Rebuilding Kegs
Used Cornelius style kegs are widely available at reasonable prices. A considerable amount of money can be saved if you buy kegs that have not been worked on in any way and rebuild them yourself. This process requires nothing but a little time, a limited amount of mechanical skills and most of the tools should be in every kegger’s tool kit.
Recently, I rebuilt two used 5-gallon (19-L) Cornelius kegs. Used kegs are not in pristine condition on the outside, however they should be fine on the inside where it counts. They should only have been used for soda syrup, such as that for Pepsi or Coke. (Note that almost all soda fountains have switched to the bag-in-a-box setup. So, if you buy a used keg that still has syrup in it, it may have been there awhile.)
New, Used or Reconditioned?
For those who either do not have the time, or do not want to go to the trouble, new Corny kegs are available. New kegs usually cost more than $100, but they are shiny, dent-free and their rubber gaskets and O-rings don’t carry any off flavors or odors. Also, their poppet valves will not need to be replaced for some time. Reconditioned used kegs are also available, with typical prices starting around $35. When comparing prices between vendors, be sure to check on what has been done to the keg to recondition it. At a bare minimum, kegs should be pressure tested. Some sellers will also replace the O-rings and clean the keg. Others will additionally disassemble the keg, clean the dip tube and inspect and replace faulty poppet valves. In practical use, a fully reconditioned keg will work as well as a brand new one.
Cleaning the Outside
The outside of the keg can be cleaned using Bar Keeper’s Friend, an oxalic acid based cleanser that is not harmful to stainless steel. It can be purchased in most grocery stores.
Use a soft nylon cleaning pad or sponge and follow the instructions on the can. Do not use steel wool or any other metallic cleaning pads. They will scratch the stainless steel, and sometimes embed small pieces of the steel in the surface, which will cause rust.
The popular heavy duty Scotch-Brite pads (or “green scrubbies”) will also leave scratches in stainless steel. (The blue Scotch-Brite scrubbing pads and sponges — the ones that say “No Scratch” on the package — are fine.) Test your scrubbing pad on the outside of the keg first, before cleaning any surface that will contact beer.
Cleaning the outside of the keg is optional, but I prefer all of my equipment to be clean. If you are going to clean the outside, I strongly suggest doing it before disassembly. I also suggest wearing latex or rubber gloves, as it is a dirty process.
An alternative I have found, which is almost as good as using Bar Keeper’s Friend, is to soak the kegs overnight in a mixture of 1.0 oz. of PBW (Powdered Brewery Wash) per gallon (7.5 g/L) of hot water. At this same concentration, a PBW solution heated to 120–160 °F (49–71 °C) will clean almost any stainless surface, without scrubbing, in 30 minutes. If you are cleaning multiple kegs, a 100-qt. (95-L) picnic cooler holds enough liquid to submerge a Corny keg.
Disassembling the Keg
Before starting disassembly, relieve any pressure in the keg by either lifting the relief valve or depressing the poppet valve on the top of the post with a small tool. I have a small piece of wood dowel that I use, so I am sure not to damage the poppet. Be sure to put a rag or towel over the relief valve or post prior to relieving the pressure, as there will most likely be some syrup remaining in the keg.
Once the pressure is relieved, remove the keg cover by lifting the latching lever, then lowering the cover into the opening and turning it slightly to align it. Remove and discard the lid O-ring. You will need a 3/8” drive ratchet wrench and either an 11/16” or 7/8” deep socket to remove the posts. I bought both sizes at Home Depot for less than $5 each. Since some posts are eight sided and others twelve sided, I would suggest buying twelve point sockets in both sizes. In the case of my kegs, which are Firestone Challenger VI, I needed the 7/8” for both posts. Unless you are certain what type of socket you need for your keg, it is a good idea to bring the posts, or the whole keg, with you when you go to the hardware store. On one side of each of the handles on top of the keg on the “gas in” side, it will have “in” markings. Take a good look at that post so you are sure to install it in the right place during re-assembly. At a quick glance, they look to be identical, but there are subtle differences, one of which is a small difference in size.
Once the posts have been removed, I use a small jeweler’s type screwdriver to get the O-ring on the posts started, then slip a slightly larger screwdriver in beside it and pry the O-ring high enough to be able to slip it off the post. In my experience, this normally prevents damage to the O-ring. It is not critical at this time because you will replace all of the O-rings with new ones, but will be good practice. Discard the O-rings.
Next, remove the dip tubes. You will notice the gas-in dip tube is short, and the liquid-out is long. The liquid-out tube is either straight or curved. Stick your hand through the opening and push up on each tube. They will usually slip out easily, but sometimes it requires a little effort. Once you have both dip tubes removed slip the O-rings off them and discard.
Cleaning Chemicals
It is now time to clean the inside. I like using PBW, however many homebrewers use the unscented version of OxiClean, whose active ingredients are sodium percarbonate and sodium carbonate. (The “oxi” in OxiClean refers to the fact that sodium percarbonate reacts with water to release hydrogen peroxide and sodium carbonate.) Other homebrew cleaners that contain sodium percarbonate include One-Step, B-Brite and Straight-A. PBW’s material safety data sheet (MSDS) lists only sodium metasilicate (30%), although their website also claims that it includes sodium carbonate. (It is also widely believed to contain sodium percarbonate.) Another common brewing cleaner is TSP (trisodium phosphate). Because of environmental concerns with the release of phosphate into the environment, many products sold as TSP actually contain up to 90% sodium carbonate.
Cleaning the Inside
Put the cover, posts and dip tubes in the keg. I put the keg in the basement shower and pour my cleaner into the keg, then fill it with household hot water.
I like to run a tubing brush through the dip tubes a couple of times. Let the keg soak overnight, then give it, and the other parts, a thorough hot water rinse. Turn the keg upside down and let it drain and dry. You will need some food grade lubricant for the O-rings. Only a small film evenly spread on each O-ring is needed. First, lubricate and install the dip tube O-rings, and insert the dip tubes in the proper holes. Next, install the posts and tighten. Lubricate the post O-rings, and install them in the post grooves. Some homebrew shops sell colored O-rings for keg posts and I like to use a red one on the “gas in” post to identify it. Lubricate the large O-ring and fit it onto the lid. Install the lid and latch it.
Testing for Pressure
Now that the keg is clean and rebuilt, it is time to check if it holds pressure. Connect the “gas in” disconnect to the “gas in” port and pressurize the keg to 12 PSI. That should be sufficient to seat the lid gasket. Use a small bowl and add a couple of teaspoons of dishwashing detergent to some tap water. Use a small (about 1 inch) paint brush, or a spray bottle, and liberally apply the detergent mixture to all of the gas fittings, connections and around the keg cover. If there are any leaks, you will see bubbles. If leaks are found, check the connections to make sure they are tight. When there are no leaks, pressurize the keg again to 12 PSI, and let it sit for a day. Use a pressure gauge attached to the “gas in” connector to monitor the pressure. (Some homebrew shops sell these, or build the spunding valve on page 54.) If the keg maintained pressure, you are ready to sanitize it.
Sanitizing the Keg
Mix two gallons of your preferred sanitizer solution and pour it in the keg. Shake and roll the keg to make sure it contacts all surfaces. I use Five Star brand Star San. Star San contains 50% phosphoric acid and 15% dodecylbenzenesulfonic acid. At a concentration of 1.0 fl. oz. per 5 gallons (1.6 mL/L), it provides 300 ppm of the dodecylbenzenesulfonic acid and it only requires 1–2 minutes of contact time to sanitize.
Another popular sanitizer is iodophor. At a concentration of 0.5 fl. oz. per 5 gallons (0.78 mL/L), it provides 12.5 ppm of free iodine, with a required contact time of only 1 minute. Older formulations of iodophor required users to adjust the pH. Newer formulations, such as BTF iodophor, do not. Both Star San and iodophor are no rinse sanitizers. Do not use bleach (sodium hypochlorite xc) or chlorine-based cleaners or sanitizers on kegs as they can pit the stainless steel.
If the sanitizer you use requires a rinse then do so. Some people like to leave the cover off and invert the keg until it is dry. When the sanitizing step is completed the keg is ready for service. If I am not going to use the keg immediately, I hang a string tag from one of the handles with “sanitized” written on it and put a clear plastic bag over the top. When I’m ready to use the keg, I spray the top surface with Star San to sanitize it.
