Once fully conditioned and carbonated, the beer is transferred from the conditioning tank to the serving tank. Cornie kegs will do just fine but the tube in the conditioning tank should be about 1 – 1.5 cm shorter than in the serving tank, for the simple reason not to pick up any sediment from the bottom. This is effectively like racking under counter-pressure where the fully matured beer is transferred without running into danger of oxygenation.
Umdrücken is a bit hard to translate. Literally translated it means “pressing into” which describes the process succinctly.
And here is how it’s done:
- The target vessel is (naturally) sanitised
- Any Oxygen is purged from the target vessel
- The “Spundungsapparat” (pressure valve with manometer) is connected to the CO2 inlet of the target vessel and the valve calibrated to release any excess pressure above the pressure in the source vessel
- Pressure in the target vessel is set to the same as in the source vessel
- Pressure of the CO2 bottle is set to the same pressure as both vessels
- Both vessels are connected. Target vessel first!
- Then the pressure of the CO2 bottle is opened to a value of 0.1Bar above the pressure of both vessels
- Beer will start flowing a bit now… by slowly opening the valve in the target vessel more beer starts flowing without foaming
It’s pretty much like a counter-pressure filler works. I like it because it makes it easy to work in a clean environment with little danger of contaminating the beer. After that long wait, it’s the last thing I want!