pressure chamber construction

by **missndog** » Wed Feb 28, 2007 2:12 pm

Does anyone have any idea on how to build a pressure chamber, I have heard of chambers being injected with nitrogen? that bring the internal pressure up/ to 2000 psi(?).
Has anyone built a pressure chamber that can be opened to include materials.
I wondered if something like a pressure cooker could be altered to be used as a non heated pressure chamber, and what would I need to increase the interanl pressure, gas's etc.
This is different from a vacuum system because the latter would be internal pressure out, what I would like to build would be interanlized pressure, pressure in... would that be combustion?
Anyone is welcome to respond or please send me an email at missndog@hotmail.com
Thnx for the opportunity to post.
MSD.

by **Freefall** » Wed Feb 28, 2007 2:38 pm

Sure. I could design a pressure chamber, it's not too difficult. Of course, I'd hire a certified welder to build it.

You want it to be opened? Design in some sort of port. Bolt flanges tend to be good for this, but there are other options. It depends on what you want to do.

Sure, a pressure cooker could be modified. Simply replace the wobbler nipple with an appropriate fitting. (OK, so maybe newer pressure cookers don't use wobblers anymore) How much pressure would it hold? I don't know, but I wouldn't want to put 2000 psi in one.

If you're pumping gas in from outside, that's just pressurizing, not combustion.

What exactly is it that you're trying to accomplish?

by **missndog** » Wed Feb 28, 2007 3:57 pm

Hey Thanx for this, well I need a system to inject a very thin resin into organic materials, including very thin stone and weathered shell.
I think that what I would like to accomplish per psi is more like 250 and not above 150 degrees if it's heated. I would need it to have some sort of lid that I could put several items in at a time.
Really I am toatlly "found dumb" on this one so any help that you can offer would be great, what do you think a pressure cooker/ canner can sustain? I am sure that there are manufacturers spec's, but just asking.
Thanx once again. MSD

by **Freefall** » Wed Feb 28, 2007 4:59 pm

I've seen methods to inject resin into porous materials that usually involve vacuum, not pressure.

Place the object in the resin, then place everything in your vacuum chamber. Pump out the air. Your porous object should release bubbles as the air expands. When you've pumped down as far as you can go and the bubbling stops or at least slows considerably, let the air back in. The vacuum inside the objects will draw in the resin, and you won't have to worry about internal stresses due to pressure.

But...
Per USDA standards (From wikipedia, may not be a reliable figure), pressure cookers are typically set to maintain 15 psi above ambient during cooking.
If you must use pressure and you can afford to destroy at least one pressure cooker, I'd suggest that you just get one, modify it with an appropriate fitting, and <b>hydrotest</b> it. It might go to 250 psi, but then again it might not.

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by **missndog** » Thu Mar 01, 2007 1:14 pm

Thanx freefall for the responce; I do know about the vacuum pressure pieces and am in the middle of building one, but pressure is different than vacuum, with the pressure, I'd like it to force out what has been sucked in with the vacuum, often if there is to much adhesive in and not enough of a catalyst (as in a 2 part epoxy) then there will be a leaking effect.
I hope that you can give me some pointers about building a pressure chamber, I'd like to have both a pressure and a vacuum chamber to work with, in time one may cancel out the other in the process but currently I'd like to try and work with both.
Thanx again.
MSD

by **Freefall** » Thu Mar 01, 2007 1:20 pm

OK then...
First question: How big does this pressure vessel need to be?
Second question: Do you know a certified welder?

by **missndog** » Thu Mar 01, 2007 1:53 pm

OKAY!! Cool, well yes I do know a welder certified does that mean a college grad welder if so yes1
First question the the pressure vessel would need to be about 12inches by 12 inches, either square or round, with a port of some sort to get items in and out of the chamber.

by **SpudMonster** » Thu Mar 01, 2007 2:29 pm

You would need someone who is certified by ASME to weld on pressure vesssels.

by **Freefall** » Thu Mar 01, 2007 2:35 pm

Not every college grad welder is certified for pressure vessels.

If a pressure cooker is insufficient, you may want to check out a fabricator that specializes in pressure vessels. This is the first one that turned up on Google.
http://www.buckeyefabricating.com/Produ ... ssels.aspx

The problem is not so much in making the vessel, but in making one that opens wide enough to put stuff into and closing up, working, then opening again within the working time of your epoxy.

Take a look online, find a couple fabricators that specialize in this, and see if they'd be willing to work with you to design a custom vessel. It won't be cheap, but it may be your only option if you want to use more than a few PSI.

by **missndog** » Thu Mar 01, 2007 3:14 pm

Okay back to the pressure canner, can I use a pressure canner, and fit it with a guage where the "wobbler" was, and how would I go about creating pressure inside without increasing the temperature.