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Vosoryx
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[*] posted on 21-11-2017 at 22:44
My vacuum pump


Just finished making an aspirator vacuum pump, and thought I could put it up here for suggestions/criticism and as a source if anyone else wants to build one.

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The aspirator and the pump were both bought online. (Ebay) the shipping was fast, and in both cases free.
The aspirator is from Deschem, and the pump is a 100 PSI (6.8 ATM) 12VDC at 3 amps max draw.
It is powered from a supply I found at the local thrift store in the electronics section, exactly 12VDC 3 amp. The connections from the motor were soldered onto the stripped ends of the power supply. I didn't put a switch in line.
In order to get from the water pump to the aspirator, you can see quite a few converters were used. These were all very cheap for me, having most of the scrap lying around. Once on the aspirator, the vacuum must go through a valve. I installed this after various problems with water sucking into the vacuum hose - Deschem's one way valve on the aspirator sucks. (Puns!)
It should only ever be open when the pump is on, and I need the vacuum applied. Otherwise, the vacuum tube fills with water, ruining the vacuum or potentially interfering with experiments.
It is all mounted inside a plastic bucket I found in a scrap pile on the side of the road. As you can see, the bucked wasn't quite wide enough, so I had to drill two holes in it to get the output hose through. I actually like this though, as I can remove the hose if I need to. The hose loops around in the water in the bucket, and is sucked up by the pipe on the right, feeding into the pump. I also crimped a piece of door screen to the bottom of the pipe leading into the pump, just to act as a filter to get rid of some of the potential solid unwanted bits in the water that might influence the performance of the pump.
I ran I test on it involving vacuum filtration, which worked very well. (I simply created a suspension involving cornstarch and water and filtered it and dried it on the pump on my glass frit.)
It worked quite well, and I am pleased to use it in the future. It is not even close to being as strong a pull as even an expensive shop vac, but it can be run continuously, unlike simple vac cleaners. I also haven't tried it with ice water, just tap water.

I know the pictures suck, they are taken in my bathroom, not my lab.

Thoughts? Opinions?
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XeonTheMGPony
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[*] posted on 22-11-2017 at 12:42


Well for doing stuff that will gas off, put a lid on with a fan to vent out side you'd have a solid unit!
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[*] posted on 22-11-2017 at 14:27


Well, I never would have thought of doing it that way.

Thank you!
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[*] posted on 22-11-2017 at 14:53


Superb !

Great to see people Doing things in amateur chemistry.

I'm slightly confused tho.

Is it a venturi type aspirator that works by water flowing through it, augmented by having a water pump to suck water through it faster ?




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XeonTheMGPony
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[*] posted on 22-11-2017 at 15:26


Pump > Aspirator > Bucket

you're converting pressure to velocity, and that high speed jet stream of water that draws in the gasses to pull vacuum.

[Edited on 22-11-2017 by XeonTheMGPony]
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Vosoryx
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[*] posted on 22-11-2017 at 16:33


Quote: Originally posted by XeonTheMGPony  
Well for doing stuff that will gas off, put a lid on with a fan to vent out side you'd have a solid unit!


Thought about that, but due to the 3 meter tube and the fact that I wouldn't have it cycle if it were something that could damage the pump I decided against it. The length enables me to put it outside my lab for long refluxes and distillation, which I would do anyway due to the noise.
I couldn't really think of any applications where that would be practical - acids i wouldn't recirc, neither bases or organic solvents for fear of damaging the pump/aspirator/tubing/connectors. What does that reasonably leave?

Quote: Originally posted by aga  
...Is it a venturi type aspirator that works by water flowing through it, augmented by having a water pump to suck water through it faster ?


Yes, it is a venturi aspirator. I'm not sure what you mean by "augmented by having a water pump" - How else is the water going to pump through the aspirator?
Some people attach these directly to their faucet, but i'm not because the water pressure at my house is... Barely existent. Higher pressure means a better vacuum.
The water, as Xeon said, goes up into the pump from the water bucket on the right, through the pump and into the aspirator, then back into the bucket on the left.
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[*] posted on 22-11-2017 at 18:55


Bernoulli effect/Venturi effect... patata, potato.

post-64627-0-78515800-1326678394_thumb.gif - 33kB

Suction or Vacuum Power- Bernoulli




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[*] posted on 25-11-2017 at 16:23


just today i finished my vacuum system, just like yours it uses an aspirator and a 12v diaphragm pump rated for "100psi 5L/min". i had all the parts for a few months now and never assembled it, so finally today i did it. when i tested it the vacuum wasn't really what i expected...
when i put my finger on the tube opening it barely sucks it. so i connected it to my vacuum flask and buchner funnel and tried to see if it could be usable for vacuum filtration. i was in a rush so i really just dumped some water on the filter to see if it could at least suck it reasonably fast, whitch it did ;)
(i still have to try a real filtration dough). the problem is that i don't think i could use my vacuum system for vacuum distillation (i kinda built it for that reason...). tomorrow i will try to boil water under "vacuum" and correlate the boiling temperature to the pressure in the system so i have some numbers.

20171126_005812.jpg - 2.5MB20171126_005837.jpg - 2.3MB
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[*] posted on 8-12-2017 at 03:29


I like these setups! I'm wondering if it would be possible to use a setup like this to circulate water in the condenser as well as draw vacuum at the same time.

One thing I don't get is why they are all 12v and the 110-120 are about 5-8x as much!

I'm kind of interested in one of these
https://www.ebay.com/itm/SCHUCO-SCHUCO-VAC-130-ASPIRATOR-SUC... it's an aspirator vacuum pump. My main goal is to be able to help do vacuum filtration as well as vacuum distillation. IDK if this type would work or not.
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[*] posted on 8-12-2017 at 05:39


If you get yourself a chassis mount transformer like this one, you can run the pump off 120V. Programming and electronics were my first love before chemistry (~25 years doing that :cool: ). Just wire it up with some spade terminals and chop up an existing power cord to make your connection. Wire the ground to one of the bolts holding the chassis down. Should only run you about 25$ total.

[Edited on 8-12-2017 by weilawei]
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Vosoryx
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[*] posted on 8-12-2017 at 08:03


It's very possible to use the pump to circulate water, but i wouldn't advise it. Mainly because now the inside of the jacket would then be covered in water that contains whatever is dissolved in that water from the aspirator. Since the jackets are very hard to clean, i wouldn't contamimate them. It's up to you though.
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[*] posted on 10-12-2017 at 23:29


I have used a similar setup and I found that it worked best if the Venturi device is upright and the exit is directly under the water level of the reservoir. I had to adjust it to find the best vacuum. I also used a couple of metal check valves to stop the inevitable back flow when the vacuum is stopped. Also I had to replace the water pump once. After many hours of use the diaphragm crapped out and it was no longer self priming. It can pull a pretty good vacuum though. I demonstrated its use in one of my videos: a cold acetone distillation.




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[*] posted on 11-3-2018 at 08:57


hey it's me again, same pump as before but in a compact version, i realized that you really don't need all that water (being recirculating) and i wanted to insall this pump under my diy fume hood, so the smaller the better (i need the space for storage). the water aspirtor is vertical as suggested by NeonPulse, and the hose ends underwater because i noticed in my tests using a faucet that if the discharge tube is not filled with water there won't be any suction, i could have used a smaller diameter tube, but i hadn't any so i just submersed the end of it to. the pump works! i still need to measure exactly the vacuum pressure, it's won't be like a rotary vane vacuum pump but it's doing it's job.
the container i used is a plastic beverage container bought at IKEA for 3,50 euros, i made the holes on the top with a hot screwdriver barely big enough for the tubes to fit so the won't wobble around, same thing for the aspirator.


WhatsApp Image 2018-03-11 at 17.41.49(1).jpeg - 162kB WhatsApp Image 2018-03-11 at 17.41.49(2).jpeg - 163kB WhatsApp Image 2018-03-11 at 17.41.49.jpeg - 174kB

oh and i will insall also another tube connected to the fume hood so any gases won't be released in the air or under my fume hood where i keep my chemicals and other stuff:P





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[*] posted on 11-3-2018 at 09:42


If you get a chance, could you tell us at what temperature water boils so we can get an idea of how much vacuum it's pulling?
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[*] posted on 11-3-2018 at 09:47


Quote: Originally posted by monolithic  
If you get a chance, could you tell us at what temperature water boils so we can get an idea of how much vacuum it's pulling?


sure, i wan't to do exactly that





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Ubya
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[*] posted on 11-3-2018 at 10:37


soo with 20 °C water in the aspirator setup i got a boiling point of 73°C, so a pressure of about 0.31 bars.
the aspirator i bought is this
https://www.ebay.com/itm/Stainless-Steel-Aspirator-Pump-Humb...

in the specs it says that it's maximum vacuum is 420mmHg or 0,56 bars so i already beat it :D
cooling the water to near 0°C will help.
any ideas on how to make an even stronger vacuum? (i will try i few things like water level, tube length etc)





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[*] posted on 11-3-2018 at 11:25


Cool set-up. Incredibly compact and convenient.

I think aspirators of that design are generally able to make pretty high vacuum with enough pressure and flow.
Often the limiting factor is water temperature when you get down under 40 Torr , but at higher pressures the water temperature isn't as much of an issue as long as it's not too warm.


With a small reservoir it sounds like things would get pretty frothy in there when it's running.

This could mean sucking bubbles into the pump, which could be a problem.

Maybe if you put something like a few layers of screen or plastic pot-scrubber pads in the space between the input and output pipes it would help lessen any trouble with air bubbles getting in the pump. (If that is a problem...I'm just supposing here.)

They make little things that go on aspirator outlets that are kinda like little funnels packed with screen which help slow down the output velocity and cut down on splashing.

One of those might help, but I'll be damned if I can remember what they call those things.

Hey, you could maybe kill two birds with one stone by putting a mesh bag full of crushed ice in the center of the container.
Cool the water and keep bubbles out of the pump.





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Ubya
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thumbup.gif posted on 11-3-2018 at 15:48


Quote: Originally posted by SWIM  



With a small reservoir it sounds like things would get pretty frothy in there when it's running.

This could mean sucking bubbles into the pump, which could be a problem.

Maybe if you put something like a few layers of screen or plastic pot-scrubber pads in the space between the input and output pipes it would help lessen any trouble with air bubbles getting in the pump. (If that is a problem...I'm just supposing here.)



yes, i noticed bubbles being sucked, and i thought it could be a problem, indeed it is. i will try to reduce them with a screen separator of some kind as you suggest.
thank you for the tips:cool:





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[*] posted on 11-3-2018 at 16:54


I wonder how small you could make this thing. Also if you cool the water or add a salt, forgive my memory, then you will achieve a higher vacuum. Nerd Rage said something along these lines.



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[*] posted on 12-3-2018 at 02:38


When recirculating water through the pump and aspirator I would expect the water to heat up significantly,
does it ?

For vacuum filtration I highly recommend a cheaper, quieter and easier approach http://www.ebay.co.uk/itm/DC-12V-24V-80Kpa-Micro-Piston-Vacu...




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[*] posted on 12-3-2018 at 03:21


Quote: Originally posted by Sulaiman  
When recirculating water through the pump and aspirator I would expect the water to heat up significantly,
does it ?


the water is never in contact with the motor, so i don't think it would heat up, anyway i'll test the water temperature after running the pump for a while





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[*] posted on 12-3-2018 at 04:05


I meant direct mechanical heating of the water,
e.g. 60 W motor/pump x 50% efficient = 30 W power into the water,
with brief operation and a large metal reservoir you may not notice the effect
but prolonged operation with a small plastic reservoir may be problematic.




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Ubya
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[*] posted on 13-3-2018 at 02:47


Quote: Originally posted by Sulaiman  
I meant direct mechanical heating of the water,
e.g. 60 W motor/pump x 50% efficient = 30 W power into the water,
with brief operation and a large metal reservoir you may not notice the effect
but prolonged operation with a small plastic reservoir may be problematic.


you where right, after 4 minutes of running the water temperature went from 16.1 °C to 17.2 °C, i didn't measure the volume of water but surely for prolonged use it needs cooling.


SWIM, i got it working using a cleaning sponge :D
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[*] posted on 19-3-2018 at 03:56


Recently I came across a load of old glass for cheap and this was in the bundle. I’m sure it’s made of polycarbonate plastic and it works very well. Unfortunately though there’s no anti suck back device on its inlet. It may be vintage and I can’t find anything on its manufacturer. Most of the other glass was vintage too and used to Belong to an analyst. There was a lot of volumetric pipettes and burettes in the bundle as well as a large chromatography column. Just wondering if anyone has heard of this manufacturer. Pics enclosed.

F3589CC2-1CF3-4BF0-9AB3-855BF9829380.jpeg - 1.5MB90929F39-F7A8-426C-97DF-93BBA6930B1B.jpeg - 2.2MB




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[*] posted on 19-3-2018 at 08:49


Sorry if this is a stupid question, but I live in the UK and eBay will only show me water aspirator pumps being sold from the US, costing £30 each. I clicked on the link Ubya gave above for the water aspirator pump they bought (https://www.ebay.com/itm/Stainless-Steel-Aspirator-Pump-Humb...) and there are loads of different chinese ones costing below £10 suddenly. I am guessing this is the american eBay site (as all prices are given in dollars), but all these say they are selling to the UK too, and it suggests them to me on the sidebar of the UK eBay site now that I have viewed a few through the US site...

I had asked my college science technicians to place an order for me this week for a needlessly more expensive water aspirator pump so if someone could just very quickly confirm I am not a moron here before I throw around limited money, that would be very appreciated. If I can buy one of these chinese metal water aspirator pumps from here in the UK, I want to cancel that science technician order as soon as possible...

[Edited on 19-3-2018 by 18thTimeLucky?]




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