RonPaul2012
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Vacuum pump HELP
I am looking for a cheap vacuum pump for my buchner funnel / glassware.
I have wasted my money one three different hand pumps over the course of a year ; hand pumps DON'T WORK 
I want a foot pump that I can use with my table , by using a long hose ; something like this
They used to make bicycle pumps that could be inverted to be used as a vacuum but I can't find one.
I either want a "how to" on how to convert a foot pump into a good vacuum pump or I want a link to a vacuum pump.
I would really like the forum members advice/experience on this.
Is this a good idea or do you have a better solution ?
Thank you. 
[Edited on 16-3-2012 by RonPaul2012]
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neptunium
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i did see a thread on this and i`ll try to forward you the link when i find it.
However i think you are wasting your time.
I have been using refrigerator compressor for years with very little set up and great result.
i am sure there is a junk yard where you can go and salvage 4 or 5 compressors from .or a neighbor who wants to replace his...
I measure the vacuum produced by the average compressor at about 100mmHg (sometimes 50mmHg and lower!) wich is more than enough for filtration.
hook it up ,turn it on. done
oh here it is
http://www.sciencemadness.org/talk/viewthread.php?tid=16047#...
[Edited on 16-3-2012 by neptunium]
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RonPaul2012
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the vacuum pumps I used could get 760mmhg but I only could get to 500mmhg with a 500ml filter flask .
I am not well versed in pumps so I can see this will take some time.
Well I'm here to learn so I don't mind 
Maybe I would just be better off getting my hands on an electric pump since I don't want to have to pump everytime pressure drops.
I just don't want to spend much on a pump is all , so I'm going to have to jerry rig something I guess.
I'm also a little concerned about corrosion (that's what got my pumps) , is there any way to deal with corrosive gases ?
[Edited on 16-3-2012 by RonPaul2012]
[Edited on 16-3-2012 by RonPaul2012]
[Edited on 16-3-2012 by RonPaul2012]
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neptunium
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a cold trap or a bubbler or both
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DJF90
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Get a water aspirator pump. A glass one will take you down to about 60mbar, a plastic one can sometimes do better (15mbar). No need to worry about
corrosive gases for the first one, and no need to have to pump anything by hand. If you're worried about wasting water, then set up a recirculating
system. This has been mentioned before here I believe
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zoombafu
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Get this vacuum aspirator. I have it and HIGHLY recommend it.
<a
href="http://www.amazon.com/gp/product/B002VBW41E/ref=as_li_ss_tl?ie=UTF8&tag=thehomche0e-20&linkCode=as2&camp=1789&creative=390957&am
p;creativeASIN=B002VBW41E">Bel-Art Vacuum Water Aspirator </a><img
src="http://www.assoc-amazon.com/e/ir?t=thehomche0e-20&l=as2&o=1&a=B002VBW41E" width="1" height="1" border="0" alt="" style="border:none
!important; margin:0px !important;" />
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RonPaul2012
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I am not close enough to a tap to make that practical.
This doesn't mean that I play around with acid without taking safety precautions and it is close enough that I can walk across the room and reach it.
I am pretty much just interested in a pump.
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ripple
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Are you close enough to an electrical outlet?
There are plans around for hooking up 1 or 2 aspirators (in parallel) to a water pump in a closed loop with a reservoir. Used water pumps can often be
found at garage sales for cheap, surplus stores are also a good bet.
Buchi and others (Whatman?) even manufacture aspirator/pump systems for lab use. The main benefit is that no mechanical parts are exposed to vapours,
and that water soluble vapours can also be harmlessly absorbed/removed.
I dont have much experience with hand-pumps, but they might be worth another try since they vary in quality. If you're only filtering, you should be
able to find one at a decent price that does the job. Check Cole-Parmer or similar, just dont buy the cheapest one you can find.
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RonPaul2012
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Quote: Originally posted by neptunium  | i did see a thread on this and i`ll try to forward you the link when i find it.
However i think you are wasting your time.
I have been using refrigerator compressor for years with very little set up and great result.
i am sure there is a junk yard where you can go and salvage 4 or 5 compressors from .or a neighbor who wants to replace his...
I measure the vacuum produced by the average compressor at about 100mmHg (sometimes 50mmHg and lower!) wich is more than enough for filtration.
hook it up ,turn it on. done
oh here it is
http://www.sciencemadness.org/talk/viewthread.php?tid=16047#...
[Edited on 16-3-2012 by neptunium] |
Ok my captain.
I have acquired 2 yes 2 compressors.
One is from a fridge and the other is from an AC.
I'm sure I could figure it out but it always helps if you have a little understanding of what you're doing , so could you link/explain what to do
next.
If not I will see what I can do with the search button
[Edited on 23-3-2012 by RonPaul2012]
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Bot0nist
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<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=14435&goto=search&pid=186901">LET THIS SIGNAL THE END OF THE FRIDGE PUMP
QUESTIONS!
No need to UTFSE</a>
[Edited on 23-3-2012 by Bot0nist]
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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magnus454
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Harbor Freight (www.harborfreight.com) sells a good vacuum pump for around 87$ and a really good 25 micron vacuum pump for about $150. I have the 25micron unit,
have used it to run a babson/surge milking machine, and repair the A/C in my truck, You can always get yourself a neutralizing filter for your vacuum
pump system, I'd buy one for an HVAC from an online supplier or Grainger, the local shops are always a b!t@h about over charging people who do not
have an HVAC/EPA license even for non licensed parts. They have a molecular sieve that will prevent particles and debris from entering your pump, also
absorb moisture and neutralize acids. Also if your pump oil is cloudy after use, drain and refill with fresh, especially if your running with caustic
vapors.
History is repeating itself.
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RonPaul2012
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I am going to use this guys tutorial.
http://www.paragoncode.com/shop/vacuum_pump/
It seems like a good one
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watson.fawkes
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You'll be able to do vacuum filtration with this rig. According to his
own report, it gets rid of about 90% of the atmosphere pressure. That means it gets 90% of the force that "total" vacuum would provide, and that's
plenty.
For corrosive gases, beware. Because these are sealed compressors, you'll have a hard time changing out the oil completely. The innards are not
serviceable should you have a trap failure.
It will get you started, at least.
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Chordate
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| Quote: Originally posted by ripple |
There are plans around for hooking up 1 or 2 aspirators (in parallel) to a water pump in a closed loop with a reservoir. Used water pumps can often be
found at garage sales for cheap, surplus stores are also a good bet.
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Wait, I thought the lower limit of aspirators was a function of the vapor pressure of the cold water. Why would hooking up two in parallel give you
any kind of improvements?
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watson.fawkes
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| Quote: Originally posted by Chordate | | Wait, I thought the lower limit of aspirators was a function of the vapor pressure of the cold water. Why would hooking up two in parallel give you
any kind of improvements? |
Two aspirators in parallel yields higher pumping rates, which is useful if you
are trying not just to evacuate a chamber faster, but also to get rid of vapors that might be produced by a reaction.
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arsphenamine
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YES! It's like a Welch 1402-lite except you can move it around without a dolly.
Add a gas trap with calcium carbonate chunks and you have a winner.
Usage tip: straight 30W or 20W50 automotive oil will do fine if you run out of expensive uber-oil for vacuum pumps.
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magnus454
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Hey thanks for the tip on the oil, I have a US general 3cfm 25 micron vacuum pump I use for some of my physics work, I did rig up a
neutralizing/moisture trap for an ac unit to protect it, but it required some odd oil that I haven't been able to locate. When I looked at all the
charts what you stated was very similar to the ISO ratings on the pump oil they list, I'd probably use fully synthetic 20w50.
History is repeating itself.
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