resveratrol
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compressor safety
I have an old compressor/aspirator, this model actually:
http://www.ebay.com/itm/Air-shields-Dia-Pump-Vac-Aspirator-C...
it says explicitly not to use in the presence of flammable anesthetics, which tells me that one of its intended purposes was not for removal of
organic solvents. So I am also assuming it is not immune to chemical attack. However....i know many use refrigerator compressors as an improvised
vacuum pump, and I assume my pump operates similarly.
Maybe if I ran the gas through a condenser and a chamber of activated carbon before it reached the pump this would help ease my concern?
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bahamuth
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That pump is a diaphragm pump and works nothing like a refrigirator compressor except that both compresses gas.
The diaphragma or membrane is made of either rubber or teflon(FEP most likely), if teflon you are good but most rubbers are attacked by solvents and
thus will kill your pump.
The special thing about that pump you got there is that it does not contaminate the air passed through with oil as it is a respiration pump, even the
water saturator is depicted on that ebay listing.
The means it does not have a spark safe motor, thus making
it a potential firestarter.
Pick it apart, care to not destroy any gaskets, and see what the diaphragm is made of. Only this would give you a good idea if it is usable for
organic vapors.
Quote: Originally posted by resveratrol  | | Maybe if I ran the gas through a condenser and a chamber of activated carbon before it reached the pump this would help ease my concern?
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A condenser is always a good thing (a must really, big no-no not to use one. I myself might be sloppy in that regard..), as solvents tend to condense
in those pumps and make them sputter solvent through the exhaust port, but you will need a mighty long activated carbon column to get rid of all the
organic vapors, plus it will get saturated at one point anyways.
Edit: This is not supposed to be in the organic chemistry section...
[Edited on 21-2-2012 by bahamuth]
Any sufficiently advanced technology is indistinguishable from magic.
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resveratrol
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Thank you, bahamuth. Would you consider this carburetor example to be a reasonable depiction of the pump I have?
http://www.cdxetextbook.com/fuelSys/gasoline/carbsysComp/fue...
If so, I have a better understanding as to how it works now. I understand why there is potential flammability. But just to be clear, the
electromagnet, and 'sparks' (if present), are clear of the path of solvent vapors, correct? So long as the thing isn't sucking up solvent I should be
good (with regards to potential fire hazards). But as far as maintenance of the diaphragm I should probably take it apart to see what it's made of so
I'm not dissolving it.
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bahamuth
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That fuel pump gives the basic idea.
Concerning the path of the solvent vapor, if there is vapor at the exhaust port it will be evenly distributed in all three dimensions if not directed
through tubing and so on.
If the pump manufacturer explicitly says it not should be in an area with flammable it probably produces sparks, though you can easily check this by
looking if the motor is brushless or not (brushless equals no sparks). Either way you might get a leak and (example follows..) set aflame the 10s of
grams of diethyl ether you just passed through your pump and blow the walls of the room a meter wider apart in the process.
One additional note, those pumps usually don't pull low enough vacuum to be used for anything other than vacuum filtrations IMO as in my experience
one needs sub 1 mbar pressures to really affect distillations, and I would guess thet pump can't "suck" harder than down to 20-200 mbar.
Any sufficiently advanced technology is indistinguishable from magic.
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Hexavalent
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This should be in Reagents and Apparatus Acquisition, no?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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ScienceSquirrel
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Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
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Yes, moved
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ScienceSquirrel
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Thread Moved
21-2-2012 at 14:35 |
resveratrol
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| Quote: Originally posted by bahamuth |
Concerning the path of the solvent vapor, if there is vapor at the exhaust port it will be evenly distributed in all three dimensions if not directed
through tubing and so on. |
Of course.
| Quote: Originally posted by bahamuth | If the pump manufacturer explicitly says it not should be in an area with flammable it probably produces sparks, though you can easily check this by
looking if the motor is brushless or not (brushless equals no sparks). Either way you might get a leak and (example follows..) set aflame the 10s of
grams of diethyl ether you just passed through your pump and blow the walls of the room a meter wider apart in the process.
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So if it's brushless, I'm probably fine - but either way there's a potential for ignition of solvent vapors. I don't like the sound of that, and that
was my initial concern.
| Quote: Originally posted by bahamuth | | One additional note, those pumps usually don't pull low enough vacuum to be used for anything other than vacuum filtrations IMO as in my experience
one needs sub 1 mbar pressures to really affect distillations, and I would guess thet pump can't "suck" harder than down to 20-200 mbar.
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it's sucking power isn't really an issue. I know it's powerful enough to boil off volatile solvents. It pulls to around 600 mm Hg (at least), so
that's around 800 mbar
Perhaps I should look into buying a better pump.
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bahamuth
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May I suggest one of these:
Vacuubrand MZ 2C
Ilmvac MPC 101 Z (I have this one and I love it for rotavapor and filtering jobs, pulls ~13mbar)
But if you want to vacuum distill some high boiling stuff you should just buy a small cheap rotary vane pump used by those refrigeration guys. Or read
the thread on fridge compressors, LET THIS SIGNAL THE END OF THE FRIDGE PUMP QUESTIONS! though I myself actually have no idea how low the fridge pumps can pull a vacuum.
Edit: Actually today I was with some friends working at the University today, dismanteling an old SEM to trash it, leaving behind two oil diffusion
pumps and a giant high flow vacuum pump. Some inhouse guys wanted the Edwards 18 rotary vanes. Neither did I take anything else as I did not have
proper transportation or storage in the apartment.... Was a Jeol 840 Scanning Electron Microscope.
[Edited on 22-2-2012 by bahamuth]
Any sufficiently advanced technology is indistinguishable from magic.
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resveratrol
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hm. i do have a mini fridge i could take apart and hijack its compressor. Seems like it might be a lot of work though.
too bad none of those videos work in peach's thread.
i hope nothing went to waste with the SEM
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resveratrol
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sifting through all of the penis pumps on eBay, i found this:
http://www.ebay.com/itm/ELECTRIC-VACUUM-PRESSURE-DIAPHRAGM-P...
i do not think 16 in Hg is sufficient though, to boil RT solvents.
what if I was to employ TWO condensers (Allihn --> Grahams), which terminate into a large column filled with activated carbon....which then leads
to my current vacuum pump. This would be very easy to set up....i just don't know if the vacuum would pull hard enough through all that activated
carbon.
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bahamuth
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That's actually another thing, if you have to narrow tubing, and to long a path very low pressures will take a long time.
Anyways, that last pump looks like crap to me, and 16 in. Hg. is very very poor, know a couple of girls that can suck harder than that....
Think your best bet is to check the pump you have and get a set of wash bottles (after the cryo-condenser and filled with e.g. activated charcoal) and
a in-line cryo-condenser which you can fill with e.g. one of these freezing mixtures. -70 degrees C. is good enough for most jobs if you periodically remove the condensed solvent and don't plan for sub mbar
pressures, though any drop in temperature will greatly reduce the amount of vapor you pull into your pump..
You know you can sort by category, like
business and industrial...
Any sufficiently advanced technology is indistinguishable from magic.
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resveratrol
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It would be nice to have a Dewar style condenser for this job, that way i could just throw in some dry ice/acetone and be done with it. I could even
recollect my solvent. Hmmmm.....
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resveratrol
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Fuck it. I'm buying one.
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GreenD
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does anyone want my alcatel 2002bb? I've been trying to sell it on here for a year!!
100$ including shipping - fresh oil, refurbished by me (motor had a chunk of metal in there that kept it from circulating - no real damage though)
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resveratrol
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Hmm. I might actually be interested in that.
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resveratrol
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How strong of a vacuum does it pull, and how loud is it?
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GreenD
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never tested, never verified the vacuum, I put my finger on the inlet - that brought the heart rate up.
It is loud enough to keep you awake. If you attach it to a bench top that will help considerably since most of the noise I experienced was from it
wanting to bounce up and down off the floor.
I don't know what I would equate the sound to...
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