Half filling a 9 gallon keg

[matty]

Would putting only 5 gallons in a 9 gallon keg ( aluminium )cause any problems ? i.e large volume of air space not filled, will it still fermment as it should ???

[DarloDave]

Yeah It will be fine, I always do 5 Gallon brews in the 10G H&G Bucket.

[jamesb]

Would putting only 5 gallons in a 9 gallon keg ( aluminium )cause any problems ? i.e large volume of air space not filled, will it still fermment as it should ???

Are you talking about kegging/casking the beer?

If so, you'll end up with flat beer as there's too much air space to build up CO2 pressure. You may also end up with slightly oxidised beer also due to the larger air space above the beer having - it will take longer to get a layer of CO2 above the beer.

[yashicamat]

If you have a CO2 cylinder handy, you could purge the cask before you fill it. Should be fine then, but as has been said, unless you're feeding it an artificial carbon dioxide pressure, it won't carbonate much though.

As for drinking, there seems to be a lot of hype about how quickly barrels should be drunk once cracked, but I've not had any issues with my 5 gallon kegs when I've let air into them, even when it's been weeks before the beer is finished (rare but it happens when I have multiple beers on ).