Inline Carbonation Guide
How to carbonate beer, cider, seltzer or soda as it moves from one vessel to another, instead of waiting for it to absorb CO2 in the tank. This guide covers the Pin Point inline carbonator for tank-to-tank transfers, the Keg-2-Keg Quick Carb for small batches, how to work out how much CO2 you need, and how to use the same setup to add nitrogen.
An inline carbonator injects fine CO2 bubbles through a stone into cold product as it flows past. How much CO2 ends up dissolved depends on three things you control: product temperature, product flow rate and gas flow rate. Colder product absorbs more CO2.
1. Tank-to-Tank Carbonation with the Pin Point Carbonator
The Pin Point carbonator mounts in the transfer line between the pump and the receiving tank. It is designed to raise the carbonation of cold liquid during the transfer.
What comes with the carbonator
- Tri-clamp check valve
- Pressure gauge
- Sight glass
- Gas check valve
What you need to supply
- A pump to move the product at a steady rate
- A liquid flow meter, so you know the transfer rate
- A CO2 pressure regulator that can deliver the volume of gas you need (see below)
- A CO2 flow meter, so you know the gas rate
- A CO2 equalization line between the headspaces of the two tanks
- Enough hose after the carbonator for the gas to dissolve: about one foot of hose for every barrel per hour you transfer. At 15 barrels an hour, that is about 15 feet.
What to know before you start
- The product temperature
- The transfer rate
- The carbonation level you want in the finished product, and the level it starts at
Watch the sight glass. If you can see large bubbles that do not dissolve, the product cannot take up gas at that rate. Lower the gas flow, slow the transfer down, or chill the product further.
2. How Much CO2 You Need
Carbonation is measured in volumes of CO2: one volume is the amount of CO2 that would take up the same space as the liquid at normal temperature and pressure. By weight, one volume is 1.969 grams of CO2 per liter of product.
Pounds of CO2 needed to raise a batch
| Batch | Add 0.5 vol | Add 1.0 vol |
|---|---|---|
| 7 bbl | 1.8 lb | 3.6 lb |
| 10 bbl | 2.5 lb | 5.1 lb |
| 15 bbl | 3.8 lb | 7.6 lb |
| 30 bbl | 7.6 lb | 15.3 lb |
Turning that into a gas flow rate
The gas has to go in at the same pace as the product. Multiply your transfer rate in barrels per hour by the volumes you are adding and by 0.51 to get pounds of CO2 per hour, then by 8.7 to get standard cubic feet per hour (SCFH).
Example: transferring 15 barrels an hour and adding 1.0 volume needs about 7.6 lb of CO2 an hour, which is about 66 SCFH or 1.1 standard cubic feet per minute (SCFM). Transferring 30 barrels an hour and adding 1.5 volumes needs about 23 lb an hour, or about 3.3 SCFM.
These figures assume all of the gas dissolves. In practice, start here and adjust using a carbonation tester.
Make sure your regulator can keep up
A regulator that cannot deliver the flow will starve the carbonator, and the product comes out under-carbonated. As a guide from one regulator maker (Taprite): their high-flow primary regulators, with "HP" in the model number, deliver about 9 SCFM from an 850 psi cylinder; standard primaries deliver about 6 SCFM; and secondary regulators deliver about 2 to 4 SCFM depending on supply pressure. The second example above would already be near the limit of a secondary regulator. Check the gas line size as well, so it can carry the flow you need.
3. Keg-to-Keg Quick Carb
The Keg-2-Keg Quick Carb carbonates as you push product from one keg to another. It is a good fit for small batches, test batches and correcting a keg that came out flat.
- Start with cold product in the supply keg. Connect it with the coupler that has the built-in check valve.
- Put about 15 psi (1 bar) on the supply keg.
- Set the CO2 to the inline carbonator between 20 and 45 psi (1.4 to 3 bar). You will need to experiment a little to find the setting that gives the carbonation you want.
- Pressurize the receiving keg to just below the supply keg's pressure. The receiving keg must be under pressure, or the product will foam as it fills.
- Use the valve on the receiving keg's gas outlet to control the flow. Open it slowly so the product moves gently from the supply keg into the receiving keg.
- Adjust and repeat. Product temperature, product flow and gas flow all change the result. Change one at a time.
Filling smaller kegs from a large one? When you fill, say, sixth barrels from a half barrel, add a fill stop to the gas outlet of the keg being filled. It shuts off the flow of beer when that keg is full.
4. Nitrogenation
Adding nitrogen works the same way, with higher pressures:
- Pressurize the cold product tank to 30 psi.
- Set the nitrogen to the inline carbonator at 30 to 45 psi.
5. Checking the Result
Measure carbonation with a carbonation tester once the product has settled in the receiving vessel, and keep a record of temperature, flow and gas settings for each run. After a few batches you will have settings you can repeat. If a tank comes out low, you can bring it up with a carbonation stone in the tank.
Products for Inline Carbonation
Pin Point Carbonator System Keg-2-Keg Quick Carb (Sankey) In-Line Carbonation/Aeration System CO2 Flow Meter for Pin Point Replacement Stone for Pin Point Keg Fill Stop Beer Carbonation Tester