Priming sugar after fermenting under pressure

[LRAT]

Hey there,

I've been pondering a question for a while and I'd appreciate some guidance:
How can I calculate the necessary priming sugar after pressure fermenting?

A little while back, I got myself a Fermzilla conical fermenter from Kegland.
I recently brewed a simple SMASH beer (OG 1.051 FG 1.012).
During fermentation, I kept the beer under 50 kPa pressure at around 20°C.
Once I hit the FG, I let the beer sit in the fermenter for an additional three days while maintaining the pressure.
Two days ago, I initiated a cold crash to 2°C, and the beer has been chilling at that temperature since then.
While it was cooling, I connected a CO2 bottle and used a pressure regulator to sustain the pressure at 50 kPa to prevent suck-back and fermenter collpase.
I know that colder beer absorbs more CO2 compared to warmer beer.
Now, I'm looking to bottle the beer (totaling 37 liters), but I'm uncertain about the amount of priming sugar required.
My aim is to achieve a CO2 concentration of 2.4 in the beer. Can anyone provide guidance on how to tackle this?
Many thanks in advance!
Luke

 

[Half-baked]

I think the big variable here is how much CO2 has absorbed into the beer. I wouldn’t assume it’s 50kpa worth… suggest giving it a couple of days disconnected from the gas, then use the reading then as your value to adjust from

 

[MHB]

Interesting. There are several things that come to mind, first work out what you have and we can go from there.

There are two ways to measure dissolved CO2. The modern metric g/L (grams/Litre), Germans sometimes express it as % CO2 WV but its the same thing. The other is the old (American) Volumes. All the calculations are done in g/L and then converted to Vol if you really have to.
The conversion is Vol*1.97 = g/L. You want 2.4 Vol. If you look at the carbonation section in Braukaiser you will find the equation for dissolved CO2 as a function of temperature and pressure. There are also tables based on the equation.
At 2oC and 50 kPa you have 4.42g/L right now. From the above you want 4.73g/L. So we arent talking about much extra.

This is where it starts getting a bit more interesting.
If you fill bottles from the pressurised fermenter, well its going to be very foamy and you will lose some of your fizz.
If this is how you are planning to turn out your beer I would think seriously about getting a Counter Pressure Filler. Just bump up your 50kPa to 60kPa and you will be there (that’s at 2oC and assuming low to no losses, and enough time to equilibrate).

The addition of priming sugar is easy enough to calculate if you know that 1g of sugar 0.488g of CO2.
So to get from the 4.42 that you have to the 4.73 g/L that you want in 30L of beer -
30*(4.73-4.42) = 9.3g would take 19g of fermentable sugar.
Sucrose (white sugar) is 100% fermentable so 19g of Sucrose. Dextrose is 91% fermentable so 21g to give the same amount of fizz.

You will run into problems getting the sugar equally divided between the bottles. If cold fizzy beer hits sugar in the bottle it's going to foam like a bugger.
The easiest way would be to dissolve it in the right amount of water and measure the syrup into the bottles. Say 5mL/bottle if you have 40 of 750ml bottles, 200mL
Again you will get some loss of fizz on transfer (don’t ask me how much, I don’t know) so you would be well advised to bump up the sugar addition a bit (careful guessing required)

Another option would be to let the beer warm up to say 20oC and do the calculations again.
It would be a good idea to rack the beer off any trub in the fermenter, if you do that you can bulk prime which would make life easier.

Do a bit of thinking and work out a plan, talk it through before you start if you want to.
Mark

 

[LRAT]

Thank you both Mark and Half-baked,
I didn't expect it was going to be a straightforward answer.
I am anxious about bottle bombs and want to avoid them by all means.
Now that fermenting under pressure has become the norm I am waiting for some YouTube clips to appear that explain the whole process. However, so far, I haven't seen any of them.
I probably going to remove all pressure and leave it for a couple of days and hopefully, it will gas off.
Then, I can add dextrose as normal.
Anyway, Mark has put me on the right track and whilst the beer is off-gassing I will do further research.
Cheers and thanks!
Luke

 

[wide eyed and legless]

Hey there,

I've been pondering a question for a while and I'd appreciate some guidance:
How can I calculate the necessary priming sugar after pressure fermenting?

A little while back, I got myself a Fermzilla conical fermenter from Kegland.
I recently brewed a simple SMASH beer (OG 1.051 FG 1.012).
During fermentation, I kept the beer under 50 kPa pressure at around 20°C.
Once I hit the FG, I let the beer sit in the fermenter for an additional three days while maintaining the pressure.
Two days ago, I initiated a cold crash to 2°C, and the beer has been chilling at that temperature since then.
While it was cooling, I connected a CO2 bottle and used a pressure regulator to sustain the pressure at 50 kPa to prevent suck-back and fermenter collpase.
I know that colder beer absorbs more CO2 compared to warmer beer.
Now, I'm looking to bottle the beer (totaling 37 liters), but I'm uncertain about the amount of priming sugar required.
My aim is to achieve a CO2 concentration of 2.4 in the beer. Can anyone provide guidance on how to tackle this?
Many thanks in advance!
Luke

I don't think you would have had suck back enough to collapse the fermenter, at 50 kPa you would have had a volume of about 15 kPa dissolving into the beer at 0-1 C cold crash. Something I read somewhere but you would see the drop in pressure on the gauge. Whatever it drops has gone into the beer. That is how I understand it.

 

[clickeral]

Hey there,

I've been pondering a question for a while and I'd appreciate some guidance:
How can I calculate the necessary priming sugar after pressure fermenting?

A little while back, I got myself a Fermzilla conical fermenter from Kegland.
I recently brewed a simple SMASH beer (OG 1.051 FG 1.012).
During fermentation, I kept the beer under 50 kPa pressure at around 20°C.
Once I hit the FG, I let the beer sit in the fermenter for an additional three days while maintaining the pressure.
Two days ago, I initiated a cold crash to 2°C, and the beer has been chilling at that temperature since then.
While it was cooling, I connected a CO2 bottle and used a pressure regulator to sustain the pressure at 50 kPa to prevent suck-back and fermenter collpase.
I know that colder beer absorbs more CO2 compared to warmer beer.
Now, I'm looking to bottle the beer (totaling 37 liters), but I'm uncertain about the amount of priming sugar required.
My aim is to achieve a CO2 concentration of 2.4 in the beer. Can anyone provide guidance on how to tackle this?
Many thanks in advance!
Luke

How are you planning on bottling the beer? it may be easier to carbonate slightly higher then your target CO2 concentration and then bottle straight from the fermenter?

What size bottles are you looking at filling? are you wanting to bulk prime or prime each bottle?

MHB has given a really detailed answer, if it was me in this instance I would bulk prime into the pressure fermenter and then fill into each bottle using a bottling wand via a disconnect (lowest pressure added to get the liquid to siphon)

I've got a Boel Itap that I use to bottle from whatever vessel I carbonate in, the only thing I don't like about it is despite all the tests and reviews I am always worried the bottles don't purge properly as there is no tube to take the co2 down to the bottom of the bottle

I like it as I can use it without holding anything

Haven't been a fan of various other counterflow bottle fillers, and I think about can filling now and then (don't like the idea of the cost of cans though)

I know Keglands new filler is something that I wouldn't mind giving a go when they bring out V2 (for bottling) have heard good things about it with cans, I like the duofillers as well but not sure if they can be used for bottling and they are expensive