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Oxygen Free Keg to Keg Transfers

Even though are many resources across the web describing the so-called "oxygen free" transfer, I thought it would be worth having a post that details keg to keg transfers.



The real question here is "For small batch brewing (2-3 Gallons) is it really necessary to transfer to a serving keg after cold crash but before carbonation?"


If you answer Yes, you would assume that:

  • Yeast will affect the beer on trub, giving a bready or yeasty flavor

  • Yeast autolysis will occur, causing a burnt rubber flavor

  • Your beer will be more clear when you transfer off trub

  • It's more work to transfer over to serving keg

  • You will use far more CO2 and need to refill your tanks more frequently

  • There is a risk of O2 pickup in the transfer


If you answer No, you would assume that:

  • Brulosophy and others have reported no sensory differences between the 2 methods on a Kolsch experiment

  • New products from Clawhammer and others offer floating dip tubes and serving off 1 vessel

  • I have done it this way for years and my beer gets completely clear given time

  • I am lazy perhaps and want to enjoy the hobby as much as possible

  • Anecdotal Evidence: Most of my beers look and taste great, at least for the top 1/2 of the keg

  • I will admit to perhaps picking up a yeasty character as the beer level gets near the trub


I keep talking about it but I need to actually try to replicate the Brulosophy experiment they did on a Kolsch. I need to brew 5 gallons then split the batch, finish out fermentation then transfer one to a serving keg & leave the other in the same keg. Then cold crash and carbonate and start sampling each beer over time. Coming soon, I'm thinking German Pilsner


So here are the steps to make a keg to keg transfer as oxygen free as possible:


A keg-to-keg oxygen-free transfer moves beer or cider between two soda kegs using a closed loop that pushes out oxygen with sanitizer and CO2.


Equipment Needed

  • Two Corny Kegs: One source keg (filled with beer) and one destination keg.

  • CO2 Tank and Regulator: To purge and apply low pressure.

  • Jumper Liquid Line: Beverage tubing with liquid ball-lock disconnects on both ends.

  • Gas Jumper Line: Gas tubing with gas ball-lock disconnects (or a spunding valve/blowoff setup).

  • Sanitizer: Food-grade, no-rinse sanitizer like Star San.


Step-by-Step Transfer Process

  • Sanitize and Purge the Destination Keg

  • Completely fill the receiving keg with a mixture of water and no-rinse sanitizer.

  • Seal the lid and pressurize the keg with CO2 (around 10–12 PSI).Use the CO2 to push all the liquid out through the "Out" post into a bucket. This liquid displacement method leaves the keg entirely filled with pure CO2, which is more effective than just flushing air.


Connect the Closed Loop

  • Connect your liquid jumper line to the "Out" post of the full source keg and the "Out" post of the empty, purged destination keg.

  • Connect a gas line from the "In" post of the source keg to the "In" post of the destination keg. This allows displaced CO2 to flow back and forth, equalizing pressure without letting in room air.


Initiate the Transfer

  • Elevate the source keg or apply very low CO2 pressure (1 to 3 PSI max) to the gas-in post of the source keg to start the flow.

  • Monitor the transfer using a digital scale or by listening/feeling for the liquid flow.

  • Vent a tiny amount of gas from the destination keg's PRV (Pressure Relief Valve) if the flow slows down, keeping the system closed.


Finalize

  • Once the transfer finishes, disconnect the ball locks.



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