CycloRook
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Want to buy vacuum pump
Want to buy a direct drive rotary vane vacuum pump with an exhaust port that can have a hose attached to fumes can be directed outside.
I would like this pump to pull a deep vacuum.
My budget is $500.
Does anyone have a pump or have any suggestions?
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Sulaiman
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a typical Chinese made two-stage oil-sealed rotary-vane HVAC pump is a good option due to relatively low cost.
But maybe not the best choice for general chemistry use.
For better advice you need to be more specific with your requirements.
CAUTION : Hobby Chemist, not Professional or even Amateur
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CycloRook
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Basically I need to be doing distillations of solvents water organic oils.
Possibly some HCL vapor but I doubt it.
It must vent to outside.
Needs to be in the .01 torr range
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CycloRook
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This one would be perfect bit way too expensive
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monolithic
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https://www.ebay.com/sch/i.html?_from=R40&_nkw=2+stage+v...
You might want to avoid the HVAC grade pumps (Robinair, JB Industries, Yellow Jacket, etc.) because they can't pull as low a vacuum as the others.
Leybold and Edwards are good brands. Savant is another good one. I don't think you need to spend $500 to get a good pump. But whatever you get, be
sure to see if replacement parts are available. "Make + model + rebuild kit" should show you.
edit: Just saw your post about HCl vapors. You'll probably want to have a good trap, and have some spare vacuum oil on hand. Vacuum pumps are
typically cast iron -- not that great when it comes to HCl fumes.
[Edited on 3-12-2022 by monolithic]
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CycloRook
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Ok I'm just concerned about being able to get accessories to do my exhaust fumes. You would imagine that would be a primary concern.
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Sulaiman
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The Chinese pumps have an oil mist trap on the exhaust port,
remove it and replace with pvc pipe or tube.
Very easily done.
Ventng the exhaust outside removes oil and chemical vapours
and also significantly reduces the noise level.
CAUTION : Hobby Chemist, not Professional or even Amateur
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CycloRook
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I have such a pump but threading it with pvc was impossible
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Fantasma4500
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if you have an issue with the fumes coming out of the machine, you could make a cardboard box and seal the sides with either aluminium tape or duct
tape, sealing all the corners up well with hotglue or silicone glue and then punch a hole in it where you insert a tube, then maybe you want some bits
of the vacuum pump to stick out so you modify the box accordingly to that.
cheap quality vacuum pumps can be acquired on ebay, i just got myself one of these, it makes many reactions actually possible and some filtrations
also possible. especially nice that you can keep water volumes down from double displacement reactions
https://www.ebay.de/itm/284695509730?hash=item42492cbae2:g:v...
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Mateo_swe
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I bought a used vaccubrand diaphragm vacuum pump on ebay quite cheap.
These can be a little expensive but does pop up quite cheap sometimes if one just wait.
They can handle chemicals much better than a rotary vane pump and good brands have replacement parts.
Good rotary vane pumps can get higher vacuum than the diaphragm pumps.
I would try find a diaphragm pump if its for general chemistry work and you dont need very high vacuum.
They can do distillations of solvents, water, organic oils e.t.c. and are usually used as vacuum source in rotovaps.
Very high vacuum also is quite dangerous but you probably know that.
You have to protect the pump from corrosive chemicals, especially a rotary vane pump that doesnt have chemical resistant diaphragms.
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Antigua
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Yes, diaphragm pumps with PTFE lined insides can last a long time.
Keep in mind that high vacuums aren't significantly more dangerous than medium vacuums. There's no big difference in the pressure with which the
atmosphere pushes onto a flask under 5mbar of pressure and 0.5mbar of pressure. If a flask cracks under high vacuum it would probably also crack under
diaphragm pump vacuum.
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Invictus
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I sent you a U2U message CycloRook so give that a read.
I'm replying to this thread with some of the same info in the private message as a PSA to anyone else looking to vacuum distill high b.p. organic oils
— you will not be able to properly vacuum distill the vast majority of high boiling point organic oils without spending multiple thousands
of dollars or getting extremely lucky and finding a suitable PTFE/chemically resistant vacuum pump capable of pulling a strong enough vacuum
to properly vacuum distill.
I've personally vacuum distilled a certain... primary amine widely enjoyed as a CNS stimulant... and doing so required a vacuum pump capable
of pulling <2 torr (or 1-2 mbar), and even that was just barely enough to get it done nice and clean. (For reference the pump I own is a
KNF Laboport N 842.3 FT.18... and I think I was the luckiest person alive in purchasing the only one I've ever seen appear on eBay or anywhere
else that isn't selling it at retail price and god damn do I feel bad for the idiot of a seller for not knowing how egregiously underpriced that godly
piece of equipment was listed for... sorry, I'm still thanking the chemistry gods for that acquisition).
Basically, the bottom line is this: compact vacuum pumps that can achieve sufficient vacuum to properly vacuum distill in a clandestine setting AND
have suitable chemical resistance like the KNF PTFE diaphragm pump I've got will cost you thousands of dollars. Not to mention the
chemically resistant tubing, high quality glassware, the whole nine yards.
It's also worth noting whether or not your desired pump is oil sealed, liquid ring, or diaphragm in
nature. The reason I keep bringing up KNF pumps are because they are, in my opinion, the best compact laboratory vacuum pumps money can buy for
various reasons.
Pumps that can pull down to single-digit torr levels must be high quality and powerful, obviously, and unless you have an industrial-level laboratory
and tens of thousands of dollars, the vacuum pump you will have as a clandestine chemist will absolutely be a typical positive displacement
type pump.The cheapest high quality positive displacement pumps available are invariably going to be oil sealed rotary vane vacuum
pumps (i.e. "wet positive displacement" type) and are generally what everyone thinks of when imagining a vacuum pump. They are, however, usually
extremely loud, require messy maintenance and oil changes and normally struggle to pull under 30 mbar unless you were to get a top of the line unit.
Diaphragm pumps (which are "dry positive displacement" type) on the other hand are fucking awesome. They are
extremely quiet in comparison, require no oil whatsoever, and quite literally demand zero continual maintenance at all if you take proper care of it.
Moreover they can achieve vacuum down to 1 mbar as a single compact unit (and ridiculous ultra-vacuum in the order of 1x10-8 mbar if you
couple it with a turbo-molecular pump). The downside is they're significantly more expensive. You can however get yourself an excellent diaphragm pump
for under $500 suitable for vacuum filtration and reduced pressure distillation, but don't even think of attempting true vacuum distillation of high
b.p. organic oils with anything less than a pump capable of pulling ~8 mbar or lower.
TL;DR — you cannot vacuum distill drugs without spending multiple thousands of dollars on an extremely high quality vacuum pump along
with glassware, tubing and the like to conduct proper vacuum distillation.
[Edited on 6-4-2022 by Invictus]
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mackolol
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Invictus, you're bullshitting right now.
For first, rotary vane pumps usually pull much higher vacuum than diaphragm ones, hence diaphragm pumps that pull few Torr are very expensive. One can
get used rotary vane that pulls even 0,001 Torr, with proper gas ballast quite cheaply. For sure not multiple thousand dollars. I think you mistaked
diaphragm pumps with RV, because these are the diaphragm that usually don't go below 30mbar
And if it comes to diaphragm pumps, they're never meant for high vacuum distillation, at most I would call it "medium" vacuum, hence distillation of
chemicals with b.p. at most of 250C and mainly for corrosive or volatile chemicals, which when used with rotary vane would destroy your oil and damage
the pump. For high boiling substances, the organic oils you mentioned, one is going to need rotary vane. And to be honest even the diaphragm ones that
pull ~2torr vacuum can be found in reasonable price and it doesn't have to be KNF. I have bought myself and Alcatel AMD1 that pulls around 3torr for
like 150eur and it's in very good condition...
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Invictus
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Quote: Originally posted by mackolol  | Invictus, you're bullshitting right now.
For first, rotary vane pumps usually pull much higher vacuum than diaphragm ones, hence diaphragm pumps that pull few Torr are very expensive. One can
get used rotary vane that pulls even 0,001 Torr, with proper gas ballast quite cheaply. For sure not multiple thousand dollars. I think you mistaked
diaphragm pumps with RV, because these are the diaphragm that usually don't go below 30mbar
And if it comes to diaphragm pumps, they're never meant for high vacuum distillation, at most I would call it "medium" vacuum, hence distillation of
chemicals with b.p. at most of 250C and mainly for corrosive or volatile chemicals, which when used with rotary vane would destroy your oil and damage
the pump. For high boiling substances, the organic oils you mentioned, one is going to need rotary vane. And to be honest even the diaphragm ones that
pull ~2torr vacuum can be found in reasonable price and it doesn't have to be KNF. I have bought myself and Alcatel AMD1 that pulls around 3torr for
like 150eur and it's in very good condition... |
I'd be thrilled to be wrong about everything I said, truly. Also I did not mean to imply that KNF was the only brand worth purchasing — my
experience with them in a professional environment has been nothing but exceptional so I'm definitely biased.
Would you mind providing links to product pages for examples of a suitable rotary vane and gas ballast that supports your point?
I'm eager to learn more and I'm happy to admit my mistakes. If you provide links to some examples (retail prices would obviously not represent the
value of a used unit) I would really appreciate it. Cheers mate
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Texium
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Here you go: https://www.welchvacuum.com/en-us/belt-driven-pump/duoseal/d...
These pumps are awesome. Pulls down to 0.001 torr. They’re tough as nails, and very easy to repair if you have at least rudimentary mechanical
skills. Retail price is half of your measly 1.5 tore diaphragm pump, and used ones can easily be found on eBay for a few hundred bucks.
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Herr Haber
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I have a Rocker Chemker 300 PTFE membrane that I'm very happy about but as already mentioned by others it doesnt pull a huge vacuum (120 mbar - 18
l/min).
Better PTFE membrane are insanely expensive. I got mine a bit less than 800 Euros and I seen it's now at almost a thousand euros (but that supplier is
expensive).
Good enough for everything I do but as I have been thinking about getting a dessicator I've also been looking at rotary vane pumps because they are
relatively cheap, pull a stronger vacuum and, if used with a dessicator are much less likely to be subjected to harsh chemicals than my membrane pump.
And... after buying resin on Amazon I found there are very nice kits with the pump and steel vaccum chamber with a thick transparent polycarbonate
top. It has a few pros and cons compared to a glass dessicator.
Check them out. You'd kill two birds with one stone and would still be well within your budget.
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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mackolol
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This one pulls ultimate vacuum of 10^-4 torr (of course ultimate vacuum is for new pump expensive proper oil etc.):
https://www.ebay.com/itm/194698947276?_trkparms=amclksrc%3DI...
I myself have 2012A and am very satisfied with that. Below this offer you have a lot of other with similar price. I can add that alcatel is a brand of
pumps dedicated for lab unlike many others, which either way would fit into a lab as well.
What's probably a downside is that generally two stage pumps (that pull below 0,1 Torr) are quite big and heavy, at around 20-30kg, but you won't get
that vacuum with smaller pump.
If it comes to Rocker, I've bought a rocker 300 and what I don't likeis that the liquid trap is made of some super crappy plastic. I have used it for
filtration of warm acetone twice and I know that it was very stupid, but the trap just became dissolved and ripped off. I mean this element is super
expensive, yet made from some shit.
Even plain coca cola bottle is more chemically resistant that this...
[Edited on 6-4-2022 by mackolol]
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SWIM
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How about putting the whole pump outside and using a long vacuum hose?
Not the most convenient way to solve your problem, but a very cheap solution if the vacuum line doesn't have to be too long.
I had a friend in San Jose who used to put his pump in a window box (those little flower planters hung outside of windows) and close the window as far
as possible while still leaving room for the hose and power cord.
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Herr Haber
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| Quote: Originally posted by mackolol |
If it comes to Rocker, I've bought a rocker 300 and what I don't likeis that the liquid trap is made of some super crappy plastic.
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Sorry to hear that. In my case in came as an option. I asked three times for a quote and never got one. Now I feel slighly better 
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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Invictus
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Well color me corrected! That's incredible. I'd suspect it sounds a bit more engine-like when it runs, but I won't try and argue against you because
you came through with a link that perfectly backs your claim. I appreciate the info, mate! I might try and obtain one of these for myself and compare.
Again, I appreciate it. I was definitely incorrect in my assessment of rotary vane pumps and the cost of achieving high vacuum in a personal lab.
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mackolol
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That's what this topic is for Invictus,
I'm glad because of your discovery, now you will be able to distill high b.p chemicals with even less effort!
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monolithic
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Even cheap single stage Chinese HVAC pumps from Amazon can pull 250-500 microns real world (0.25 to 0.50 torr) and a good two stage HVAC style pump
can pull <50 microns real world (<0.05 torr.) For many uses this is perfectly fine. Your "primary amine widely enjoyed as a CNS stimulant" would
come over at 50 C or less.
Lab pumps are nicer if you have the money and the space. I had a Precision Scientific D75 that was rated at 0.1 micron (0.0001 torr.) It also weighted
over 50 pounds and took a little over a quart of oil, which was a pain in the ass. If you're chasing a "deep vacuum" to vacuum distill some really
high boiling point stuff it might be worth dealing with this, but my replacement pump will be an HVAC style pump. Also much less stressful if your
reaction mixture might have some residual corrosives in it. If you're lazy with oil changes and rust up your $70 Chinese vacuum pump, who gives a
shit. Just buy another one.
[Edited on 4-10-2022 by monolithic]
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Bubbles
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Yeah the cheaper 1 stage chinese pump broke after some abuse, I now have a 2-stage one and am a bit more careful with it.
For low vacuum I bought 3 fridge compressors for €30 alltogether, expecting them to break because I never use a trap not even for HCl and do not
change the oil. They have a convenient outlet to put a pvc tube down the drain past the U-bend.
However the first of the compressors I used, an oldie made in West-Germany, has survived for three years already.
I guess they really wanted to rub the engineering advantage of the West over the Sovjets in their faces on all possible levels.
I hope she stays with me for a while more because she sucks down to 20 torr without ever complaining.
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Herr Haber
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| Quote: Originally posted by Bubbles |
I guess they really wanted to rub the engineering advantage of the West over the Sovjets in their faces on all possible levels.
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Osram (East Germany) meeting their colleagues from Philips in Eindhoven at a fair or conference during the cold war.
Osram engineers: We keep our jobs by making bulbs that dont break.
Philips engineers: Oh... We keep ours by making bulbs that do break.
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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