Vacuum chambers

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benniejordaan

Sealiner
I want to build a vacuum chamber and have a design that will work but I was wondering if you guys have any "simple" solutions.

Here is my idea:
I will use 2 pneumatic cylinders, one powered by air via a hand valve and the stroke governed by 2 pneumatic limit switches and a 5 port/2 way pneumatic valve. That should cause the cylinder to move back and forth at a high speed. This cylinder's shaft is connected to a second cylinder's shaft (shafts connected together). The second cylinder, I'll turn the seals around so the cylinder now works on vacuum. Then the 2 ports are connected to the chamber with 2 one way valves on each line. When the cylinder draws air it pulls from the chamber and when it expels air it pushes it to atmosphere. This stroke happens 2 times per cycle. when one draws, the other end expels. I should be able to draw a vacuum oposite to my air pressure. 6 bar in -6bar in the chamber.

The chamber is just too easy.

Does it make sense?
Is -6 bar enough?

Cheers
B
 
A

AndriesH

Sealiner
Time is your other factor.
If you need a fast vacuum time, connect your compressor to a "storage" cylinder, like a vented 48kg LPG or similar via a T piece and let it run for a while.
Once the vacuum is drawn in the cylinder, connect to your product chamber and open the inline valve, and whooosh - emptiness.
 
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benniejordaan

Sealiner
AndriesH wrote:
Atmosphere is only 1 bar, so at most you can draw that out of the chamber.
Click to expand...
Hey bud,
I'm not a Scientist but here is the scenario. I want to pull air bubbles out of liquid silicone. What you think is the simplest way to achieve this? I got a quote for a chamber... R10k. The pneumatic version will cost around R1500.
 
B

benniejordaan

Sealiner
AndriesH wrote:
Time is your other factor.
If you need a fast vacuum time, connect your compressor to a "storage" cylinder, like a vented 48kg LPG or similar via a T piece and let it run for a while.
Once the vacuum is drawn in the cylinder, connect to your product chamber and open the inline valve, and whooosh - emptiness.
Click to expand...
:fbash

I got time, probably 20 min. But the vacuum must be sufficient.
 
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PH

Senior Member
I've got a fridge vac pump for eactly the same reason. Have'nt used it yet. It is said to remove pressure to only.05 of atmosfeer. Bennie if you want to try it out for a cpouple of days, your welcome
 
A

AndriesH

Sealiner
I'll find some supporting info and post it for you.

You need your rtv in a strong pot - like a steampot that will not collapse at 1 bar pressure. (When you draw vacuum inside, the outside feels the 1 bar atmospheric pressure from outside)

If you can make a bolt on perspex lid, say 30mm thick and clamp it on, like those big 25 liter spray pots with G-clamps, you can see the bubbles coming off the silicone.

Then just find a pressure / vacuum level at which you are satisfied that the bubbles have been sufficiently removed.
 
B

benniejordaan

Sealiner
PH wrote:
I've got a fridge vac pump for eactly the same reason. Have'nt used it yet. It is said to remove pressure to only.05 of atmosfeer. Bennie if you want to try it out for a cpouple of days, your welcome
Click to expand...
^^..^^..
And if in the event it does, how much do they cost and where can I get one?
 
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PH

Senior Member
Got it for free from a contact who is in the water purification business. I'll find out.
 
A

AndriesH

Sealiner
Hand operated unit - it explains the principle
http://www.donjarrs-place.com/07-how-to-vacpot
(Taken from some SFX dude's website)
 
B

benniejordaan

Sealiner
AndriesH wrote:
I'll find some supporting info and post it for you.

You need your rtv in a strong pot - like a steampot that will not collapse at 1 bar pressure. (When you draw vacuum inside, the outside feels the 1 bar atmospheric pressure from outside)

If you can make a bolt on perspex lid, say 30mm thick and clamp it on, like those big 25 liter spray pots with G-clamps, you can see the bubbles coming off the silicone.

Then just find a pressure / vacuum level at which you are satisfied that the bubbles have been sufficiently removed.
Click to expand...
Got that part down, I will make a "pot" and fit the top with an "O" ring. no need for clamps really as it is under vacuum and will pull the lid down. I have tons of 325mm X 6mm wall piping here. Weld a bottom and a ring for the top. Machine a groove for the "O" ring and bobs your auntie.
 
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