Corny Keg Beer Flow Problem

[CUPCAKE]

Hi can anyone help, I keep getting back flow in my corny keg beer line, no leaks in line or gas line, which results it over frothy beer, glasses of it, as anyone fitted a John Guest back flow valve into the beer line to prevent this happening

 

[peebee]

You'll have to elaborate. Backflow of beer in the beer line is impossible when there is presumably some pressure in the keg and none in the tap: The beer can only go one-way.

 

[CUPCAKE]

Hi, my keg is connected to beer tap via a cooler, after a couple of hours after pulling a pint, the tube leading from the cooler to the keg is clear and I have watched the beer flowing backwards into the keg, the psi from the keg is 12, I have tried to increase the psi but just get very frothy beer, I have checked both keg and gauges for leaks and none have been found, I have had the coils in the cooler pressure tested and these are sound, any ideas??

 

[foxbat]

Maybe it's to do with temperature difference. If your cooler reduces the temperature of the liquid in the pipe then it might contract back into the keg. The problem with that theory though is that it ignores the regulator at the other side that's supposed to stop the pressure falling. Anyone got any better ideas?

 

[simon12]

Trying to get my head round what happening and have started to type a few things then realised there are wrong. When you say "the tube leading from the cooler to the keg is clear" do you mean this part of the line is full of gas not beer? and is the problem the same or different if your pouring a few pints in a row? What happens if you drop the pressure to half and release any over that?

 

[peebee]

Hi, my keg is connected to beer tap via a cooler, after a couple of hours after pulling a pint, the tube leading from the cooler to the keg is clear and I have watched the beer flowing backwards into the keg, the psi from the keg is 12, I have tried to increase the psi but just get very frothy beer, I have checked both keg and gauges for leaks and none have been found, I have had the coils in the cooler pressure tested and these are sound, any ideas??

Beer is probably degassing in the lines as it warms up. I get it even without the b*** breaking pressures. The "clear" line will contain gas from the degassing so will be under the same pressure as the keg - but liquid beer in the lines might get pushed back to the keg because the gas will have more volume for the given pressure. Inserting a check valve (near the keg out) might help, but I've got non-return valves in the beer line and beer still seems to mysteriously vanish in the lines between sessions. You might try 3/16" line after the cooler to minimise the issue (reduces foaming too, but beer doesn't pour too quick). Or employ "python" coolers, but that's a bit extreme.

 

[Fil]

its a consiquence of a drop in pressure along the length of beerline/chiller between tap and keg,( closer to the tap the pressure drops.. ) And perhaps a difference in temperature post chiller of the line when stood still and perhaps unlagged??

the beer looses some condition to both the lower pressure and higher temp sat in the line post chiller and thats whats filling your line,, its not a problem, more a 'feature' of your home bar..

some lagging on the post chiller line may help, also as suggested above using 3/16" line post chiller will reduce the volume of beer effected and therfore the volume of co2..

me i just accept a burpy tap when first cracked after an hour or so..

 

[divrack]

thin/long lines reduce foaming as they maintain more pressure on the beer through fluid friction when the tap is open. I don't see how back flow would be a significant cause of foaming even if I understood how it was possible which I don't. as said above it's probably just offgassing as the alternative is that you have some pressure source pushing on the beer from the tap which is reverse of physics in a leak situation. higher temp will cause beer to lose gas and the balance will go backwards.
if you are getting more than it takes to refill the lines with beer of foam they are too large and or too short. I find I need 7mtrs of thin line for pilsner to not get excessive foam. it's a pain in the erse having all three could of it in my fridge but worth it.