If you’re buying a used keg and don’t know what coupler you need, you’re going to have a bad time. The good news: there are really only five fitting types you’ll encounter in the US used keg market, and once you know them, you can shop with confidence.
The two categories: commercial Sankey vs homebrew ball/pin lock
Before getting into specifics, it helps to understand the split.
Commercial kegs (half barrels, quarter barrels, sixth barrels) use Sankey-style couplers. The coupler locks onto a single valve on top of the keg. Different Sankey variants exist for different markets and brewery origins.
Homebrew kegs (Cornelius/corny kegs) use either ball lock or pin lock fittings — two separate posts on top of the keg, one for gas (CO2 in) and one for liquid (beer out).
Sankey D coupler — the US standard
The Sankey D is the dominant coupler type in the American market. If you’re buying a used commercial keg in the US, there’s a strong chance it uses a Sankey D valve.
Commonly used by: Anheuser-Busch (Budweiser, Bud Light, Michelob), MillerCoors (Miller Lite, Coors Light, Blue Moon), most American craft breweries, and most import brands sold through US distribution (Corona, Heineken US).
How to identify it: The valve stem sits in a single D-shaped ring with a probe that enters from the side. The coupler handle locks with a quarter-turn. If you’re buying a used commercial keg for homebrewing or dispensing, this is almost certainly what you want. Sankey D equipment is the most widely available and least expensive in the US.
Sankey S coupler — European lagers
The Sankey S (also called the European S-type or “Grundy S”) is used by major European lager brands distributed in European-market kegs.
Commonly used by: Heineken (imported European kegs), Amstel, Stella Artois, Kronenbourg 1664, and most German lager brands sold in Europe.
How to identify it: Looks similar to the D coupler but the probe angle and locking mechanism differ slightly. S-type fittings are not interchangeable with D-type — using the wrong coupler won’t connect properly and won’t seal. In the US used keg market, Sankey S kegs turn up occasionally, usually from bars that imported European-market kegs.
Sankey G coupler — German draft
The Sankey G type is used by German draft systems, particularly for specialty German imports.
Commonly used by: Paulaner, Spaten, Franziskaner, and some Weihenstephan imports.
How to identify it: The G type valve has a wider probe and different locking geometry than D or S types. G-type kegs are the least common Sankey variant in the US used market. If you’re buying one, make sure you can source a G-type coupler before committing.
Ball lock — the homebrew standard
Ball lock fittings are the default for Cornelius (corny) kegs in homebrewing. They use spring-loaded ball bearings to create a secure, quick-disconnect seal.
The system has two posts: a gas post (smaller, where CO2 enters) and a liquid post (larger, where beer exits). The disconnect fitting clicks on with a push-pull action — press in, push down to lock, pull up to release. The gas and liquid posts are different sizes to prevent cross-connection.
Ball lock is the most popular fitting for homebrew Cornelius kegs in the US. Parts are widely available: disconnects, posts, o-rings, and poppets are stocked by most homebrew supply shops. Ball lock and pin lock disconnects are not interchangeable — make sure your system matches before you buy.
Pin lock — Coca-Cola heritage
Pin lock Cornelius kegs were originally used by Coca-Cola for syrup distribution before the switch to bag-in-box. They’re less common than ball lock but still circulate in the used market.
How to identify it: Pin lock posts have two small pins protruding from the sides. The disconnect has corresponding slots — you push down and turn to lock (bayonet style). The gas post has 2 pins; the liquid post has 3 pins, making cross-connection mechanically impossible — a distinction some homebrewers prefer.
Pin lock kegs are slightly shorter and fatter than ball lock kegs. Equipment is less widely available than ball lock, but still findable. If you’re starting from scratch, ball lock is the more versatile choice.
Quick reference
| Fitting type | Used on | US availability |
|---|---|---|
| Sankey D | Commercial US kegs | Very common |
| Sankey S | European lager kegs | Occasional |
| Sankey G | German import kegs | Rare |
| Ball lock | Cornelius/corny kegs | Very common |
| Pin lock | Cornelius/corny kegs | Common |
What to check on the valve or posts before buying
Regardless of fitting type, inspect the valve or posts before committing:
- Corrosion or pitting around the valve base or posts indicates the keg wasn’t cleaned properly and suggests o-ring failure
- Sticky or frozen valves on Sankey kegs can sometimes be freed with penetrating oil, but a completely seized valve may need professional service
- Damaged or missing poppets on ball/pin lock posts are cheap to fix — but confirm they’re present or price accordingly
- Cracked or missing o-rings are inexpensive to replace but signal the keg was stored improperly
If you’re buying locally and can inspect in person, ask the seller to demonstrate that the valve moves freely. That’s five seconds of due diligence that can save you a frustrating afternoon.
Bottom line
For most buyers in the US used keg market: buying a commercial keg means Sankey D. Buying a Cornelius keg for homebrewing means ball lock (unless you’re already running pin lock). Buying a European bar keg means checking the valve type first and confirming you can source the matching coupler.
Valve and fitting type is one of the first questions to ask any seller. A good seller will know what they have. If they don’t know, the fitting type is usually identifiable by sight once you know what you’re looking for.
