Kegs are an awesome way to store and serve beer, but there’s one catch: until you figure out the fittings, that beer isn’t going anywhere. You can shake it, you can pray to it, you can bang on the shell — nothing’s coming out.
Why? Because the fitting is the official gatekeeper. It decides who gets in (CO₂) and who gets out (beer).
The tricky part? There are several different kinds of these “locks,” and none of them are intuitive.
Don’t panic. Let’s break it down.
1. What Is a Keg Fitting?
A fitting is the connector built into the top of a keg. It handles two jobs:
- lets gas into the keg to build pressure
- sends beer out of the keg to your tap
It acts like a valve that only opens when you attach the correct coupler (a.k.a. dispenser head). Without it, the keg stays sealed tight — as if nothing’s happening at all.
2. How a Fitting Works — In Two Sentences
1. You lock the coupler onto the fitting.
2. CO₂ flows in → pressure builds → beer gets pushed through the liquid channel → hose → glass.
Remove the coupler — valve closes. End of story.
The mechanics are simple. The interface is what matters.
3. Types of Keg Fittings
Here’s where the real confusion starts. Different breweries and keg manufacturers use different fittings — and they do not work with each other.
Classic Sankey-Style Fittings
Type:
A - German breweries (Paulaner, Köstritzer) / “The German”
M - Germany/Austria (Franziskaner) / “The Rare Beast”
S - International standard (Heineken, Carlsberg) / “The American” — Most common
! Important: A ≠ M ≠ S. If you have an A-type fitting and an S-type coupler — nothing happens.
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Cornelius (Corny) Kegs with Lids
Homebrewers’ favorites. Instead of a single fitting, they use two separate connectors:
Type Locking Mechanism Look Known As
Ball-lock Ball bearings Slim cylindrical head Pepsi style
Pin-lock Pin-based latch Wider head with pins Coca-Cola style
Gas and liquid ports are separate — don’t mix them up.
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By Material
Material Best For Pros Cons
Stainless Steel Serving beer Strong, sanitary, pressure-safe More expensive
Plastic / Rubber Cleaning & sanitizing Easy to disassemble Not always beverage-safe
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Final Cheat Sheet
• A / M / S = commercial kegs with one fitting.
• Ball-lock / Pin-lock = homebrew Corny kegs with two connectors.
• Steel = for beer. Plastic = for cleaning.
Now look your keg in the eye (well… the top) and say with confidence:
“I know your fitting — and I am ready.”
