A barrel is one of several units of volume applied in various contexts; there are dry barrels, fluid barrels (such as the U.K. beer barrel and U.S. beer barrel), oil barrels, and so forth. For historical reasons the volumes of some barrel units are roughly double the volumes of others; volumes in common use range approximately from . In many connections the term is used almost interchangeably with barrel.
Since medieval times the term as a unit of measure has had various meanings throughout Europe, ranging from about 100 litres to about 1,000 litres. The name was derived in medieval times from the French , of unknown origin, but still in use, both in French and as derivations in many other languages such as Italian, Polish, and Spanish. In most countries such usage is obsolescent, increasingly superseded by SI units. As a result, the meaning of corresponding words and related concepts (vat, cask, keg etc.) in other languages often refers to a physical container rather than a known measure.
In the international oil market context, however, prices in United States dollars per barrel are commonly used, and the term is variously translated, often to derivations of the Latin / Teutonic root fat (for example vat or Fass).
In other commercial connections, barrel sizes such as beer keg volumes also are standardised in many countries.
Dry goods in the US
US dry barrel: Defined as length of stave , diameter of head , distance between heads , circumference of bulge outside measurement; representing as nearly as possible 7,056 cubic inches; and the thickness of staves not greater than (diameter ≈ ). Any barrel that is 7,056 cubic inches is recognized as equivalent. This is exactly equal to . US barrel for cranberries Defined as length of stave , diameter of head , distance between heads , circumference of bulge outside measurement; and the thickness of staves not greater than (diameter ≈ ). No equivalent in cubic inches is given in the statute, but later regulations specify it as 5,826 cubic inches. Some products have a standard weight or volume that constitutes a barrel: Cornmeal, Cement (including Portland cement), or Sugar, Wheat or rye flour, or Lime (mineral), large barrel, or small barrel Butter and cheese in UK, Salt,
Fluid barrel in the US and UK
Fluid barrels vary depending on what is being measured and where. In the UK a beer barrel is . In the US most fluid barrels (apart from oil) are (half a hogshead), but a beer barrel is . The size of beer kegs in the US is based loosely on fractions of the US beer barrel. When referring to beer barrels or kegs in many countries, the term may be used for the commercial package units independent of actual volume, where common range for professional use is 20–60 L, typically a DIN or Euro keg of 50 L.
History
Richard III, King of England from 1483 until 1485, had defined the wine puncheon as a cask holding 84 wine gallons and a wine tierce as holding 42 wine gallons. Custom had made the 42 gallon watertight tierce a standard container for shipping eel, salmon, herring, molasses, wine, whale oil, and many other commodities in the English colonies by 1700. After the American Revolution in 1776, American merchants continued to use the same size barrels.
Oil barrel
Definitions
In the oil industry, one barrel (unit symbol bbl) is a unit of volume used for measuring oil defined as or .
According to the American Petroleum Institute (API), a standard barrel of oil is the amount of oil that would occupy a volume of exactly at reference temperature and pressure conditions of and . This standard barrel of oil will occupy a different volume at different pressures and temperatures. A standard barrel in this context is thus not simply a measure of volume, but of volume under specific conditions. ()