A keg is a small barrel
A barrel or cask is a hollow cylindrical container, traditionally made of vertical wooden staves and bound by wooden or metal hoops. Traditionally, the barrel was a standard size of measure referring to a set capacity or weight of a given commodity. A small barrel is called a keg.For example, a...


Traditionally, a wooden keg is made by a cooper
Cooper (profession)
Traditionally, a cooper is someone who makes wooden staved vessels of a conical form, of greater length than breadth, bound together with hoops and possessing flat ends or heads...

 used to transport items such as nails
Nail (engineering)
In woodworking and construction, a nail is a pin-shaped, sharp object of hard metal or alloy used as a fastener. Formerly wrought iron, today's nails are typically made of steel, often dipped or coated to prevent corrosion in harsh conditions or improve adhesion...

, gunpowder
Powder Keg
A powder keg is a barrel of gunpowder. The powder keg was the primary method for storing and transporting large quantities of black powder up until the 1870s and the adoption of the modern cased bullet...

., and a variety of liquids.

More recently, a keg is often constructed of aluminum or steel. It is commonly used to store, transport, and serve beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...

. Other alcoholic
Alcoholic beverage
An alcoholic beverage is a drink containing ethanol, commonly known as alcohol. Alcoholic beverages are divided into three general classes: beers, wines, and spirits. They are legally consumed in most countries, and over 100 countries have laws regulating their production, sale, and consumption...

 or non-alcoholic drinks, carbonated or non-carbonated, may be housed in a keg as well. Such liquids are generally kept under pressure.

Beer keg

Beer kegs are made of stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....

, or less commonly, of aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

. A keg has a single opening on one end. A tube called a "spear" extends from the opening to the other end. There is a self-closing valve
A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...

 that is opened by the coupling
A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. Couplings do not normally allow disconnection of shafts during operation, however there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded.The...

 fitting which is attached when the keg is tapped. There is also an opening at the top of the spear that allows gas (usually carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

) to drive the beer out of the keg. The coupling fitting has one or two valves that control the flow of beer out of and gas into the keg. The keg must be in the upright position, that is, with the opening on top for the beer to be dispensed. Kegs can be contrasted to cask
Peripheral plasma membrane protein CASK is a protein that in humans is encoded by the CASK gene. This gene is also known by several other names: CMG 2 , calcium/calmodulin-dependent serine protein kinase 3 and membrane-associated guanylate kinase 2.-Genomics:This gene is located on the short arm of...

, which have two or more openings and no spear.


Historically a beer barrel was a standard size of 50 gallons, as opposed to a wine barrel at 32 gallons, or an oil barrel at 42 gallons. Over the years barrel sizes have evolved and breweries throughout the world use different sized containers. Even when the content capacity of two kegs are equal - e.g. metricized
Metrication refers to the introduction and use of the SI metric system, the international standard for physical measurements. This has involved a long process of independent and systematic conversions of countries from various local systems of weights and measures. Metrication began in France in...

 to 50 liter - the keg shape and keg tap system may differ heavily.

U.S. keg sizes

Most U.S. brewers sell beer in 1/2 barrels between 14 and 16 gallons, 1/4 barrels between 7 and 8 gallons, and 1/6 barrels between 5 and 6 gallons.

Since keg sizes are not standardized, the keg cannot be used as a standard unit of measure
Unit of measure
Unit of measure may refer to:* Units of measurement for relevance to weights and measures* Unit of account for relevance in economics* Unit of Measure , a 2000 album by Tony Rice...

 for liquid volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....

s. This size standard varies from country to country and brewery to brewery with many countries using the metric system
Metric system
The metric system is an international decimalised system of measurement. France was first to adopt a metric system, in 1799, and a metric system is now the official system of measurement, used in almost every country in the world...

 rather than U.S. gallons.

A full keg is a 15.5 U.S. gallon barrel, routinely called a half-barrel. A Quarter Barrel has a volume of 7.75 U.S. gallons. Generally a keg is a vessel smaller than a barrel; thus, it is 30 gallons or smaller.

In the U.S. the terms half-barrel and quarter-barrel are derived from the fact that a U.S. beer barrel is legally defined as being equal to 31 U.S. gallons (note that this is not the same volume as some other units commonly known as barrels). A 15.5 U.S. gallon keg is also equal to:
  • 12.7 Imperial gallons
  • 58.67 liter
    - External links :*...

  • 103.25 Imperial pints
  • 124 U.S. pints
    The pint is a unit of volume or capacity that was once used across much of Europe with values varying from state to state from less than half a litre to over one litre. Within continental Europe, the pint was replaced with the metric system during the nineteenth century...

  • 165 twelve fluid ounce
    Fluid ounce
    A fluid ounce is a unit of volume equal to about 28.4 mL in the imperial system or about 29.6 mL in the US system. The fluid ounce is distinct from the ounce, which measures mass...

     (U.S. measure) drinks
  • About 90 bombers (A 22oz Bottle)
  • About 6.88 24-unit cases
    Case (goods)
    A case of some merchandise is a collection of items packaged together. In the United States, typically a standard case contains a certain number of items depending on what the merchandise is. For consumer foodstuffs such as canned goods, soda, cereal and such, a case is typically 24 items,...

     of 12 fl oz cans.
  • About 5.5 30-racks of 12 fl oz cans.
  • 1,984 fluid ounces (U.S.)

However, beer kegs can come in many sizes:
Size (US gal
The gallon is a measure of volume. Historically it has had many different definitions, but there are three definitions in current use: the imperial gallon which is used in the United Kingdom and semi-officially within Canada, the United States liquid gallon and the lesser used United States dry...

Size (liter
- External links :*...

No. of 12 fl oz drinks No. of 16 fl oz drinks No. of 20 fl oz drinks Weight of full keg (lb) Also known as
1.32 5 14 10.6 8.5 - Mini Keg / Bubba (single-use/recyclable)
5 18.9 53 40 32 55-60 Soda syrup / Corny Keg
Cornelius kegs
A cornelius keg is a metal container originally used by the soft drink industry, and can be used to store and dispense Homemade Sodas and home brewed beer...

 / Home Brew
5.23 19.8 56 42 33 58-60 Sixth Barrel / Torpedo Keg
6.6 25 70 50.25 42 - "Half Barrel" (Europe)
7.75 29.3 82 62 49 90 Quarter Barrel / Pony Keg
9.2 35.15 99 74 59 - Wall ("99 Bottles of Beer")
13.2 50 140 105 84 - Import Keg (standard European "Barrel")
15.5 58.66 165.33 124 99 140 - 170 Half Barrel / Full Keg

DIN-keg and Euro-keg

In European countries the most common keg size is 50 liters - this includes the UK with its non-metric keg system where the standard keg of 11 imperial gallons is almost exactly the size of 50 liters in the metric system. The German DIN
Deutsches Institut für Normung
is the German national organization for standardization and is that country's ISO member body. DIN is a Registered German Association headquartered in Berlin...

 6647-1 and DIN 6647-2 have also defined Kegs in the sizes of 30 and 20 liters. A newer Euro regulation defines 50, 30, 25 and 20 liters where the Keg shape is usually thicker but less tall than the German keg specifications.
content DIN 6647-1/-2 DIN-Keg Diameter Euro-Keg Euro-Keg Diameter
50 l (13.21 gal) 600 mm (high) 381 mm (ø steel keg) 532 mm (high) 408 mm (ø steel keg)
30 l (7.93 gal) 400 mm (high) 381 mm (ø steel keg) 365 mm (high) 408 mm (ø steel keg)
25 l (6.61 gal) - - 327 mm (high) 395 mm (ø steel keg)
20 l (5.28 gal) 310 mm (high) 363 mm (ø steel keg) 216 mm (high) 395 mm (ø steel keg)

In some areas it is common to refer to the size not in liters but in beers. In areas where the standard beer size is 0.5 liters (e.g. Germany) that makes a 50 liter keg to be 100 beers.

Specifications for a U.S. 1/2 barrel keg

Accepted specifications for a standard keg are:
Height of keg 23.3 inches
Diameter of keg 16.1–17.15627 inches
Contents 1984.0 U.S. fluid ounces
15.5 U.S. gallons
12.91 imp. gallons
58.7 liters
Full keg weight 160.5 pounds (72.8 kg)
Empty keg weight 29.7 pounds (13.5 kg)
Beer weight 130.8 pounds (59.3 kg)
24×12 fl oz case equivalent 6.9 cases
12 fl oz servings 165.6
16 fl oz (1 U.S. pint) servings 124

Tapping a keg

There are two different types of tapping equipment that are available for kegs, party pumps and gas taps. Party pumps utilize outside air, which introduces bacteria inside the keg and will certainly introduce oxygen, which will cause the beer to oxidize, creating a wet cardboard taste, therefore reducing the quality of the beer. Kegs operating a party pump should be used within 18–24 hours otherwise the beer may become unpalatable. Gas pumps normally use CO2, but certain brewers require a mix of other gases (Guinness requires 25% CO2 and 75% nitrogen). Gas pumps can preserve a keg up to 120 days with proper refrigeration.

As with any pressurized container, a keg can cause injury, even at normal operating pressure, whether with compressed air
Pneumatics is a branch of technology, which deals with the study and application of use of pressurized gas to effect mechanical motion.Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or compressed inert gases...

 or carbon dioxide:
"The tapping system and pressure regulator both should be equipped with a pressure relief (blow off) device. If you are not familiar with tapping equipment, consult your retailer..." (printed on an Anheuser-Busch
Anheuser-Busch Companies, Inc. , is an American brewing company. The company operates 12 breweries in the United States and 18 in other countries. It was, until December 2009, also one of America's largest theme park operators; operating ten theme parks across the United States through the...

's keg cap)

Generally, in the US and Australia kegs or the beer coil are kept in a bucket of ice and/or water, in order to keep the beer cool.

Cornelius keg

A cornelius keg (also known as a Corney or soda keg) was originally used by the soft drink
Soft drink
A soft drink is a non-alcoholic beverage that typically contains water , a sweetener, and a flavoring agent...

 industry, now commonly used to store and dispense beer
Beer is the world's most widely consumed andprobably oldest alcoholic beverage; it is the third most popular drink overall, after water and tea. It is produced by the brewing and fermentation of sugars, mainly derived from malted cereal grains, most commonly malted barley and malted wheat...

, especially homebrewed.

Cornelius kegs were originally made by the IMI Cornelius Company. Since the arrival of newer technology such as Bag-In-Box
In packaging, a bag-in-box or BiB is a type of container for the storage and transportation of liquids. It consists of a strong bladder , usually made of several layers of metallised film or other plastics, seated inside a corrugated fiberboard box. The bag is supplied to the 'filler' as an empty...

 (BIB) packages soft drink bottlers have mostly abandoned their Cornelius kegs, often making them available to hobbyists

Mini keg

The mini keg is a 5-liter keg produced for retail sales. Some brands come with a spout and pour from the bottom via gravity, while others may use a low cost pressurized tap. Mini kegs are typically not returned to the manufacturer for cleaning and refilling. The kegs, being made of aluminum, may be recycled.

In Canada, Molson
Molson-Coors Canada Inc. is the Canadian division of the world's fifth-largest brewing company, the Molson Coors Brewing Company. It is the second oldest company in Canada after the Hudson's Bay Company. Molson's first brewery was located on the St...

 brewery dubbed the mini keg "Bubba". This name has now been genericized to generally apply to all 5-liter mini kegs in Canada. This might cause confusion, as a company called Bubba Keg is established in the U.S., and appears to not be associated with Molson.

Beer ball

Another type of mini keg is the "beer ball" or the "party ball", a disposable plastic ball that usually holds around 5.2 gallons, roughly the equivalent of 55 twelve-ounce
The ounce is a unit of mass with several definitions, the most commonly used of which are equal to approximately 28 grams. The ounce is used in a number of different systems, including various systems of mass that form part of the imperial and United States customary systems...

 beers, though they can also be found in a smaller 3.8 gallon size. Like kegs, it is necessary to tap
Beer tap
A beer tap is a valve, specifically a tap, for controlling the release of beer. While in other contexts, depending on location, a "tap" may be a "faucet", "valve" or "spigot", the use of "tap" for beer is almost universal. This may be because the word was originally coined for the wooden valve in...

 the ball before the beer inside can be served.

Oneway kegs

Another type of keg is the "oneway keg" which is now available in most global markets. Ecokeg, an Australian invention, provides one way kegs that are mostly recyclable and much lighter than steel kegs. They provide kegs in 30L and 38L sizes only with two outer options plastic or reinforced cardboard BoxKeg. The PubKeg, manufactured by Rehrig Pacific Company, is another oneway keg available on the market. The PubKeg comes in a 20 L size and is completely recyclable. Other oneway kegs on the market are keykeg and Schaeffer aluminium keg.

Quarter Barrel (Pony keg)

A quarter barrel, more commonly known as pony keg is a beer vessel containing approximately 7.75 U.S. gallons (29.33 liters) of fluid. It is half the size of the standard beer keg and equivalent to a quarter of a barrel. It will serve roughly 82 twelve ounce cups. The shape of a pony keg resembles that of a full-sized keg, while being much easier to move manually. However, it shares many inconveniences with the bigger kegs, such as: often requiring a deposit
Deposit account
A deposit account is a current account, savings account, or other type of bank account, at a banking institution that allows money to be deposited and withdrawn by the account holder. These transactions are recorded on the bank's books, and the resulting balance is recorded as a liability for the...

 when purchased; needing a tap
Beer tap
A beer tap is a valve, specifically a tap, for controlling the release of beer. While in other contexts, depending on location, a "tap" may be a "faucet", "valve" or "spigot", the use of "tap" for beer is almost universal. This may be because the word was originally coined for the wooden valve in...

 to serve the contents; and posing difficulties in determining the amount of beer remaining (weighing the keg or observing its buoyancy are common techniques). Despite this, a pony keg can be a cheap way to provide beer for a medium-sized party.

Sixth Barrel

A sixth barrel keg is becoming the choice for many establishments and breweries that wish to use kegs smaller than a half barrel. The sixth barrel kegs are the same size and volume as a Cornelius keg. The small foot print of a sixth barrel allows retailers have a greater variety of beer in a small space. This size keg is quickly replacing the quarter barrel size which has the same foot print as a half barrel keg. Other than size the sixth barrel kegs are very similar to their full-sized counterparts. A stainless Micromatic brand sixth barrel keg weighs approximately 14-15 pounds (6.3-6.8kg) when empty, and approximately 58-60 pounds (26.3-27.2kg) when full.

UK and Irish keg supply structure

The beer vessel supply structure in the UK and Ireland is quite different, whilst the couplers for kegs have been largely standardised to sankey, grundy and interbrew, a couple of others exist such as UEC and U-Type; however these are much less common. The kegs themselves are either steel or increasingly the more lightweight aluminum variety. The standard keg size is 11 imperial gallons (50 liter/88 imperial pints approx) and the vast majority of keg beers are supplied in this keg size. There are also smaller 30 liter (54 imperial pints approx) kegs usually reserved for more specialist and or premium European beers.

A number of manufacturers also produce 18 imperial gallon (approximately 82 liters/144 imperial pints) and 22 imperial gallon (approximately 100 liters/172 imperial pints) kegs, however owing to their size they are not so popular as manual handling is seen by some to be difficult, and as a result they tend to be used only for large scale events and bars with high throughput.

For bars that sell an excessive volume of beer there is the 36 imperial gallon (150 liter/260 imperial pint) keg, however due to its very large size few people can move them making it an impractical choice.

Keg laws

In the U.S. as of 2005, there are 21 states and numerous localities that have keg registration laws. The laws vary widely in terms of whom they target, what their intended purpose is, and how strongly they are enforced. Most major breweries now use internally speared kegs.

Scotland requires a dye to be used in drip trays to prevent the resale of beer from the drip tray; many health departments elsewhere still recommend its use.


  • Soroka, W, "Fundamentals of Packaging Technology", IoPP, 2002, ISBN 1-930268-25-4
  • Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.