Draft beer referred to in contrast to the bottles or cans of beer which the barrel ( beer barrel ausgeschenkte) beer . In a broader sense, the term now also includes beers that are served from stainless steel tanks. The breweries usually fill 30 or 50 liter barrels. But there are also smaller sizes (party kegs) for private consumption. Until the 1970s, barrels with a capacity of 100 liters were also common. At major events, 200 liter kegs (see Hirsch (beer keg) ) are occasionally used.
When serving, the beer is transferred from the kegs to glasses or mugs using special tap systems . By using compensator taps , fine-pored foam crowns can now be achieved, so that the draft beer does not reach room temperature and loses carbon dioxide . Carbon dioxide is one of the propellants used in the dispensing systems .