Simple DIY Vacuum Chamber and Pump

This is an easy to build vacuum chamber that is power with a garden hose.  you can draw 30 cm of vacuum with your hose. simple and easy way to degas fluids like silicone for mold making without buying an expensive vacuum pump.

Step 1 Parts

you will need the following parts. many of they can be found or scrounged for free is you have the time.

1 - 6" x 24 " PVC pipe                                Lowe's                                       $16
2 - 1/4 " x 12" x 12" acrylic sheets           (www.estreetplastics.com)   $12
2 - 1/ 8" x 12 " x 12" neoprene sheets   (www.smallparts.com)           $20
1 - vacuum Aspirator                                 (csrscience.ecrater.com)      $25
1 - vacuum gauge                                     harbor freight                            $13
1 - 3" x 3/8" air hose                                  harbor freight                            $4

                                                                                                                                                                 Total = $90

Comments

[TheREALfatNINJA]

Hmm.... I wonder if this could be used to construct a home food freeze drying device.

[Pazzerz]

You need a much higher vacuum, preferably with a piston type pump which can be gotten rather inexpensively at places like Harbor Freight. This is one of the projects I am currently working on, which is why I happened to come across this Instructable. The chamber is good, just need a heavier duty pump.

[TheREALfatNINJA]

Well I was thinking of re-purposing an old vacuum pump used for the repair and maintenance of automotive air conditioning systems. Is that what you're referring to?

[Pazzerz]

Yes! I just got a fairly new one and it works very well for that. I'm hoping to find a short section of fairly large PVC drain pipe to better accommodate a standard drying tray, otherwise I'll make mini-trays for it.

[jschumaker]

Where'd you find a 24" piece of 6" pvc at Lowe's? All I could find were 10' lengths. Also, any particular reason you used the green pvc?

[jlin is]

if you go to homedepot or lowes, they will cut what ever length you need and sell per foot

[jschumaker]

That is great to know.

[heathbar64]

So, still thinking about this project. I'm a little confused again. You mention your use for it as de gassing silicone for moldmaking. I am familiar with the idea of using a pressure tank to squeeze the bubbles out of a molded item, but seems to me like a vacuum would create bubbles. Am I wrong about this? Can you give more info on that use of it?

[bassman76jazz]

you just pull air out of the silicone before you pour it into your mold. less bubbles means better finish on a part. the silicone looks to boil as the vacuum reaches 25" and then falls back as most of the air in the solutions is extracted.

[heathbar64]

Ok, thanks for the education. I'm into molding stuff so I'm definitely gonna play with this.

[stringstretcher]

Then, if you are pressed for perfection,after degassing and pouring you let the silicone harden/cure under pressure, which serves to compress any remaining small air bubbles. The result is smooth and faultless.

[The Ideanator]

Vacuums tend to remove all gases and things with low enough (or was it high?) vapor points from the chamber which means that all the gas in said mold *should* come out, however if you have trapped gases, they will expand (they went in compressed at nearly 15 psi from the vacuum's point of view)

I imagine that if you put a carbonated drink inside there, it would de-carbonate (I'd like to see a video of that, I can't find any)

[Pazzerz]

I know this is OLD, but a carbonated drink is dissolved CO2, like dissolved oxygen in the water that fish breathe. It would probably 'de-carbonate' like you said, but would take a lot longer to do than with just air or CO2 bubbles. FYI

[rimar2000]

This is very interesting. I need one of these for permeate wood with liquids.

Can you put a layout (schema) of the inner of the vacuum aspirator of step 2?

[DaveB13]

I'm off topic for this article. Regarding "permeate wood" is this material I'd stumbled across just yesterday when looking for info regarding a stunning wooden bridge constructed recently ->

Acetylated wood
http://www.accoya.com/technology/
http://www.accoya.com/
Titan Wood Inc.
modified wood by Accsys Technologies
http://www.ufpi.com/product/accoya/index.htm

Brug = Bridge Akkerwinde = name of a road
Sneek = name of a city in the Neatherlands
Brug Akkerwinde
Akkerwinde Sneek
http://www.bsbstaalbouw.nl/bruggen
http://www.achterboscharchitectuur.nl/page.php?id=97
http://nl.wikipedia.org/wiki/Houten_bruggen_bij_Sneek
(for me Google Toolbar can translate Dutch to English)

[rimar2000]

Thanks for this abundant info!

[bassman76jazz]

i bought it at
http://csrscience.ecrater.com/p/11338240/aspirator-with-garden-hose-adapter
you can get it with or without the hose adapter.
there is a detailed description there.

[rimar2000]

Thanks, but I live in Argentina. Maybe it is simply a Venturi tube, very easy to do.

[johnny3h]

I'm no expert, but I've had/used one of these hose end vacuum aspirators since high school chemistry some 53 years ago, and it works exceptionally well.

And to answer your question, YES, it does work on the venturi principle.

In studying mine, it is fabricated to very small and tight tolarances which with 30 to 50 psi water pressure allows me to get a vacuum in the 25 to 28 inch range on my cheap vacuum guage.

If you build it well, one of your own making should also work well.

I noticer in the parts section, that bassman bought some of his components from an outfit called Harbor Freight and Tool, which also has a website and sells online.  Check them out and maybe you can get one without having to build it yourself.

Harbor Freight has been a mailorder cataloge sales outfit for YEARS, but now has many stores across the USA, and now has added a website.

Much of their product is made in China, thus the relatively lower prices, but I take good care of all my tools and instruments, and get good service life for the price I pay.  Every once in a while I do get "stung" by a defective product, but it's not often, and they usually "make it right."

And NO, I am NOT an employee of Harbor Freight, and my only connection with them is as a retail customer.

[rimar2000]

Thanks for the info.

[askjerry]

I did a bit of searching and found this... it may help you.

http://www.sciencemadness.org/talk/viewthread.php?tid=437&page=2

Jerry

[rimar2000]

Thanks, but I get "Error. The item you requested could not be found."

[askjerry]

I don't know why... I just tried it again and it worked perfectly. Perhaps the server was down when you tried.

I'll try making a link... CLICK HERE

Good Luck,
Jerry

[rimar2000]

Thanks, now works.

[bassman76jazz]

it is similar, and works on the same concept. the one i use has a back flow valve that prevents water from being sucked in when the water pressure is turned off. It also keeps the vacuum in the chamber when the water is shut off. I'm sure you could make on if you wanted to. it just has two small veins that rotate the water form the inlet and a hole behind one of them that draws the air in.

[rf]

The big production with the 6" tube, acrylic and neoprene was to create a vacuum reservoir?

That 6" tube has end caps and all kinds of other fittings waiting at the hardware store to be used with it. One or two end caps and some glue would seem to simplify things quite a bit. Or perhaps I'm missing something. If you want the ends to be removable there are threaded fittings too.

End caps are nice and thick and can be drilled for smaller fittings too.

Just a thought.

[bassman76jazz]

for one i wanted to see into the chamber and the end caps are rounded not flat so its difficult to degases fluids without a flat bottom. i actuality was looking for a pressure cooker at the thrift shop but i did not find one. also the fittings for 6" pvc are about the same price as the acrylic.

[rf]

What you want is a bell jar. They're really not that expensive. You can get a 14-inch diameter bell jar for about the same cost as your materials here. And you can see into it much better.

Not that you didn't learn a lot building yours.

[bassman76jazz]

I got it up to 42cm today while degassing some silicone.

[bassman76jazz]

the max i have been able to reach is 25" or just over 60 cm Hg

[codongolev]

my chemistry teacher had a smaller version of this that attached to the sink. he said he used it to draw liquids out of precipitates when filtering.

[Skipper333333]

Great Instructible!
I wonder where you came up with the vacuume asparater?
It's a venturi that creates the vacuum, the same as a car carburetor, that's how the fuel gets from the bowl into the throat of the carburetor. They sell vacuum generators but the only way I've seen them is compressed air to vacuum.
If you came with on your own your a genius!

Alan Hale
Fluidpower Specialist

[bassman76jazz]

its a common lab tool used for as an easy source of vacuum. I just wanted a cheap vacuum chamber an thought it was worth a shot. it has its limits but its great for hobby use. I'm still testing to see how far it will go. i got to 45cm Hg today.

[heathbar64]

You all confused me for a bit there. I'm used to working in inches Hg, and Y'all are talking cm. 45 cm is only about 18" which aint very good. I did better than that with my rigged air compressor mentioned earlier.

[bassman76jazz]

but i built it with a chamber for less than the price of an air compressor.

[heathbar64]

Sorry, didn't mean for my comment to be critical. I had the old compressor for other purposes. It is a cool project. I think I'll build a smaller one.
I did a little google search for the aspirators and found many of them claimed 28" or 73cm draw with 60 psig.water pressure.

[tmarosites]

Hello bassman,
Have you tried to hook it to a pressure washer?
That should jack it up quick since the draw is based on the water speed.

great tool and instructable

[aholcomb]

The draw is actually based on the vapor pressure of water at the temp of the water stream. The colder the water, the deeper the vacuum possible.

[tmarosites]

Hmmmm, I can see that the colder the water the , the deeper the vacuum possiable because the water is more dense ,like in a carb on a car,  . Now when you add on a turbo charger It increase the air but it also increase the temp so this is why it is best to cool the air , But it is the spead of the air that increase the pull, just as the increase in the water speed should increase the pull on the vacuum much more then the temp.
Could you tell where i am wrong.
Thanks
Terry

[aholcomb]

Pressure certainly does help to a point, but the problem is that when you start getting a decent vacuum formed, the water will actually boil. The water is then in a gas form, and will end up in your vacuum chamber, decreasing the vacuum just like a leak of air would. Keeping the water temperature low makes it take more vacuum to cause the water to turn to a gas.

If you get a really good electric vacuum pump (piston, rotary vane, etc.) and chamber, you can make a cup of water inside the chamber "boil" so much that it freezes. Even at room temperature, water is full of really hot molecules and really cold ones. It's the average of those hot and cold molecules that we call temperature. When you reduce the pressure, there's no air molecules pushing down on the surface of the water anymore, so those hot water molecules are able to leave the surface of the water easier, and the colder ones are left behind...lowering the temperature. Neat :)

There's a bit of info on Wikipedia about aspirators here: http://en.wikipedia.org/wiki/Aspirator