Flat Beer

[BeerandWhisky]

I have my latest beer on tap and it's completely flat. It's not foaming and knocking all the CO2 out, it's just not in there to begin with. It's been on 15 psi for two weeks. I've got 13 feet of 3/16" beverage line. I can hear the regulator allowing more gas into the keg as beer is dispensed and pulling on the PRV releases gas as one might expect 15 psi to come out. I'm completely stumped as to why there would be no carbonation in the beer. I've kegged about ten batches using all the same equipment and this is the first instance of this problem. I've turned the valve off from the gas manifold to the keg and will keep it off overnight to test if I have a pressure leak, but I doubt that's the cause. In the meantime, I turn to you fine folks to see if someone has an answer.

 

[day_trippr]

The last time a similar scenario popped on here I suggested it had to be a leak, most likely the keg.
That was dismissed by a few, perhaps not without good reason, but eventually the poster found a leak in the keg.
So, I'm going with that until proven otherwise

One can wrap duct tape around the rubber handles atop a cornelius style keg to form a pool that can be filled with sanitized water to test for leaks even with the QDs attached...

Cheers!

 

[doug293cz]

I'm one of the ones @day_trippr mentioned.

The carbonation process doesn't care if you have a leak, unless it is fast enough that the CO2 pressure in the keg is at least a few psi lower than at the regulator. If you have this bad of a leak, you will empty a CO2 bottle in short order. Carbonation depends on the CO2 pressure in the keg headspace, and the beer temperature, and nothing else (unless not enough time has been allowed for equilibrium to to be approached.)

Is it possible that you failed to purge the keg headspace of air after keg filling? Air in the headspace will reduced the effective (more rigorously the partial) pressure of CO2. This would cause your beer to be way under carbed. Air (more specifically oxygen) in the headspace will also cause your beer to oxidize before its time.

Brew on

 

[day_trippr]

lol! Happy Easter, Doug!

So, I'm treading in your wheelhouse, but gas laws would obviate the headspace thing, yes?
I mean, CO2 will plow right through any air if its solubility is higher than the other gases, right?

Cheers!

 

[BeerandWhisky]

Day trippr, I’m currently checking for a leaking keg. Never thought of the duct tape trick you mention but I’ll keep it in mind. Maybe try it tomorrow if the keg is down on pressure from today.

Doug, the keg was fully purged with CO2 and filled through the liquid out post under pressure.

Thank you both for the replies.

 

[doug293cz]

lol! Happy Easter, Doug!

So, I'm treading in your wheelhouse, but gas laws would obviate the headspace thing, yes?
I mean, CO2 will plow right through any air if its solubility is higher than the other gases, right?

Cheers!

Partial pressure doesn't work that way. Gauge pressure is the difference between the absolute (relative to vacuum) vessel pressure and atmospheric pressure. The absolute pressure is equal to the sum of the partial pressures of each individual gas in the volume of interest. Henry's law, which describes gas solubility in a liquid, is based on partial pressure. All of the charts and calculators are based on the headspace being 100% CO2, as the amount of carbonation is dependent on the CO2 partial pressure. If there are other gases in the headspace, then the CO2 partial pressure is less than the gauge pressure plus atmospheric pressure (14.7 psi), and the carbonation will be lower.

If you didn't purge the headspace, and pressurized to 12 psi, then the partial pressures of air (O2, N2, Ar, etc.) totals 14.7 psi, and the CO2 partial pressure is 12 psi. However the carb chart/calculator assumes the CO2 partial pressure is 12 psi + 14.7 psi = 26.7 psi. If the air wasn't purged, then the effective gauge pressure of CO2 is -14.7 psi - try to find that on your carb chart.

Brew on

 

[doug293cz]

Day trippr, I’m currently checking for a leaking keg. Never thought of the duct tape trick you mention but I’ll keep it in mind. Maybe try it tomorrow if the keg is down on pressure from today.

Doug, the keg was fully purged with CO2 and filled through the liquid out post under pressure.

Thank you both for the replies.

Is this a high ABV beer? I have heard anecdotal accounts where high ABV beers absorb CO2 slower than lower ABV beers. The charts only tell us about equilibrium carbonation level vs. pressure and temp, but not about rates of carbonation. Also, I believe the charts are all based on about a 5% ABV beer, and am not aware of any data that shows how carb level vs. pressure might change as a function of ABV.

Brew on

 

[day_trippr]

Ime there is no doubt on the relationship between FG and time-to-equilibrium, all other factors being equal. I see a huge difference between an 8 point wheat beer vs a 26 point imperial stout, for the two extremes in my recipe catalog...

Cheers!

 

[BeerandWhisky]

Beer is 5.2% pale ale, same as the batch before it.

 

[BeerandWhisky]

The last time a similar scenario popped on here I suggested it had to be a leak, most likely the keg.
That was dismissed by a few, perhaps not without good reason, but eventually the poster found a leak in the keg.
So, I'm going with that until proven otherwise

One can wrap duct tape around the rubber handles atop a cornelius style keg to form a pool that can be filled with sanitized water to test for leaks even with the QDs attached...

Cheers!

Ten points to mister day trippr. After reconnecting the keg to gas, I could hear it filling up again. I tried your tape and water trick but couldn't see a leak, but it must be somewhere. I'll track it down some other time. Rigged a jumper line and transferred to a fresh keg and burst carbonated. Will sample tonight after it's settled some.

Thanks all for your help and replies.