Barrel (volume)

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For other uses, see Barrel (disambiguation).
"bbl" redirects here. For other uses, see BBL (disambiguation).

The barrel is the name of several units of volume:

  • Oil barrel: 42 US gallons, 158.9873 litres,[1] or 34.9723 Imperial (UK) gallons.
  • UK beer barrel: 36 UK gallons (163.7 litres).
  • US beer barrel: 31 US gallons (117.3 litres), the result of tax law definitions.
  • US non-beer liquid barrel: 31½ US gallons (119.2 litres), or half a hogshead.
  • US dry barrel: 105 dry quarts (115.6 litres).
  • Somali water barrel: 200 litres - used in Horn of Africa to measure water and diesel.

Contents

[edit] Oil barrel

Modern day steel drum
Modern day steel drum

The standard oil barrel is used in the United States as a measure of crude oil and other petroleum products. Elsewhere, oil is more commonly measured in cubic metres (m3) or in tonnes (t), with tonnes often being used by companies that ship most of their oil by sea.[citation needed]. International companies listed on American stock exchanges tend to convert their oil production volumes to barrels for global reporting purposes, and those listed on European exchanges tend to convert their production to tonnes.

The wooden oil barrel of the late 1800s is different from the modern day 55-gallon steel drum (known as the 44-gallon drum in Britain and the 200-litre drum in Australia). The 42-US gallon oil barrel is a unit of measure, and is no longer used to transport crude oil - most petroleum is moved in pipelines or oil tankers.

The 42 US gallon size of barrel as a unit of measure is largely confined to the American oil industry, since other sizes of barrel were used by other industries in the United States, and nearly all other countries use the metric system. Many smaller or poorer countries that do not have the technical expertise to develop their own domestic oil industry standards use the American oil barrel for the sake of convenience. It is important to note that not all contents of a barrel of oil may be used for purposes like gasoline. Rather, it must be refined first which leads to fewer gallons of oil than you started with.

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 different shapes and sizes for beer, fish, molasses, turpentine, etc. Both the 42-US gallon barrels (based on the old English wine measure, the tierce (159 litres) and the 40-U.S.-gallon (151.4-litre) whiskey barrels were used. 45-gallon barrels were also in common use. The 40-gallon whiskey barrel was the most common size used by early oil producers, since they were readily available at the time.[2]

The origins of the 42-gallon oil barrel are obscure, but some historical documents indicate that around 1866 early oil producers in Pennsylvania came to the conclusion that shipping oil in a variety of different containers was causing buyer distrust. They decided they needed a standard unit of measure to convince buyers that they were getting a fair volume for their money. They agreed to base this measure on the more-or-less standard 40-gallon whiskey barrel, but added an additional two gallons to ensure that any measurement errors would always be in the buyer's favor as an additional way of assuring buyer confidence (The same principle as behind the baker's dozen and some other long units of measure.) By 1872 the standard oil barrel was firmly established as 42 US gallons.[3]

The abbreviations 1 Mbbl and 1 MMbbl have historically meant one thousand and one million barrels respectively. They are derived from the Latin "mille" meaning "thousand" rather than the Greek "mega". However, this can cause confusion with the SI abbreviation for Mega- (and in non-industry documentation Mbbl, "megabarrel", can sometimes stand for one million barrels).

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. Some sources claim that "bbl" originated as a symbol for "blue barrels" delivered by Standard Oil in its early days; this is probably incorrect because there are citations for the symbol at least as early as the late 1700s, long before Standard Oil was founded.[4]

[edit] See also

[edit] References

  1. ^ B. N. Taylor. B.8 Factors for Units Listed Alphabetically - Section B. Guide for the Use of SI units. NIST. Retrieved on 2007-10-18.
  2. ^ Judith O. Etzel (2008). The 42 Gallon Barrel [History]. The 150th Anniversary of Oil. Oil Region Alliance of Business, Industry and Tourism. Retrieved on 2008-10-11.
  3. ^ Barrel (of petroleum). Units and Systems of Units. Sizes, Inc (2004). Retrieved on 2008-10-11.
  4. ^ Russ Rowlett. How Many? A Dictionary of Units of Measurement. The University of North Carolina at Chapel Hill. Retrieved on 2007-10-18.

[edit] External links