Carbonate once frozen keg

I brewed a Helles in January. Fermented for 10 days at 53ºF raised to 65º until terminal gravity reached. Once kegged, I placed in my garage for largering. Temps in the garage are typically outdoor ambient temp + 10º. This would out great when temps are in there usual range of 20-30F. Unfortunately, the temps in Michigan fluctuated greatly this winter. There was a week of single digit temps. The beer frozen solid in the keg. I did not think it was a big deal. They where not pressurized. Only enough pressure to get a good seal on the lid. The kegs where placed in my keggerator set at 42º. Once unthawed, I forced carbonated as usual to 2.5 volumes (13psi). I cannot figure out why I am not getting good carbonation.

I have tried bumping up the psi and changing regulators with out success. I do not have a leak or I would have run out of gas by now. I get a limited amount of rolling bubbles out of the tap, but it still is flat. The beer is crystal clear and refreshing, but needs those bubblse & a little carbonic bite to balance it out.

How long has it been on the gas? I wouldn't think that the keg freezing has anything to do with a lack of carbonation at serving.

If the beer is fully thawed I can't think of what could keep it from behaving like any other keg o' beer.

Are you sure you don't still have a beer iceberg in that keg?

Cheers!

No ice in keg. it has been at 42F for a month. When I pour one, I get tiny rolling nitro type bubbles. [I should have mentioned that in my original post]
I spoke with a brewer at one of the local breweries. He believes that I have nitrogen in the beer. I am not sure how
I have vented the kegs & will let them off gas for a week. Then I will force carb with CO2.

Wait - you were trying to carbonate that beer using beer gas?

No. just co2

I had a doppelbock that froze during lagering ... it sat frozen for a month. It won BOS in three competitions. That's not the issue. Is it possible you did not get your headspace purged?

Not purged completely is possible. What are you thinking?

hs1149 said:

Not purged completely is possible. What are you thinking?

Click to expand...

Air is 80% nitrogen. If you pressurized the headspace without purging it's possible you've got a close approximation to beer gas in there without knowing it.

There's also Dalton's law which basically means that the pressure you see in the gage may not be the pressure exerted upon the liquid by the CO2 if there are other gasses present.

Either way give it a good purge and try again.

Purge time it is. Thanks Lee. I'll report back in a week or so. Congratulations on your BOSs.

LBussy said:

Air is 80% nitrogen. If you pressurized the headspace without purging it's possible you've got a close approximation to beer gas in there without knowing it.

There's also Dalton's law which basically means that the pressure you see in the gage may not be the pressure exerted upon the liquid by the CO2 if there are other gasses present.

Either way give it a good purge and try again.

Click to expand...

Yes, carbonation tables and calculators assume the headspace is 100% CO2. Since your gauge reads the difference between atmospheric pressure (14.7 psi) and the headspace pressure, the absolute pressure in your keg is 14.7 psi + the gauge reading. So, if the carb table/calculator tells you that you need 10 psi, you really need 24.7 psi absolute pressure of CO2. If you don't purge the headspace, and just pressurize to 10 psi, you only have 10 psi of CO2, not 24.7 psi (absolute), and you will be way undercarbed.

Even if you put a little pressure on the keg initially, freezing could have dropped the pressure below 0 psi gauge pressure (due to CO2 absorption and thermal contraction), possibly allowing air to leak back into the headspace. Thus requiring re-purging.

It takes more cycles than you would think to get O2 down to insignificant levels (about 0.2 ppm.) See the table and chart below. The table/chart assumes starting at 100% air in the headspace, and you are likely to be less than that, but there is no way of knowing (unless you have an O2 meter), so best to be safe and assume it is all air.





Brew on

I took the kegs off the co2 & vented the kegs for a week. I gave the a good shake once in a while. Once I could not hear any gas escaping from the vent, I closed it and reapplied the co2. I now have carbonated beer and it is delicious!


Thanks for sharing your knowledge doug293cz & LBussy.