So far, that hasn't happened to us, fortunately. But we've also quit bottling for the most part. With kegs, there is a spring-loaded airlock that gives way slightly if there is too much pressure within the keg. This lets out the extra carbonation and prevents the keg from bursting.
Aside from serving finished beer, kegs can also be helpful in the fermentation process for this reason. They can hold much more pressure from the build up of carbon dioxide than standard home-brewing equipment. Lots of people ferment in glass jugs called carboys or plastic buckets; both have openings at the top where you can fit an air lock which is comprised of two cheap pieces of plastic. The main piece narrows the opening of the fermentor to a little less than a centimeter while the second piece floats above in a reservoir of sanitizer or liquor (to keep bacteria from falling inside). This floating piece allows CO2 to bubble out from within while keeping everything else out.
This normally works perfectly well.
Philipp and I brewed ten gallons yesterday. It is a nut brown that I hope turns out like AleSmith's Nautical Nut Brown that is only available at your local pub in kegs. No retail bottles so far. Our standard practice is to brew ten gallons at a time so we both come away with a five gallon keg. After mashing, we boiled 13 gallons of wort down to just around 11 gallons. Each of our bucket fermentors will hold 7 gallons or so of liquid so our nearly 5.5 gallons of boiled wort fits just fine. The extra gallon and a half of space is much needed for the krausen that will soon form during fermentation. This is a foamy substance which resembles the beer's head and is a good sign of proper primary fermentation.
We had so much krausen and such fierce fermentation during the initial 18 hours after pitching in the yeast that it started to come out of the airlock. We've had this happen before so I was not surprised but a little annoyed because there will be a mess to clean up after it drips out of the airlock and down the side of the bucket. Regardless, fermentation was working very well and I was happy.
I decided to set up a time-lapse camera to capture the battle between yeast and barley sugar raging within the fermentor. I thought it would be fun. Why not? I set the two fermentors inside larger pots and lifted them a couple feet off the garage floor to get a better angle with the camera. I programed the camera to take a picture every ten seconds.
While working at home, I get the benefit of watching over the beer from time to time. My dog Oscar was first to alert me that something was awry. If a tree falls in the woods and no one...
Yes, if there is a time-lapse camera present. See for yourself:
If you watched long enough, you'd see the top of both buckets blew off due to clogged air locks. It was pretty damn messy. All over my car, all over the floor, all over my kegerator... an hour later, I realized I should look toward the ceiling. That's where most of it ended up.
The Brewline:
Every brew session seems to be unique and you can't always plan on what's to come. Just be safe and avoid glass carboys if you have any doubts.
