Why Do I Have Bubbles in My Beer Line?

Thanks to u/Procrastinator548 on Reddit for this photo

Got Bubbles?

Bubbles in your beer line can point to a several potential problems. These problems can lead to small bubbles… foam or larger CO2 bubbles breaking out of solution. These issues can occur at different points in your kegerator. The point at which they occur and specific behaviors can help us to track down the problem.

An Unbalanced System

You need the right combination of temperature, pressure and resistance to serve a proper pint of beer.

This will be a recurring theme throughout this article. Balancing your system is an important baseline. Most, but not all, of the troubleshooting steps outlined here revolve around diagnosing different versions of an unbalanced system.

See: Step by Step: Balancing Your Kegerator Draft System

Over-Carbonated Beer

Thanks to u/Procrastinator548 on Reddit for this photo

Your beer has been over carbonated because of an unbalanced system or over zealous force carbonation.

A sign that this could be the problem is that multiple pints served one after another pour foamy.

See: Fix Over-Carbonated Beers with a Spunding Valve

Beer Line Too Warm

Heat rises. This causes the top of your kegerator to be warmer than the center and bottom of your kegerator. In all likelihood your faucets, shanks and some tubing are in the warmer part of your kegerator. This causes CO2 to come out of solution and causes foam.

A sure sign that this is the problem is that the first pint pours foamy and subsequent pints poured soon after pour correctly. The problem comes back again after a longer period of time as things warm up again.

A solution to this is to add a recirculating fan to even out temps.

See:

Pressure is Too Low

Photo via the BA’s Great Resource, Demystifying Dispense Gas

Another problem related to improper balancing. If your serving pressure is too low for the resistance of your system you can get foaming or bubbles.

A sign that this could be the problem is foam starts occurring at some point after leaving your keg. There is a length of tubing that looks good and then later you can visibly see foam in the tubing.  This can be while you’re serving beer or co2 can breakout causing visible pockets in the beer line.

See: Step by Step: Balancing Your Kegerator Draft System

Pressure is Too High

If pressure is set too high you’ll get foaming at the faucet. It’s also quite likely that your beer will also be over-carbonated.

A sign that this could be the problem is that beer looks good in tubing and you get excessive foam at the faucet. This would typically be accompanied by the beer serving too quickly.

See:

Beer Line Too Short

If pressure is set too high you’ll get foaming at the faucet. It’s also quite likely that your beer will also be over-carbonated.

A sign that this could be the problem is that beer looks good in tubing and you get excessive foam at the faucet. This would typically be accompanied by the beer serving too quickly.

See:


Diagnosing Between: Pressure Too High vs Beer Line Too Short

These issues can present themselves the same way. Fast pours and excessive foam that starts at the faucet. One troubleshooting step you can take is decreasing pressure, venting keg head space and serving a pint. If the pint is too carbonated and excessively foamy, it’s probably a pressure issue. If the beer serves okay, it’s probably a beer line length issue.


Slow Flow, Cavitating Bubble When Serving

Thanks to u/lolwatokay on r/homebrewing for this photo!

This problem presents itself at the faucet with cavitation at the tap. An air bubble is trapped within the beer while serving.  This is generally a flow rate issue, caused by incorrect pressure or resistance, a blockage or potentially a dirty faucet that’s gumming up the works. If you’re certain your system is correctly balanced, clean the line and faucet and take apart everything on the liquid side to ensure it’s properly assembled.

CO2 Bubbles in Beer Line

Keg Dip Tube O-Rings - Food Safe Silicone

Continual, larger CO2 bubbles in your beer line while serving.

In my experience this is a rare problem. It can be caused by… bad or improperly seated o-rings.

A bad gas dip tube o-ring or a gas post o-ring is allowing head space CO2, in the case of the dip tube o-ring, or atmospheric air, in the case of the post o-ring, into the line at the time of vending.

Replace both post and dip tube o-rings and re-assemble everything on the gas side to make sure everything looks good and is installed and seated properly.

See:

What Else?

Diagnosing these sorts of issues can be frustrating. Have you run into a scenario that isn’t outlined here? Got a comment or tip related to one of these conditions?  Got a correction? Do you have a photo that nicely illustrates one of these issues that you can share to help your fellow homebrewer?

Let me know!

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co2 bubbles in beer line

Make sure the components you use are compatible and rated for your intended application.  Contact manufacturer with questions about suitability or a specific application.  Always read and follow manufacturer directions. toppost:linebubbles tag:tpr

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