Vacuum Chamber

A rigid enclosure from which air and other gases are removed by a vacuum pump.

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Details on the construction and use of three different size vacuum chambers and related pumps. A vacuum chamber is a very handy tool to have. It is also quite simple to construct and you can save a lot of money if you build it yourself. Many parts of these chambers were left over from other projects, but could easily be sourced if you are not so lucky.

I built these chambers to vacuum de-gas epoxy and resin. But you can easily adapt this design for other uses as well.

The construction of a vacuum chamber is quite simple. I suspect that most people could easily design and build one with little or no instructions. However, I will document the three which I have experience with and perhaps it will be helpful to someone.

All three of these vacuum chambers are built from PVC pipe. The smallest and largest are made from a PVC pipe coupler. This is a short section of over sided PVC pipe, used to join two normal pieces of PVC pipe. The advantage of these are that they are cheap and easy to fine. Both ends are also very smooth and do not require any special machining. The middle size is made from a section of PVC pipe. It was cut to length, but the edges were not very smooth. A rough edge will make it impossible to get a tight seal. I am fortunate enough to have access to a metal lathe, so I was able to turn the ends and make them very smooth. The dark gray chambers are CPVC, which is stronger, but honestly for this application plain PVC will be fine. Any thick walled rigid cylinder with smooth edges will work.

Once you have your section of PVC, the next step is to attach your fittings and gauges. There are many options you can choose from, but this is the standard method I use. One tee fitting will have the vacuum guage, and connect to a second tee fitting. The second tee fitting will have a ball valve on either side. One of these ball valves will be capable of connecting to your vacuum pump.

Depending on the vacuum pump which you are using you will need to determine which fitting will match. Many vacuum pumps come with fittings used for replacing refrigerants such as R12 or R134a. It took me a while to figure out these were called 'Flare Fittings', but once I found the name it was easy to find fittings for it. The smallest of my vacuum pumps uses a barb fitting and clear hose, my middle size pump uses a 1/4" Male Flare Fitting, and the largest pump uses a 3/8" Male Flare Fitting. So be sure you find the one that works best for you.

I build the middle size chamber last and had some spare fittings. So I chose to put a 1/4" male flare fitting on one side, and a 3/8" male flare fitting on the other side. This way I could use either pump I wanted with this chamber. I thought it was a smart idea.

The basic idea is you will hook your pump up to one side of this assembly. Open the ball valve closest to the pump, close the other ball valve and turn on the pump. This will draw the air out of the chamber and your gauge will read the vacuum. When you are finished you can open the second ball valve to let back in.

I recommend assembling all of the hardware before attaching it to your PVC pipe. It is a little easier to work with and the PCV is the weakest connection. So you don't want to stress it by trying to tighten all the fittings. Use Teflon tape, or pipe dope to get a good seal. Then drill a hole in the PVC and tap it. For my setup I used a 1/4" male pipe tap. You can get it at the hardware store. Be sure you drill the hole in your PVC pipe in a place where the gauge will not stick up above the edge of the pipe, and the ball valves can be opened without hitting anything.

Make sure you get a vacuum gauge and not a pressure gauge. 29.92 inches of mercury (in Hg) is a perfect vacuum, at sea level. But depending on where you are at it could be slightly different. The higher in altitude you live the less atmospheric pressure there is, which will change the value for a perfect vacuum. Where I live has an altitude of 1365 feet, so my max vacuum reading is about 28.86.

Next you will need a way to seal the top and bottom of the chamber For this you really just need any flat and smooth surface and some rubber mat. I used acrylic sheet. Keep in mind that the larger the pipe you use, the thicker you will want the acrylic to be. I used 1/4" thick for the 3" diameter chamber, 3/8" thick for the 6" diameter chamber, and 1/2" for the 12" diameter chamber. Place one sheet of acrylic on the table, lay the rubber mat on top of...

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  • 1 × Vacuum Gauge
  • 2 × Tee Fitting
  • 2 × Ball balve
  • 1 × NPT x 1/4 Male Flare Fitting

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  • Vacuum Pump Comparison

    jupdyke12/12/2015 at 03:10 0 comments

    In the past year I have been using three different vacuum chambers and three different vacuum pumps. I thought I would give a little comparison.


    I only used this one a few times. It is quite small. 4" diameter PVC coupler I believe. The vacuum pump is an Air Cadet Model 420-1901. It is a single stage pump and does not quite pull a full vacuum. I was getting about 26 inches of mercury.


    This one is the one that I have been using most of the time. A coworker of mine built this a few years ago and my work has used it ever since. The pump is a Robinair VacuMaster 2 Stage Pump, Model 15500, 5 CFM. This pump works great. It is very powerful and 5 CFM is very fast. Even with this 12" diameter vacuum chamber it only takes a little over a minute to get to full vacuum. One thing I will say about this pump is that it is quite heavy and costs over $200.

    Baby Bear

    I named this vacuum chamber baby bear because the first one was too small, and the second one was too big. This one is just right. Actually, the other two were not my to own and I was tired of borrowing them from my work. I was having to carry the Big Boy back and forth from work. UGH.

    The pump is a Pittsburgh Tools, 3 CFM two stage pump. I got this from harbor freight. It is a little smaller pump than the RobinAir so it would take longer to pull a vacuum on the same size chamber. But since this chamber is smaller than the other one it actually takes less time to reach full vacuum.

    The only think I don't like about this pump is that it make some oil vapor. I have only used it a few times so far and at first I thought something must be wrong. I did a little research and is sounds like all oil vacuum pumps do this. But the RobinAir vacuum pump does not seem to do this. I read that these pumps tend to make more vapor when they are brand new. I will post an update after I use it for a little bit. Anyone have experience with this?

    Here is a link to a video of someone else's pump doing the same thing.

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