bag-in-box carbonisation

[Christian_Berlin]

Hi,

I read a lot the last days, posts from peebee being very informative. But I haven't found an answer to my special problem.

I have been doing bottle conditioning since. Never bothered about keg and never wanted to. I do the eventual bitter and mild an Riggwelter-clone amongst belgian and other styles. Now I have bought myself a pint365 and only then started to think about the next step...
This being that I bought some bag-in-boxes. Those are made for apple juice and are not keeping any pressure. I thought maybe they don't need to. Most (all?) aproaches go through kegs before filling bag-in-box. What if I don't have Kegs?
Now a promising-looking Thwaites Nutty Black is done fermenting and I need to bottle, uhm bag the stuff. But should I add sugar? The beer has been sitting around 19°C for the last days. So not a high carbonisation. The only sources I found suggest to put in some amount of sugar and then vent the bags several times. Coming from bottles, I usually calculate the exact amount and do not vent my bottles. But what should I aim for with those bags? Don't want them to explode or just start leaking...
My dream-thinking is to find the right amount of sugar (or fresh wort) to have the bags inflate a bit, but not burst. Then I would transfer to colder storage and connect to my beer engine.

I guess this reads a bit chaotic. If I would narrow it down, it comes to the question: How much g/l of CO2 should I aim for and is my bag likely to hold the pressure when conditioning around 20°C?

confused,
Christian

 

[Dads_Ale]

I have tried using the bag-in-a-box with the two layers on the inner container. These proved problematic trying the secondary fermentation as the inner layer was gas permeable so any excess gas ended up between the two layers and I couldn't vent it. the beer didn't really carbonate either as the gas came out of solution and again ended up between the layers.. They did hold the pressure though but had to reinforce the box with a few cable ties.

You may have better success if the ones you have are single layer as you would be able to vent any excess pressure from these via the tap.

 

[Christian_Berlin]

unfortunately, my bags seem to be two-layered, too...
Sounds like and can't use them at all, not even with properly carbonated beer?

 

[Dads_Ale]

Its worth a try as I might have got it wrong. I looked on the manufacturers web site and they said you could secondary ferment and vent excess gas but it didn't work for me.
I did get a single layer one but never got round to trying it as went down adapting corny keg route for my beer engine.

 

[Christian_Berlin]

which puts me back to my problem of how much sugar to add. The recent video of the craft beer channel has been very instructive. Except that I think he is adding way too much sugar and subsequently having to vent it off. But I don't really know...

 

[Christian_Berlin]

from playing back and forth with some carbonisation calculators, I now assume, that 3,5g of CO2 per liter would come down to the 0.9-1.3 "volumes" of CO2. That's what I will go for and hope it works.

 

[peebee]

In a Cornie keg (19-20L) 0.5-0.75g per litre will produce about 1.3 volumes (3-5PSI). After removing 1/2 pint or so that quickly drops to about 2PSI (which will maintain about 1.1 volumes dissolved CO2) because of the increasing headspace (hence you have a very-low-pressure regulator on a keg if you want to keep it like that for weeks rather than a day or two).

I wouldn't like to have 3-5PSI in a polypin or the like! But the actual pressure will depend on how much gas can be created to swell the bag to capacity. The beer remains at 0.8-0.9 volumes until the bag is swollen to capacity and pressure then starts to increase.

Obviously as beer is drunk and the bag deflates the beer must return (slowly) to 0.8-0.9 volumes (the amount of CO2 that can remain in solution at atmospheric pressure). A trick I've heard of to keep dissolved CO2 a bit higher (1.0 - 1.1 volumes) is to place a heavy book on the bag to maintain a scrap of pressure. This trick works longer for the reactively impermeable BIB type bags than for the permeable traditional "polypins" (polythene) which will retain virtually no CO2 if left long enough (many months, but the beer is well and truly oxidised by then).

 

[Christian_Berlin]

I thought that the level of CO2 that can remain in solution also depends on the temperature. Since I have to condition around room temperature, I need some pressure resistance. But when cooled to 12°C, more gas is being disolved in the liquid. Or did I get this completely wrong?
I still struggle with the relation of g of CO2 per litre (g/l), bar, PSI and "volumes". Since I used to calculate my desired carbonisation on g/l, I am still searching for the best number there. I just bottled (and bagged) with 3,5 g/l. I will just have to watch what happens to my 3l bag.
If everything else fails, I will try to pump out of a 1l-bottle. Just to see how it works. And if I am unlucky I will have to invest into some cornie after all...

 

[peebee]

I base all my CO2 content about 13-4C; "ideal" cellar temperature, but I would find that a tad cool for my tastes which is a good thing 'cos I rarely get serving temperature below 16-17C and at this time of year the cooling isn't on. So reality has slightly lower carbonation values than I calculate; I don't care. You don't wont to believe those American tables because they "fail" at low pressures (most Americans, and Brits, can't understand why anyone would want such low pressures).

There is a bit of "trial-and-error" involved. You can certainly get very good results from polypins, and no doubt from bag-in-box setups (which I've never tried) but you do need to learn the idiosyncrasies involved. I can't help, I abandoned polypins years ago.

 

[Christian_Berlin]

thank you nevertheless. Your intelligence has been usefull already.
My bag started to inflate. And separate. Gas is between the two layers. I guess I will punctuate the outer layer to prevent explosion. And I'll write off this part of the batch, as it will probably turn out flat. Good enough to test the beer engine and who knows, maybe it is great...

 

[Dads_Ale]

I found a picture of what mine looked like. I didn't puncture the outer layer but instead reinforced the box.
I can't remember if the beer was carbonated or not but assume it wasn't brilliant as I gave up with the bag in a box and went over to cornies (which I already had so not any great expense).
Maybe a single layer polypin would work better as you would be able to vent any excess pressure.

 

[peebee]

I think I've got a diagram of that in my "treatise" (which is now linked in my signature; I've fixed the broken link it had to start with!):

(The diagram is of 60/70s keg beer, but fits @Dads_Ale's piccie quite well!).

Reminds me of Scotty in Star-Trek "I'm giving her all she's got, Captain. She's gonna blow!".