Keg

A 15.5 US gallon keg, cutaway

This article is about the metal container. For the drum, see music of the Virgin Islands.

A keg is a metal container (usually constructed of stainless steel) used to hold beer and other alcoholic or non-alcoholic drinks, carbonated or not carbonated, generally under pressure. The keg was introduced in the early 1960's to allow for more efficient cleaning and filling in the brewery. The essential differences between a traditional cask and a keg are that the latter has a concentrically located downtube and a valve that allows beer in and gas out when filling and vice versa when beer is dispensed. Also kegs have a simple concave bottom whilst the barrel or cask design allowed sediment to be retained in the cask. This aspect of keg design meant that all the beer in the keg was dispensed which therefore required that the beer be processed by filtration, fining or centrifuging, or some combination of these, to prevent sediment formation. Lastly, kegs have straight sides unlike the traditional barrel or cask shape. (Note: A figal mostly used for soft drinks with two valves on the top is not considered to be a keg in spite of being known as a cornelius keg.)

Formerly a keg was a small barrel made by a cooper used to transport items such as nails.

Metrology

A keg is also a standard unit of measure, named for the container described above. A full keg is a 15.5 US gallon barrel, routinely called a half-barrel; a half keg or pony keg is called a quarter-barrel and has a volume of 7.75 US gallons.

A 15.5 US gallon keg is equal to:

• 12.5 Imperial gallons (UK)
• 58.67 litres
• 100 Imperial pints (UK)
• 120 US pints
• 164 12 oz drinks

A 15.5 US gallon keg holds about the same amount of beer as six and a half, 24 pack cartons of 375ml bottles of beer.

However, beer kegs can come in many sizes:

Size (US gal)	Size (litres)	No. of 12 oz drinks	No. of 16 oz drinks	No. of 20 oz drinks	Weight of full keg (lbs)	Also known as
5	18.9	53	40	32	55-60	Home Brew / Corny Keg
5.23	19.8	56	42	33	-	Sixth Barrel
7.75	29.3	82	62	49	90	Quarter Barrel / Pony Keg
13.2	50	140	105	84	-	Import Keg
15.5	58.7	164	124	99	140 - 170	Half Barrel / Full Keg

See also barrel, firkin, kegger party.

The Mini Keg

Many beer brands are now producing a 5 liter keg. The so called "mini keg" can be obtained at most local supermarkets. The mini keg typically contains 5 liters of beer and can be conveniently stored inside the refrigerator. Some brands come with a spout and pour from the bottom via gravity; while other's such as the Heineken DraughtKeg comes pressurized, includes a tap and pours from the top.

The Pony Keg

A pony keg is a beer vessel containing 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 when purchased; needing a tap 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.

In Cincinnati, Ohio, the term "pony keg" is widely used to refer to a carry-out store that has either a drive-through passage or a loading dock to which customers can pull up and receive service. This kind of store is much less common now than it was a generation ago, but people still speak of neighborhood stores that sell mainly beer and soft drinks as "pony kegs".

UK keg supply structure

The beer vessel supply structure in the UK 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 gallon (50 liter/88 imperial pints approx) and the vast majority of 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 22 imperial gallon (100Litre/172 imperial pints approx) kegs, however due to their size they are not very popular as manual handling is extremely difficult and as a result tend to be used for large scale events and bars with high throughput.

A further keg type exists within the UK beer industry, which is a 9 imperial gallon (72 imperial pints approx) firkin for cask ales. Whilst not strictly a keg in terms of being a pressurised vessel the basic function as a receptacle for containing beer and out of which beer is dispenses is the same. The cask contains beer in a live form, in that the beer is still respiring up until the point of consumption and is not pasturised like 'keg' beers, therefore the cask is also part of the brewing and maturation process.

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 introduce bacteria inside the keg, reducing the quality of the beer. Kegs operating a party pump should be used within 18-24 hours otherwise the beer will become undrinkable. 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 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's keg cap)

Homebrewing kegs

Homebrewers often use kegs for aging, filtering, and storing beer. These are seldom the standard kegs used by major brewers to transport draught beer to wholesalers, but instead are reconditioned Cornelius kegs (colloquially known as "cornies,") many of which formerly contained soda.

These kegs are stainless steel cylinders that hold approximately 5 U.S. gallons of liquid. The keg is filled with liquid (wort or beer) via a removable hatch on the top, which is then closed and sealed. Carbon dioxide is added to pressurize the keg via an inlet port on the top and is facilitated by gently rocking the brew back and forth. Liquid is dispensed via an outlet port attached to a tube that extends to the bottom of the keg. Pin-lock and ball-lock fittings (or posts) are the two types of couplings used on the inlet and outlet ports. Older kegs tend to use pin-lock fittings, while newer kegs tend to use ball-lock fittings, though the fittings themselves are removable, serviceable, and interchangeable parts.

Kegs should not be cleaned with bleach but instead with a iodine based cleaner. The ball lock valves may be unscrewed using wrenches to allow further cleaning or replacement of O-rings or poppet valves.

Homebrewers often use 15.5 U.S. gallon kegs for boiling vessels in creating wort. The kegs are drilled for a drain at the bottom, and the top cut open to create a large stainless steel cooking kettle.

All kegs may have residual pressure, this must be vented to avoid having the valve explode and injure or kill a person as the valve shoots out. Conventional 15.5 U.S. gallon kegs have circle spring clips that can be removed to release the tap valve. Some kegs such as those used by Miller have [threaded valves http://www.kegs.com/valvegaskets.html] from Micromatic that, after venting, can be opened by lightly tapping the valve ears with a mallet or using a pry bar spun out counterclockwise. These valves then need to have the ball lock depressed while the valve head is lifted to overcome a safety. The safety prevents the valve from releasing under pressure.

Keg laws

Main article: Keg registration

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.

Games involving kegs

There are many games that involve kegs, including keg races, keg riding and keg tossing. Keg games may or may not involve drinking as an integral part of the competition; games in which the keg is carried or thrown require the use of an empty keg.

"Keg Races" may refer to a competition in which the participants must spin around a keg a number of times, and usually consume some amount of beer, or the keg may have to be carried as an extra large "baton" in an athletic race. Another variant Keg Race, (known as "Continuous Keg" in Australia) involves large teams who attempt to drink an entire keg without ever turning off the tap. Various Universities have their own variant of the Keg Race. They commonly involve purchasing two kegs and assembling a decent sized group of people. The group is divided and each is assigned to a keg. The team which finishes their keg first wins. A relatively new, and often dangerous, keg game called "Donkey Keg" involves an empty keg being rolled down a flight of stairs. Then a person must reach the top of the stairs while attempting to duck, dodge, or jump over the keg.

In America, kegs have become synonymous with college parties, which are sometimes called "keggers". These parties, however, typically only utilize the beer inside the keg for games such as beer pong and flip cup, and do not use the empty barrel in a competitive way.

Another game popular in America is the "keg stand", in which people are held upside down with the tap in their mouth, and try to consume beer for as long as possible.

Keg hiring

Keg hiring is the act of obtaining a keg for the purposes of consumption, typically at an event or party.

In the US and Australia the typical application of the keg hire is by using either a keg stored in a bucket of ice or water and/or the beer is passed through a beer line coil in ice to cool the beer. The beer is then usually dispensed directly from the keg via an attached tap where the beer is cooled by the bucket method, the latter method is usually dispensed by a tap on the side of an insulated cool box (which contains ice and the coil). The keg in this scenario is typically manually pumped using air (picnic pumps as described above) to pressurise the keg thereby maintaining carbonation and providing enough force to expel the beer from the keg. The kegs are not usually gas dispensed however for more permanent setups such as home bars this is more common due to freshness issues. Example firms from the US and Australia respectively for more up-to-date information: Mr KegsKegs on LegsAmazing Wheelie Keg

In the UK the keg hiring scene is significantly less well developed and is in its infancy, this is likely to be from a number of factors such as the relatively poor weather in contrast to the US and Australia making outdoor oriented parties less popular, also due to the restrictive nature of the industry supply structure and the pronounced UK 'pub' culture. A notable difference in the UK market however is the method of dispensing which focuses on cooling the beer primarily after it leaves the keg. Because the US and Australia tend to have high ambient temperatures, keeping the keg itself cold is essential to ensure the carbon dioxide in the beer does not separate and therefore cause the beer to fob (go frothy). The UK does not usually have the same problem as temperatures are lower. By cooling outside the keg and the limited supply of ice commonly available it is common to use under bar 'flash' coolers, these operate on the same basic principle as the cool box and the coil however are electrically powered and cool a bath of water into an ice block around the coil. This provides a very tidy and effective method for dispensing cold beer. An example of a UK keg hire firm based in Scotland: Kegless Keg Hire

Keg Storage

The latest development in keg storage is the Stack-Em (UK trade name) or the [http://www.klever.fr/ Pile Up (French Trade name) a patented system that allows kegs to be safely stacked allowing more barrels to be stored in a smaller area safely reducing the inherent risk of toppling and other congenital health and safety issues surrounding the storage of kegs. Also by reducing the size of a cellar the Stack-Em can help reduce the carbon foot print of cellars due to a smaller area being cooled.

References

• Brooks, Michael. "Space Bar". New Scientist, 22 Dec. 2000
• Keg Beer Dispensing Articles and Education
• OSHA: Beverage Delivery Ergonomics
• DOCEP: Manual handling of beer kegs
• Micromatic FAQ about Beer