Kegs themselves are considered either open system or closed keg systems.
Open-keg systems are characterized by their barrel shape and bunghole on the side by which the interior can be readily accessed without extracting the valve body or spear. The bunghole is closed by a wooded or plastic bung plug. Hoff-Stevens kegs and the almost-extinct Golden Gate kegs are two examples of open-keg systems. These kegs are frequently stored and shipped on their side because of their barrel shape, though they must be upright when served. Hoff-Stevens kegs are larger in circumference than the American Sankey kegs and are without handles, making them more difficult to move and stack than Sankey kegs.
Closed-keg systems are identified by their typically straight sides, with a rim, called a chime, on each side (Figure 19.1). The top chime has integrated handles for easy handling. The top also contains a concentric valve fitting in the center allowing for easy cleaning and filling by automated systems. Draught accounts prefer closed-keg systems over open-keg systems for several reasons including ease of tapping, ease of storage and handling, and the improved profit margin due to the reduction of beer loss that is commonly associated with older keg styles. Unlike open-keg systems, closed-keg systems can be accessed only through the valve housing.
The newer, more common single-valve keg (SVK) or “Sankey” keg (Figure 19.2) has a valve arrangement that consists of a stainless steel, rod housing, called a combination fitting that is permanently installed into the top center of the keg and sealed with a spring-loaded check ball. The tapping device, or coupler, fits into the lug housing of the valve.
Kegs come in many shapes and sizes. The predominant keg packages are the European-barrel keg, the half-barrel keg, slim-quarter keg, the quarter-barrel keg, and the sixth-barrel keg. The table below compares five common types of kegs, including how much beer they hold, their overall size, shape, dimensions, as well as their most common uses and nicknames. The vast majority of the kegs are made from stainless steel. Those most common to brewing are 304 and 316 stainless steel which have very good corrosion-resistance properties and are easily welded.
Click on the following topics for more information on kegging beer.