I've been fermenting in sanke kegs (1/4 and 1/2 barrel) for about 5 years now. There is no need to buy any special equipment to convert anything, at least I don't.
Pull the spear, clean, boil water to sanitize (I put the spear through the retaining ring and set on top and allow steam to hit all of that as it blows out), fill, pitch yeast, put the spear back in and seal back up with the retaining ring. I cut the bottom 1/2" or so off the spear which gives me clearer beer immediately when racking and leaves a little liquid behind for yeast harvest.
Take any sanke coupler you like and remove the check valve from the gas side. Run a tube from the gas side into a cup or bowl or whatever of star-san. On the liquid (top) side I just put a nickel inside a beer nut and gasket and seal up. As your beer ferments nothing will escape via the liquid side and CO2 will blow out the gas side.
When you are near terminal gravity just pop the coupler off bunging the keg and getting a little free CO2 into your beer.
Closed transfers are great! Hook your gas in and run the liquid out to your corney keg. I use a mail flare tailpiece on the liquid side and just screw on my liquid line. Gas on, engage the coupler and watch the beer flow. When complete vent off CO2, pull the spear, harvest yeast (just dump into a funnel going into whatever container you like).
- Fully closed transfers. My beers never touch oxygen (I fill the corny with star-san and then purge with CO2.)
- Some free CO2 to prime your beer, plus I find it helps drive yeast to the bottom of the fermenter. Clearer beer, more yeast to harvest.
- No glass (break). No plastic (scratch). No light.
- sanitize by boiling and steam. Never a question if star-san was mixed properly or touched everything or whatever.
- Far cheaper than conicals and any fancy engineered keg-mentor type products.
- Difficult access to beer as it ferments. You can hook things up and push out some beer mid-ferment to test but I prefer to just let everything be. Less chance of infection. It helps to have some "feel" as to when your beer is nearly done. I find experience helpful here. Worst case....bung a little early and check it daily. If you have a ton of CO2 blowing off then just keep degassing until you're comfortable.
- More difficult to clean then fermenters you can get your arm and eyes into, but it isn't that much more difficult after doing it a while. There is a product called The Carboy Cleaner (you buy the keg version of this) that goes on the end of a drill and you can spin around inside the keg. Works really well, but I've stopped using it the past couple years. I find I can clean everything off with hot water and a carboy brush. And again, if I missed a tiny bit of something all that steam destroys it.
If you have any questions or want photos feel free to inquire.
I built a spunding valve but have yet to use it. Just hook it up to that gas out.
Edited by TAPPER, 17 July 2019 - 07:29 PM.