ASTM F1332-99

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An American National Standard
Designation: F 1332 – 99
Standard Practice for
Use of SI (Metric) Units in Maritime Applications (Committee
F-25 Supplement to IEEE/ASTM SI 10)
This standard is issued under the fixed designation F 1332; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
INTRODUCTION
The International System of Units (SI) was developed by the General Conference on Weights and
Measures (CGPM), which is an international treaty organization. The abbreviation SI, derived from
the French “Le Système International d’Unités,” is used in all languages.
On Dec. 23, 1975, Public Law 94-168, “The Metric Conversion Act of 1975,” was signed by
President Ford, committing the United States to a coordinated voluntary conversion to the metric
system of measurement. The Act specifically defines the “metric system of measurement” as “the
International System of Units as established by the General Conference on Weights and Measures in
1960, 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 and
Competitiveness Act of 1988. The Act specifies that “metric” means the modernized metric system
(SI). The Act then amended the Metric Conversion Act of 1975 to designate the metric system of
measurement 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 industry by providing a technical
reference for the International System of Units (SI). The practice is not intended to cover all aspects
ofSIusage,buttoserveasareadyreferenceespeciallytailoredtotheoperatingneedsoftheindustry.
For further information on SI usage and conversion factors for units not found herein, refer to
IEEE/ASTM SI 10, upon which this practice is based. In the event of a conflict, IEEE/ASTM SI 10
shall take precedence. (See also NIST Special Publication 811.) Hardware and other standards in SI
are currently being developed.
1. Scope 2. Referenced Documents
1.1 ThispracticecoverstheuseofSI,whichiscomprisedof 2.1 ASTM Standards:
base and derived SI units.Also discussed are non-SI units that IEEE/ASTM SI 10 Standard for Use of the International
have been accepted and recognized by the CGPM as appropri- System of Units (SI): The Modernized Metric System
ateforlimiteduseortime.BasicrulesforstyleandusageofSI 2.2 NIST Publications:
are set forth, as well as methods for conversion from non-SI NIST Special Publication 811 Guide for the Use of the
units to SI units. Tables of quantities used by the marine International System of Units (SI)
industryareincluded,withpresentunitsandconversionfactors NIST Special Publication 330 The International System of
given. Units (SI)
3. Terminology
3.1 Definitions:
This practice is under the jurisdiction ofASTM Committee F-25 on Ships and
3.1.1 quantity, n—measurable attribute of a physical phe-
Marine Technology and is the direct responsibility of Subcommittee F25.07 on
nomenon.
General Requirements.
3.1.2 SI, n—The universally accepted abbreviation for the
Current edition approved April 10, 1999. Published July 1999. Originally
published as F1332–91. Last previous edition F1332–93.
International System of Units as defined in the document Le
Annual Book of ASTM Standards, Vol 14.04 (Excerpts in Related Materials
Système International d’Unités, 6th Edition, published by the
section of all other volumes).
3 InternationalBureauofWeightsandMeasures(BIPM),Sevres,
Available from National Institute for Standards and Technology (NIST),
Gaithersburg, MD 20899. France, 1991, and as interpreted and modified for the United
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1332 – 99
TABLE 1 SI Base Units
States by the U.S. Department of Commerce.The U.S. version
of the defining document is published by the National Institute
Quantity Base SI Unit Symbol
of Standards and Technology as NIST Special Publication
3,4
Length metre m
330.
Mass kilogram kg
3.1.3 unit, n—referencevalueofagivenquantityasdefined
Time second s
by CGPM Resolution or ISO standards. There is only one unit Electric current ampere A
Thermodynamic temperature kelvin K
for each quantity in SI.
Amount of substance mole mol
3.2 Definitions of Terms Specific to This Standard:
Luminous intensity candela cd
3.2.1 coherent system of units—a system of units of mea-
surement in which a small number of base units, defined as
dimensionally independent, are used to derive all other units in
TABLE 2 SI Derived Units with Special Names
the system by rules of multiplication and division with no
numerical factors other than unity. Name of Derived Expressed in Terms
Quantity SI Symbol of Base and Derived
unit SI Units
4. The Concept of SI
Angle, plane radian rad mm = 1
4.1 TheInternationalSystemofUnits(SI)wasdevelopedto 2 2
Angle, solid steradian Sr m /m =1
−1
provideauniversal,coherent,andpreferredsystemofunitsfor Frequency hertz Hz s
Force newton N kg·m/s
world-wide use and appropriate to the needs of modern
Pressure, stress pascal Pa N/m
science, technology, and international commerce.
Energy, work, quantity of heat joule J N·m
Power, radiant flux watt W J/s
4.2 The principal features of SI are:
Electric charge, quantity of coulomb C A·s
4.2.1 There is one and only one unit for each quantity.
electricity
4.2.2 The system is fully coherent.
Electric potential, potential volt V W/A
difference, electromotive
4.2.3 Designated prefixes can be attached to units to form
force
multiples and submultiples of ten raised to a power. Use of the
Electric capacitance farad F C/V
prefixes provides for convenient numerical values when the
Electric resistance ohm V V/A
Electric conductance siemens s A/V
magnitudeofaquantityisstated,andavoidstheneedformany
Magnetic flux weber Wb V·s
insignificant zeroes. The system is decimal, the same as the
Magnetic flux density tesla T Wb/m
commonly used numerical system.
Inductance henry H Wb/A
Luminous flux lumen lm cd·sr
4.2.4 Unitsandprefixesarerepresentedbystandardizedand
Illuminance lux lx lm/m
internationally recognized symbols.
A
Celsius temperature degree Celsius °C K
−1
4.3 Afewspecificallyacceptednon-SIunitsarepermittedin
Activity (of a radionuclide) becquerel Bq s
Absorbed dose gray Gy J/kg
conjunction with SI.
Dose equivalent sievert Sv J/kg
4.4 SI units, acceptable non-SI units, and prefixes are
A
See 5.4.
discussed in Sections 5 and 6.
5. SI Units
degree Celsius is equivalent to kelvin with a different zero
5.1 SI includes two classes of units:
point on the scale. Celsius temperature t equals kelvin tem-
5.1.1 Base units and
perature minus 273.15 ( t = T − T where T = Kelvin and T
5.1.2 Derived units. o o
= 273.15).
5.2 Base Units—The International System of Units is based
5.5 SI Prefixes—TheprefixesandsymbolsshowninTable3
on seven base units, listed inTable 1, which by convention are
are used to form decimal multiples and submultiples of SI
regarded as dimensionally independent.
units.
5.3 Derived Units—Derived units are formed by the alge-
5.6 Selection of Prefixes:
braic combination of base units and derived units. Derived
5.6.1 Aprefixshouldbeselectedsothatthenumericalvalue
units with special names are listed in Table 2.
of the unit expressed will fall between 0.1 and 1000. An
5.4 Temperature—The SI unit of thermodynamic tempera-
exception to this rule arises in the preparation of tables of
ture is the kelvin, and this unit is properly used for expressing
values of the same quantity and in discussion of such values
thermodynamic temperature and temperature intervals. The
within a given context, when it is better to use the same unit
multiple.Also, for certain applications, one particular multiple
willcustomarilybeused;forexample,useofthemillimetrefor
The U.S. edition of the English translation of the BIPM SI publication differs
fromthetranslationintheBIPMSIpublicationonlyinthefollowingusage:(1)The
linear dimensions in engineering drawings.
dot is used as the decimal marker and (2) the spelling of English-language words,
5.6.2 Compound prefixes should not be used; for example,
for example, “meter,’ liter,” and “deka” are used instead of “metre,” “litre,” and
use GJ, not kMJ.
“deca”inaccordancewiththe U.S. Government Printing Offıce Style Manual,which
5.6.3 Prefixes should preferably not be used in the denomi-
follows Webster’s Third New International Dictionary rather than the Oxford
Dictionary used in many English-speaking countries.
nator of compound units. Example, use V/m not mV/mm. The
The spelling of “meter” and “liter” in preference to “metre” and “litre” is
exception is the kilogram as it is the base unit: J/kg, not kJ/g.
recommended by the U.S. Department of Commerce as preferred for U.S. use and
5.6.4 Errors in calculation may be avoided by using powers
is mandated by the Department of Commerce for use by all agencies of the Federal
government. of ten with the units rather than prefixes.
F 1332 – 99
TABLE 3 SI Prefixes
exa E 10 1 000 000 000 000 000 000
peta P 10 1 000 000 000 000 000
tera T 10 1 000 000 000 000
giga G 10 1 000 000 000
mega M 10 1 000 000
kilo k 10 1 000
A 2
hecto h10 100
A 1
deka da 10 10
A −1
deci d10 0.1
B −2
centi c10 0.01
−3
milli m 10 0.001
−6
micro µ 10 0.000 001
−9
nano n 10 0.000 000 001
−12
pico p 10 0.000 000 000 001
−15
femto f 10 0.000 000 000 000 001
−18
atto a 10 0.000 000 000 000 000 001
A
To be avoided where practical.
B
Usually avoided, but used in some disciplines.
A
TABLE 5 Units in Use Temporarily with SI
6. Non-SI Units in Use with SI
6.1 Units in Use with SI—Certain units that are not SI have Name Value in SI Unit (exact)
been accepted for use with SI units. Some of these units,
nautical mile (nmi) 1852 m
knot (kn) nmi/h = (1852/3600 m/s)
currently recognized as acceptable for use with SI, are listed in
4 2
Hectare (ha) 10 m
Table 4 and Table 5.
B
bar 100 kPa
6.2 Time—The SI unit of time is the second. This unit is curie (Ci) 3.7 3 10 Bq
−4
roentgen (R) 2.58 3 10 C/kg
preferred and should be used when practical, particularly in
C −2
rad (rad) 1 3 10 Gy
technical calculations. −2
rem (rem) 1 3 10 Sv
6.3 Plane Angle—The SI unit of plane angle is the radian.
A
Because their usage is already well established, these units may be used
When the radian is not a convenient unit, the degree should be
subject to further review.
B
Usage is restricted to meteorology.
used with decimal submultiples. Minutes and seconds should
C
If there is risk of confusion with the symbol for radian, rd may be used as the
be used only when required (as in navigation).
symbol for rad.
6.4 Area—The SI unit of area is the square metre. The
hectare (ha) is a special name for square hectometre (hm ).
prefixes should be used with it. To avoid confusion, use of the
Largelandorwaterareasaregenerallyexpressedinhectaresor
term “tonne” to indicate metric ton is discouraged.
in square kilometres.
7. Mass, Force, and Weight
6.5 Volume—The SI unit of volume is the cubic metre. The
cubicmetre,oroneofitsmultiplesorsubmultiples,ispreferred
7.1 SI, being coherent, is different from the older metric
for all applications. The special name litre has been approved
systems in the use of distinctly separate units for mass and
by the CGPM for the cubic decimetre.
force. In SI, the unit of force, the newton (N), is derived as the
6.6 Mass—The SI unit of mass is the kilogram. The
laws of physics dictate, instead of being related to gravity, and
kilogram, or one of the multiples or submultiples formed by
is defined as being equal to the force that imparts an accelera-
attaching an SI prefix to gram, is preferred for all applications.
tion of unit (1 m/s ) to a unit mass, the kilogram (kg).
For large masses (such as have been expressed in tons), the
7.1.1 Mass—The mass of a body is a measure of its inertia,
megagram is the appropriate unit. The term metric ton should
that is, its resistance to a change in its motion. In practical
be restricted to commercial and maritime usage, and no
terms, mass represents the quantity of matter in a body (not to
be confused with amount of substance expressed in moles).
The SI unit of mass is the kilogram (kg).
TABLE 4 Non-SI Units in Use with SI
7.1.2 Force—Force is the mechanical action on a body
resultingfromphysicalcontactwithanotherbodyortheaction
Quantity Unit Symbol Definition
resulting from gravitational or electromagnetic fields. The SI
time minute min 1 min = 60 s
unit of force is the newton (N).
hour h 1h=60min= 3600
s
7.1.3 Weight—The weight W of a body is the effective
day d 1d=24h=86400
gravity force acting on it and equals the product of its mass m
s
and the local acceleration of free fall, g, so that W = mg.InSI,
plane angle degree ° 1° = (p/180) rad
minute 8 18 = (1/60)°
weightismeasuredinnewtons(N).Becausetheaccelerationof
p/10 800) rad
gravity (the acceleration of free fall) varies slightly over the
second 9 19= (1/60)8 =
(p/648 000) rad surface of the earth, the weight of a body varies accordingly,
3 −3
volume litre L 1 L = 1 dm =10
whereas its mass is a constant.
m
3 7.1.4 Discussion—The existence of clearly separate units
mass metric ton t 1 t =10 kg
for mass and force in SI contrasts with the widespread use of
F 1332 – 99
the units lb and kg for both mass and force. Whereas the word 8.4.1 At present, the period will be used for the decimal
“weight” has been commonly used when mass is intended or marker.Fornumbersoflessthanone,azeroshouldprecedethe
implied, especially in commerce and everyday life, this use
decimal; for example, 0.964.
should in time disappear with growing acceptance and use of
8.4.2 Recommended international practice calls for the use
SI units, and the word mass (rather than weight) will be used
of a half space to separate large numbers into groups of three.
when mass is meant. The use of weight for mass should be
Do not use a comma. The digits should be separated into
avoided altogether in scientific and technical communication.
groupsofthreecountingfromthedecimalpointtowardtheleft
andtheright,andusingasmallspacetoseparatethegroups.In
8. Rules for Style and Usage of SI
numbers of four digits, the space is usually not necessary
except to provide uniformity in tables, columns, and so forth.
8.1 Rules for Writing Unit Symbols:
For example, 16390
...