Instructables
Picture of 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.
 
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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


Step 4: Neopreen gaskets

use the top and bottom pieces to trace around with a knife to cut out the neoprene.
find the center and then cut out the center circle by hand.

Step 5: Make the conections

drill tow hole just a little bit smaller than the fittings (the vacuum gauge came with a bunch of extra fittings)
heat up the fitings with a soldering iroen and scre them in. when they cool down take them out and wrap with plumbers tape and reinsert them.
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en2oh16 hours ago

nice instructable just one question. How can a vacuum aspirator using water as the working fluid generate a pressure of 30cm of water? If I recall correctly, the limit for that type of pump is the vapor pressure of water at any given temperature I.e. The pressure where water boils at the temperature the pump is operating at. At 25 deg C, that's about 24torr or 24mm Hg. 30cm of water is about 22mmHg wouldn't your water start to boil at 24 mm Hg? You could cool the water some, but this is a practical limit to a vacuum aspirator

nsalling2 days ago

I really like your Vacuum chamber, it was really cool. I do have a small question: I found a pressure sprayer (one like this: http://tinyurl.com/onke786 ) and got the idear that i could make it into a vacuum, chamber. Do you think that is possible?

KDS444410 months ago

Um... What about the "pump" part? You showed several brass attachments and you mention a garden hose, but there's no pump here anywhere or am I missing something? Because a vacuum chamber without a pump is just a pretty tube.

bassman76jazz (author)  KDS44449 months ago
that is the pump. it uses the a garden hose to pull vacuum.

I don't seem to understand where the garden hose attaches or how it draws the vacuum. You have laid out all of the parts of your vacuum chamber, but I don't grasp what "mechanism" is actually "pumping" the air out of it (you say this is a garden hose, and I believe you, but I don't know how to attach one to this to cause it to draw a vacuum).

Hieu KDS44445 months ago

So you are not understanding the definition of "aspirator" then as Bassman pointed out. The garden hose attach to the end he cut and hose clamped the aspirator to the chamber.

From the physics of things as they are presented here -- the water running draws the air away from the that tube he made air-tight creating a vacuum chamber. A vacuum pump is just something that draws out all the air/fluid from whatever space you need to be left completely devoid of air/fluid. So he did in fact create a vacuum chamber and pump as he stated in his title. If you still don't believe this you can just look at the vacuum gauge and see for yourself if you build one.

A little physics lesson if you still need explanation. As the water rushes out of the garden hose and pass by the tube he created it draws air away from it. As no air can enter the chamber, ultimately the chamber will be left completely empty of air.

So water rushing by the chamber is THE PUMP.

aspirator-definition.png
KDS4444 Hieu1 month ago

I am understanding better, but why does the pump not just start to fill with the water? What keeps the water from filling the vacuum created as it sucks out the air?

There is no pump.There is only a water hose (e.g. a garden hose) with water running through it. Into this hose, another hose has been attached, and this hose goes to the vacuum chamber. The connection of the hoses is shown in the 1st picture in "Step 2: The vacuume asparater". The thin pipe outlet is for the hose that goes to the vacuum chamber, and the water runs through the thicker pipe (direction does not matter).

As water running through the pipe will draw fluid (gas and liquid) from the connected, thinner pipe, a vacuum starts to build into the vacuum chamber. This is known as the Bernoulli principle / the Venturi effect. (Both dudes made huge contributions to the field of fluid dynamics, and I am so waster ATM that I cannot remember which one dealt more with this phenomenon...)

You can see this effect in real life, for example, if you have access to a (small) motor boat that has a (corked) hole on the bottom (to drain out rainwater): Get some water into the boat, go for a ride and when the boat is moving at a decent speed, pull out the cork. The water in the boat will get drawn out, and after it's all gone, air will get sucked through the hole (not that you will notice it).

You either have to run the water as long as you wish to have the vacuum, or install a valve into the vacuum chamber hose and close it when you have reached the maximum vacuum (recommended).

Nevertheless, as I wrote earlier, if you by any means can scrape together the 60USD that a vacuum pump costs, do not even consider this water thing. You would need a 'weapons grade' water pump to get enough vacuum for e.g. stabilizing wood.

BruceC2 Hieu1 month ago

Nice explanation, but kind of an assholish and snarky tone.

bassman76jazz (author)  KDS44448 months ago
http://en.m.wikipedia.org/wiki/Aspirator_(pump)
RyanG1820 days ago

if you used a 1/2 or 1/3hp submersible pump, you could connect it up to that and get crazy water pressure (much, much higher then you can get from a garden hose) - and you could recycle the liquid back into the same water basin you are drawing from - so it'd be a closed system with the power source being the electricity powering the submersible pump

That is true. I reckon a pressure washer would work also nicely. However, the pressure itself does not matter, only the flow rate of the fluid. Thus, you obviously want to make the water hose as short as possible and/or have a large diameter that reduces only just around where the air tube is connected.

Then again, as you can buy a Chinese low-quality vacuum pump for, what, 50-60USD, nowadays, I wouldn't really even consider anything that uses the Bernoulli principle / Venturi effect. Unless, of course, if you have no electricity available. Otherwise, an electrical pump is the way to go: better vacuum, no worries about the water (easy to use indoors), less electricity consumed as with a water pump, etc.

nice kids !…
bassman76jazz (author)  vincent75201 year ago
thanks...
rf3 years ago
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 (author)  rf3 years ago
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.
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.

You guys need to be careful when pulling a vacuum on a piece of glass. I managed to avoid the shards when the lid, a piece of 8mm thick glass exploded and flew all over the room. I learned a lesson that day :) Keep the pressures down to safe levels and let time do its part.
rimar20003 years ago
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?
bassman76jazz (author)  rimar20003 years ago
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.
2011-07-08 15.11.53.jpg2011-07-08 15.17.30.jpg
Thanks, but I live in Argentina. Maybe it is simply a Venturi tube, very easy to do.
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
Wow, I have some old french horn mouthpieces that would make a perfect venturi tube like this! That is what they are, in fact, since they are most often a small bore opening up into a larger bore, increasing the airspeed through the venturi principle.
Thanks, but I get "Error. The item you requested could not be found."
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
Thanks, now works.

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.

Thanks for the info.
bassman76jazz (author)  rimar20003 years ago
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.
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)
Thanks for this abundant info!
Hmm.... I wonder if this could be used to construct a home food freeze drying device.
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.
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?
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.
heathbar643 years ago
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?
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)
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
bassman76jazz (author)  heathbar643 years ago
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.
Ok, thanks for the education. I'm into molding stuff so I'm definitely gonna play with this.
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