Cobra Tap Surging?

[InertZero]

I'm pretty new to kegging, currently have my third batch on tap. I have some surging issues. I have a fairly used keg, I actually think it was a soda keg; it had pepsi distributor stickers on it when I got it (which might be most of the problem). I'm using a cobra tap at the moment, bought pre-configured with about six feet of hose connected to a black keg fitting Currently, when the tap is opened, the line drains out, then air seems to surge back into the keg before the line refills and drains into a glass. This makes the beer super foamy, basically an entire glass of foam that I have to wait for to settle out. It's pretty much done this since day one, and seems to be getting worse.

I have been employing a "burst carbing" method per the sticky. Not sure if that makes a difference or not.

My question is: what are the possible causes/solutions to this? I think it can only really be down to having a cobra tap vs a faucet, not enough line, or a bad keg. What do you guys think?

Thanks for the help.

 

[DrunkleJon]

Sounds like your systems pressures are not balanced. If your beer is carbonated at higher pressures than your serving pressure over time gas will come out of suspension into the beer line/dip tube area. If you can be patient the set and forget method should not cause that issue. Otherwise you need to either disconnect the keg from gas and purge the pressure off of it periodically over a couple days, hook back up to gas and repeat until it is balanced, or turn up the gas pressure until you no longer see bubbles forming in the lines.

Alternately, there is the possibility that there is a seal problem with your dip tube which is allowing it to drain over time when not in use.

What is your serving pressure and at what temperature are you serving your keg?

 

[DrunkleJon]

Re-reading your original post. When you say air surging back into the keg, do you hear bubbles actually going into the keg? That really shouldnt happen as a keg should be a pressurized system and if it sucked back it wouldnt start pouring beer afterwards. Do subsequent pours foam as well or do they pour fine?

 

[InertZero]

I'm not sure if air is actually coming into the keg, but what's left in the line drains out, then it's almost like there's a vacuum. The line empties completely, then there's gas spurting (maybe? not sure if gas coming out or going in), and then nothing but foam. Every pour is like this. I did "set and forget" carb this batch to see if it was overcarbonation, but I still have these issues. Kegged a few weeks ago, took about a week for there to be any noticeable amount of carbonation, then the last few days I'm pouring foam. Serve at 10 psi, 40 degrees plus or minus a few degrees.

 

[DrunkleJon]

hmm... weird. You say this is your third kegged batch. Did the previous ones do this too? It almost seems like there may be a leak somewhere from the post to the dip tube where you are getting gas in the pour as well. This could explain the lines pouring the trapped beer then starting after that. You may want to do a full disassembly/clean out after this keg kicks and look for things like bad o rings or cross threading or something of the sort

 

[InertZero]

The first two batches did it a bit, but it seems to be worse this one. More research I've done, I'm thinking more and more it might be an issue with the dip tube. After this batch is gone, I'm planning on taking the dip tube apart. It came from the cheap-o section at Adventures in Homebrewing near Ann Arbor ($35). I think they're still inspected well, and issues looked cosmetic on the outside (though nothing apparent on the inside). I'm going to try and make the keg last until February. If I still have issues then, I think I'm going to start with replacing the keg.