Monday 3 May 2021

How to do an Oxygen Free Pressure Transfer to Keg

One of the biggest benefits of fermenting in a closed/pressurised vessel such as the Fermzilla is the ability to eliminate the introduction of oxygen into the fermented beer - during fermentation and during packaging/transferring. 

It is well known that oxygen is the arch nemesis of beer - and is responsible for creating off flavours likened to wet cardboard or sherry like tastes in the event of your beer being exposed to oxygen. It's certainly something I've experienced in my previously bottled beers after more than a couple of weeks in storage. 

Now that I've moved from bottling to kegging my beers, I wanted to document the process used to transfer the fermented beer from the fermenter to the keg using a closed transfer method which eliminates exposure to air/oxygen.

  1. Make sure your keg is cleaned, sanitised and pre-pressurised with 10psi of CO2.

  2. Pressurise the fermenter with 10psi of CO2 as well. You can equalise the pressure between the vessels by connecting a gas to gas connection from the fermenter gas post to the keg gas post (but disconnect this when done and continue with the instructions below).

  3. Leave the pressure on your CO2 bottle regulator to 10psi with the gas open/on.

  4. Connect your liquid/gas lines as outlined below (refer to diagram for corresponding numbers)
    * CO2 gas cylinder/regulator (1) to gas input of fermenter (2)
    * Liquid Out of fermenter (3) to Liquid Out post on keg (4)
    * Spunding valve (fully closed) connected to Gas In post on keg (5)

  5. Begin slowly unwinding the adjustment on the spunding valve until you can hear gas escaping. The transfer of beer should now be underway.

  6. The process can be quite slow - but hey, what's the hurry? Taking it slow will help to reduce foaming in the keg. 

  7. If your keg is at room temperature (or at least warmer than the beer being transferred into it) - you should be able to see frost forming on the outside of the keg showing the current fill level - see item 6 in the photo above.

  8. You can speed up the process if necessary by further reducing the pressure in the keg (by pulling the pressure release valve or opening the spunding valve further).

  9. To stop the process, disconnect the liquid line between the keg and the fermenter.

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