Sciencemadness Discussion Board

Has anyone tried the "Lab Portable Oilless Diaphragm Vacuum Pump"?

SuperOxide - 27-9-2021 at 21:21

Im looking for something that can pull a decent vacuum without needing much maintenance or requiring water. I have an aspirator pump, but sometimes I don't want to hook what I'm pulling a vacuum on to water. And I could get a rotary vacuum pump, but Id prefer to not have to deal with pump oil (or getting solvents into it).
The main things I'll be using it for is vacuum distillation and vacuum filtration, and maybe a vacuum desiccator if I get one. I use to have a crappy little pump that was nice and quiet and worked well for vacuum filtrations, but the inside parts were made of a cheap plastic that was eventually ruined by some solvents I use.

From what I understand, a decent diaphragm based vacuum pump would be the best bet for this. And on Amazon I've seen this one from a few providers: Lab Portable Oilless Diaphragm Vacuum Pump

Its a 110V-220V vacuum pump capable of pulling 10L/min (though there are 15L/min and 30L/min versions).

Does anyone here have this pump? would you recommend it?

Fyndium - 27-9-2021 at 23:44

It appears to me that you are being robbed. With a crappy plastic toy gun.

https://www.ebay.com/itm/224200363652

I use these for vacuum filtrations. Have had one running for several hundred hours now, almost 8 hours non-stop couple of weeks ago when I had to wash and suction dry some large cakes.

For distillation I use these. With the remaining $150 you can buy technical paraffin oil for 5$ a liter for the rest of your life to do oil changes.

https://www.ebay.com/itm/254455748012

[Edited on 28-9-2021 by Fyndium]

[Edited on 28-9-2021 by Fyndium]

Organikum - 28-9-2021 at 00:27

In this price range I would suggest this:

https://www.alibaba.com/product-detail/Vacuum-Pump-Gm-0-5b-D...

What is a decent pump, chemical resistant, allparts exposed are PTFE or other fluoroplastics, it is a direct knockoff if not copy from KNF pumps. It should be easy to bargain a set of replacement PTFE membranes and valves for cheap when ordering one of those and I would recommend to do this.

There is the cheaper 1 head version but that is only down to 200mbar, this one is rated down to 50mbar what is not the world but at least honest and it suffices for most applications.
Should you need more, you can always rig the aspirator as a forpump what should get you into the single mbar range for sure and thats the maximum one can get from this kind of vacuum pumps.

It is a realistic price too, the fact is just that vacuumpumps from the big brands (as all lab equipment) is insanely overpriced, those companies are no better then the light bulb manufacturers have been in the past.


On a sidenote:
Rotary vane oil pumps can tolerate water if they are equipped with a forpump, but an aspirator won't do the job properly one would need something like a Roots blower, or if the oil in the pump is at a temperature of about 115°C what calls for a pump with separated motor (which is superior to direct drive pumps anyways) and an oil-heating (easily done and preheating the oil before startup is so much easier on the machine and allows to use oil of a much higher viscosity)

regards
/ORG

monolithic - 28-9-2021 at 04:46

The pump in your link only gets down to 160 torr which isn't that good, and the diaphragm is "imported rubber" which would probably be destroyed by solvent vapors. If it was a $50 pump it might be worth it, but $180 is a ripoff.

I have a KNF vacuum pump, no complaints. Look around eBay and you can sometimes find a good deal -- just be mindful of the exact model you're buying, as not all of their models have corrosion resistant heads and diaphragms. See https://www.ebay.com/itm/303381964407 The maximum vacuum is 75 torr and the head/diaphragm are corrosion resistant, check the datasheet at https://knf.com/en/us/solutions/laboratory-equipment/details...

SuperOxide - 28-9-2021 at 06:59

Quote: Originally posted by Fyndium  
It appears to me that you are being robbed. With a crappy plastic toy gun.

https://www.ebay.com/itm/224200363652

I use these for vacuum filtrations. Have had one running for several hundred hours now, almost 8 hours non-stop couple of weeks ago when I had to wash and suction dry some large cakes.
yeah, I wasn't sure if these were strong enough for some vacuum filtrations, but they're cheap enough, ill get one (maybe two, and pair them up in parallel if needed).

Do you just connect it right to a 12v power supply? Or do you have a way of varying the current to get different vacuum pressures?

Quote: Originally posted by Fyndium  
For distillation I use these. With the remaining $150 you can buy technical paraffin oil for 5$ a liter for the rest of your life to do oil changes.

https://www.ebay.com/itm/254455748012
Right, and these seem to be the common vacuum pump that most people get, but if possible I was hoping to get a diaphragm, no need to worry about changing the oil or getting solvents in the oil.
Here's an example of one that I mean. No oil and highly resistant to all types of fumes. Its also relatively quiet (from what I can tell in some videos). But that's expensive as hell, lol.
Quote: Originally posted by Organikum  
In this price range I would suggest this:

https://www.alibaba.com/product-detail/Vacuum-Pump-Gm-0-5b-D...

What is a decent pump, chemical resistant, allparts exposed are PTFE or other fluoroplastics, it is a direct knockoff if not copy from KNF pumps. It should be easy to bargain a set of replacement PTFE membranes and valves for cheap when ordering one of those and I would recommend to do this.

There is the cheaper 1 head version but that is only down to 200mbar, this one is rated down to 50mbar what is not the world but at least honest and it suffices for most applications.
Should you need more, you can always rig the aspirator as a forpump what should get you into the single mbar range for sure and thats the maximum one can get from this kind of vacuum pumps.

It is a realistic price too, the fact is just that vacuumpumps from the big brands (as all lab equipment) is insanely overpriced, those companies are no better then the light bulb manufacturers have been in the past.
I've seen those around, ill look for the stronger ones on ebay. I don't mind if its used, as long as it works well.
Quote: Originally posted by Organikum  
On a sidenote:
Rotary vane oil pumps can tolerate water if they are equipped with a forpump, but an aspirator won't do the job properly one would need something like a Roots blower, or if the oil in the pump is at a temperature of about 115°C what calls for a pump with separated motor (which is superior to direct drive pumps anyways) and an oil-heating (easily done and preheating the oil before startup is so much easier on the machine and allows to use oil of a much higher viscosity)
Right, but this is the kind of stuff I would like to be able to avoid if possible, lol. That's why I was hoping for a diaphragm pump with PTFE internals.


Quote: Originally posted by monolithic  
The pump in your link only gets down to 160 torr which isn't that good, and the diaphragm is "imported rubber" which would probably be destroyed by solvent vapors. If it was a $50 pump it might be worth it, but $180 is a ripoff.
yeah, you're right. I should have seen the "imported rubber"...


Quote: Originally posted by monolithic  
I have a KNF vacuum pump, no complaints. Look around eBay and you can sometimes find a good deal -- just be mindful of the exact model you're buying, as not all of their models have corrosion resistant heads and diaphragms. See https://www.ebay.com/itm/303381964407 The maximum vacuum is 75 torr and the head/diaphragm are corrosion resistant, check the datasheet at https://knf.com/en/us/solutions/laboratory-equipment/details...

Hm, that ebay listing seems like a great deal. I just might purchase that! I might have to wait a bit longer, or try to bargain for an even lower price.
You said you have the same pump - Is it very loud? Being loud wouldn't be a deal killer, im just curious.

[Edited on 28-9-2021 by SuperOxide]

[Edited on 28-9-2021 by SuperOxide]

monolithic - 28-9-2021 at 07:52

Quote: Originally posted by SuperOxide  

Hm, that ebay listing seems like a great deal. I just might purchase that! I might have to wait a bit longer, or try to bargain for an even lower price.
You said you have the same pump - Is it very loud? Being loud wouldn't be a deal killer, im just curious.


I actually have a KNF 726.3FTP which is a dual head PTFE model. https://www.atecorp.com/atecorp/media/pdfs/data-sheets/KNF-U... They go for around $200-250 if you're patient and wait out the ripoff artists asking $500-600. They are a little loud but not too much. There's some videos on YouTube of them running.

SuperOxide - 28-9-2021 at 08:50

Quote: Originally posted by monolithic  
Quote: Originally posted by SuperOxide  

Hm, that ebay listing seems like a great deal. I just might purchase that! I might have to wait a bit longer, or try to bargain for an even lower price.
You said you have the same pump - Is it very loud? Being loud wouldn't be a deal killer, im just curious.


I actually have a KNF 726.3FTP which is a dual head PTFE model. https://www.atecorp.com/atecorp/media/pdfs/data-sheets/KNF-U... They go for around $200-250 if you're patient and wait out the ripoff artists asking $500-600. They are a little loud but not too much. There's some videos on YouTube of them running.


Like this one? https://www.ebay.com/itm/324328564746

monolithic - 28-9-2021 at 09:01

Quote: Originally posted by SuperOxide  
Quote: Originally posted by monolithic  
Quote: Originally posted by SuperOxide  

Hm, that ebay listing seems like a great deal. I just might purchase that! I might have to wait a bit longer, or try to bargain for an even lower price.
You said you have the same pump - Is it very loud? Being loud wouldn't be a deal killer, im just curious.


I actually have a KNF 726.3FTP which is a dual head PTFE model. https://www.atecorp.com/atecorp/media/pdfs/data-sheets/KNF-U... They go for around $200-250 if you're patient and wait out the ripoff artists asking $500-600. They are a little loud but not too much. There's some videos on YouTube of them running.


Like this one? https://www.ebay.com/itm/324328564746


Pretty much, although that's the single head model. The one I have has two heads: https://www.ebay.com/itm/224626140763?hash=item344cc2e65b:g:... The benefit of dual heads is twice the airflow, or better vacuum if the heads are hooked up to pump in serial / 2 stage mode. (You can re-configure serial/parallel pumping yourself, if you have some spare hose.) The manual lists the maximum flow rate and vacuum: https://atecorp.com/atecorp/media/pdfs/data-sheets/KNF-UN726... Just be careful and do research on the exact model you want to buy. I believe the "FTP" models are PTFE heads with corrosion resistant diaphragms. Not all of the KNF pumps are like this, and sometimes resellers will mislabel them out of ignorance.

I bought mine a few years ago in good, working condition for $170. It's just a matter of waiting and keeping an eye out. The one I linked you to in this post, for example, costs $300 and is "for parts." Not a particularly good deal. I've torn my pump down to clean it, they're not very complex. As long as the motor isn't burnt out and the diaphragms aren't torn from age, they're good to go.

In addition to KNF, Vacuubrand diaphragm pumps are supposed to be good. In general they are $$$ but sometimes you can find a good deal on eBay. Same caveats apply, do research and make sure the particular model you're bidding on has PTFE/chemically resistant pumping paths.

[Edited on 9-28-2021 by monolithic]

SuperOxide - 28-9-2021 at 11:33

Look what I just purchased :-D

KNF Lab Filtration Pump Type UN811 KV.45P Mini Diaphragm Vacuum Pump - $150.

Screen Shot 2021-09-28 at 12.32.10 PM.png - 512kB

He was selling it for $200, I thought he would turn down $150 (and I couldn't go any higher, really), so im glad he accepted.

Woot!

monolithic - 28-9-2021 at 12:23

Nice, always great to see someone get a good deal on eBay lab equipment. :)

SuperOxide - 28-9-2021 at 12:48

Quote: Originally posted by monolithic  
Nice, always great to see someone get a good deal on eBay lab equipment. :)

I certainly hope it ends up being a good deal, haha.

Thanks for the input guys!

macckone - 28-9-2021 at 13:03

I use a regular cheap a/c system pump, changing the oil regularly has kept it running.
I use a modified aquarium pump for filtration.
I used a cheaper pump with a different style valve but the principle is that same:
https://www.instructables.com/Vacuum-Pump-from-Aquarium-Air-...

SuperOxide - 28-9-2021 at 17:21

Quote: Originally posted by macckone  
I use a regular cheap a/c system pump, changing the oil regularly has kept it running.
I use a modified aquarium pump for filtration.
I used a cheaper pump with a different style valve but the principle is that same:
https://www.instructables.com/Vacuum-Pump-from-Aquarium-Air-...

Funny you say that... I've wondered a few times why not just reverse the flow of an air pump from walmart or something. Glad to know it works!

Fyndium - 29-9-2021 at 00:06

Ok, I admit it, I have used up two rotary vanes so they do not produce more than 50mbar vacuum at max, even when taken apart and cleaned. I just bought a third one. 50 bucks a shot, I still think they are the best bang for buck for a hobbyist, as one kept good will last at least a couple of years, unless you push in nitric acid and don't change the oil often. Another issue is that they heat up, but I have solved this problem by putting it in a small box and suctioning air through it with a large duct fan, which I have an activated carbon filter unit, so any odors will be filtered off at once. Over the forced airflow, the pump remains cool to touch, but without, it will heat up too hot in 15 minutes or less.

In this case, I'm gonna use the older pumps as stripping pumps. I use them to strip the volatiles and water from a distillation first, and when the system is dry, I perform the actual distillation with the new pump. This way I can limit the amount of vapors getting into the pump. I will use the oldest and most worn pump as a filtration pump, because 50mbar or a bit over is hugely enough for filtrations, but really lacks the edge for distilling higher bp liquids at ease.

A new rotary will carry 180C liquid over at 45C.

I was looking into a two-phase KNF 8mbar pump, and saw one for sale for $800, but decided not to pull the trigger.

Organikum - 29-9-2021 at 14:59

Quote: Originally posted by monolithic  
The pump in your link only gets down to 160 torr which isn't that good, and the diaphragm is "imported rubber" which would probably be destroyed by solvent vapors. If it was a $50 pump it might be worth it, but $180 is a ripoff.

I have a KNF vacuum pump, no complaints. Look around eBay and you can sometimes find a good deal -- just be mindful of the exact model you're buying, as not all of their models have corrosion resistant heads and diaphragms. See https://www.ebay.com/itm/303381964407 The maximum vacuum is 75 torr and the head/diaphragm are corrosion resistant, check the datasheet at https://knf.com/en/us/solutions/laboratory-equipment/details...


I do not know where you get this nonsense from but for sure not from the link I provided as the model I recommended is the chemical resistant two head variation which has PTFE membranes etc and the vacuum is 50mbar which would be lower but there is an automatic ballast valve integrated for safe operation with water vapors.

It is the GM-0.50B model as it states in the headline with the product description. You then have to look under GM-0.50B in the table with the data. I can make you a pictogram if you need one?

clowns
/ORG

monolithic - 29-9-2021 at 17:46

Quote: Originally posted by Organikum  
Quote: Originally posted by monolithic  
The pump in your link only gets down to 160 torr which isn't that good, and the diaphragm is "imported rubber" which would probably be destroyed by solvent vapors. If it was a $50 pump it might be worth it, but $180 is a ripoff.

I have a KNF vacuum pump, no complaints. Look around eBay and you can sometimes find a good deal -- just be mindful of the exact model you're buying, as not all of their models have corrosion resistant heads and diaphragms. See https://www.ebay.com/itm/303381964407 The maximum vacuum is 75 torr and the head/diaphragm are corrosion resistant, check the datasheet at https://knf.com/en/us/solutions/laboratory-equipment/details...


I do not know where you get this nonsense from but for sure not from the link I provided as the model I recommended is the chemical resistant two head variation which has PTFE membranes etc and the vacuum is 50mbar which would be lower but there is an automatic ballast valve integrated for safe operation with water vapors.

It is the GM-0.50B model as it states in the headline with the product description. You then have to look under GM-0.50B in the table with the data. I can make you a pictogram if you need one?

clowns
/ORG


I was responding to SuperOxide's original post where he linked to a rubber membrane pump on Amazon. If I was responding to you then I would have quoted your post, as I am right now. Calm down. :)

SuperOxide - 10-10-2021 at 13:29

It finally came in! He took a week to send it, and when it got here I could tell it definitely was dropped - The vacuum gauge was totally fucked and facing down. But the pump and regulator seem to work fine :-)

https://imgur.com/a/X2NJI4x (It's an imgur video of me testing the pump out - I couldn't find a way to embed it like a photo).

[Edited on 10-10-2021 by SuperOxide]