Barrel (unit)
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- See Barrel (disambiguation) for other uses.
The barrel is the name of several units of volume:
- Oil barrel: 42 U.S. gallons, 158.9873 litres,[1] or 34.97231575 Imperial (UK) gallons.
- UK beer barrel: 36 UK gallons (163.7 litres).
- US beer barrel: 31 U.S. gallons (117.3 litres), the result of tax law definitions.
- US non-beer liquid barrel: 31.5 U.S. gallons (119.2 litres), or half a hogshead.
- US dry barrel: 105 dry quarts (115.6 litres).
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[edit] Oil barrel
This unit is used in North America for crude oil or other petroleum products. Elsewhere oil is more commonly measured in cubic metres (m³) and less commonly in tonnes (t).[citation needed] Natural gas is measured differently.
The measurement originated in the early Pennsylvania oil fields. In the early 1860s, when oil production began, there was no standard container for oil, so oil and petroleum products were stored and transported in barrels of all different shapes and sizes (barrels for beer, fish, molasses, turpentine, etc.). Both the 42-U.S.-gallon barrels (based on the old English wine measure, the tierce) and the 40-U.S.-gallon (151.4-litre) whiskey barrels were used. The 40-gallon barrel was the most common size early on, but companies often underfilled them.
However, the Standard Oil Company shipped its oil in barrels that always contained exactly 42 U.S. gallons. Customers began to refuse to accept anything less and by 1866 the oil barrel was standardised at 42 U.S. gallons. This was 2 gallons per barrel more than the 40-gallon standard used by many other industries at the time.[citation needed] The extra 2 gallons was to allow for evaporation and leaking during transport (most barrels were made of wood).
The Standard Oil monopoly was broken up into 34 different companies in 1911. Oil has not been shipped in barrels for a very long time[2] but the "blue barrel" is still the standard unit for measurement and pricing of oil in the U.S. today.
The abbreviations 1 Mbbl and 1 MMbbl are generally accepted to mean one thousand and one million barrels respectively. (In non-industry documentation Mbbl, "megabarrel", can sometimes stand for one million barrels.) It is sometimes claimed that since Standard Oil painted its barrels blue, it was abbreviated "bbl" for "blue barrel". There is, however, some dispute over this.
The "b" may have been doubled originally to indicate the plural (1 bl, 2 bbl), or possibly it was doubled to eliminate any confusion with bl as a symbol for the bale (see above). Note: Some web sites are claiming that "bbl" originated as a symbol for "blue barrels" delivered by Standard Oil in its early days; this is almost certainly incorrect because there are citations for the symbol at least as early as the late 1700s, long before Standard Oil was founded.[3]
[edit] References
- ^ NIST Guide to SI Units - B.8 Factors for Units Listed Alphabetically - Section B
- ^ Slate Does Oil Really Come in Barrels?
- ^ Russ Rowlett How Many? A Dictionary of Units of Measurement
