When working with used kegs, there are a number of different types of posts, valves, and disconnects available. It is important to select compatible hardware to ensure your kegs hold pressure.
There are two basic types of soda kegs: pin lock and ball lock kegs. Pin lock kegs are identifiable by the nubs or “pins” that stick out perpendicular to the posts. Northern Brewer only carries ball lock kegs, so that’s what this guide will discuss.
Once you have identified that you have ball lock kegs, the next thing you may want to identify is the type of posts you have on the keg. The posts are the round stainless steel fittings on top of the keg, on either side of the lid hatch, that accept disconnects. They screw on to the kegs, and they have a small, spring-loaded poppet valve in the center which keeps the keg pressurized when not in use. Aside from o-rings, posts and post poppets are the most common items that need to be replaced.
All keg posts are designated for either gas or liquid. They can be distinguished by a horizontal notch around the base of the gas post - liquid posts do not have this notch. Type A posts have a very short, flat base which is either hex-shaped or star-shaped. Type B posts have a taller base which is also sometimes slimmer, requiring a ⅞” socket. If your posts fit this type of socket, you have type B posts. Type C posts are fairly rare; they have a large hex-shaped base and include a plastic spacer inside the post, underneath the poppet. A quick internet search should help you determine the exact post type, if needed. The poppet valves on posts may need to be replaced if they are leaking or sticking.
All ball lock kegs accept universal ball lock disconnects. Gas disconnects can only be used on gas posts, and the same goes for liquid. To attach the disconnect, pull up on the collar at the bottom of the disconnect, snap it on the keg post by pushing down and twisting, and then release the collar to ensure it’s attached. When selecting your disconnects you can either choose ones with barbed fittings or threaded MFL fittings for keg tubing. MFL disconnects require an additional barbed swivel nut in order to be attached to tubing, but this makes it easier to disconnect and reattach tubing for cleaning. Barbed disconnects function just as well, but they require a little more elbow grease.
O-rings are the most common item on a keg that will need to be replaced. Old age can cause them to leak, or they may need to be replaced if they have absorbed odors from soda, wine, smoked beers, etc. The Used-Keg Seal Kit has all of the o-rings required for a ball lock soda keg. It is a good idea to purchase one of these with each keg, or at least to have some around when replacements are needed.