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After several weeks of patience, your fermentation is finally complete. It’s time to move on to the crucial conditioning stage.
Kegging not only allows you to store large volumes of beer protected from air, but it’s also the starting point for serving your beer on draft at home.
Whether you choose the traditional method or a closed‑loop transfer, discover our practical guide to setting up your equipment.
1. Path 1: Keg refermentation (The simple but limited method)
Just like with bottles or cans, it is entirely possible to naturally referment your beer inside a keg to create carbonation:
- The principle: You transfer your flat beer into your clean, sanitised keg, then add a sugar syrup to reactivate the yeast in a closed environment. This technique works equally well in stainless steel kegs and lightweight PET formats such as Oxebar.
- The dosage (Important!): This is the major difference compared to bottling. In a keg, the headspace and gas‑saturation dynamics require drastically reducing the sugar dose. To avoid uncontrollable foam when serving, it is recommended not to exceed 4 g/L of sugar (compared to the usual 6–7 g/L).
- Why it’s not ideal: Although economical in terms of CO₂, this method takes time and produces a yeast sediment at the bottom of the keg. During the first pours, you’ll get very cloudy glasses. To eliminate this issue and obtain clear beer, forced carbonation remains the best method.
2. Path 2: Forced carbonation (The gold‑standard method)
To avoid sugar and yeast sediment, the professional method consists of saturating the cold beer directly by injecting gas under pressure. This is where your setup becomes essential:
- Basic equipment: The process requires a pressure‑rated, airtight keg such as a stainless steel 19L Soda Keg or an Oxebar model (from 4L to 20L). To inject CO₂, you need a gas cylinder and a CO₂ regulator with gauges to precisely control pressure.
- The golden rule of cold: CO₂ dissolves infinitely better and faster in very cold liquid. Always chill your filled keg in the refrigerator (between 2°C and 3°C) before connecting the gas. At this temperature, a constant pressure of 1 to 1.5 bar for a few days will produce perfect, stable carbonation.
3. Closed‑loop (isobaric) transfer from fermenter to keg
If you have a pressure‑rated fermenter and your beer is already carbonated, transferring it into a keg without losing gas or introducing oxygen is surprisingly easier than bottling. It’s the perfect closed circuit.
The exact list of connectors and tubing required
To connect your fermenter to your keg, here is the precise list of parts you’ll need:
- Fermenter side: 1 Ball Lock Liquid connector (black or yellow) + 1 Ball Lock Gas connector (grey or red).
- Keg side: 1 Ball Lock Liquid connector (black or yellow) + 1 spunding valve or flow stopper (gas side).
- The lines: Rigid tubing such as John Guest or EVA Barrier (recommended diameter 5/16" or 3/8" to limit pressure loss), along with the appropriate Duotight/John Guest fittings to assemble everything cleanly. You will need a “Liquid” line (connecting the fermenter to the keg’s dip tube) and a “Gas” line (to equalise pressures).
Pressure‑control protocol
To ensure the beer flows smoothly without degassing or foaming, you must work with a slight pressure differential. If your fermenter shows a residual pressure of 10 PSI, connect your CO₂ cylinder to the fermenter and raise the regulator slightly to 12 or 14 PSI.
Before sending the beer, bring your receiving keg to the same pressure (10 PSI) by injecting CO₂. To control the transfer flow, connect a spunding valve (adjustable counter‑pressure valve) to the keg’s gas port. By gently opening the spunding valve, you allow gas to escape slowly: the keg pressure will drop slightly, allowing the beer to flow from the fermenter to the keg smoothly, steadily, and without any foam.
How to avoid overflow?
Since the keg is opaque and sealed, it’s impossible to see the fill level. You have two options: place your keg on a kitchen scale (1 kg of added weight equals roughly 1 litre of beer transferred), or use a Duotight Flow Stopper anti‑overflow system. Connected to the keg’s gas outlet, this clever little accessory contains a float that instantly stops gas escape as soon as the beer reaches the top of the keg, halting the transfer before disaster strikes.
For Oxebar kegs, this isn’t an issue — you can see the fill level directly.
4. Comparison table: Choosing your kegging method
To summarise the logistical options available when kegging, here is a quick comparison:
| Evaluation criterion | Option 1: Natural refermentation | Option 2: Forced carbonation / Isobaric |
|---|---|---|
| Clarity | Cloudy at first (yeast sediment at the bottom) | Perfect (clear beer from the first pour) |
| Gas equipment required | None for carbonation (table sugar) | CO₂ cylinder + dual‑gauge regulator |
| Sugar dosage | Strictly limited to 4 g/L maximum | 0 g/L (no sugar added) |
| Oxidation risk | Moderate (open‑air filling) | None (sealed closed‑loop under CO₂) |
| Final waiting time | 2 to 3 weeks warm | A few days in the fridge (immediate with isobaric transfer) |
Rolling Beers Team Tips
Before starting a pressure transfer to your Soda Keg or Oxebar, always make a habit of purging the entire receiving keg with CO₂.
First fill it completely with sanitising solution (such as Chemipro), then push the liquid out by injecting CO₂ through the gas port. You’ll end up with a keg filled 100% with pure gas, guaranteeing absolute protection against oxidation when your beer arrives!