1、Designation: E 1594 06Standard Guide forExpression of Temperature1This standard is issued under the fixed designation E 1594; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indica
2、tes the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers uniform methods for expressingtemperature, temperature values, and temperature differences.1.2 This guide is intended as a supplement to IEEE/AS
3、TMSI-10.2. Referenced Documents2.1 ASTM Standards:2E 344 Terminology Relating to Thermometry and Hydrom-etryIEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Terminology3.1 GeneralStandard terms used in this guide are definedin Terminology E 344 an
4、d in IEEE/ASTM SI-10.4. Basic Concepts4.1 Temperature is a fundamental measurable quantity des-ignated by the symbol T or the symbol t (see 5.1). Inexpressions of dimensions the symbol u is sometimes used toindicate the dimension temperature.4.2 A temperature value is expressed in terms of a tempera
5、-ture scale. The complete description consists of a numericalvalue designating the magnitude, a unit, and, where appropri-ate, a tolerance or uncertainty. Both the numerical value andunit depend upon the scale.4.3 A unit of temperature is understood to mean an intervalon a temperature scale.4.4 A te
6、mperature difference, interval, or increment is alsodescribed by a numerical value designating the magnitude, aunit, and, where appropriate, a tolerance or uncertainty.5. Temperature Scales5.1 Thermodynamic Temperature Scales:5.1.1 By international agreement, the theoretical tempera-ture scale to wh
7、ich all temperature values should be ultimatelyreferable is the Kelvin Thermodynamic Temperature Scale(KTTS). A value of temperature expressed on the KTTS isknown as a thermodynamic temperature, symbol T.5.1.2 The unit of thermodynamic temperature is the kelvin,symbol K. The kelvin is a base unit in
8、 the International Systemof Units (SI).NOTE 1The symbol for the kelvin is the capital letter K only; thedegree sign () is not used.5.1.3 The expression of a value of thermodynamic tempera-ture is written:T 5 nkK (1)where:nk= a numerical value designating the magnitude,K = the symbol for the unit kel
9、vin.The magnitude may also be represented by the notation T/K.5.1.4 A thermodynamic temperature may be expressed as aCelsius temperature. The symbol t is to be used to designate aCelsius temperature, but if this symbol leads to a conflict innotation in a given context, it is acceptable to use the sy
10、mbolT instead to designate a Celsius temperature.5.1.5 The unit of Celsius temperature is the degree Celsius,symbol C. The degree Celsius is a derived SI unit.NOTE 2The symbol for the degree Celsius consists of the degree sign() followed by the capital letter C. Neither the degree sign nor the lette
11、rC alone represents the degree Celsius.5.1.6 The expression of a value of Celsius temperature iswritten:t 5 ncC (2)where:nc= a numerical value designating the magnitude,C = the symbol for the unit degree Celsius.The magnitude may also be represented by the notation t/C.1This guide is under the juris
12、diction of ASTM Committee E20 on TemperatureMeasurement and is the direct responsibility of Subcommittee E20.91 on Editorialand Terminology.Current edition approved Nov. 1, 2006. Published December 2006. Originallyapproved in 1994. Last previous edition approved in 1999 as E 1594 99.2For referenced
13、ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
14、ohocken, PA 19428-2959, United States.5.1.7 By definition, at any temperature, a temperature incre-ment of one degree Celsius is equal to a temperature incrementof one kelvin.5.1.8 By definition, the Celsius temperature t = 0 C is thesame as the thermodynamic temperature T = 273.15 K. Therelation be
15、tween numerical values associated with both expres-sions of a temperature is therefore given by:nc5 nk2 273.15 (3)where:t = ncC is the same temperature as T = nkK.5.2 Practical Temperature Scales:5.2.1 Practical temperature scales have been established byinternational agreement for the practice of t
16、emperature mea-surement; among them are the International Practical Tempera-ture Scale of 1968, the International Practical TemperatureScale of 1948, and the International Temperature Scale of1927.35.2.2 Practical scales are designed so that a numerical valueof temperature expressed on the scale is
17、close to the numericalvalue of thermodynamic temperature. Because the KTTS isdifficult to implement, the vast majority of temperature mea-surements are based on a practical scale.5.2.3 There are two practical temperature scales now in use,superseding all others. The International Temperature Scale o
18、f19904defines temperatures above 0.65 K. The ProvisionalLow-Temperature Scale from 0.9 mK to 1 K5defines tempera-tures between 0.9 mK and 1000 mK5.2.4 A value of temperature on a practical temperaturescale may be expressed either in kelvins or in degrees Celsiususing the designations, symbols, and r
19、elations given in 5.1.6. Expression of Values of Temperature6.1 Temperature Scale Identification:6.1.1 It is important that the temperature scale upon whichvalues of temperature are expressed be identified in a docu-ment. When reference to more than one scale is made in adocument, or when critical d
20、ata are presented, scale identifi-cation is essential.6.1.2 Thermodynamic temperatures may be identified assuch, or with reference to the KTTS. If values of temperatureare expressed on a practical temperature scale, the scale shouldbe identified. The identification may be an abbreviation, asdefined
21、in the text of the scale; for example, the InternationalTemperature Scale of 1990 is abbreviated ITS-90 and theProvisional Low-Temperature Scale from 0.9 mK to1Kisabbreviated PLTS-2000.6.1.3 Scale identification may be placed in text, in foot-notes, in table headings, or in figures, as appropriate.6
22、.1.4 A scale may also be identified by a subscript associ-ated with a quantity symbol; for example, TThand tThforthermodynamic temperatures and T90and t90for temperaturevalues on ITS-90.6.2 Numerical Format:6.2.1 Numerical values of temperature should be expressedas decimal numbers.6.2.2 Except in v
23、ery special circumstances, exponentialformat should be avoided.6.3 Unit Symbol Format:6.3.1 The unit symbol should be separated from the numeri-cal value by a single space. There should be no space betweenthe degree sign and the letter C. Punctuation is not part of theunit symbol; only punctuation r
24、equired by context or grammarshould follow the unit symbol.6.3.2 In an expression of a range of temperature values, thesame unit symbol should be used with each value in the range;for example: “over the temperature range 16 K to 50 K” or“any temperature between 20 C and 30 C.”6.3.3 Multiple and subm
25、ultiple prefixes should not normallybe used with the unit for the expression of values of tempera-ture, for temperatures above 1 K. For temperatures below 1 K,a submultiple may be used. The preferred submultiple is 0.001(prefix “milli,” symbol m).6.3.4 When a tolerance or uncertainty is associated w
26、ith avalue of temperature, both the value and the tolerance oruncertainty should be expressed with the same unit. Unitprefixes should not normally be used. The unit symbol shouldfollow each numerical value. For example:t905 60.0 C 6 1.5 C (4)T905 273.150 K 6 0.001 K (5)6.3.5 When a tolerance or unce
27、rtainty is presented in aformat not directly associated with a value of temperature, aunit prefix may be used. The preferred submultiple is 0.001(prefix “milli,” symbol m). For example, the uncertainty u of atemperature value may be expressed:ut90! 5 0.7 mK (6)7. Expression of Temperature Difference
28、s, Intervals, andIncrements7.1 Temperature differences, intervals, and increments arenormally understood to be expressed with reference to thesame temperature scale as are values of temperature, within agiven context. Where there is a possibility of misunderstand-ing, the temperature scale should be
29、 explicitly identified.7.2 A small temperature difference, interval, or incrementmay be expressed in terms of a submultiple of the appropriateunit of temperature. The use of unit prefixes to indicatesubmultiples should follow the guidelines in IEEE/ASTMSI-10. The preferred submultiple is 0.001 (pref
30、ix “milli,”symbol m).7.3 The magnitude of a temperature increment at a particu-lar temperature is sometimes expressed as a relative fraction ora percentage of the numerical value (on a particular tempera-ture scale) of the temperature. Such usage should be carefullyexplained so that the expression i
31、s meaningful and unambigu-ous.3Evolution of the International Practical Temperature Scale of 1968, ASTM STP565, ASTM, 1974.4Preston-Thomas, H., “The International Temperature Scale of 1990 (ITS-90),”Metrologia, Vol 27, No. 1, 1990, pp. 310. For errata see ibid, Vol 27, No. 2, 1990,p. 107.5Rusby, R.
32、L., Durieux, M., Reesink, A. L, Hudson, R. P., Schuster, G., Khne,M., Fogle, W. E., Soulen, R. J., and Adams, E. D., “The Provisional LowTemperature Scale from 0.9 mK to 1 K, PLTS-2000.” J. Low Temp. Physics Vol 126,2002, pp. 633642.E15940627.4 When a tolerance or uncertainty is associated with them
33、agnitude of a temperature difference, interval, or increment,both the magnitude and tolerance or uncertainty should beexpressed in the same numerical format and with the same unit.An appropriate unit prefix may be used (see 7.2). The resultingunit symbol should follow each numerical value in the exp
34、res-sion. For example:Dt 5 10.00 C 6 0.01 C describes a temperature interval ofabout 10 C (7)DT 5 9.8 mK 6 0.2 mK describes a temperature interval ofabout 9.8 mK (8)7.5 In the expression of derived quantities the unit oftemperature should be the kelvin. For example, the preferredexpression for heat
35、capacity is joules per kelvin, JK1or J/K;for temperature gradient, kelvins per metre, Km1or K/m.8. Units Other Than SI8.1 Values of temperature are sometimes expressed in de-grees Rankine, symbol R, instead of kelvins, and in degreesFahrenheit, symbol F, instead of degrees Celsius. Neither thedegree
36、 Rankine nor the degree Fahrenheit are part of the SI.8.2 At any temperature, a temperature increment of onedegree Rankine is equal to a temperature increment of 5/9kelvin. The relation between numerical values associated withboth expressions of a temperature is given by:nr5 9nk /5 (9)where:T = nrR
37、is the same temperature as T=nkK.8.3 At any temperature, a temperature increment of onedegree Fahrenheit is equal to a temperature increment of 5/9degree Celsius. The relation between numerical values associ-ated with both expressions of a temperature is given by:nf5 9nc /5 1 32 (10)where:t = nfF is
38、 the same temperature as t=ncC.8.4 From the relations in 5.1, 8.2, and 8.3, it follows that:8.4.1 At any temperature, a temperature increment of onedegree Rankine is equal to a temperature increment of onedegree Fahrenheit.8.4.2 If T=nrR and t = nfF are the same temperature,then the relation between
39、 the numerical values is given by:nr5 nf1 459.67 (11)8.4.3 If a temperature interval expressed in degrees Rankineor degrees Fahrenheit has a magnitude n1, and the sametemperature interval expressed in kelvins or degrees Celsiushas a magnitude n2, then the relation between n1and n2is givenby:n15 9n2
40、/5 (12)8.5 Both thermodynamic temperatures and values of tem-perature on a practical temperature scale may be expressed indegrees Rankine or degrees Fahrenheit. In both cases theconsiderations of Section 6 apply.8.6 The use of multiple and submultiple prefixes with thedegree Rankine and the degree F
41、ahrenheit is not recom-mended.9. Keywords9.1 degree Celsius; degree Fahrenheit; degree Rankine;kelvin; SI; temperature; temperature difference; temperatureincrement; temperature interval; temperature scales; tempera-ture value; thermodynamic temperatureASTM International takes no position respecting
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45、s standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E1594063
