Thursday, May 20, 2010

Transferring Your Homebrew via CO2

We made a major improvement to our home brewery last night, one that Mr Wort Hog's been bugging me about for a while. If you've ever had to transfer beer from a carboy to another container, you know what a pain in the ass it can be. We've tried it all - blowing on one end of the carboy cap (too germy), creating a siphon by filling the tubing with StarSan (fails regularly), creating suction by using a turkey baster at the output end of the tubing (rarely works), and squeezing the carboy to create pressure (never got that one to work). The whole carboy + racking cane/carboy cap/tubing assembly was frustrating to no end. And an auto-siphon just introduces too much oxygen to the process, so it's not even a participant.

Enter CO2 transfer.

Mr Wort Hog found some information on the Maltose Falcons website and sent me a link back in, uh, January? I finally took the time to order the parts online and we assembled & used it last night. The verdict? Best way to transfer beer. Ever.

The basic hookup goes like this: Connect a CO2 tank to the carboy containing the fermented beer, which pushes the beer through a racking cane and some beer line. The beer line is hooked up to the keg through a flare fitting, going in through the "out" beer line dip tube and into the keg. The benefits to this are multiple, but the greatest improvement is the introduction of a completely closed transfer - and CO2 purging of the lines. That is, there's no introduction of oxygen (or mouth-based germs) to the transfer. Let's take a look.

CO2 tank > gas line > carboy cap > carboy > racking cane > beer line > flare fitting > keg

From the CO2 tank, we've got a male/female quick disconnect from the regulator to the carboy cap. In the picture below, the keg is to the lower right (yes, that's the regulator peeking out there) and a freezer containing the carboy on the left. And a roll of paper towels lurking in the background.

The gas line then goes into the carboy: A 1/4" flare-to-barb fitting goes into the small little outlet on the carboy cap and a 1/4" nut & 5/16" barb fitting connects that to the gas line. In other words, shove the 1/4" fitting into the carboy cap and the nut fitting into the end of the gas line then screw them together. Here, we have the nut fitting in the gas line secured by a worm clamp. Click on the picture to see a much better picture of the detail.
A racking cane goes through the main opening in the carboy cap (this can take a little smooth talking and cajoling) and connects to beer line. I got the wrong size beer line (it doesn't fit onto the racking cane), so we used a bit of 3/8" ID silicone tubing and a worm clamp to ensure a tight transfer. Hey, it works.

That beer line, then, goes to the keg. The other end of the beer line has a barb quick disconnect that goes to the OUT line on the keg. That's it.

So before the transfer, fill the keg with CO2 and assemble the liquid end (racking cane, carboy cap, beer line, keg disconnect) with sanitizer. Purge some of the CO2 from the keg just to get a bunch of it out of there, then hook the assembly up to the keg before putting it in the carboy, and this will cause the CO2 in the keg to exit via the assembly. You've just purged your liquid lines with CO2.

Put the liquid assembly onto the carboy and turn on the CO2 to about 3psi. This will push the beer back through the liquid assembly and into the keg.

A few minutes later, you've got all your beer in your keg and have minimized its exposure to oxidation.

Sounds like a lot of work, I guess, but I assure you it is FAR less work and MUCH more sanitary (and O2-free) than other transfer methods. I only wish I'd ordered the parts a lot longer ago...


  1. That maltose falcons site is great. I've been considering this as well for transfers and glad to hear that it works so well!

  2. Great write-up. I used a bit of keg lube to get the racking cane and the barb fitting in the carboy cap. It made it MUCH easier than my previous attempt


Tasting Notes