Carbonation In Kegs

[clessock]

I'm curious. No doubt there are many variables but what is the rate at which CO2 is absorbed into beer?

For example, say you have a chilled keg at 4degrees, you hook up the gas and give it 100kpa then remove the gas. How long til the pressure goes back to nothing in the keg? How long would it take to carb a keg by giving it top ups of gas to 100kpa say each morning and/or evening?

 

[brettprevans]

have a search. theres a spreadsheet somewhere on AHb with all the temp/absorbtion rates

 

[clessock]

Is that the balancing your system spreadsheet?

 

[Adamt]

Dissolution rate of CO2 into beer depends on:

Interfacial area (between gas and liquid), Diffusivity, molar concentration difference of CO2 between gas and liquid.

Molar concentration in the headspace is proportional to headspace pressure. If your headspace in the keg is small, your headspace pressure will drop very quickly at the start of carbonation, dropping the gas concentration, slowing down dissolution. Near the end of carbonation, the concentration difference will be very small and there will be little dissolution every "top up".

Force carbonating works by increasing the pressure (hence increasing the concentration and difference), and by shaking (greatly, greatly increasing the interfacial area).

Another way is to shake your keg with gas connected at 100kPa for a few minutes... no chance of overcarbonating there.

 

[Adamt]

have a search. theres a spreadsheet somewhere on AHb with all the temp/absorbtion rates

Is that the balancing your system spreadsheet?

These calculations assume the pressure you apply is constant (i.e. connected to the gas 24/7) and do not apply to clessock's conditions.

 

[brettprevans]

clessocks smeshocks

I think the spreadshet yor refering to is here

The one im refering to is here. post 25 by crozdog

 

[paul]

I usually rock the keg 100 times at 300kpa with warm beer then throw it in the chest freezer. Once its cold I have a taste and if it needs more gas I rock it at 100kpa, and sample often until its carbonated.

 

[clessock]

Thanks chaps, all very interesting :icon_cheers:

 

[BOG]

I always gas at serving pressure of about 70Kpa. I'm lazy and , well it just works.

Gas on a Sunday. Drinking for a taste on Wednesday, Ready and gassed by Friday.

My kegs can take weeks , some months to drink down. (I'm the only drinker).

After about 2 weeks a beer will pull with the right head and crust over with a fine cream head.
From there it's always the same until the keg pulls dry.



BOG

 

[whitegoose]

Is it okay to 'slow carbonate' like this? I'm not in any hurry and had been planning to get my first ever keg nice and cold, then hook it up to serving pressure (~80 kpa) and leave it for a week... will this carbonate okay? Is there any difference in the end result between doing it this way and force carbonating with the shaking etc?

 

[newguy]

Is it okay to 'slow carbonate' like this? I'm not in any hurry and had been planning to get my first ever keg nice and cold, then hook it up to serving pressure (~80 kpa) and leave it for a week... will this carbonate okay? Is there any difference in the end result between doing it this way and force carbonating with the shaking etc?

Nothing wrong with that method. The differences between gassing & rocking, gassing at high pressure for a short time and gassing at low pressure for a long time come down to 1) your physical effort and 2) your patience. There is no difference in the finished product that I've ever been able to discern.