Sciencemadness Discussion Board

My vacuum pump

Vosoryx - 21-11-2017 at 22:44

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?

XeonTheMGPony - 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!

zed - 22-11-2017 at 14:27

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

Thank you!

aga - 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 ?

XeonTheMGPony - 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]

Vosoryx - 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.

Bert - 22-11-2017 at 18:55

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

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Suction or Vacuum Power- Bernoulli

Ubya - 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.

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RogueRose - 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 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.

weilawei - 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]

Vosoryx - 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.

NeonPulse - 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.