vacuum degassing rubber

[Ken_Shea]

There is a reason for ASME certification, tanks under pressure are very dangerous. I saw pictures of a pressure tank that was at 110psi, it was used for pressure casting bricks. The door failed and it leveled the brick building it was in, e.g. blew the roof off and walls down. The tank shot out of the building like a cannon ball and blasted through the side of a school 200 yards away.

110 PSI huh ? , Well I do not use any pressure pots but I would have to see the above to believe it, perhaps it was a leaking 500 pound propane tank with a 110 PSI

[HuFlungDung]

Ken,

Maybe it had a significant volume. A big tank would make quite a pop!

[ESjaavik]

I got my pumps from a couple of old photocopy setups. The ones they had before the scanners entered the market. If you have a printshop in your area that did not throw out their old spares, they may still have one. For sure they don't have any use for it. So if you find one, it's going to be cheap.

They are also used in the woodwoking industry for laminating. But those are your "competitors", so no use in asking there for anything in good condition.

[CNCPlastic]

Back when I was "thinking" of fashioning my own pressure vessel for pressure casting someone sent me a link to the pics, that scared me right out of building my own. I can't find it but the building was destroyed, just a pile of bricks left. This was a very large tank, they shoved pallets of bricks into it for curing under pressure.

I did a google though and found some smaller explosive examples...

Check out what this little 5 gallon water heater did to a school when it blew

A video store water heater blew and landed 460 feet away blowing out the front of 3 stores

This guy got the bright idea of converting his old water heater tank to an air compressor, it raised the roof, blew out the walls, and the roof collapsed back onto the pile of rubble. (no pics)

Lifted the roof off the house and blew out the walls with a water heater tank

[Ken_Shea]

The 5 gal heater incident was quite impressive, but also noticed that is was extreme pressure built up from boiling temperatures held under control because of the pressure but when it let loose, boom.

Not to make light of what pressure can do, it can be seriously deadly, your warnings are well justified.

[flannman]

Hi guys.

I have used an old fridge motor as a vacuum pump with great success but it does take time. If you coupled it to a reservoir and left all the air get out of it before you mix and degass your rubber it could be a very cheap way of doing it. This however depends on the quantity you want to degass at a time. Hope this helps

Lee

[MadMax]

Careful with lexan windows for pressure casting various resins. Lexan is sensitive to some chemicals which make it less prone to crazing. Definitely bad for something you depend on being tough.

It sounds like you're not planning on pressure casting. There are vacuum venturi devices for compressed air lines which draw a pretty hard vacuum. You will need a decent sized compressor, not a dinky 1gal type portable comp. I've used a similar device to this for silicone rubber casting.

http://www.wicksaircraft.com/catalog...php/subid=654/

Works nice, but the combined shriek of the vacuum generator and comp' can get annoying.

[ookpic]

Depending on how serious of a degassing chamber you want you..

I was able to make a degassing vacuum by poking a hole in the top of a mason major and simply sucking out the air with a brake bleeder i was able to pull a max of 27 in of mercury just enough to degass my HS III silicone

it cant boil water but it seemed sufficient for removing bubbles from the silicone. I was able to set it up in literally one minute and for only $22