BARRELS, KEGS, CASKS, VATS, TANKS...
It is believed that wooden barrels or casks may have been made as long as 2,000 years ago by the Celtics. These wooden containers were adopted by the Gauls and then by the Romans, replacing clay and ceramic containers known as amorphaes, which would break more easily and were somewhat awkward to move. In comparison, the barrels broke less often and their round shape allowed them to be rolled, making them easier to move. They could also be stacked. Such barrels or casks were originally used for food, liquids, gun powder and other purposes. The use of tar allowed these vessels to be waterproof. They were used for wine by the Romans, and possibly beer. The oldest surviving beer barrel used in Europe dates from the 1500s, over 500 years ago. The making of barrels is known as cooperage, and people working in this trade are known as coopers.
COMPONENTS OF OAK BARRELS, KEGS...
There are several different parts to a wood barrel or cask. The main component are wood "staves" which are held in place by galvanized metal strips or bands called "hoops." A diagram showing the components of a barrel is on the side. Not shown on the diagram is that there can also be a hole on the head near the croze of chime for a spigot or valve to drain liquids from the barrel when it rests on its side. The head can also contain a hole off-centered on that allows for liquid to be accessed when the barrel is upright (as shown) with a metal tube that extends to the bottom connected to a handle and spout, and with pressure to draw out the liquid possibly from the assistance of CO2 canister or cartridge. An example of this is shown in a photo below.
Often the above terms barrels, casks, kegs, vats, etc., are used interchangeably. They can also be called vessels. Technically, however, there are some differences among the terms as explained below.
A barrel is a standard measurement that can be dry or fluid, and it can vary in size and weight depending upon the product. The size of barrels varies between countries. For instance, in the U.S. the standard beer barrel is 31 gallons, but in the UK a beer barrel is slightly larger. The capacities and sizes of barrels for other alcoholic beverages is greater, with a bourbon barrel containing 52 gallons, a wine barrel ordinarily with 59 gallons and a cognac barrel with 79 gallons. Usually wood barrels in the U.S. are made of white oak, whereas, in Europe barrels are made of French oak. The materials are similar, but the French Oak requires more time to treat and prepare for barrel making. Barrels for bourbon are charred on the inside and never reused for making that liquor. However, micro-breweries often age and flavor beer using these once used bourbon barrels.
Wood barrels were used for beer and ale in America beginning with the first settlers through the 1940s. In the early 1940s metal barrels were introduced and wood barrels were gradually phased out by the early 1950s. Metal beer barrels and kegs began to replace those made of wood in the later 1940s, mostly after WWII. The metal barrels were easier to clean, more sanitary and required less maintenance. This allowed the beer's taste characteristics to be more consistent.
Most of the photos above show how beer barrels were stored, filled, distributed and washed at the Bavarian Brewing Co. in the lat 1940s. Above upper left is a wooden Student Prince barrel from the 1930s or 1940s from Heidelberg Brewing Co., which Bavarian Brewing Co. acquired in 1949. To its right are examples of similar wood barrels that are stacked near the Wash Room. The top right photo shows barrels entering the Wash Room of the brewery.The interior picture on the lower left shown the Rack Room where wood barrels being filled in the foreground, along with metal barrels are in the background. In lower middle photo, a customer is buying a barrels of beer from Bavarian that are being rolled out to his vehicle. The last photos on the lower row above show a beer tap, which was was inserted on the "head" or top of a barrel. The close up photo of the middle section of the tap indicates it was made for the Bavarian Brewing Co.
Today, craft barrel-aging breweries sometimes use wood barrels (or casks) that were previously used for either whiskey or wine. Aging beer in former wood whiskey containers is usually done only once or twice. Whereas, wine barrels can be used for flavoring beer much longer. In order for craft breweries to use such barrels, it is normally necessary to obtain them directly after they are used by whiskey or wine makers and before the barrels "dry out." The normal cleaning process for the interior of barrels by craft brewers can involve steam, which may also reduce some of the flavor the barrels impart, or soaking them in hot water. The aging process for beer can take months to up a few years. Barrel beer can age with different taste characteristics, and is sometimes blended with other barrels for fuller and more balanced qualities, as is wine. Craft breweries using wood barrels do so to obtain more varied types of beer with different characteristics. This is a major difference between craft breweries and the largest breweries. Even though the large brewers continue to mostly produce a standard tasting lager beer, they are providing different variations of their main beers, and new varieties, in order to better compete with microbreweries and to satisfy the more varied tastes of beer consumers.
A keg is only a portion of a barrel and they come in three principal sizes; half barrels, quarter barrels and sixth barrels. However, there are a couple versions of each as described and shown below.
A Half Barrel Keg contains 15.5 gallons.
A European Keg (Import or 50 Liter Keg) contains somewhat less than an American Keg, with 13.2 gallons.
A Tall Pony Keg (Slim Quarter or Tall Quarter Keg), contains 7.75 gallons.
A Short Pony (Stubby or Quarter Keg) has a rather short height, but also contains 7.75 gallons.
Incidentally, a Pony Keg is also a colloquial term for a drive-thru liquor store, primarily only in the Cincinnati area.
A Torpedo (Sixth Barrel or Sixtel Keg), contains 5.16 gallons.
A Cornelius Keg (Corney Keg or Soda Keg) is just slightly smaller with 5.0 gallons.
This keg is also used by soda companies, and reflected by one of its names.
A Mini Keg (or Bubba Keg) is the smallest of the kegs with only 1.32 gallons. (It is not shown below.)
The diagram above is supplied courtesy of Barfly Staff Monitoring Service.