Can I force carbonate a half-full keg of homemade cola?

Question

I make some small batches of home-made cola, tonic water, and ginger ale - usually making a batch of syrup, then mixing up a corny keg full and force-carbonating it over a few days. Normally I bottle and sell these at a market, so having a keg of each is a good amount.

I've just had someone wanting to place a small order - roughly half a keg's worth of bottles. I'm hoping I can just make up a half-keg, and force carbonate it as normal, but is there anything I should consider before I try?

Some specifics:

• Will the extra head space in the keg have any effect?
• Will I need more or less pressure?
• Will it take more time or less?

I have been pressurising a full keg up to 45psi for 72 hours, with some gentle agitation whenever I remember to do it. This yields a nice gentle carbonation that I'm happy with.

The drinks don't stay in the keg any longer than required to carbonate and bottle - 72 hours, tops.

Answer 1

It's no problem carbonating half a keg, other than you use twice as much gas (you still have to fill the whole keg of gas at the same pressure.)

For me, a refill for my 20lb CO₂ tank costs about $120 so it's quite expensive. So, to get the most from the CO₂ I'd just make up a full keg of syrup and carbonate that. Give your customer the half keg he wants and use the rest yourself. If you can chill the keg while carbonating that will be ideal since you'll get more carbonation for less CO₂ used, and the CO₂ will stay in solution better when transferring to bottles so you lose less.

Answer 2

I have had some accidents with my new brewing software and I ended up with 10 liters of beer instead of 18. I kegged and carbonated and it worked fine.

I have never tried kegging cola, but I am sure that the process is the same. As long as the regulator is set to a specific level you should be good.

Answer 3

You can also get 9L kegs. If you think there's scope in the future to do half batches, then this would allow you do that easily.