No carbonation yet

[NaymzJaymz]

I have been attempting to carbonate an imperial stout. My refrigerator is very cold at about 36-37 degrees. I set me pressure at 5psi, which is within range for this beer on the carbonation chart. After 2 weeks there is not even a hint on carbonation. This is a big beer that started at 1.098 and finished at 1.022. Any thoughts on what I've done wrong here? The C02 tank is at least half full. The keg is holding pressure fine. Thanks!!!!

 

[Dixon9717]

I set mine for 30psi for a day then 20 psi for a day then serving pressure which for my setup is usually 12psi.
5psi will take forever to see any carbonation if any at all.

 

[doug293cz]

How many times did you purge the keg headspace after filling the keg? You have to get the air out of the headspace in order to get the proper pressure for carbonation. Also, you want to purge 10+ times @ 30 psi to get the O2 level in the headspace low enough that you won't have oxidation over the life of the beer.

Brew on

 

[zachattack]

Aside from the fact that it could easily take 3 weeks to fully carbonate, 2 volumes of CO2 (5 psi @ 36 degrees) is a very low carbonation level. I understand that stouts are better with lower carbonation, and the style guidelines point you towards 2 volumes, but personally I'd go with 2.5 volumes (10 psi for you) like most other beers. Stouts are also better on the warmer side, so as you wait a few minutes for the beer to warm up it will release some of the carbonation.

 

[dancingfetus]

After 2 weeks, I would think you should have some carbonation. Since it is a stout, and some people get into nitrogen conditioning with stouts, are you carbing with CO2 or beergas?

 

[NaymzJaymz]

Thank you for the responses. Doug, I'm clueless as to the 30psi figure. Yes I purged the head space many times, but at a much lower pressure. I've heard people say that you will push the O2 down into the beer at the pressure you mention.

 

[doug293cz]

Thank you for the responses. Doug, I'm clueless as to the 30psi figure. Yes I purged the head space many times, but at a much lower pressure.

It's possible to calculate the concentration of O2 in the headspace assuming that it starts out as air prior to purging. The more CO2 you push into the headspace on the pressurize part of the purge cycle, the more O2 gets removed when you vent the headspace. Higher CO2 pressures push more CO2 into the headspace.

Purging the keg is equivalent to diluting a solution and dumping the excess mixture to get back to the original volume. If you have a cup of solution, add a cup of water, and then dump a cup of the resulting solution, you are left with a cup of solution at half the original concentration. If instead you add two cups of water to the original one cup, then dump out two cups, you are left with one cup at one third the original concentration. With the headspace, the volume is constant, so the amount of gas is proportional to the pressure of the gas.

The net is that you can dilute the O2 in the headspace with fewer purge cycles by using higher CO2 pressures. The goal is to get the O2 in the headspace down to concentrations that won't cause bothersome oxidation over the life of the beer. Acceptable O2 concentration for commercial brewers are less than 1 ppm. So, the 10+ cycles at 30 psi comes from the following chart that shows how O2 gets diluted at different purge pressures and number of cycles.

I've heard people say that you will push the O2 down into the beer at the pressure you mention.

Gases don't work that way. Each is absorbed into the beer based only on its own concentration (partial pressure) in the headspace, independent of the concentrations (partial pressures) of other gases in the headspace.

Brew on

 

[NaymzJaymz]

Thank you, Doug. The technique I use is to start out with low pressure and purge the head space, which is very minimal, several times then increase the pressure and purge many times. I'm somewhat of a kegging newby after filling untold hundreds of bottles. If I see the chart says 5psi is at the mid to upper range for this style at this temp, I never would've thought to go to 30psi and then 20psi. Are there any good references for this kind of thing, or do you have to "get the hang of it"? When I kegged my first ever batch, I did an IPA that seemed over carbonated. I carbed at 13psi at 38 degrees and received comments that I went to the upper levels of psi for that style. I was able to smooth things out with that batch by learning more on this forum about line length, ect.. Incidentally, I've been very careful on all the beers I've kegged, transferring with CO2 from the carboy into the CO2 purged keg. I also gently purge the headspace of all my carboys before capping them. If CO2 is heavier than 02, won't even a gentile purge eventually remove the oxygen from the minimal headspace of a keg or carboy?(with all respect to the chart)

 

[NaymzJaymz]

Dancingfetus, I'm not sure what you mean by "beergas".?

 

[doug293cz]

... I never would've thought to go to 30psi and then 20psi. Are there any good references for this kind of thing, or do you have to "get the hang of it"?

Most of the recommendations for a short high pressure dwell, followed by serving pressure, are based on trial and error. I haven't seen an analysis based on CO2 absorption rates vs. pressure and temp. I usually do 30 psi for 36 hrs when targeting ~2.5 volumes, followed by serving pressure. If I was shooting for 2 volumes, I would probably only go 24 hrs at 30 psi. If you have less than a full keg, you want to drop the high pressure dwell proportionately to the fill level (1/2 a keg - 1/2 the time.)

When I kegged my first ever batch, I did an IPA that seemed over carbonated. I carbed at 13psi at 38 degrees and received comments that I went to the upper levels of psi for that style. I was able to smooth things out with that batch by learning more on this forum about line length, ect..

13 psi at 38˚F should get you 2.66 volumes. Not outrageously high for an IPA. Unless you are preparing for a competition, you should carb to your tastes, and not care what others say.

Incidentally, I've been very careful on all the beers I've kegged, transferring with CO2 from the carboy into the CO2 purged keg. I also gently purge the headspace of all my carboys before capping them. If CO2 is heavier than 02, won't even a gentile purge eventually remove the oxygen from the minimal headspace of a keg or carboy?(with all respect to the chart)

Gases do not stratify by molecular weight. They do the opposite and spontaneously homogenize. Watch the video. Br2 as a molecular weight about 3.6 times air, and it homogenizes with air in about 30 minutes. If there are any "air" currents, homogenization will occur even faster. CO2 is much lighter than Br2, so will mix with air even faster. CO2 and NO2 are very similar in molecular weight, so behave vary similarly.

[ame]https://www.youtube.com/watch?v=_oLPBnhOCjM[/ame]

Brew on

 

[SMPress]

How much beer is in the keg? I had one when I first started kegging that wouldn't carb. Apparently, my beer came up to the bottom of the gas in tube, and therefore wouldn't carb. I emptied a couple of pints out, and it carbed right up... I now leave beer in the fermenter just to assure that I have enough headspace to carb a beer.

 

[doug293cz]

How much beer is in the keg? I had one when I first started kegging that wouldn't carb. Apparently, my beer came up to the bottom of the gas in tube, and therefore wouldn't carb. I emptied a couple of pints out, and it carbed right up... I now leave beer in the fermenter just to assure that I have enough headspace to carb a beer.

It would have carbed eventually. The CO2 absorption rate is proportional to the area of the beer/headspace interface. If the beer level gets above the cylindrical portion of the keg, the gas/liquid interface area drops very rapidly, and carbonation times increase dramatically.

Brew on

 

[dancingfetus]

Dancingfetus, I'm not sure what you mean by "beergas".?

Beergas is a mixed gas between co2 and nitrogen. Nitrogen is much tougher to absorb into the beer, and could result in drastically under carbed beer. But some stouts like Guinness use nitrogen, which can lead some people attempting a stout to use beer gas, but I've read that it's best to lightly carb with co2 then top up with beer gas.

 

[NaymzJaymz]

SMPress, this keg is very full, so maybe that is a part of it, although I always brew 6 gallon batches so the 5 gallon keg is full. I've never had any problem. I'm still trying to understand the carbonation chart. If you need the appropriate level for this stout I'm carbing and the chart says 5psi, how do you use these much higher levels of pressure(30-20psi) that have been mentioned here, and then cut it back at the right time. The serving pressure alone is over double what the chart says to use to carbonate a stout. Doug, thanks for the video!

 

[dancingfetus]

30-20 psi wont work for a nice pour. I personally set my beers to 30PSI for two days( it just gives a nice start to carbonation, so if I'm desperate, and can choke a few down.) Then back down to around 12-15 psi to top up. I am by no means experienced at brewing, However it is better to keg condition consistently at a recommended PSI as it can take time to keg condition. I think if there's an idea of a high PSI is to ramp up the saturation and it may just be troubleshooting.

If you are set on having a balanced system, then serving pressure can vary, based on your line length. You can still serve a low carbed beer, at a low serving pressure on CO2, If line length is adjusted for then serving pressure is a moot point. or if you need a longer line length, you can push with nitrogen, which will keep the pressure in the keg consistent, however not alter the beer carbonation too much.

Had a few, may not be well written, but I think it corrects a few items.