How to Carbonate Stout on Beer Gas?

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Clint Yeastwood

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I haven't used beer gas in forever. I just kegged a dry stout with a stout faucet and beer gas. I know the right pressure for dispensing is around 35-38. What do I do about carbonation, though? I don't remember. Do I force it with CO2 at first, or do I just leave it on beer gas at 37?
 
Carbonate it with CO2 first. Beer gas is mostly nitrogen, which doesn't dissolve very well in beer (hardly at all). Once you get it carbed up to the pressure you want, then switch to Beer Gas. The nitrogen pressure is to trip the pressure plate in stout faucets but still keep the Stout at low carb levels. About 2/3 of the pressure will come from nitrogen. The 1/3 CO2 is to keep the beer carbonated while serving it.
 
Thanks. Using CO2 first made sense to me, too. I have it on 15 psi of CO2 right now. I will try to figure out if I need to move that up or down. I want to get CO2 into it by tomorrow.
 
If that stout is cold I wouldn't leave it anywhere near 15 psi for long. If you're going to dispense through an actual stout faucet you want to keep the CO2 content around 1.2 volumes and definitely not higher than 1.4, and as our favorite carbonation table shows you kinda need to warm the beer up to carbonate it that low :)

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Cheers!
 
First of all, looks like it's more like 20 psi at the moment. I got that wrong. Second, I have no idea how soon I should move back to beer gas. Third, I'm not too sure what the final temperature of the stout will be. I have it on that wooden platform where I've never put anything else. I am really winging it here.

I think maybe I'll check it every couple of hours.

I have had the keezer at 38 for a while. Maybe it's time to bump it up a little. It's pretty cold for ales, and I don't have a lager yet.
 
I set and forget on CO2. I use the same pressure as the partial pressure in the beer gas; for my gas, that’s a quarter of the ~40 psi serving pressure, so ~10 psi. And I find it needs to sit on beer gas for a day or so — getting nitrogen into solution actually does matter, and takes a little time.
 
My stout finally has some CO2 in it. I poured a beer using my stout faucet, and right when I started, I got a lot, but not an insane amount, of foam. I switched from CO2 to beer gas and continued pouring.

So how long should 3/16" EVAbarrier be for a stout faucet at 38°?
 
My stout finally has some CO2 in it. I poured a beer using my stout faucet, and right when I started, I got a lot, but not an insane amount, of foam. I switched from CO2 to beer gas and continued pouring.

So how long should 3/16" EVAbarrier be for a stout faucet at 38°?
Short as is convenient. Restriction comes from the faucet.
 
Right. Line restriction on a true stout faucet is counterproductive. Restriction comes from the restrictor plate inside the faucet.
I run the same 6.5 feet of 4mm ID EVAbarrier as my "regular pressure" CO2 runs even though the beergas pressure is 35 psi.

All your stout passes through one of these...
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Cheers!
 
I made a rookie mistake and hooked CO2 up when I thought I was switching to beer gas. Lots of foam now.

I got smart and labeled my disconnects and regulator bodies. A little late.
 
If that stout is cold I wouldn't leave it anywhere near 15 psi for long. If you're going to dispense through an actual stout faucet you want to keep the CO2 content around 1.2 volumes and definitely not higher than 1.4, and as our favorite carbonation table shows you kinda need to warm the beer up to carbonate it that low :)

View attachment 811994

Cheers!
what am I missing here? If about 1/4 of the pressure comes from CO2, then the partial pressure of the CO2 would be 9 psi at 36 psi serving. You would have to keep it 64F during serving to keep it below 1.4 You could lower the pressure to allow for colder temps, but doesn't the faucet need over 30 psi to really get the stout effect?
 
Guinness recommend serve at 43F or 6 to 7 Celsius.

The " pressure" is whatever the gauge is set at.
As you can see in above posts the stout faucet is very effective at making foam if " overcarbonated " with CO2 alone at 15 psi.
The Nitrogen doesn't really dissolve in the stout and it's only CO2 that carbonate, Nitrogen doesn't nitrogenate the stout it really just pushes the stout out of the keg along the beer line and through the faucet.
 
OK, to keep it below 1.4 at 43F, you are allowed 1 psi CO2 by that chart, that would be roughly 4 psi of 75/25 beer gas. Nowhere near enough pressure to cause the stout effect and rip the CO2 out of solution. So I am still missing something in the statements above....
 
I set and forget on CO2. I use the same pressure as the partial pressure in the beer gas; for my gas, that’s a quarter of the ~40 psi serving pressure, so ~10 psi. And I find it needs to sit on beer gas for a day or so — getting nitrogen into solution actually does matter, and takes a little time.

what am I missing here? If about 1/4 of the pressure comes from CO2, then the partial pressure of the CO2 would be 9 psi at 36 psi serving. You would have to keep it 64F during serving to keep it below 1.4 You could lower the pressure to allow for colder temps, but doesn't the faucet need over 30 psi to really get the stout effect?

Guinness recommend serve at 43F or 6 to 7 Celsius.

The " pressure" is whatever the gauge is set at.
As you can see in above posts the stout faucet is very effective at making foam if " overcarbonated " with CO2 alone at 15 psi.

OK, to keep it below 1.4 at 43F, you are allowed 1 psi CO2 by that chart, that would be roughly 4 psi of 75/25 beer gas. Nowhere near enough pressure to cause the stout effect and rip the CO2 out of solution. So I am still missing something in the statements above....

When working with beer gas (CO2/N2 mix) you have to adjust gauge pressure to absolute pressure by adding 14.7 psi to the gauge reading. You can then do your partial pressure calculations using the absolute total pressure. For @TheBluePhantom 's example, 1 psig (gauge pressure) the absolute pressure, and CO2 partial pressure is 15.7 psia (absolute.) Therefore, with 25/75 (CO2/N2) the required total absolute pressure is 15.7 * 4 = 62.8 psia, or 48.1 psig. Edit: red numbers are corrected from original.

The Nitrogen doesn't really dissolve in the stout and it's only CO2 that carbonate, Nitrogen doesn't nitrogenate the stout it really just pushes the stout out of the keg along the beer line and through the faucet.

The solubility of N2 in beer is about 100X lower than the solubility of CO2. But, you do get some N2 dissolved. Due to the physics of bubble formation in liquids, gases with lower solubility tend to create smaller bubbles, and these smaller bubbles are a big part of the "Nitro" experience.

I am at around 32 psi at 35 degrees, and all is well.

At 35°F and 32 psig beer gas at 25/75, the equilibrium carbonation level is 1.19 volumes, which is totally acceptable for a nitro stout.

I am attaching my carbonation calculator, which also handles beer gas (with variable CO2/N2 ratios) below.

Brew on :mug:
 

Attachments

  • Carbonation Pressure Calculator.zip
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The solubility of N2 in beer is about 100X lower than the solubility of CO2. But, you do get some N2 dissolved. Due to the physics of bubble formation in liquids, gases with lower solubility tend to create smaller bubbles, and these smaller bubbles are a big part of the "Nitro" experience.
To wit, much slower disproportionation and much longer-lasting foam, smooth mouthfeel, and (I don’t know that anyone knows why but) muted hop aroma.
 
Muted hop aroma? Interesting. I've only ever dispensed my imperial chocolate stouts on beer gas (continuously for well over a decade without a gap) and I'd be the first to inform that there has never been an intent to bang the aroma meter. Hops are there simply to balance the residual sweetness - which for a 1.107 brew that typically finishes around 1.025 there is plenty.

I do remember about 10 years ago folks were talking about putting all kinds of styles on beer gas, including ipas of various sub-styles. I don't believe there was much actualization of all that talk. It would have been interesting to see if an neipa, for instance, would be aromatically muted when dispensed with beer gas...

Cheers!
 
When working with beer gas (CO2/N2 mix) you have to adjust gauge pressure to absolute pressure by adding 14.7 psi to the gauge reading. You can then do your partial pressure calculations using the absolute total pressure. For @TheBluePhantom 's example, 1 psig (gauge pressure) the absolute pressure, and CO2 partial pressure is 15.7 psia (absolute.) Therefore, with 25/75 (CO2/N2) the required total absolute pressure is 15.7 * 4 = 62.8 psia, or 48.1 psig.
Thank you. I forgot to convert to absolute. I knew I was missing something in the math. Chemistry class was over 40 years ago. The numbers just weren't making sense in my head.
 
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Yup. That's exactly where my stout lives 👍

Cheers!
You keep your stouts at 35-36*? Not 40-45 ? Just wondering because Im trying to get into stout to make atleast one and was shopping for another chest freezer to keep it at 40 as my other is set at 36*. I mean I need more room anyways but I can always get a big one to replace my 3 tap. Or get an addition tiny chest freezer to just have solo as nitro single tap
 
My stout lives in the same keezer as the rest of my beers, and majority rules wrt the temperature :)
If I use an un-chilled glass the pour will end up at 40°F, which is fine imo...

Cheers!
Same kegland 5g kegs or do I need a special keg that gas goes down to the bottom?
 
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There's no need for anything special about the keg to dispense beer using beer gas at high pressure (30~35 psi).
I've never actually read of any special keg for that purpose. I use conventional cornelius kegs...

Cheers!
 
Well, I am going to fess up; I have my cooler set 46° for everything. That being said, I typically ALWAYS have an Irish Dry Stout in there. It’s the household favorite, so it trumps the majority.

From December through March, I can usually depend on my utility room off the carport staying in the mid-forties, so sometimes, I don’t even put my stout in the cooler.

In any case 46° is a cold 🥶 beer when you live here in the sunny South! Also, I have never tried beer gas. I just recently picked up an extra, used tank, so I’m thinking about it. On the other hand, with all the complications expressed above, I may just stick with my CO2 and Tapits.

I like beer, and beer people; all kinds of options to enjoy! 😁
 
So my neighbor works for airgas I give him my CO2 tanks and he brings them back next day. That being said for stout or nitro beers. They have 25/75 and 30/70 which one should I get for my stout keg? I want to make sure I tell him the best one or preferred one. @day_trippr it may not even matter
 
It comes down to the precise math - the temperature you hold your stout, and the pressure you use for the beer gas - that would determine exactly which blend would be the best.

I'm using 75/25 these days and if you go back to @doug293cz's post here with my temperature and pressure combination that works out to around 1.2-ish volumes of CO2 - close enough to what I try to carbonate the stout to before putting it on beer gas. Otoh, if you're going to keep your stout warmer but use the same 35 psi pressure, you may want to go with the 70/30, so the higher CO2 content will counter the warmer temperature...

Cheers!
 
It comes down to the precise math - the temperature you hold your stout, and the pressure you use for the beer gas - that would determine exactly which blend would be the best.

I'm using 75/25 these days and if you go back to @doug293cz's post here with my temperature and pressure combination that works out to around 1.2-ish volumes of CO2 - close enough to what I try to carbonate the stout to before putting it on beer gas. Otoh, if you're going to keep your stout warmer but use the same 35 psi pressure, you may want to go with the 70/30, so the higher CO2 content will counter the warmer temperature...

Cheers!
Thanks. I think I'm able to stuff.( It will be tight as heck) 4th keg in my keezer so I ordered the tank/reg and another kegland 5g pony. I'll have my neighbor put 25/75 in tank since I'm using my same kegerator that keeps beer at 36*
 
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