1、FEDEIWL STANDARD 376BdIPREFERREDMETRIC UNITSFORGENERAL USEBY THEFEDERALGOVERNMENTI*9;skQmmAL SEHvt= ADMINlsTRmoNCopyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-(This pag
2、e intentionally left blank.)Copyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fed-Std-376B.Foreword.I .8This standard was developed by the Standards and Metric PracticesSu
3、bcommittee of the Metrication Operating Committee, which operates underthe Interagency Council on Metric Policy. It is the basic Federal standard thatlists metric units recommended for use throughout the Federal government,and is specified in the Federa/ Standardization Handbook, issued by theGenera
4、l Services Administration in accordance with 41 CFR 101-29. Beforeissue, it was coordinated with the departments and agencies of theInteragency Council on Metric Policy.The General Services Administration has authorized the use of this Federalstandard by all Federal agencies.Civilian Agency Coordina
5、ting Ati”vity:Federal Supply Service, General Services AdministrationMilitary Agency Coordinating Activity:Standardization Program, Office of the Assistant Secretary(Production and Logistics), Department of DefensePreparing Activity:Metric Program, National Institute of Standards and Technology,Tech
6、nology Administration, Department of CommerceChangesWhen a federal agency determines that there is a need for a revision of thisstandard, a written request for revision should be submitted to the GeneralServices Administration, Federal Supply Service. Environmental andEngineering Policy Division (FC
7、RE), Washington, DC 20406, The request shallinclude data that support the proposed change. The Metric Program, NationalInstitute of Standards and Technology, as custodian of this standard, willcoordinate all proposed changes with the Metrication Operating Committee.Copyright National Institute of St
8、andards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-(This page intentionally left blank.)Copyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo repro
9、duction or networking permitted without license from IHS-,-,-Fed. Std. 376B.1.2.3.4.50Table of ContentsScope . . . . . . . . . . C. . . . . C CAuthoritative Document . . . . . . . . . . . . . . .Definitions . . . . . . . . . . . . . . . . . . . . . . . . .General Requirements . . . . . . . . . . . .
10、 . . . . .Detailed Requirements . . . . . . . . . . . . . . . .11118Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . 21Index . . . . . . . . . . . . . . . . . . . . . 23.Ii.IllCopyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for Resale
11、No reproduction or networking permitted without license from IHS-,-,-(This page intentionally left blank.)Copyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IFed. Std. 376B
12、1. SCOPE1“.This standard lists preferred metric units (See 4.1 ) recommended for usethroughout the Federal Government. It gives guidance on the selectionof metric units required to comply with the provisions of the MetricConversion Act of 1975 (P.L. 94-168), as amended by the Omnibus Tradeand Compet
13、itiveness Act of 1988 (P.L. 100-418), and Executive Order(EO) 12770 of July 25, 1991. The guidance in this standard applies to,but is not limited to, the drafting of laws, regulations, contracts, andpurchase orders; and the preparation of reports, statistical tables, anddatabases.2. AUTHORITATIVE DO
14、CUMENTThe following document forms the authoritative basis of this standard tothe extent specified herein:American National Standard for Metric Practice, ANS1/lEEE Std 268-1992,Institute of Electrical and Electronics Engineers, Inc.3. DEFINITIONS3.1 S1 Units, Units belonging to the International Sys
15、tem of Units, which isabbreviated SI (from the French Le Systhe /nternationa/ dUnites), asinterpreted or modified for use in the United States by the Secretary ofCommerce (55 F.R. 52242, Dec. 20, 1990).3.2 Inch-pound Units. Units based upon the yard and the pound, commonlyused in the United States,
16、and defined by the National Bureau ofStandards (now the National Institute of Standards and Technology). Inthis standard, the term inch-pound unit includes other customary units,such as the degree Fahrenheit, used extensively in the United States atpresent. Some inch-pound units used in the United S
17、tates, such as thegallon, have the same name as units previously used in other countriesbut differ in magnitude.4. GENERAL RE(NJIREMEIVIS4.1 Preferred Metric Units. Preferred metric units for use throughout theFederal Government are:The S1 units (together with their multiples andsubmultiple);Three o
18、ther metric units-he liter, hectare, andmetric ton-that are accepted for use withCopyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fed. Std. 376Bthe S1 units because of th
19、eir prscticalimportance; andA small number of other metric units, listed inSection 5, that are accepted because of theiruse in specialized fields.Thepreferred metric units listed in Section 50fthis standard have beenselected in accordance with the recommendations of ANS1/lEEE Std 268.4.1.1 S1 Bass U
20、nite and Supplementary Unite, The S1 is constructed fromseven base units for independent quantities plus the two supplementaryunits for plane angle and solid angle.Quantity Unit Name Unit Svmbollength meter mmass2 kilogram kgtime secondelectric current ampere ithermodynamic temperature kelvin Kamoun
21、t of substance mole molluminous intensity candela cdplane angle radian ra dsolid angle eteradian sr4.1.2 S1 Derived Units. Derived units are formed by combining baseunits, supple menta units. and other derived units according to thealgebraic relations linking the corresponding quantities. The symbol
22、s forderived units are obtained by means of the mathematical signs formultiplication, division, and use of exponents, For example, the S1 unitfor velocity is the meter per aecond(m/s or m. s), and that for angularvelocity is the radian per second (rad/s or rad. s). Some derived S1units have been giv
23、en special names and symbols, as follows: Ae used in this standard, “qua u the technical word for measurable attributes ofphenomena or maner,z In commercial a71nd averyday usa a71nd m many tachniml fields, the term weiEhr is usually usedu a71 synonym for mass. This m %fetghr m used m mom Unired StaI
24、ea laws and regulations.Saa tha note ar 5.21 for further expbnmon2Copyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fed. Std. 376B.IIQwui!Y Unit Name Unit SvmbolAbsorbed d
25、ose, specificenergy imparted,kerma, absorbed dose indexActivity (of a radionuclide)Celsius temperatureDose equivalentElectric capacitanceElectric charge,quantity of electricityElectric conductanceElectric inductanceElectric potential,potential difference,electromotive forceElectric resistanceEnergy,
26、 work, quantity of heatForceFrequency (of aperiodic phenomenon)IlluminanceLuminous fluxMagnetic fluxMagnetic flux densityPower, radiant fluxPressure, stressgraybecquereldegree CelsiussievertfaradcoulombsiemenshenryvoltohmjoulenewtonhertzIuxlumenwe berteslawattpascalGyBqcSvFcsHvQJNHzlxImWbTwPa4,1.3 S
27、1 Prefe8. The common metric prefixes are:Exmession inTerms of OtherS1 UnitsJ/kg1/sKJ/kgc/vA. SANWb/AW/AVIAN.mkg”m/s21/sim/m2cd” srV“sWb/m2J/sN/m2Multic)lication Facto Prefix Name Prefix Svmbol1000000000000 = 1o1000000000 = 1Oe1000000 = 1(Y1000 = 1(P100 = 10210 = 100.1 = 10”10.01 = 10”2000:”: : ;:0.0
28、00”000001 = 10“0,000000000001 = 1012teragigamegakilohectodekadecicentiminimicronanopicoTGMkhdadcmMnPCopyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. . .,4-Fed. Std. 37
29、6BThese prefixes are part of S1. They are attached to an S1 unit name orsymbol to form what are properly called “multiples” and “submultiple” ofthe S1 unit. Prefixes produce units that are of an appropriate size for theapplication, e.g., millimeter or kilometer. Examples that show reasonablechoices
30、of multiples and submultiple for many practical applications aregiven in Section 5. While all combinations are technically correct, manyare not used in practice. The prefixes deci, deka, and hecto are rarelyused; prefixes that are multiples or submultiple of 1000 are generallypreferred. When the uni
31、t name is written in full, the prefix is written infull: megahertz, not Mhertz. When the unit symbol is used, the prefixsymbol is used: MHz, not megaHz. Only one prefix should be used informing a multiple of an S1 unit, e.g., Mg, not kkg; or vV, not mmV. Prefixsymbols for the values a million or gre
32、ater are capitalized and those belowa million are written in lower case.4.1.4 Editorial Style. The names of all SI units begin with a lower caseletter except, of course, at the beginning of a sentence or when othergrammar rules dictate capitalizing nouns. There is one exception: in“degree Celsius” t
33、he term “degree” is lower case but “Celsius” is alwayscapitalized. Unit symbols are always written in lower case except for theliter and those units derived from the name of a person (e.g., W for watt,Pa for pascal, etc.). S1 symbols are unique “letter shorthand” for unitnames-they are not abbreviat
34、ions ald should therefore not be followedby a period (except at the end of a sentence). Likewise, symbols stand forboth the singular and plural of the unit and should not have an “s” added.S1 units are always written in an upright typeface with a space betweenthe numeric value and the symbol. See AN
35、S1/lEEE Std 268 and otherdocuments listed in the Bibliography for further usage rules.4.2 Accepted Unite. For practical reasons a number of non-metric units areaccepted for use. These include units of time (minute, hour, etc.), units ofplane angle (degree, etc.), and a few units for special applicat
36、ions, such asthe nautical mile, used in navigation. Section 5 includes accepted units andshows their areas of application. These units may be used in fullcompliance with the provisiona of the amended Metric Conversion Act, EO12770, and the Federal Register Notice, “Metric System of Measurement;Inter
37、pretation of the International System of Units for the United States”(55 F.R. 52242, Dec. 20, 1990).4.3 Unacceptable Metzic Un-ti. Many older metric practices do not complywith the amended Metric Conversion Act, EO 12770, and 55 F.R. 52242.Particular care shall be taken to avoid introducing non-Sl p
38、ractices into theUnited States in areas where such practices are not now established. Theunits listed in the following three subsections shall not be used.4Copyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking perm
39、itted without license from IHS-,-,-4.3.1 CGS Units. Units with special names peculiar to(centimeter-gram-second) systems shall not be used.are the following that have been commonly used:Fed. Std. 376Bthe various cgsAmong these unitserg, dyne, gal used in mechanics;poise, stokes used in fluid dynamic
40、s;stilb, phot, Iambert used in photometry;emu, esu, gauss, oersted, maxwell, gilbert, biot,franklin, abampere, abvolt, I used in electricity and magnetism.statvolt, etc. J4.3.2 Deprecated Names or Symbols. Other units from older versionsthe metric system and metric jargon that shall not be used incl
41、ude:Incorrect termkiloarecandle orcandlepowerfermi -gammamicronmillimicronmhoCorrect Unitkilogramsquare dekametercandelafemtometernanoteslamicrometernanometersiemensmicrogramcubic millimeter or microliter4.3.3 Miscellaneous Non-Sl Units Not to be Used. Additional unitsthat are not accepted for use i
42、nclude the following:Angstromcaloriegas a unit of acceleration (g = 9.81 m/s2)grade or gon 1 grade = (x/ZOO) radkilogram-forceIangley (1 Iangley = 1 cai/cm2)metric caratmetric horsepowermillimeter of mercurymillimeter, centimeter, or meter of waterstandard atmosphere (101 .325 kPa)technical atmosphe
43、re (98,0665 kPa)torr (133.322 Pa)of1.5Copyright National Institute of Standards and Technology Provided by IHS under license with NISTNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fed, Std. 37604.4 Conversion. Conversion factors in Section 5 are shown from inch-p
44、oundunits to metric units, generally to seven significant digits. The first column,labeled From, lists inch-pound and other units commonly used to expressthe quantities; the second column, labeled To, gives Ed units or otherpreferred units; and the third column, labeled Multiply By, gives theconvers
45、ion factors by which the numerical value in From units must bemultiplied to obtain the numerical value in To units. For conversion frominch-pound units to metric units, multiply by the factor. For example, toconvert 10.1 feet to meters multiple by 0.3048; the answer is 3.078 meters,which can be roun
46、ded to 3.08 meters (see Section 4.5 on rounding). Forconversion from metric units to inch-pound units, divide rather thanmultiply by the factor. For example, to convert 16.3 meters to yards divideby 0.9144; the answer is 17.826 yards, which can be rounded to 17.8 yards.4.5 Rounding. For rounding of
47、metric values obtained by conversion frominch-pound values, the following simplified rules are suggested. A morecomplete treatment of rounding rules is given in Appendix C of ANSMEEEStd 268.4.5.1 If the inch-pound value is expressed by a combination of units suchas feet and inches, or pounds and oun
48、ces, it should first be converted tothe smaller unit.Examples: 12tt5in=149in1 lb 3-1/2 02 = 19.5024.5.2 Multiply the inch-pound value by the conversion factor. If the firstsignificant digit of the metric value is equal to or greater than the firstsignificant digit of the inch-pound value, round the
49、metric value to thesame number of significant digits as there are in the inch-pound value.Examples: 11 mi x 1.609 = 17.699 km, which rounds to 18 km61 mi x 1.609 = 98.149 km, which rounds to 98 kmtf the first significant digit of the metric value is smaller than the firstsignificant digit of the inch-pound value, round to one more significa
