Could serving line shutoff valve cause foamy pour?

[dnslater]

I recently started kegging and have built a kegerator with two kegs/taps. I'm still getting foam on my first pour. Taps are in the doors. Keg is a steady 38 degrees with a fan circulating air to even it out. 10' of 3/16" beer line is coiled neatly on top of each keg. I've done all of the standard trouble shooting recommended here. I do have an inline shutoff valve a few inches behind the shank, spliced into the line of each faucet. It is similar to this:

I did this to future proof it from my teenage son, as I can quickly shut off the line and lock the door. Could this restriction cause foam? Seems like the first 2-3 seconds of each pour has foam, and then it runs clear. Suppose I could try moving the valve near the keg post?

 

[Homercidal]

This may cause enough turbulence to increase foam, but if it were the case, I think you'd get foam throughout the whole pour, not just in the first few seconds.

I get this sometimes. If I carb too much for the line length, etc. I sometimes back the pressure down. Therefore beer has more CO2 in solution than the head pressure can balance. It takes a while for everything to equalize, so what seems to happen is the beer in the line bubbles CO2 causing pockets of gas in the line. Then when you pour it takes a few seconds to clear the bubbles from the line and to get a nice flow of beer.

It seems to go away if/when I purge some of the excess CO2 from the beer. (rock the keg, wait, release pressure. rock the keg, wait, release pressure.)

Once the beer is decarbed, the foam goes away.

Well, I must also say that a SMALL amount of foam at first is normal. If I haven't used my kegerator all day I might pour 1-2 ounces into a small cup if I want to get the best pour possible. This seems to be common at bars and breweries I've visited as well.

 

[dnslater]

Then when you pour it takes a few seconds to clear the bubbles from the line and to get a nice flow of beer.

This is exactly what happens. When I open the kegerator, I see bubbles gathered in about 6 inches of line before the valve. It made me think that the turbulance from the valve caused bubbles to gather there. I may try to move the valve to the keg side of the line just as an experiment.

Everything should be balanced, except I just installed the fan late last week, and have still been tweaking the thermostat, as the fan is allowing the fridge to cool more effectively and it sometimes gets down in the low 30's. I suppose this could also cause foaming, as it would raise the carbonation level of the beer in the exposed lines. 32 degrees at 12 psi is 2.9 volumes while 38 degrees is 2.6 volumes.

 

[Homercidal]

That may be a problem too. I know I need to get a fan in mine, but I've been dinking around instead of doing those little projects.

This time I have two kegs and they are different. one was burst carbed, but when I dropped the pressure after a day or two it somehow creeped back up some, so it tended up overcarbed and foams for a few seconds after I dropped the pressure again. The other one was carbed normally and exhibits no foam problems at all. Both lines are same length and pressure and everything. I should really purge some more CO2 from the Pale Ale and reset the carb level.