Too Much Beer Foam From A Keg

I was recently invited to a home brew tasting party… and being the home brew enthusiast that I am, I couldn’t help but to show up with a keg of my own…

Needless to say I magically made dozens of new friends the moment I stepped foot on the party…

… until I set up my keg and poured nothing but foam…

Buzz kill…

Since I’ve researched like crazy why beer comes out foamy from a keg…

See, I never had a problem when serving from the tap out of my kegerator, but whenever I attached my cobra tap and the little paint ball sized CO2 cartridge I got nothing but foam…

At first I thought it was foamy from it being shaken during transportation even though I didn’t hit many bumps on the drive there… and while that may have added to the effect, it wasn’t the main cause…

So here’s the deal…

Foamy beers from a kegerator are a different problem than the way I was trying to dispense… I’ll refer to it as the mobile keg to make things easier to explain…

In my kegerator I have a CO2 tank hooked up to the keg… that CO2 tank is set at ~12 psi… that means it’s putting about 12 psi of pressure into the keg…

So whenever I open up the tap handle, beer comes out and new CO2 from the tank replaces any beer that goes out… foamy beer in a kegerator set up usually happens when the line is too short and the beer is pushed out too fast… to avoid that a longer beer line is set up to ‘balance’ the system, meaning to restrict the flow rate of the beer, which will avoid too much foam…

For the mobile keg, however, things are a bit different… when you attach a paintball sized CO2 cartridge, you don’t get the same constant pressure you do with a CO2 tank in a kegerator set up… CO2 from a paintball size CO2 cartridge only comes out when you depress the trigger…

So here’s what was going on…

When I tried pouring beers on my mobile keg setup the CO2 pressure in the headspace would push the beer out… but since no new CO2 would replace the beer going out a vacuum would form and the CO2 in the headspace was the first thing that wanted to come out making all the foam jet out of my cobra tap…

To solve that, I tried just about everything I picked up when I first learned how to keg beer… I tried a short beer line, a long beer line… I had heard low head pressure could cause foam so I pressurized it even more and that was a bad idea…

So, I ended up releasing all the CO2 from the headspace and pumped back only enough to push beer out…

This allowed me to push beer out and it didn’t serve a foamy beer like the other methods did…

Now, when you release all the CO2 from the headspace no pressure pushes beer out, but the beer is still carbonated since CO2 has already dissolved into the beer… so you’ll have to play with the amount of CO2 you pump back in… one to two seconds is usually enough… I think I did two in the video and seemed to have overdone it just a bit… you can always release pressure if you overdo it…

Also… this is a temporary fix… You can serve beer like that and beer will be carbonated, but you’ll need to re-pressurize the keg when you get home or you will lose carbonation in the beer… other than that, this worked great…

Last I had a $5 dollar lesson…

If you watch my Foamy Beer From A Keg video… around second 00:57 I pick up the CO2 cartridge and notice that it’s attached to the ball valve… that’s bad juju…

I wasted two CO2 cylinders for doing this…

The correct way of hooking up the keg charger to the ball valve is to have the ball valve snapped into the keg “in” port first… note that when you do this any CO2 in the headspace will come out of there… and that’s fine since we’re going to de-pressurize it anyway…

I still release all CO2 first, then snap in my CO2 ball valve and then hook up the CO2 cartridge…

So there you go… 2-4-1 advice in today’s newsletter… must be that I’m happy spring training started!!

Cheers!