Kegging/Carbonation advice

[x3la]

I bottle all of my beers, adding priming sugar and then leaving them a month to do their thing - everything turns out as I want. Primarily Bitters, Milds, Porters.

Occasionally I'll keg a beer to share. The last batch was an experiment in naturally carbonating as I do with the bottles as I prefer the flavour over forced carbonation.

I added priming sugar for 2.2 volumes CO2. I did not choose "Keg (Sugar)" when calculating the sugar content, using exactly the same amount as I would for the bottles.

The beer sat in the keg for 48 days at room temperature (~20c).

The keg then sat in a fridge for 4 days before tapping.

The flavour profile was spot on.

The beer was horrible to pour and I'd like to understand where I went wrong. We ended up pouring the froth into jugs and waiting for it to settle before pouring into glasses to serve, once it was in the glass it wasn't overly carbonated.

Was 4 days in the fridge not long enough for the CO2 to reabsorb?

Could this have been rectified on the day by releasing some CO2 via the release valve?

If this was a result of over carbonation by adding too much sugar, wouldn't the beer just be incredibly fizzy rather than foamy?

The keg was a 5 gallon micromatic cleaning keg if that's relevant? (similar to this: 4 Valve Cleaning Can)

(apologies for the awful photos)

 

[beren]

How long is your serving line?
Under 10’ and there’s not enough pressure in the line and the co2 will come out of solution. Beer Line Length Calculator

 

[x3la]

How long is your serving line

I think it's probably 12ft. Another beer was pouring perfectly through before we tapped mine.

 

[SFC Rudy]

When I prime a keg I only use half the amount of priming sugar needed for bottling.

 

[x3la]

When I prime a keg I only use half the amount of priming sugar needed for bottling.

And you meet the desired level of carbonation? Do you use a spunding valve to check? I've heard conflicting stories over this and added sugar as I would for bottling (there's virtually no headspace in the keg when it's full).

I don't believe I actually over carbonated, I think my issue was due to it not being refrigerated for long enough before serving but was hoping someone who kegs more frequently than me could advise.. Henry's Law?

 

[SFC Rudy]

And you meet the desired level of carbonation? Do you use a spunding valve to check? I've heard conflicting stories over this and added sugar as I would for bottling (there's virtually no headspace in the keg when it's full).

I don't believe I actually over carbonated, I think my issue was due to it not being refrigerated for long enough before serving but was hoping someone who kegs more frequently than me could advise.. Henry's Law?

My beer comes out carbonated. If it was under carbed it would be, well, be half flat and continue to carbonate when I tap it and have it at serving pressure.

I can't find the post but someone did the math on the amount of headspace and surface area in a keg vs the headspace and surface area in 53 bottles. Anyway, I tried it once and it worked, and If I know I have extra kegs waiting for a tap I add half the amount of priming sugar and let them sit.

 

[mac_1103]

When I prime a keg I only use half the amount of priming sugar needed for bottling.

Please explain why you think the biology, biochemistry or physics would be any different in a keg vs a bottle.

I can't find the post but someone did the math on the amount of headspace and surface area in a keg vs the headspace and surface area in 53 bottles.

On a percentage basis, the amount of headspace in a five gallon corny keg is nearly identical to that in a 12 ounce long neck bottle. Unless you cut the gas dip tube and overfill the keg. OTOH, lots of people overfill bottles to minimize headspace and reduce oxidation. I could be wrong, but I don't think the amount of headspace is that important for natural carbonation.

You are under-priming your beer and making up for it with bottled CO2.

 

[Somesaymybeerisdrinkable]

After fermentation at atmospheric pressure the beer should have around 0.8 volumes of CO2 which means you only need to add 1.7 volumes, if you add 1/2 the sugar you will only be at 2/3 the desired carbonation. A few days at serving pressure will probably make up the difference. Also 1.7 volumes of CO2 in a corny keg would be approximately 34 liters which would weigh about 68 g, since about 1/2 of the priming sugar becomes CO2 you need about 136g of sugar just for the CO2 in solution.

Not sure what your foaming issue is other than maybe a problem with the line. Was there foam in the beer line, or was it only after pouring?

 

[x3la]

After fermentation at atmospheric pressure the beer should have around 0.8 volumes of CO2 which means you only need to add 1.7 volumes, if you add 1/2 the sugar you will only be at 2/3 the desired carbonation. A few days at serving pressure will probably make up the difference. Also 1.7 volumes of CO2 in a corny keg would be approximately 34 liters which would weigh about 68 g, since about 1/2 of the priming sugar becomes CO2 you need about 136g of sugar just for the CO2 in solution.

Not sure what your foaming issue is other than maybe a problem with the line. Was there foam in the beer line, or was it only after pouring?

I don't use half the sugar. I'm fully on board with treating the keg like a bottle.

The previous beer on that line was pouring perfectly before it was switched out for mine...

 

[SFC Rudy]

Please explain why you think the biology, biochemistry or physics would be any different in a keg vs a bottle.

On a percentage basis, the amount of headspace in a five gallon corny keg is nearly identical to that in a 12 ounce long neck bottle. Unless you cut the gas dip tube and overfill the keg. OTOH, lots of people overfill bottles to minimize headspace and reduce oxidation. I could be wrong, but I don't think the amount of headspace is that important for natural carbonation.

You are under-priming your beer and making up for it with bottled CO2.

Again, if my beer was under primed/carbonated it would be half flat when I tap it and it would continue to carbonate when sitting at serving pressure.

When I do this my beer is carbonated when I tap it and the carbonation does not increase as time goes on. Try it sometime, it works

 

[Somesaymybeerisdrinkable]

I don't use half the sugar. I'm fully on board with treating the keg like a bottle.

The previous beer on that line was pouring perfectly before it was switched out for mine...

I was wondering if there could be a restriction that caused foaming in the line. I am just speculating, since I think 4 days would have been enough time to absorb the CO2.

 

[Somesaymybeerisdrinkable]

Again, if my beer was under primed/carbonated it would be half flat when I tap it and it would continue to carbonate when sitting at serving pressure.

When I do this my beer is carbonated when I tap it and the carbonation does not increase as time goes on. Try it sometime, it works

Actually it would be about 1/3 flat, but you are correct having it at serving pressure will make up the difference within a few days.

 

[x3la]

I was wondering if there could be a restriction that caused foaming in the line. I am just speculating, since I think 4 days would have been enough time to absorb the CO2.

I'm confident it's not the line. The next keg had no issues. If it's not the refrigeration then I'm wondering if a cleaning keg cannot be repurposed for serving beer.

 

[mac_1103]

After fermentation at atmospheric pressure the beer should have around 0.8 volumes of CO2

Actually 0.86 volumes at 68F. This is true no matter what kind of vessel the beer is in. Priming calculators account for the CO2 already in the beer.

Try it sometime, it works

Try chilling the half primed keg without hooking it up to CO2 and see what happens.

 

[Closet Fermenter]

I have been putting full amount of sugar into my kegs to carbonate (I got smacked back here once before for repeating the ½ amount idea. 😁) I have not been doing this long, so I’m still adjusting my process. I simply use a Tapit on top of my keg, so no beer lines at all. The last one I tapped did give me a bit more foam than I wanted. First of all, it had only been in there one day, so I had not given it adequate time to equalize.

But I had this thought; who turns a bottle upside down over a mug an pops off the cap? A bottled beer has pressure in excess of pouring pressure. So, I thought that after allowing the keg time to cool a bit, perhaps it would be a good idea to vent all the pressure (“pop the cap”) then connect to serving pressure. This seemed to work; I only had a few pours with excess foam. On those few, I shut off the gas, vented, turned the gas back on. After about the third glass, all was good. I have to admit, additional cooling could have been a factor.

Any thoughts?

 

[pvpeacock]

I can't explain the science, but I had too many kegs over-carbonate using the same amount of priming sugar as for bottling. So I started using 1/2 the sugar to naturally carbonate in the keg at room temp. Then I put the keg in the keezer on CO2 and let it sit for a week or more before tapping it to make up the difference in carbonation. Problem solved whether it makes scientific sense or not.

 

[x3la]

Completely hijacked post. Lol.