Grain (mass)

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A grain (symbol: gr) is a unit of mass equal to exactly 64.79891 milligrams, in all English mass and weight systems (avoirdupois, Apothecaries’ and troy).[1]

An avoirdupois ounce is equal to 437.5 grains, whereas a troy ounce is equal to 480 grains. With the differing number of ounces in their respective pounds, an avoirdupois pound is 7,000 grains, whereas a troy pound is 5,760 grains. There have been other English pounds with round sizes in grains.[1]

A metric or pearl grain is equal to 50 milligrams or 1⁄4 of a carat as used in pearl and diamond nomenclature.

Originally, a grain was the weight of a grain seed from the middle of an ear of barley; 64 wheat berries were set to weigh as much as 45 barleycorns (i.e., a wheat kernel was conventionally considered to be 45⁄64 of the grain used as a unit of mass). (A barleycorn was also 1⁄3 inch as a unit of length). A grain based on the weight of a wheat grain seed was used as the basis for the first English coins.

[edit] Usage

Grains are currently used in the United States and Canada to measure the mass of bullets and gunpowder, and scales for handloading measure in grains; bullets are generally measured in increments of 1 grain, gunpowder in increments of 0.1 grains.[2][3] Grains are used to weigh the tools involved in the sport of fencing, including the foil. Grains are used to measure arrows, and arrow parts in archery. Grains are also used in environmental permitting to quantify particulate emissions. Grains are used to measure the amount of moisture per cubic foot of air, a measure of absolute humidity.[4]

[edit] See also

[edit] References

  1. ^ a b NIST General Tables of Units of Measurement. United States government. Retrieved on 2007-12-01.
  2. ^ International Practical Shooting Confederation. IPSC Canada (Jan 4, 2004). Retrieved on 2007-11-30.
  3. ^ UNITED STATES MARINE CORPS BOO2710 Student Handout M249 SQUAD AUTOMATIC WEAPON (SAW) (.Doc and HTML). Retrieved on 2007-11-30.
  4. ^ AA - AB Glossary. United States Department of the Interior. Retrieved on 2007-12-01.
ast:Granu (unidá)

cs:Grain de:Gran (Einheit) et:Graan es:Grano (unidad de masa) fr:Grain (unité) he:גריין nl:Grein (gewicht) ja:グレーン no:Nürenberggran pt:Grão (medida) ru:Гран sl:Grain

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