Rebuilding a Used Soda Keg

Soda kegs (aka Cornelius or Corny kegs) are a great tool for the aspiring home brewer. Soda kegs are the re-purposed remnants of one phase of the soft drink industry, when soda syrup was mixed into water and then force-carbonated and hooked up to the old soda fountain. The main difference with the way soda kegs have been re-purposed by the home brewing community is that we allow the sugar to ferment first. Rebuilding used soda kegs is the most efficient way to prepare your home brew for consumption, in terms of both time and money.

Used Soda Kegs
Rebuilding a Used Soda Keg

There are two kinds of soda keg, but both designs function with the same basic principal.

Usually you can get a used soda keg for anywhere between $30 and free. When it comes to used kegs, it is best to rebuild them, then you will know for sure how much life is left in them. The first step in rebuilding your soda keg is taking it all apart.

There are two kinds of soda keg, but both designs function with the same basic principal. CO2 is pumped into the gas port, and beer is forced out the liquid port. In between, we have a number of gaskets and valves which have to be looked at. You will need some wrenches, some sanitation supplies, and perhaps some specialty parts in order to rebuild your soda kegs. First, check to see what parts need replacing - and that your keg has all the parts necessary to keep the beer flowing. The wrenches you will need in order to unscrew the gas in and liquid out valves will most likely be 7/8 or 11/16 SAE sizes, and you will want a skinny little screwdriver and needle nose pliers to help pry out the old O-rings and such.

When dis-assembled, your soda keg should have the following parts:

1. Tank

2.Liquid Tube (approx. the length of the keg) & O-ring

3. Gas Tube (shorty) & O-ring

4. Lid & O-ring

5. Gas Plug Post & O-ring

6. Liquid Plug Post & O-ring

7. Two Poppet Valves (weird springy things)

8. Possible Relief Valve on Lid

If you are missing any of this list of parts, you will need to replace them. You will definitely need to replace all five O-rings when rebuilding your soda keg, because the O-rings can harbor flavors from soda or the beer of the previous owner, and can conceal bacterial contamination as well, neither of which you want to affect your beer. There are many places online that you can order replacement O-rings, or you can take them to your local plumbing supply store to replace them.

Once you have your replacement parts, you should scrub, clean, and sanitize all parts of the keg. Make sure to use Iodophor or other non-bleach cleaning chemicals, because bleach will mess up your stainless steel - it causes corrosion and pitting in stainless. Once you have scrubbed and sanitized, simply put the parts back together, then test for leaks with a CO2 canister supplying 30 pounds of pressure. Soapy water can be used to spot even the tiniest leaks and their origins. If you have any leaks in your poppet valves, try cleaning them again and re-assembling the valve post. If it still leaks, you may need to replace the poppet valve. If your keg has a purging valve, you can pull it to purge the tank of all remaining air. This will ensure the final step in the sanitization and rebuilding process of your soda keg.

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