Hey guys, I've been working on constructing a pressure vessel.  I went to walmart to see what they had as far as coolers (cylindrical beverage coolers), and came up with the 1/2gal "Bubba keg". 

http://www.recarda.co.uk/images_products/59.jpg
The high points of this were it's manageable volume (~2L), the fact that it only had one hole, instead of a lower pour spout, and it's [relatively] thick construction.

Without modification, other than attaching my brass manifold, I was able to pull almost full vacuum.  The gaskets wouldn't allow it all the way to full, but I'm sure it would have taken that.  However, upon pressurizing, it didn't take more than a couple psi before the plastic threads let loose.  I fiberglassed the outside with one solid layer, and the inside of the lid to seal all holes.  After it dried, I bought 'hanging tape' which is sorta like a roll of sheet metal the width of scotch tape.  I attempted to fasten down the lid with this, but it was clear that this wouldn't work too well immediately after bolting it together.  However, it did hold up to about 10psi with hissing, and at 15psi it blew the lid out enough to let off all the pressure.  Tomorrow I'll run back to the hardware store and see if I can buy 6 of their cheapest smallest C-clamps and see what I can do with that.

The plastic of this should hold up to the solvents I throw in it.  What I am worried about is the fact that stir bars tend to wear holes in the bottom of plastic containers.  I bought a wide mouth container so that if I do notice wear, I can throw a layer of fiberglass on the inside to combat this.  My goal is 100psi without blowing, but it will be kept around 60-90 (4-6atm) for most reactions. 

Anyone have any input or ridicule? Clearly, the greatest flaw in the design is the large surface area of the lid.  This will cause a greater force to be exerted on the sealing surface (and thus more counter-force required to keep it sealed).  However, the convenience of this vessel is enough for me to keep trying.

Why not use a modified fire extinguisher or perhaps some large metal pipes?

I'd go with the pipe, or a pop bottle, they can hold more then 15PSI pressure wise, though I don't know how well the solvents would resist the container and.. vice versa.

If you could find it, you could epoxy in teflon sheet on the inside of the vessel. That would probably eliminate most of the reactivity problems.

This is the type of fire-extinguisher I mentioned in my methylamine thread.  With no sealant on the 4" brass pipe through the neck, it bled off ~15psi over 1.5hr, starting at 60psi.  We'll see how it does now that I've put some epoxy on the pipe.  It's hard to tell, but the black plastic is actually the nozzle of the fire extinguisher, I just sodomized it with a drill and a dremel.  The threads on the tank are no where near standard, so I had to work with what I could.  The tank says it's been tested to 300psi, and fire extinguishers are normally pressurized to 100psi, so I feel completely safe running at sub-100psi pressures. 

To make it, I just disassembled the nozzle portion of the extinguisher, and first jammed a 1/2" drill bit through it.  I would have jammed a 5/8" bit next, but I bought the wrong chuck size, so I just made due with a 5/8" paddle bit (wood boring) and the dremel - worked well enough.  I cut off unnecessary plastic around the top then after some enlarging of the hole, jammed a 3/8" brass pipe through it.  The top, I placed a reducer to 1/4" since that's what my manifold is based off.  The bottom just has a double female 3/8" pipe coupler.  As for the manifold, I would have condensed it more, but no one has 4-way brass adapters at 1/4" so I made due with the 'tee's.  It has a pressure gauge on top, a vacuum take-off preceded by a ball valve, and a standard schrader valve.  For those who don't know, a shrader valve is the type of valve that is used on tires.  I might change this with a quick disconnect type fitting.  That way, I could just set the gas regulator at a certain PSI and leave. 

The beautiful thing about the sodomized black plastic part, is that the threads are all universal on kiddie brand fire extinguishers of similar duty.  If I wanted to upgrade to a larger size, I just have to find an empty fire extinguisher... that or just add the 'empty' adjective to an extinguisher.  The tank volume is ~820ml so a 500ml reaction should leave enough headspace.  Stirring isn't a problem so far, and tomorrow I will be coating the inside with the same rust-proofing polymer that I used on my car floor pans.

It might just be a stirred hydrogenator.  I'll also be using it for catalytic oxidations though, so it's not limited to hydrogen.  As a matter of fact, it's first test will be a catalytic oxidation, I'll likely post results in that one place.

And of course, be sure to tilt it on its side, rather that then the bottom, eh?

Well, bad news.  Under pressurized oxygen, heat, and methanol, the coating managed to soften to the point where the CuCl2 could work its way under.  Fortunately, there was only 5g in the mixture so it didn't dissolve (and thus weaken) the fire extinguisher.  Back to plastics I suppose.

It was POR-15 which I used for my restoration on my car.  I have found a much more suitable vessel.  A reverse osmosis sediment filter canister - rated to 125psi, widemouth lid, polypropylene construction with 3/16" thick walls.  The top already has two 3/4" NPT openings.  I havn't measured the volume yet, but I assume it to be around 1L total.  Right now, my stir bar is too big so it doesn't create a large enough vortex so I'm limited to smaller volumes.

I have considered it, and was going to result to that until I remembered about RO units.  

Good news!
I had my first successful pressurized chemical reaction yesterday.  I'm doing the work-up as I type this.  I will be posting the actual results, so look towards that.  The pressure vessel (RO sediment filter canister) shows no damage or wear from the 9hr run under 60psi and constant stirring.