1、Designation: F1332 99 (Reapproved 2011)An American National StandardStandard Practice forUse of SI (Metric) Units in Maritime Applications (CommitteeF25 Supplement to IEEE/ASTM SI 10)1This standard is issued under the fixed designation F1332; the number immediately following the designation indicate
2、s the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the
3、 Department of Defense.INTRODUCTIONThe International System of Units (SI) was developed by the General Conference on Weights andMeasures (CGPM), which is an international treaty organization. The abbreviation SI, derived fromthe French “Le Systme International dUnits,” is used in all languages.On De
4、c. 23, 1975, Public Law 94-168, “The Metric Conversion Act of 1975,” was signed byPresident Ford, committing the United States to a coordinated voluntary conversion to the metricsystem of measurement. The Act specifically defines the “metric system of measurement” as “theInternational System of Unit
5、s as established by the General Conference on Weights and Measures in1960, and as interpreted or modified for the United States by the Secretary of Commerce.”On Aug. 23, 1988, President Reagan signed into law P.L. 100-576, the Omnibus Trade andCompetitiveness Act of 1988. The Act specifies that “met
6、ric” means the modernized metric system(SI). The Act then amended the Metric Conversion Act of 1975 to designate the metric system ofmeasurement as the preferred system of weights and measures for United States trade and commerce.This practice will help obtain uniform SI practice in the marine indus
7、try by providing a technicalreference for the International System of Units (SI). The practice is not intended to cover all aspectsof SI usage, but to serve as a ready reference especially tailored to the operating needs of the industry.For further information on SI usage and conversion factors for
8、units not found herein, refer toIEEE/ASTM SI-10, upon which this practice is based. In the event of a conflict, IEEE/ASTM SI-10shall take precedence. (See also NIST Special Publication 811.) Hardware and other standards in SIare currently being developed.1. Scope1.1 This practice covers the use of S
9、I, which is comprised ofbase and derived SI units. Also discussed are non-SI units thathave been accepted and recognized by the CGPM as appropri-ate for limited use or time. Basic rules for style and usage of SIare set forth, as well as methods for conversion from non-SIunits to SI units. Tables of
10、quantities used by the marineindustry are included, with present units and conversion factorsgiven.2. Referenced Documents2.1 ASTM Standards:2IEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units (SI): The Modernized Metric System2.2 NIST Publications:NIST Special Publication 811 Guid
11、e for the Use of theInternational System of Units (SI)3NIST Special Publication 330 The International System ofUnits (SI)31This practice is under the jurisdiction of ASTM Committee F25 on Ships andMarine Technology and is the direct responsibility of Subcommittee F25.07 onGeneral Requirements.Curren
12、t edition approved May 1, 2011. Published May 2011. Originallyapproved in 1991. Last previous edition approved in 2005 as F1332 99(2005).DOI: 10.1520/F1332-99R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
13、of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.1Copyright ASTM International, 100 Barr Harbor Drive,
14、PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 Definitions:3.1.1 quantity, nmeasurable attribute of a physical phe-nomenon.3.1.2 SI, nThe universally accepted abbreviation for theInternational System of Units as defined in the document LeSystme International dUnits, 6
15、th Edition, published by theInternational Bureau of Weights and Measures (BIPM), Sevres,France, 1991, and as interpreted and modified for the UnitedStates by the U.S. Department of Commerce. The U.S. versionof the defining document is published by the National Instituteof Standards and Technology as
16、 NIST Special Publication330.43.1.3 unit, nreference value of a given quantity as definedby CGPM Resolution or ISO standards. There is only one unitfor each quantity in SI.3.2 Definitions of Terms Specific to This Standard:3.2.1 coherent system of unitsa system of units of mea-surement in which a sm
17、all number of base units, defined asdimensionally independent, are used to derive all other units inthe system by rules of multiplication and division with nonumerical factors other than unity.4. The Concept of SI4.1 The International System of Units (SI) was developed toprovide a universal, coheren
18、t, and preferred system of units forworld-wide use and appropriate to the needs of modernscience, technology, and international commerce.4.2 The principal features of SI are:4.2.1 There is one and only one unit for each quantity.4.2.2 The system is fully coherent.4.2.3 Designated prefixes can be att
19、ached to units to formmultiples and submultiples of ten raised to a power. Use of theprefixes provides for convenient numerical values when themagnitude of a quantity is stated, and avoids the need for manyinsignificant zeroes. The system is decimal, the same as thecommonly used numerical system.4.2
20、.4 Units and prefixes are represented by standardized andinternationally recognized symbols.4.3 Afew specifically accepted non-SI units are permitted inconjunction with SI.4.4 SI units, acceptable non-SI units, and prefixes arediscussed in Sections 5 and 6.5. SI Units5.1 SI includes two classes of u
21、nits:5.1.1 Base units and5.1.2 Derived units.5.2 Base UnitsThe International System of Units is basedon seven base units, listed in Table 1, which by convention areregarded as dimensionally independent.5.3 Derived UnitsDerived units are formed by the alge-braic combination of base units and derived
22、units. Derivedunits with special names are listed in Table 2.5.4 TemperatureThe SI unit of thermodynamic tempera-ture is the kelvin, and this unit is properly used for expressingthermodynamic temperature and temperature intervals. Thedegree Celsius is equivalent to kelvin with a different zeropoint
23、on the scale. Celsius temperature t equals kelvin tem-perature minus 273.15 ( t = T Towhere T = Kelvin and To= 273.15).5.5 SI PrefixesThe prefixes and symbols shown in Table 3are used to form decimal multiples and submultiples of SIunits.5.6 Selection of Prefixes:5.6.1 Aprefix should be selected so
24、that the numerical valueof the unit expressed will fall between 0.1 and 1000. Anexception to this rule arises in the preparation of tables ofvalues of the same quantity and in discussion of such valueswithin a given context, when it is better to use the same unitmultiple. Also, for certain applicati
25、ons, one particular multiplewill customarily be used; for example, use of the millimetre forlinear dimensions in engineering drawings.5.6.2 Compound prefixes should not be used; for example,use GJ, not kMJ.5.6.3 Prefixes should preferably not be used in the denomi-nator of compound units. Example, u
26、se V/m not mV/mm. Theexception is the kilogram as it is the base unit: J/kg, not kJ/g.5.6.4 Errors in calculation may be avoided by using powersof ten with the units rather than prefixes.6. Non-SI Units in Use with SI6.1 Units in Use with SICertain units that are not SI havebeen accepted for use wit
27、h SI units. Some of these units,currently recognized as acceptable for use with SI, are listed inTable 4 and Table 5.6.2 TimeThe SI unit of time is the second. This unit ispreferred and should be used when practical, particularly intechnical calculations.6.3 Plane AngleThe SI unit of plane angle is
28、the radian.When the radian is not a convenient unit, the degree should beused with decimal submultiples. Minutes and seconds shouldbe used only when required (as in navigation).6.4 AreaThe SI unit of area is the square metre. Thehectare (ha) is a special name for square hectometre (hm2).Large land o
29、r water areas are generally expressed in hectares orin square kilometres.4The U.S. edition of the English translation of the BIPM SI publication differsfrom the translation in the BIPM SI publication only in the following usage: (1) Thedot is used as the decimal marker and (2) the spelling of Englis
30、h-language words,for example, “meter, liter,” and “deka” are used instead of “metre,” “litre,” and“deca” in accordance with the U.S. Government Printing Offce Style Manual, whichfollows Websters Third New International Dictionary rather than the OxfordDictionary used in many English-speaking countri
31、es.The spelling of “meter” and “liter” in preference to “metre” and “litre” isrecommended by the U.S. Department of Commerce as preferred for U.S. use andis mandated by the Department of Commerce for use by all agencies of the Federalgovernment.TABLE 1 SI Base UnitsQuantity Base SI Unit SymbolLength
32、 metre mMass kilogram kgTime second sElectric current ampere AThermodynamic temperature kelvin KAmount of substance mole molLuminous intensity candela cdF1332 99 (2011)26.5 VolumeThe SI unit of volume is the cubic metre. Thecubic metre, or one of its multiples or submultiples, is preferredfor all ap
33、plications. The special name litre has been approvedby the CGPM for the cubic decimetre.6.6 MassThe SI unit of mass is the kilogram. Thekilogram, or one of the multiples or submultiples formed byattaching an SI prefix to gram, is preferred for all applications.For large masses (such as have been exp
34、ressed in tons), themegagram is the appropriate unit. The term metric ton shouldbe restricted to commercial and maritime usage, and noprefixes should be used with it. To avoid confusion, use of theterm “tonne” to indicate metric ton is discouraged.7. Mass, Force, and Weight7.1 SI, being coherent, is
35、 different from the older metricsystems in the use of distinctly separate units for mass andforce. In SI, the unit of force, the newton (N), is derived as thelaws of physics dictate, instead of being related to gravity, andis defined as being equal to the force that imparts an accelera-tion of unit
36、(1 m/s2) to a unit mass, the kilogram (kg).7.1.1 MassThe mass of a body is a measure of its inertia,that is, its resistance to a change in its motion. In practicalterms, mass represents the quantity of matter in a body (not tobe confused with amount of substance expressed in moles).The SI unit of ma
37、ss is the kilogram (kg).7.1.2 ForceForce is the mechanical action on a bodyresulting from physical contact with another body or the actionresulting from gravitational or electromagnetic fields. The SIunit of force is the newton (N).7.1.3 WeightThe weight W of a body is the effectivegravity force act
38、ing on it and equals the product of its mass mand the local acceleration of free fall, g, so that W = mg.InSI,weight is measured in newtons (N). Because the acceleration ofgravity (the acceleration of free fall) varies slightly over thesurface of the earth, the weight of a body varies accordingly,wh
39、ereas its mass is a constant.7.1.4 DiscussionThe existence of clearly separate unitsfor mass and force in SI contrasts with the widespread use ofthe units lb and kg for both mass and force. Whereas the word“weight” has been commonly used when mass is intended orimplied, especially in commerce and ev
40、eryday life, this useshould in time disappear with growing acceptance and use ofSI units, and the word mass (rather than weight) will be usedwhen mass is meant. The use of weight for mass should beavoided altogether in scientific and technical communication.8. Rules for Style and Usage of SI8.1 Rule
41、s for Writing Unit Symbols:8.1.1 Particular care must be taken to use the correctsymbols for units and prefixes (for example, K for kelvin, k forkilo, M for mega, m for milli). When using systems withlimited character sets, as in Telex transmission or computerprintout, the standard symbols cannot be
42、 used. For thesepurposes, refer to ISO 2955 or ANSI X3.50.8.1.2 Unit symbols are symbols and do not vary fromsingular to plural.8.1.3 Unit symbols should be printed in roman (upright)type, regardless of the type style used in the surrounding text.8.1.4 Unit symbols are not followed by a period excep
43、twhen used at the end of a sentence.8.1.5 The numerical value associated with a symbol shouldbe separated from that symbol by a space. For example, 25.4mm, not 25.4mm. The only exception to this rule is that nospace is left between the numerical value and the symbols ofdegree, minute, and second of
44、plane angle and degree Celsius.8.1.6 Unit symbols should be used in preference to the unitnames except when a number written out in words precedes theunit; for example “seven metres” not “seven m.”8.2 Rules for Writing Unit Names:8.2.1 The first letter of a unit name is not capitalized exceptat the
45、beginning of a sentence or in capitalized material such asa title.8.2.2 Plurals of unit names are formed in the ordinarymanner, except for lux, hertz, and siemens, which remain thesame.8.2.3 No space or hyphen is used between a prefix and theunit name; for example, kilonewton.8.3 Product, Quotient,
46、and Powers:8.3.1 To indicate the product of units when using theirnames, a space is left between the names (for example, newtonmetre). When using symbols, a centered dot should be placedbetween the symbols (for example, Nm).8.3.2 To indicate the quotient of units when using theirnames use the word “
47、per” (for example, metres per second).When using unit symbols, a solidus (/) or negative exponentshould be used (for example, m/s or ms1). Do not use morethan one solidus in the same expression. Use parentheses toavoid any ambiguity (consider m/sA can mean m/(sA) or(m/s)A).8.3.3 To indicate powers w
48、hen using unit names, the words“square,” “cubic,” “squared,” “cubed,” and so forth should beTABLE 2 SI Derived Units with Special NamesQuantityName of DerivedSIunitSymbolExpressed in Termsof Base and DerivedSI UnitsAngle, plane radian rad mm = 1Angle, solid steradian Sr m2/m2=1Frequency hertz Hz s1F
49、orce newton N kgm/s2Pressure, stress pascal Pa N/m2Energy, work, quantity of heat joule J NmPower, radiant flux watt W J/sElectric charge, quantity ofelectricitycoulomb C AsElectric potential, potentialdifference, electromotiveforcevolt V W/AElectric capacitance farad F C/VElectric resistance ohm V V/AElectric conductance siemens s A/VMagnetic flux weber Wb VsMagnetic flux density tesla T Wb/m2Inductance henry H Wb/ALuminous flux lumen lm cdsrIlluminance lux lx lm/m2Celsius temperatureAdegree Celsius C KActivity (of a radionuclide) becquere
