Know Your Keg Taps: Why and How Keg Couplers and Keg Tapping Equipment are Different for Various Brands of Beers

In the past, beer kegs were wooden barrels with stoppers and the beer was released simply using gravity and air. Today, kegs are sterile stainless-steel containers and inert pure gases are used to drive beer out of the keg using a keg tap or keg coupler.

The Evolution from Wooden Kegs to Stainless Steel Kegs

When you think of wine, ale, and other spirited drinks you may think of a large winery with wooden kegs lining the shelves. Originally, wooden kegs were the form that most alcohol was preserved and fermented. Today, the brewer has a number of choices for finishing, and storing his brew.

Wooden kegs (or casks) today are quite often used for cask conditioned ales. A cask has non-pasteurized beer that has live yeast still fermenting. This style, the cask beer style, may be the old-fashioned style that comes to mind: the one where one uses a mallet to hammer in the “tap” into the keg, then a spigot is opened to allow the beer to flow via gravity. Once tapped you use a beer engine to “pull” the beer from the cask. This process is referred to as “draughting:” the art of pulling a pint of beer.

Kegs created from aluminum or stainless steel were first introduced to the market with 2 ports: where the gas connection was one port and the beer outlet another port (i.e. Golden Gate). Then kegs evolved to a single port (Peerless, Hoff-Stevens, Sankey). The single port keg is considered the most hygienic and easiest to clean and fill.

This single port keg system is the Sankey-style and has become the standard keg package. Sankey-style has a number of keg valve/coupler systems. In the US, the standard keg valve/coupler system is the D System; in Europe it is primarily the S System. In the UK, Grundy was the initial producer of the single valve Sankey-style system, and so their system has been called the G System. Breweries choose their keg/valve system for a variety of reasons, but predominately they were to identify their kegs, and regional unification.

To learn more about the anatomy of a beer keg, check out our video below:

Why aren’t keg taps all the same? Why isn’t there a universal coupler system?

The biggest reason there is not a ‘universal’ keg tap or keg coupler is branding: different tap systems have become associated with specific breweries. The different keg coupler and valves have been used to differentiate kegs so that breweries got their kegs back for refilling. Not all brands of draft beer use the same type of keg valve system for this reason.

Each distinct "system" requires matching the appropriate keg coupler to the keg valve. Here in the US most breweries use the D System. The different keg systems are typically used in by brewers in the same region, i.e. A System (German slider) is used predominately by German breweries.

In the U.S., there are eight different "systems" in use:

  1. D System
  2. S System
  3. A System
  4. M System
  5. G System
  6. U System
  7. Twin Probe
  8. Homebrew

What are the differences between keg valve/coupler systems?

Although most keg couplers might appear similar at first, each ‘style’ is shaped to fit into the different valves. The foot/base of the keg coupler is like a key as it must fit properly with the keg valve in the keg to be tapped. If you are trying to identify the type of coupler, the foot/base is a good starting point to identify the difference.

To better understand some of the differences between keg taps, let’s take a look at the various keg systems:

D System Keg Coupler - American Sankey-Style Valve

This is the most common system available in the US, also known as American Sankey. The valve has two lugs, the coupler base has a ramp on either side, you tap a D System keg by dropping it into the well, and then turning it clockwise into the keg valve, until it stops at the lugs. Once the coupler is engaged with the valve, you pull out the handle and “tap” the keg – beer will start flowing immediately. The D System is used by all the major breweries, including Anheuser-Busch, Miller, Molson-Coors, and Labatt as well as most craft breweries.

S System Keg Coupler - European Sankey-Style Valve

Many European breweries use this system, and so it also referred to as a European Sankey. The keg valve connection is the sme method as the D System, but the coupler is easily distinguished by its probe, which is longer, narrower than the D System. The S System keg coupler is used by breweries such as Heineken, Becks, Amstel Light, and Pilsner Urquell.

A System Keg Coupler- Sankey Single Style Valve

This keg coupler system is commonly referred to as the “German Slider” because it slides onto the valve face. After you align the base of the coupler with the side of the keg valve, you’ll simple slide it into place on the valve. Once the coupler is engaged with the valve, you pull out the handle and “tap” the keg – beer will start flowing immediately. The A System Keg Coupler is used by breweries such as Hoegaarden, Paulaner, Spaten, and Warsteiner.

M System Keg Coupler

Recently introduced to the U.S. market. Body is the same as the German Slider, but the probe configuration is unique. It is very easy to engage: you simply slide it onto the keg valve. Once the coupler is engaged with the valve, you pull out the handle and “tap” the keg – beer will start flowing immediately. The M System Keg Coupler is used by breweries such as Schneider, Aventinus, and Einbecker.

G System Keg Coupler - Sankey Single Style Valve

This system gets its name from the English developer, Grundy. The valve face can be thought of as a circle with three sides cut off. Drop this coupler on top of the valve and twist to engage the two. Once the coupler is engaged with the valve, you pull out the handle and “tap” the keg – beer will start flowing immediately. This system is used by breweries such as Bass, Boddingtion’s, Caffrey’s.

U System Keg Coupler- Sankey Single Style Valve

This system takes its name from the English manufacturer UEC and is used by breweries such as Guinness and Harp. Match the keg coupler with the two openings in the valve, twist the coupler into place, Once the coupler is engaged with the valve, you pull out the handle and “tap” the keg – beer will start flowing immediately.

Twin Probe Keg Coupler

This system is in limited use by some regional craft breweries. This keg tap is designed for the old, two port Hoff-Stevens barrels that were common before switching to the US Sankey D System. The tap has two probes that insert into the keg—hence giving it the name ‘Twin Probe System.’ Push the coupler into the holes and then “tap” by turning the large rotating ring until it is tightly engaged.

Homebrew Keg Coupler

Two-pieces that connect to syrup (Cornelius) tank, or known as a Corny Keg by home brewers. One connection is for the gas in, the other for the liquid out.

Please see to our comprehensive keg coupler cross reference listing for additional beers. Note: Anchor has recently left the G System for their 50 liter kegs. Now all Anchor kegs will be the D System.

Determining Quality of a Keg Coupler

So, if all keg taps aren’t the same size—are they all the same quality? The quality of a keg coupler starts with its engineering, then manufacturing from casting to finish and assembly. Micro Matic couplers are engineered to fit Micro Matic keg valves which account to approximately 70% of the valves in the world.

Unfortunately, not all keg coupler and valves are created equal. Inferior keg couplers are of lower quality because don’t fit snuggly the way they should with the keg valve. A poor fit will result air contamination into the beer when tapped. This will also affect CO2 retention and keg pressure.

Another example comes to the sealing of the o-rings. In another coupler we found, the gas o-rings did not sit properly in the coupler body. This caused the pressure of the system to be off because air was being allowed in. Instead of sealing off the area, it created a problem.

In both scenarios, the customers were not only frustrated but also disappointed—for all the thought put into the right keg system, the couldn’t get their beer dispensing right leading to poor beer quality and/or loss of revenue.

Quality, Correct Sizing and Education: Where to Go Because All Keg Taps Aren’t the Same

Ensure you are getting the right coupler that is engineered for precision and quality. A low price may not lead to longevity of use in the future. Micro Matic, we strive for a quality product. In addition, knowledge is key as we strive to maintain a database of brands of draft beer and the system of valve they use in their kegs*. We’ve been dispensing draft beer for over 60 years, we are here to provide answers to your questions even after the sale.

In order to ensure you have the right combination of keg, coupler, and pump, view our "Cross Reference List."

Learn More About Keg Taps

*As there are literally tens of thousands of breweries and brands of beer available, it's simply not possible to maintain a listing of every brand of beer.

For those brands of beer not covered in our listing, we recommend simply inquiring about the system of keg coupler with the company you are purchasing your kegs from. If they do not know, they can make a quick call to the beer distributor or brewery to find out this information for you.