Keg Carbonation - Set and Forget

[Jolls]

Hi Team,

I have my first "kegged" brew conditioning and carbonating using the set and forget method I found the information on how to work out what psi at what temperature for what volumes of CO2 (style of beer) quite easily. However, the time aspect of how long at that pressure seems to be a bit of a mystery. The sources I have found range from seven to ten to fourteen days for an ale. They can't all be right, can they?

I am now looking at my next batch which should be ready to transfer to the keg mid next week. It is a different style of beer so needs a different setup. I have a four tap keezer but only a single regulator at this stage. I expect that as my experience grows I will need to get some in line regulators to manage each keg independently.

Is there a calculation that gives a better approximation of the time to reach CO2 saturation? If so I would like to understand it so I can potentially optomise my fermenting fridge/keezer usage down the track when using the set and forget method.

If not I guess I will simply start taste testing at day seven until I hit the mark and record it in my notes for future reference. This approach sounds a bit more like art than science!

Cheers n Beers
Jolls

 

[Swannie]

Off the top of my head factors that will affect it:
- Pressure of CO2 - I think that's obvious, more pressure more CO2 dissolved per hour
- Temperature - lower liquid temperature, faster dissolving due to greater differential
- Final Gravity - effectively liquid density
- Surface area of head space - the greater the contact area between the headspace and the liquid, the faster the dissolving will take place - shaking increases surface area, that's why it works.

What I don't think affects:
- Head space volume - if you're leaving it hooked up to the gas, this doesn't affect it. If you are removing/reconnecting, then the greater the volume, the faster the dissolving.
- Size/geometry of the vessel - I think it's likely that the height of the keg, etc. won't have much of an impact, as I expect the dissolved CO2 will diffuse in the water quickly.

So probably too many factors to give general guidance.

Just get the inline, they are not that expensive and will save you hassle!

 

[Jolls]

Thanks Swannie

I will bank on the two weeks. I would like to keep tasting notes from day 7 but will be away until day 10 so I will have to start then. I will start recording the next one at day 7 and see what I come up with. I will get some inlines so I can run the differnt styles side by side.

Cheers n Beers

Craig

 

[fifis101]

Brew under pressure and you don't have to worry about waiting at all. If you set your spunding valve to the appropriate pressure that matches the brewing temperature and the CO2 volume you want then all you need to do it just chill it down, transfer it into your keg and it's ready to go.

 

[duncbrewer]

@fifis101
Agreed my tactic to spund towards the end of fermentation and I never have to force carbonate. Also use the ferment gas to purge the keg it's going into. Win Win.

@Swannie

I think size / geometry does matter as it's really surface to volume ratio that is important not surface area on it's own. My water carbonated much quicker with an aeration stone on a tube from the gas in going into the water than just gas on the surface alone. Shaking accelerates CO2 uptake by disturbing the surface and helping the mixing, the lower temperature means greater or easier solubility of the CO2 in the beer at that pressure it doesn't change the differential.

 

[fifis101]

Also use the ferment gas to purge the keg it's going into. Win Win.

Yes definitely.
Another way to save on gas is to syphon from the fermentor to the keg. It's a bit slower than using a bottle push it over but it doesn't use any gas and it stops itself once full so you don't have to hang around and watch.

 

[duncbrewer]

Given that the pressure in the fermenter needs to get to say 27 psi for 2.4 vols at 22c, the keg I purge also gets to that pressure. I then disconnect the keg and put it aside. Cold crash the beer when finished so say to 4 c and the pressure is about 10 psi then.
I then purge the lines with CO2 from the keg as gas comes up the liquid line as only gas in keg and obviously gas up the gas line.
Then connect gas to gas this equalises the pressure in the keg and fermenter, diconnect the gas line at one end and then connect the liquid line to fermenter. Short tug on the prv of the keg starts the siphon then connect the gas to gas again and the whole system is balanced so as liquid fills the keg the gas leaves and replaces the loss in fermenter.
It takes more time the less height difference between the fermenter and keg, if it does overfill it will only start going up the gas line so no mess or overflow worries.
Agreed it takes time I find at least half an hour, I just go away and leave it to do it's thing.

 

[Jolls]

Thanks for the advice. I have been reading up on pressure fermentation and have a fermzilla or similar on the list of gear to get when funds permit. I would love a 1V system as well to compliment the 3V I have built. I just have to prioritise my brewery construction over the jobs SWMBO has lined up!