Here's my latest:
And a closeup:
I was looking for a way to add things to the fermenter with zero oxygen exposure. Basically, it's a 3" Butterfly valve that sits directly on top of the chronical. On top of the valve is a 3" TC Tee, with a gas in post on the side and the normal blowoff/prv fitting on top. The short blowoff tube goes to a quick disconnect and then to a ball valve attached to the underside of the shelf above the fermenter so I can completely close everything off. From the ball valve, I go to another quick disconnect, which I then run to the liquid out of a purged keg that I'll eventually rack the beer to.
During fermentation, the big butterfly valve is open and fermentation gasses go out the blowoff, into the keg and then out the gas post of the keg to a pitcher of sanitizer. This fully (or as close as possible) purges my keg for closed transfer later. When fermentation is over, I remove the keg from the loop.
If I want to add anything to the fermenter, I:
1. Close the butterfly valve and the ball valve.
2. Hook up co2 at about 1-2 psi to the gas post on the side.
3. Have my addition ready and remove the top.
4. While the top is off, the positive pressure of co2 should keep the mixing of gasses inside the chamber, which is already all co2 from the fermentation, to a minimum.
5. Add whatever it is, quickly close the top.
6. Purge the chamber multiple times with the attached co2, using the prv on top to vent.
7. Open the butterfly valve and it drops in.
8. Make sure there's a little positive pressure in the fermenter before I open the ball valve so I don't suck back from the sanitizer.
I've used it to dry hop, add gelatin, etc. Can also use it to add some positive co2 pressure when cold crashing. Works awesome.
Dan
