In the reaction vessels I see that they are closed and have no entry for air. With a vacuum regulator you could control the pressure if the reaction is weak to prevent shattering the reaction vessels but if the reaction is strong (eg atomized materials) how would you control it? The gasses would either push the conical stoppers and leaking starts. I would assume the operator has everything controlled somewhat somehow.
The reactor is not closed, the top of the condenser is open to the exhaust ductwork and I have never seen too much pressure build up to pop out the glass stoppers. When processing reactive material with high surface area, the rate of the reaction is controlled by the rate of chemical addition or the feed of the material. One of the benefits of a spherical vessel is as a reaction rises the shape seems to push the rising foam into the center and knock itself down. Of course if you overdo it you can overflow any vessel. These reactors are never filled more than 60% of capacity, so a 12 liter flask will never be filled with more than 7 liters of acid, really not too heavy to manually handle. They even make a 5 liter vessel that takes the same heads, that is lighter and I usually use them for platinum stone removal lots.
The airflow out of these reactors through the condenser is quite low and if you vent it by loosening a glass stopper the flow will increase. If you come in to your shop in the morning after a reaction was run the night before, the fume will be visible in the vessel and the connection to the condenser because there is very little fume escaping even though the condenser is open to the vent. By removing the top glass stopper, the airflow immediately evacuates all of the fume up through the condenser.
How about using PP filter cartridges for AR liquids?
I am not a big fan of poly wound cartridges, they are difficult to rinse free of values and by their very nature they are contained in an opaque cylinder so you cannot keep an eye on the filtration surface. To recover any values they must be incinerated and the ash processed. And they do not exactly burn with a clean smoke free stack.
How about stirrers? I believe the best reaction vessel should have its contents agitated without breaking the actual vessel.
I have used these vessels extensively for karat gold refining and stone removal. With karat gold I always made sure the silver content was as low as possible, never above 9%. This will allow the acid to react and minimize gold trapped in the chlorides without stirring.
As far as diamond removal, never stir the reaction. When I first started doing stone removal chemically, in the early 1980's, I thought stirring would be good. It actually makes good sense because you cannot control the assay so some pieces will have in excess of 9% silver. I learned the hard way that stirring causes the material to move about against the glass. With diamonds this meant they scrape against the glass and scratch it. This weakens the glass and eventually you pick up the vessel and the bottom piece, in the shape of a large watch glass, breaks out. Really quite the mess, destroys the mantle, gold recovery is a nightmare, not something you want to experience.
Processing jewelers sweeps in aqua regia would benefit from a stirrer but I prefer to process sweeps in a titanium bucket and stir with a stir rod.
