1、Designation: F 1332 99 (Reapproved 2005)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 F 1332; the number immediately following the designation indica
2、tes 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 (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of
3、the 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
4、 Dec. 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 U
5、nits 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 “
6、metric” 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 in
7、dustry 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 f
8、or 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 o
9、f SI, 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
10、of quantities used by the marineindustry are included, with present units and conversion factorsgiven.2. Referenced Documents2.1 ASTM Standards:IEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modernized Metric System22.2 NIST Publications:NIST Special Publication 811 G
11、uide for the Use of theInternational System of Units (SI)3NIST Special Publication 330 The International System ofUnits (SI)33. 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 U
12、nits as defined in the document Le1This practice is under the jurisdiction of ASTM Committee F25 on Ships andMarine Technology and is the direct responsibility of Subcommittee F25.07 onGeneral Requirements.Current edition approved May 1, 2005. Published May 2005. Originallyapproved in 1991. Last pre
13、vious edition approved in 1999 as F 1332 99.2Annual Book of ASTM Standards, Vol 14.04 (Excerpts in Related Materialssection of all other volumes).3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 3460, Gaithersburg, MD 20899-3460.1Copyright ASTM International
14、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Systme International dUnits, 6th 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 Com
15、merce. The U.S. versionof the defining document is published by the National Instituteof Standards and Technology as 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 Definiti
16、ons of Terms Specific to This Standard:3.2.1 coherent system of unitsa system of units of mea-surement in which a small 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 th
17、an unity.4. The Concept of SI4.1 The International System of Units (SI) was developed toprovide a universal, coherent, 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 Ther
18、e is one and only one unit for each quantity.4.2.2 The system is fully coherent.4.2.3 Designated prefixes can be attached 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 av
19、oids the need for manyinsignificant zeroes. The system is decimal, the same as thecommonly used numerical system.4.2.4 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
20、, acceptable non-SI units, and prefixes arediscussed in Sections 5 and 6.5. SI Units5.1 SI includes two classes of units: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 dimensio
21、nally independent.5.3 Derived UnitsDerived units are formed by the alge-braic combination of base units and derived 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 expressingthermo
22、dynamic temperature and temperature intervals. Thedegree Celsius is equivalent to kelvin with a different zeropoint 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
23、to form decimal multiples and submultiples of SIunits.5.6 Selection of Prefixes:5.6.1 Aprefix should be selected so 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 discussi
24、on of such valueswithin a given context, when it is better to use the same unitmultiple. Also, for certain applications, 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 ex
25、ample,use GJ, not kMJ.5.6.3 Prefixes should preferably not be used in the denomi-nator of compound units. Example, use V/m not mV/mm. Theexception is the kilogram as it is the base unit: J/kg, not kJ/g.4The U.S. edition of the English translation of the BIPM SI publication differsfrom the translatio
26、n in the BIPM SI publication only in the following usage: (1) Thedot is used as the decimal marker and (2) the spelling of English-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
27、, whichfollows Websters Third New International Dictionary rather than the OxfordDictionary used in many English-speaking countries.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 th
28、e Department of Commerce for use by all agencies of the Federalgovernment.TABLE 1 SI Base UnitsQuantity Base SI Unit SymbolLength metre mMass kilogram kgTime second sElectric current ampere AThermodynamic temperature kelvin KAmount of substance mole molLuminous intensity candela cdTABLE 2 SI Derived
29、 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 s1Force newton N kgm/s2Pressure, stress pascal Pa N/m2Energy, work, quantity of heat joule J NmPower, radiant flu
30、x 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 he
31、nry H Wb/ALuminous flux lumen lm cdsrIlluminance lux lx lm/m2Celsius temperatureAdegree Celsius C KActivity (of a radionuclide) becquerel Bq s1Absorbed dose gray Gy J/kgDose equivalent sievert Sv J/kgASee 5.4.F 1332 99 (2005)25.6.4 Errors in calculation may be avoided by using powersof ten with the
32、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 with 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.
33、This unit ispreferred and should be used when practical, particularly intechnical calculations.6.3 Plane AngleThe SI unit of plane angle is 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 (a
34、s 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 or water areas are generally expressed in hectares orin square kilometres.6.5 VolumeThe SI unit of volume is the cubic metre. Thecubic metre, or one of its multi
35、ples or submultiples, is preferredfor all applications. 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 applicat
36、ions.For large masses (such as have been expressed 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,
37、 Force, and Weight7.1 SI, being coherent, is 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
38、force that imparts an accelera-tion of unit (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 sub
39、stance expressed in moles).The SI unit of mass 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
40、 of a body is the effectivegravity force acting 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
41、, the weight of a body varies accordingly,whereas its mass is a constant.TABLE 3 SI Prefixesexa E 10181 000 000 000 000 000 000peta P 10151 000 000 000 000 000tera T 10121 000 000 000 000giga G 1091 000 000 000mega M 1061 000 000kilo k 1031 000hectoAh12100dekaAda 10110deciAd1010.1centiBc120.01milli
42、m 1030.001micro 1060.000 001nano n 1090.000 000 001pico p 10120.000 000 000 001femto f 10150.000 000 000 000 001atto a 10180.000 000 000 000 000 001ATo be avoided where practical.BUsually avoided, but used in some disciplines.TABLE 4 Non-SI Units in Use with SIQuantity Unit Symbol Definitiontime min
43、ute min 1 min = 60 shour h 1h=60min=3600sday d 1d=24h=86400splane angle degree 1 = (p/180) radminute 8 18 = (1/60)p/10 800) radsecond 9 19= (1/60)8 =(p/648 000) radvolume litre L 1 L = 1 dm3=103m3mass metric ton t 1 t =103kgTABLE 5 Units in Use Temporarily with SIAName Value in SI Unit (exact)nautic
44、al mile (nmi) 1852 mknot (kn) nmi/h = (1852/3600 m/s)Hectare (ha) 104m2barB100 kPacurie (Ci) 3.7 3 1010Bqroentgen (R) 2.58 3 104C/kgrad (rad)C1 3 102Gyrem (rem) 1 3 102SvABecause their usage is already well established, these units may be usedsubject to further review.BUsage is restricted to meteoro
45、logy.CIf there is risk of confusion with the symbol for radian, rd may be used as thesymbol for rad.F 1332 99 (2005)37.1.4 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“weigh
46、t” has been commonly used when mass is intended orimplied, especially in commerce and everyday 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 altoget
47、her in scientific and technical communication.8. Rules for Style and Usage of SI8.1 Rules 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 char
48、acter sets, as in Telex transmission or computerprintout, the standard symbols cannot be 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
49、style used in the surrounding text.8.1.4 Unit symbols are not followed by a period exceptwhen 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 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
