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kjpmi
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shocked.gif posted on 21-1-2015 at 13:54
Recommendations for a vacuum pump?


Hello everyone,

I did a cursory check thru the forums and didn't find anything recent (correct me if I'm wrong).

I'm looking at vacuum pumps and I need some recommendations.

Here are my prerequisites (which I think most people would also have):
-Relatively quiet
-Pulls a strong vacuum
-Pulls a steady vacuum (not keen on fluctuations)
-Ability to run continuous for possibly a day or two at a time
-Chemical resistance
-Heavy/Sturdy, prefer metal casing over plastic unless the plastic is very rugged
-And of course, not outrageously expensive.

I've looked for reviews online but they seem to be all over the map.

And no I'm not looking for a water aspirator. I DO have one and it works, it's just not convenient.

Thanks in advance everyone for any recommendations. I'm new here but I do have a few years of chemistry experience. Learning new stuff every day. I also plan on building my own fume hood this spring.

-Kris
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neptunium
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[*] posted on 21-1-2015 at 14:37


maybe if you could tell us what you are trying to do with a 24h running corrsion resistant steady vacuum pump we could help you better...
Also , how deep do you need to go in vacuum ?




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kjpmi
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[*] posted on 21-1-2015 at 20:24


Quote: Originally posted by neptunium  
maybe if you could tell us what you are trying to do with a 24h running corrsion resistant steady vacuum pump we could help you better...
Also , how deep do you need to go in vacuum ?


It would be a general purpose vac pump for when I need to do a vacuum distillation or to occasionally evacuate and seal my large glass desiccator. I don't have the setup for working with inert atmospheres in my home lab yet but I guess theoretically it could be used at some point for clearing air from an apparatus before introducing the inert atm.

What other exotic purposes would one regularly use a vacuum for?

And I suppose 10 to 20 torr would be sufficient.
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[*] posted on 22-1-2015 at 10:53


http://www.ebay.com/itm/Gast-MOA-P109-AA-Reciprocating-Diaph...

You could look at a pump like this link but you have not provided enough information to be useful. Exactly what do you mean by a 'strong vacuum'? Something under 1 micron? An oil diffusion pump? Since it appears you want a pump for varied uses in the lab thought needs to be given to specifications. Is your power grid 117 or 220 volts? Will you be doing vacuum distillations using solvents that could eat away at the diaphragm in a pump such as listed above, or corrosive which could eat away at the reed valves (metal)? The pump in the link could be what you are needing, but I would keep searching for a lower price. I have several of the above type pumps (both single and dual head) from ebay and I think $40 was the highest I paid for one. All are in very new condition so clearly searching pays off. Even my Alcatel was obtained for around a hundred (rotary oil type) and new they are $700 or higher so again, searching with patience yields great deals.

If you are new to this and unfamiliar with vacuum pump types and specifications (as well what type pump to use for what work you are doing) then study in order to provide a better idea of what you are needing.




"Science is the belief in the ignorance of the experts" Richard Feynman
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kjpmi
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[*] posted on 22-1-2015 at 20:18


Thank you.

I was just looking to see if anyone could recommend one they actually use and like.
I've explained what I'm looking for. How much more detailed do I need to get without having to write an essay? I'm not looking for perfect recommendations, I can do the work in deciding the right one.
I just wanted to know if anyone could point me in the direction of a website where they got a good deal, or a cheap pump that worked suprisingly well.
I guess the famed friendliness of this forum was lost on me...
I wasn't looking for egg headed snarkiness, just simple recommendations. I KNOW how to pick the correct style based on what I'm using it for. I wasn't asking YOU to do that for me. I can do the leg work, just simple recommendations.

I'll explain again what I've spent weeks looking for:
Something MORE convenient than a water aspirator that will give the same deep vacuum (greater than 28" Hg or about 40 torr, greater than 29" or less than 20 torr would be preferable) and isn't going to fucking cost me over $1000. I'm in the US we use 120V here, and even if it were 220 thats FINE I ALSO have a 220 line in my garage.

You're all on a science/chemistry forum, none of you vacuum distil anything or use a vacuum pump?
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[*] posted on 22-1-2015 at 21:07


@kjpmi
I think you have misunderstood the tone of some of the replies here. It generally works that the more specific the question, the more useful the replies. Your request was (necessarily) vague since you are considering a wide range of applications and some of them not fully known at present. It is really hard to give good advice in such situations. I don't think you were being fobbed off.

I am in much the same situation -- looking for a pump in the near future, wide range of applications, not really sure what specs I require and not wanting to spend too much money. FWIW, I was considering something like this. But I was hoping for a better price than that.

My normal practice when faced with decisions like this is to take a bit of a leap in the dark and avoid spending too much. If I land a good deal then I am happy. If I buy something inferior that doesn't last, then at least i have gotten the immediate job done and now I have some experience and a better idea of what I need. IRC's advice seemed good to me – a list of things to consider and a suggested product with his estimate of a ceiling price.
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IrC
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[*] posted on 23-1-2015 at 02:54


So far the only bad attitude in this thread is coming from the OP. I had no attitude when I wasted time trying to be helpful.

"I've explained what I'm looking for. How much more detailed do I need to get without having to write an essay? I'm not looking for perfect recommendations, I can do the work in deciding the right one."

How about "I will be doing experiments where pure O2 will be going through the pump but I am not going to mention it".

Should my reply be "since you needed a 'strong vacuum' your best bet is a rotary vane oil pump, since explosions bother me not at all"?

Or "I will be doing experiments with acid vapors".

Should my reply be "by all means use a diaphragm pump, metal reed valves being eaten away bother me not at all"?

Or "solvent fumes eating the diaphragm bother me not at all"?

"I just wanted to know if anyone could point me in the direction of a website where they got a good deal, or a cheap pump that worked suprisingly (sic) well."

If you had looked at the eBay link I gave you would have seen my best educated guess as to your needs was perfectly fulfilled with this pump.

"I guess the famed friendliness of this forum was lost on me..."

So true.

"I wasn't looking for egg headed snarkiness (sic), just simple recommendations."

Neither was I but it seems this was my punishment from you for trying to help. My questioning you about specifics was quite valid, chemistry is not safe when one works without precision, understanding, thoughtful planning. Also, expensive investments in equipment can be wasted as can be seen from my questioning about what will be going through the pump. A Gast diaphragm is likely perfect for most work you will do and in a steady long operation vacuum can be precisely controlled with a needle bleeder valve.

"I KNOW how to pick the correct style based on what I'm using it for. I wasn't asking YOU to do that for me."

Then why does this thread exist? Second, no one but you knew exactly what you would be using it for since no mention was made of what chemicals would be involved.

"I'll explain again what I've spent weeks looking for:Something MORE convenient than a water aspirator that will give the same deep vacuum (greater than 28" Hg or about 40 torr, greater than 29" or less than 20 torr would be preferable) and isn't going to fucking cost me over $1000. I'm in the US we use 120V here, and even if it were 220 thats FINE I ALSO have a 220 line in my garage."

At least we now know what range of vacuum you require. You could have omitted the 'F word' which clearly indicated the attitude you are coming from. So does the caps on 'FINE'. Did it not occur to you this forum is global and my consideration was do they live in Europe or the US, should I find a pump which operates 117 VAC or 220 VAC when considering which pump they should look at? Personally I have never been in your garage nor did I know what continent it is located on so how would I or anyone know what voltages you have available.

"You're all on a science/chemistry forum, none of you vacuum distil anything or use a vacuum pump?"

Many no doubt do, but in the decade I have been here few have come in attacking people for trying to help them within their first 4 posts. My advice is you start over without the attitude to members here. At the very least try not accusing members who spent time trying to be helpful with no preconceived attitude, of having the attitude you are displaying against them.




"Science is the belief in the ignorance of the experts" Richard Feynman
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[*] posted on 23-1-2015 at 20:57


you could theoretically use any volumetric mechanical pump with a large enough trap . i have an alcatel roughing pump that i use for physics and chemistry experiment but when i need to protect it from solvant or corrosives fumes i add a trap (or 2 ) or a filter (or both) .
theses pumps are capable to reach 50 micron the size only increases the speed . they are easy to find on ebay and are well worth the money ! they can also be re wired to accep either 11or 220 V .

http://www.ebay.com/itm/Alcatel-Model-200BA-Rotary-Vane-Vacu...

good luck!




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kjpmi
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[*] posted on 24-1-2015 at 17:25


Sorry if I misinterpreted anyone's tone. My apologies. I will look at the links provided so far. Thank you!
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[*] posted on 25-1-2015 at 11:37


My Alcatel works fine for physics/plasma experiments but even with traps I don't think I would use it for vacuum distillations. The oil is still going to be contaminated and can seriously harm the pump unless one flushes and replaces it often. To me it is too expensive for such work and the vacuum is too high, just not needed for average distillation work. I do not see why the diaphragm pump would not be the best choice. It can run for days, no oil contamination worries, and the ultimate vacuum is greater than needed for vacuum distillation. Only 2 things would be at issue, corrosive vapors attacking the steel reed valves or solvents affecting the diaphragm. Actually Trichlor was the only solvent I discovered to be really hard on those pumps. So I would think other solvent choices should be considered. Not so common today anyway. In the 60's Carbon Tet was everywhere cheap and Trichlor was really common in the 70's to 80's although today cancer concerns have made such solvents less commonly available.

Traps would I believe minimize these troubles and this type pump is not very expensive. If higher vacuum is required two in series or a dual piston model should work. As I mentioned before I have several single and dual Gast pumps and around 40 bucks for the dual was the highest I paid for any of them. Living in Phoenix I used to go surplus hunting, but it was at a swap meet at Greyhound park I bought 3 brand new single head Gast pumps for 8 bucks each. Patience and searching pays off. I would have only considered paying 80 to 120 for a new Gast pump if I had none and needed it right away. My Alcatel is my jewel of pumps, having never found a diffusion type at low cost my workaround was the Alcatel and getters for experimenting with gas lasers and various plasma tube experiments. In the 80's Phoenix was a great place to find such equipment but today it is getting harder to find, especially at low cost. This is one reason ebay has been great help to me. One can search easily, I wish ebay had been around in my younger years. Neptunium is your Alcatel a two stage? You should be able to get down to one micron using the Alcatel type 200 oil.




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[*] posted on 25-1-2015 at 13:39


i do get to 10e-2 torr as a roughing pump (i have 2 of those alcatel type) i am currently looking at a turbomolecular for deeper vacuum for my homemade mass spectrometer i am working on

http://www.sciencemadness.org/talk/viewthread.php?tid=58661#...

how about a teflon coating on the said diaphragm ? that would protect against pretty much everything !


Irc you are absolutely right about ebay! i am so grateful for it! i remember taking appart fridge for vacuum pump compressor microwave for the beryllium rings and all kinds of more or less expansive stuff for equipment and chemicals back 25 years ago! i was young and didnt have access to anything untill i got to college and played with the real thing!
Ebay is such a treasure of equipment that would have been unthinkable for us home scientist 20 to 25 years ago! we have a great opportunity to get all kinds of equipment and chemicals! i just hope it last for a long time...

[Edited on 25-1-2015 by neptunium]




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[*] posted on 25-1-2015 at 15:30


I think IrC is right in saying that for normal chemical work (vacuum distillations, etc) one does not need to get down into the sub-1mmHg, mbar, or torr range. My Harbor freight oil pump ($100) does just fine for vacuum distillations, producing a pressure of 1-2 mmHg. So far I have not needed to use a cold trap to protect the oil/pump but I can see where this might often be the case. So, looking at the Gast website I see that a 0.8 cfm one-stage diaphragm pump pulls 28.5"Hg vacuum and a 1.9 cfm 2-stage diaphragm pump can pull 29"Hg vacuum. These values are equivalent to absolute pressures of 38 mmHg and 25 mmHg, respectively. I would think that either pump would be satisfactory for most vacuum distillations. The big advantage of the ptfe diaphragm pump being that it is chemically resistant and therefore no cold trap is required.

I know that KNF Neuberger also makes such a pump. Both the Gast and KNF Neuberger are probably several (many) times the cost of the HF when new. But eBay and patience might well produce some real bargains as indicated by IrC.

I know that UC235 (UnintentionalChaos) uses a diaphragm pump for his chemical lab vacuum needs, one-stage IIRC. I wonder just what pump he has, how he likes it, and what it cost?




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[*] posted on 5-2-2015 at 13:21


Yum Yum?

http://www.ebay.co.uk/itm/Edwards-High-Vacuum-BOC-Spectron-5...
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[*] posted on 1-3-2015 at 16:25



Is this a bargain ?

http://www.ebay.co.uk/sch/Pumps-/42928/i.html
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[*] posted on 2-3-2015 at 15:41


Which one? The link is the whole Ebay page...



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[*] posted on 2-3-2015 at 17:37


if one had a choice between one of the harbor freight style guys and one of the little diaphragm versions, would there be any clear cut reason's to avoid one of them for chem? I ask, because after slaving away so far from home for a while, I get to occasionally purchase some secondhand( rarely new) stuff for the lab. I have pretty much 0 experience using a vac for my hobby, but I'm *OVER IT* as far as gravity filtration for one, and some day when I get the outbuilding all together with no safety concerns around family, I'd like to be able to do vac assisted distillations and what not.

I try to keep one small purchase like that "waiting at the end of the rainbow" on difficult jobs, for drive when ya just wanna go home. I can always play the waiting game for deals on ebay, so it's no big hurry. I mean right out the gate, I can see that it would be easier to keep the lill guy around for simple stuff. any thoughts here. I have read a lot of pump threads and comments, but I guess I am basically lacking experience enough to have a clear vision of what I would like. thanks
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[*] posted on 2-3-2015 at 17:45


I got tired of waiting around for a bargain. I did talk myself around to a diaphragm pump rather than a refrigeration unit. This is what I ended up with. http://www.ebay.com.au/itm/400527749044 It should be arriving any day now!

[edit]
I arrived home from work to find a weighty parcel. One happy home chemist.
First job will be to test my ideas for making my own gas discharge tubes. Then vacuum filtration. Then some distillation after I get some glassware. Then... well, who knows?

[Edited on 3-3-2015 by j_sum1]
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[*] posted on 3-3-2015 at 15:11
Vacuum Pums


My customers have been happy with these:

http://www.elementalscientific.net/store/scripts/prodView.as...

http://www.elementalscientific.net/store/ProdImages/SCHUCO%2...

http://www.elementalscientific.net/store/scripts/prodView.as...








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[*] posted on 3-3-2015 at 16:44




I posted the wrong link above.

http://www.ebay.co.uk/itm/151599053873?_trksid=p2055119.m143...
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[*] posted on 3-3-2015 at 18:59


Quote: Originally posted by jock88  


I posted the wrong link above.

http://www.ebay.co.uk/itm/151599053873?_trksid=p2055119.m143...
Well, it was a bargain. Did you get it?
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[*] posted on 3-3-2015 at 19:00
Vacuum Pums


My customers have been happy with these:

http://www.elementalscientific.net/store/scripts/prodView.as...

http://www.elementalscientific.net/store/ProdImages/SCHUCO%2...

http://www.elementalscientific.net/store/scripts/prodView.as...








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[*] posted on 4-3-2015 at 07:39


There are two types of vacuum pumps worth using in a real organic lab if you have any corrosion issues. A diasphram pump will work well for many cases, most are quite corrosion resistant, and can run for hours or days without problem, they also do not need as much trapping of vapors. The cost is several hundred dollars to low thousands.

The other choice I would make is a Welch ChemStar rotary pump. They go for days and years of use without problem, and are easily found used, but you have to make sure that they still work well then. New they are $1000-2500, but they will run for years with even a simple cold trap, and changing the oil occasionally. Welch is the only brand I will buy now. Skip the cheaper ones, they just are not as good, the ChemStar model is the best I have ever used.

There are slightly cheaper direct drive pumps but my experinece with them is that they are only a little cheaper and smaller then a rotary pump, but do not last long before they fail, IF EXPOSED TO CHEMICALS. They are fine for instrumental use and such, they just don't like acids or harsh environments.

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[*] posted on 4-3-2015 at 09:06


If just for vacuum filtration and partial vacuum distillation would this be suitable?
The cost is so low that it may be worth buying for evaluation of the pump itself and your actual requirements.
Destroying one of these would be a lot less painful than damaging a 'proper' pump.

oops! forgot the link
http://www.ebay.co.uk/itm/111458935603?_trksid=p2060778.m143...

[Edited on 4-3-2015 by Sulaiman]
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[*] posted on 6-3-2015 at 01:59


Two options:

1) Chemistry diaphragm pump. I have a KNF Laboport (N 810.3 FT.18). It has had all kinds of solvents go through it and the outer casing paint is wearing off (only a tiny bit of DCM will destroy almost anything) as a result of occasional carelessness but it still runs perfectly and gives under 10 millibar (i.e. under 10mm/Hg). Pumping speed is slow (10L/min) and it takes a while to evacuate things. This pump also costs around $2000 new. I bought mine second hand from eBay in Ireland ($500). Typically used for vacuum filtration or on the desiccator. Good for rotary evaporation as well. KNF make great equipment.

2) Rotary vane vacuum pumps. The best place to start, price wise, is a two stage 5cfm (~140L/min) HVAC pump available from eBay or many stores ($200). NOT suitable for vacuum filtration or stripping solvents/corrosives. Pump will die very quickly if anything like THF gets inside. Buy spare oil when you buy the pump. Excellent for vacuum distillation of high boiling point organics as the vacuum is much, much stronger (i.e. 30 millitorr instead of 10 torr)

If you want a deluxe vacuum system then you want a good quality vacuum pump (e.g. Pfeiffer, Edwards, Welch, Leybold etc) AND a cold trap. The best cold traps are made by a company called Genevac/SP Industries. This type of system is expensive. You can save money by buying a liquid Nitrogen or dry ice cold trap but the hassle of LN2 or dry ice is not worth my time.

Don't bother with expensive [rotary] pumps if you don't have a cold trap.

Overall; second hand diaphragm pump is great for most things in a home lab. Get a rotary pump for the heavy lifting.


[Edited on 6-3-2015 by adk]
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[*] posted on 10-3-2015 at 06:11


IMO it's an interesting idea to get a 2 stage oil pump, like those used by HVAC people, even if I'd use it once in a while for vacuum distill 'n stuff.
I'm currently waiting for some government research money to drop on me or for some spare money on the allowance I get from my family to be on college to appear and I'll be getting one of these pumps.
With filters\cold traps\'n stuff set I can do some occasional vacuum distillation, dry some glassware and reagents, and the higher vacuum these pumps can generate allows -at least some- fun with applications like thin film deposition... although the small MFP I'd get from these would either mean the target and the source on a thermal evaporation setup would need to be really close to each other, or that I wouldn't get very uniform results... still I'd actually save some decent money by doing this since the pump costs like 150 bucks and liquid nitrogen -for the cold trap- goes for 1.5 bucks/L on the cryogenics lab of the physics department of the university -and its only a 5 minute walk from my apartment to their lab- :D
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