have liquid nitrogen cold traps in line with the pump to keep contaminants from
getting to the oil. Never seen people putting absorbers to keep fumes off but it seems feasible.
Some HVAC pumps have meters built in it, consider one of those if you want keep costs down.
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Octavian
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Something very similar to this is what I was considering. http://www.ebay.com/itm/3-CFM-Single-Stage-Rotary-Vane-Vacuu...
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Zombie
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Wow. Just a few months ago they were selling for 100 bucks. It makes it worth the few dollars to try them right.
I've read where IF you change the oil after every "caustic" encounter, they will last. You will definitely want some form of vacuum control on it.
Maybe a needle valve set up in line will do the job.
I'm still on the fence as to what I will be using but at 60 bucks, these are taking a higher slot on the short list.
Finding a proper lab pump at a fair price is hit, and miss. Mostly miss.
They tried to have me "put to sleep" so I came back to return the favor.
Zom.
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aga
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Registered: 25-3-2014
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I went for a faitly cheap italian air-con vac pump from ebay and it works pretty well.
It all depends on your exact needs and depth of pocket.
If you really need a Fantastic vac pump, better to save the $ for a while than buy a cheap one that will not work as you want.
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