Home brewers have been using Cornelius, or soda kegs for years to brew and dispense home made draft beers. But Cornelius kegs only carry five to six gallons of beer. For the home brewer who is ready to make and serve bigger batches of beer, the transition must be made to bigger kegs. Converting full sized kegs for home brewing purposes is a matter of reverse engineering the keg to suit your needs. Ultimately, an understanding of how the keg's tap fitting and tap work together are the keys to re-using them for home brewing. Here we will discuss the standard American SanKey keg and how you can use it to your advantage for home brewing.
If your goal is to simply put home brew in the keg, you must also consider how to clean and sanitize it for the next use. This is really the hardest part of using the Sankey keg. In industrial use, caustic and acid are used to clean out the inside of the kegs, with a steam cleaning sterilization method. Practically speaking, the tooling to be able to use these kinds of chemicals for home brewing is prohibitively dangerous and costly.
This first step to re-using an American Sankey keg is removing the tap fitting without destroying it. Before any work begins on this task, you should clean the outside of the keg and, using a rag and a heavy duty screwdriver, press down on the ball valve to release any pressure that is still inside the keg. Next, in order to remove the ball lock beer tube mechanism, you must take off the retaining spring. This is a very thin spring that is circular and flat. To remove it, you must push it around with a flat-head screwdriver until the end of the spring can be seen through one of the holes in the fitting that is part of the keg. You can then, with a smaller flat-head screwdriver, pry up the end of the retainer ring through the hole and grab it with pliers.
Pull with the pliers and use the screwdriver to rotate the spring and get it out. Now, you just have to use the larger screwdriver and a hammer to rotate the inner piece around until the tabs are aligned with the keg holes on top, and then pull it out. In the end, you should be holding two pieces: the retaining spring and the beer tube ball lock stem.
Once these parts are out of the keg, it is very easy to clean them. The spring retainer is easy to remove by pressing on it and rotating widdershins. The ball and rubber seal require soaking, and that you rotate and move them around to make sure you get all the spots. Now all you have to do is clean the inside of the keg. We've heard of some brewers taking their kegs and just boiling water in them to clean them, and with much success. Boiling the tube is sure to sanitize it as well.
Now you only have to brew a big enough batch to fill that keg up with beer! Restoring the stem can be done with little more hassle than it was removed. Now, just chill, force carbonate, and serve.