Foaming at the tap at the end of a batch

[barleyfreak]

When our 7bbl serving tanks start to get low we will keg off the last 1-2 bbls or so and send them to the taps. Occasionally, and more frequently of late, we have found that the very last keg or two is somehow sending out bursts of co2 en route to the tap rendering the pouring process a big waste and PITA. I have experimented with taking the kegs off line and degassing them a number of times over a day or two and that seems to remedy the problem. So it seems that the kegs have become overcarbonated at some point during this process. Top pressure on the serving tanks and kegs alike is 11psi. Temp in the walk in is 35. When we fill kegs we temprarily push 15 psi top pressure on the serving tank. Is that too much? I read that as an SOP years ago and have been following it since. Can anyone see any obvious probs with our SOP or offer any explanation on how this is occurring?

Thanks for any help.

Dave

[Matter]

If it's happening with kegs but not serving tanks, I would look at the gaskets on the keg coupler and the CO2 valve seal on the kegs themselves, which would obviously not be present on the tanks. A worn or leaky seal could be introducing CO2 into the beer line rather than solely to the headspace of the keg, though this doesn't explain why periodically degassing the beer seems to help.

In my experience, over-carbonated beer won't cause a CO2 bubble in the line itself unless it's allowed to get quite warm, but rather excessive breakout once it hits the glass. Plus 11psi at 35* only maintains a reasonable amount of carbonation. I also wouldn't be concerned about the 15psi head pressure for filling.

Also, are you tanks/kegs by any chance at a higher elevation than the faucets?

[idylldon]

The CO2 is most likely breaking out in the line because there's not enough pressure on the kegs. I would bump the pressure on the kegs up a bit and see what happens. Might need to move it up slowly until you find the sweet spot. I have found that I need to do this pretty much every time I keg off the remainder of a brite and serve it from the keg. I keep my cooler at 37F and the pressure on my kegs at around 14 or 15, whereas in the brite it's usually 12.5 to 13.

Cheers,
--
Don

[barleyfreak]

Thanks for the advice. It has happened on multiple kegs so I am doubtful it is the seal. I also recently put in service a brand new keg coupler and it happened on that one as well. The serving tanks are not at a higher elevation than the taps.

I will try bumping up the pressure on the keg and see if that makes a difference.

Dave