For a while now I’ve wanted to try fermenting a Cornelius keg. There are several things that make the idea attractive; among them closed transfer, easier cleaning, easier handling of a full fermenter, and safety.
I never really got enthusiastic about trying a keg as a fermenter because most advice on the subject suggested cutting an inch or so off of the liquid dip tube to accommodate trub and I was hesitant to permanently alter one of my kegs. Recently, however, I found not one, but two sources for replacement dip tubes so I could revert the keg to normal if I wanted, and decided it was time to try the technique.
I have one keg with a straight dip tube as opposed the the usual curved one you see in most Corny kegs, so I decided to convert that one as my fermenter. Using a tube cutter I removed approximately one inch from the liquid and gas dip tubes, the latter to try and avoid any krausen clogging the port. Using a length of tubing in a growler half full of Star-San as an airlock and I was off and fermenting.
I can hook up gas and use my picnic tapper to easily take gravity samples. To cold crash I can just disconnect the blow off, no worries about sanitizer or oxygen suck back. The keg will fit into my keezer for crashing better and with less effort than my glass fermenter too.
After fermentation is complete I’ll seal my serving keg with some iodophor sanitizer, blow that out with CO2, use the picnic tapper to blow off the trub until the beer is flowing clear, then hook up a line from the liquid post of the fermenter to the liquid post of my serving keg, hook up CO2 at about 3-4 psi, connect a blow off valve I made with some copper tubing and a needle valve to the gas out on the serving keg and close transfer.
Future improvements will be to convert an old tap to connect directly to the keg so I don’t have to clean my picnic tapper beer line after each sample and experimenting with a spunding valve.