Thanks to Brian's build, I have been brainstorming this thing all morning. The idea of a slide valve is intriguing.
What we want is a 3-way valve, and not just any 3-way, we want a mixing valve. Most 3-way ball valves and similar are selector, rather than mixing valves.
Let's say you have a vapor source, and you have two pipes, A and B, to accept the vapor. With a non-mixing valve, you get either 100% to A, or 100% to B. What we want is the ability to route the vapor to both destinations in varying percentages, with "A" being a reflux condenser, and "B" being a collection condenser.
If we close off the reflux condenser, we get a pot still. If we close off the product condenser, we get 100% reflux, exactly as YHB described his setup. Somewhere in-between, we get VM. And if you have a LM portion in there, you can execute LM as well, as Brian did, and which I like. Easy enough to close off the needle valve if you want to, but otherwise, yank the nasty fores off.
Did some modeling. If you take a 2" pipe and bevel it exactly 45 degrees, you get a hemisphere on that end when viewed from above:
Ignore for the moment the oddly shaped slide valve in the above pic. Slide that valve into the body, and when viewed from above, you have a giant gate valve. Seals, gaskets not required or needed. If a couple % vapor leaks past the valve, the reflux condenser takes care of it. And no way to boom - the vapor goes into two open condenser circuits. I'd add a stainless steel guide pin in a slot in the slide valve to prevent rotation.
The body of the valve is where it gets tricky from a fabrication POV. To get a nice sliding fit requires telescoping tubing, and all we have is couplers for 2". The body here is tentatively two ea. 2" couplers, one mounted between a pair of ferrules, the other 90 degrees, soldered into a nice hole bored exactly 1/2 way through the upright portion. The 2" slide valve goes right in. Obviously you have 2" pipe (street ell) turning 90 degrees from the stub in the pics, leading into a product condenser.
From there, it is a matter (as YHB did) to add control to the valve... a threaded Cu bushing soldered dead center on the non-bevel end (using 4 very small Cu tubes as a "spider web" support); a lead-free brass compression fitting would make a nice ferrule for the SS threaded rod on the left side of the upright, packed with PTFE cord. Handle on the rod would be phenolic for heat.
The reflux might have a funky path past the partially closed slide valve, so I'd maybe add a centering ring below the valve, 1" or 1.25" hole in the middle. That would center the reflux and also add velocity and turbulence to the vapors.
What you'd have is a system that (again, thanks to YHB's design) can do it all. Pot, LM, VM.
Edit: Just had a thought... While modeling, I was running into serious issues because the 2" couplers that formed the valve tee were too short. We can make use of the funky plumbing pipe dimensions by ordering stainless tubing for a slide valve. Since type M copper has a 2.009" inner diameter, then 2.000" stainless tube would be perfect. The valve body and tee can be regular 2" copper. It'll make soldering a little more challenging, but with the right flux and technique, it's easy.
I'm going to keep it all 2" to match my product shotgun... by the time I add adapters into it for a smaller valve, I'm at the price of a 2" valve.
YES!! Thank you. I knew I had seen your work there browsing the forum weeks ago, but couldn't remember who did it. I think the concept is brilliant, and it satisfies my lust for fiddly adjustable bling. I hope you don't mind if I copy elements/portions of it, maybe the entire thing? I think it is compact and elegant in both form and function.
