1、Designation: E1594 11E1594 16Standard Guide forExpression of Temperature1This standard is issued under the fixed designation E1594; 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
2、indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers uniform methods for expressing temperature, temperature values, and temperature differences.1.2 This guide is intended as a supplement to I
3、EEE/ASTM SI-10.2. Referenced Documents2.1 ASTM Standards:2E344 Terminology Relating to Thermometry and HydrometryIEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System3. Terminology3.1 GeneralStandard terms used in this guide are defined in Terminology E
4、344 and in IEEE/ASTM SI-10.4. Basic Concepts4.1 Temperature is a fundamental measurable quantity designated by the symbol T or the symbol t (see 5.1). In expressions ofdimensions the symbol is sometimes used to indicate the dimension temperature.4.2 A temperature value is expressed in terms of a tem
5、perature scale. The complete description consists of a numerical valuedesignating the magnitude, a unit, and, where appropriate, a tolerance or uncertainty. Both the numerical value and the unit dependupon the scale.4.3 A unit of temperature is understood to mean an interval on a temperature scale.4
6、.4 A temperature difference, interval, or increment is also described by a numerical value designating the magnitude, a unit,and, where appropriate, a tolerance or uncertainty.5. Temperature Scales5.1 Thermodynamic Temperature Scales:5.1.1 By international agreement, the theoretical temperature scal
7、e to which all temperature values should be ultimatelyreferable is the Kelvin Thermodynamic Temperature Scale (KTTS). A value of temperature expressed on the KTTS is known asa thermodynamic temperature, symbol T.5.1.2 The unit of thermodynamic temperature is the kelvin, symbol K. The kelvin is a bas
8、e unit in the International System ofUnits (SI). Note that the symbol for the kelvin is the capital letter K only; the degree sign () is not used.5.1.3 The expression of a value of thermodynamic temperature is written:T 5nk K (1)where:nk = a numerical value designating the magnitude,K = the symbol f
9、or the unit kelvin.The magnitude may also be represented by the notation T/K.1 This guide is under the jurisdiction of ASTM Committee E20 on Temperature Measurement and is the direct responsibility of Subcommittee E20.91 on Editorial andTerminology.Current edition approved Nov. 1, 2011May 15, 2016.
10、Published December 2011May 2016. Originally approved in 1994. Last previous edition approved in 20062011 asE1594 06.E1594 11. DOI: 10.1520/E1594-11.10.1520/E1594-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Boo
11、k of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be techni
12、cally possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Bo
13、x C700, West Conshohocken, PA 19428-2959. United States15.1.4 A thermodynamic temperature may be expressed as a Celsius temperature. The symbol t is to be used to designate aCelsius temperature, but if this symbol leads to a conflict in notation in a given context, it is acceptable to use the symbol
14、 T insteadto 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 that thesymbol for the degree Celsius consists of the degree sign () followed by the capital letter C. Neither the degree sign nor the let
15、terC alone represents the degree Celsius. The Unicode value for the degree sign is 176 (00B0 in hexadecimal). The symbol may berepresented by the two separate Unicode characters, the degree sign () followed by the capital letter C. The Unicode character“C” with the value 8451 (2103 in hexadecimal) m
16、ay also be used as the degree Celsius symbol.5.1.6 The expression of a value of Celsius temperature is written:t 5nc C (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.5.1.7 By definition, a
17、t any temperature, a temperature increment of one degree Celsius is equal to a temperature increment ofone kelvin.5.1.8 By definition, the Celsius temperature t = 0 C is the same as the thermodynamic temperature T = 273.15 K. The relationbetween numerical values associated with both expressions of a
18、 temperature is therefore given by:nc 5nk2273.15 (3)where:t = nc C is the same temperature as T = n k K.5.2 Practical Temperature Scales:5.2.1 Practical temperature scales have been established by international agreement for the practice of temperaturemeasurement.Among them are the International Pra
19、cticalTemperature Scale of 1968, the International PracticalTemperature Scaleof 1948, and the International Temperature Scale of 1927.35.2.1 Practical scales temperature scales have been established by international agreement for the practice of temperaturemeasurement. Practical scales are designed
20、so that a numerical value of temperature expressed on the scale is close to the numericalvalue of thermodynamic temperature. Because the KTTS is difficult to implement, the vast majority of temperature measurementsare based on a practical scale.5.2.2 There are two practical temperature scales now in
21、 use, superseding all others. The International Temperature Scale of19903 defines temperatures above 0.65 K. The Provisional Low-Temperature Scale from 0.9 mK to 1 K4 defines temperaturesbetween 0.0009 K and 1 K.5.2.3 Examples of previously used practical temperature scales are the International Pra
22、ctical Temperature Scale of 1968, theInternational Practical Temperature Scale of 1948, and the International Temperature Scale of 1927.55.2.4 A value of temperature on a practical temperature scale may be expressed either in kelvins or in degrees Celsius usingthe designations, symbols, and relation
23、s given in 5.1.6. Expression of Values of Temperature6.1 Temperature Scale Identification :6.1.1 It In a document containing temperature values, it is important that the temperature scale upon which those values oftemperature are expressed be identified in a document. identified. When reference to m
24、ore than one scale is made in a document,or when critical data are presented, scale identification is essential.6.1.2 Thermodynamic temperatures may be identified as such, or with reference to the KTTS. If values of temperature areexpressed on a practical temperature scale, the scale should be ident
25、ified. The identification may be an abbreviation, as defined inthe text of the scale; for example, the International Temperature Scale of 1990 is abbreviated ITS-90 and the ProvisionalLow-Temperature Scale from 0.9 mK to 1 K is abbreviated PLTS-2000.6.1.3 Scale identification may be placed in text,
26、in footnotes, in table headings, or in figures, as appropriate.6.1.4 A scale may also be identified by a subscript associated with a quantity symbol; for example, TTh and tTh forthermodynamic temperatures, T90 and t90 for temperature values on ITS-90, and T2000 for temperature values on PLTS-2000.5
27、Evolution of the International Practical Temperature Scale of 1968, ASTM STP 565, ASTM, 1974.3 Evolution of the International Practical Temperature Scale of 1968, ASTM STP 565, ASTM, 1974.3 Preston-Thomas, H., “The International Temperature Scale of 1990 (ITS-90),” Metrologia, Vol 27, No. 1, 1990, p
28、p. 310. For errata see ibid, Vol 27, No. 2, 1990, p.107.4 Rusby, R. 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 Low TemperatureScale from 0.9 mK to 1 K, PLTS-2000.” J. Low Temp. Physics Vol 126, 2002, pp. 6336
29、42.E1594 1626.2 Numerical Format:6.2.1 Numerical values of temperature should be expressed as decimal numbers.6.3 Unit Symbol Format:6.3.1 The unit symbol should be separated from the numerical value by a single space. There should be no space between thedegree sign and the letter C. Punctuation is
30、not part of the unit symbol; only punctuation required by context or grammar shouldfollow the unit symbol.6.3.2 In an expression of a range of temperature values, the same unit symbol should be used with each value in the range; forexample: “over the temperature range 16 K to 50 K” or “any temperatu
31、re between 20 C and 30 C.” These examples can alsobe expressed as “over the temperature range (16 to 50) K” or “any temperature between (20 and 30) C” respectively.6.3.3 Multiple and submultiple prefixes should not normally be used with the unit for the expression of values of temperature,for temper
32、atures 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 with a value of temperature, both the value and the tolerance or uncertaintyshould be expressed with the same unit
33、. Unit prefixes should not normally be used. The unit symbol should follow each numericalvalue. For example:t90 560.0 C61.5 C (4)T90 5273.150 K60.001 K (5)6.3.5 When a tolerance or uncertainty is presented in a format not directly associated with a value of temperature, a unit prefixmay be used. The
34、 preferred submultiple is 0.001 (prefix “milli,” symbol m). For example, the uncertainty u of a temperature valuemay be expressed:ut90!50.7 mK (6)7. Expression of Temperature Differences, Intervals, and Increments7.1 Temperature differences, intervals, and increments are normally understood to be ex
35、pressed with reference to the sametemperature scale as are values of temperature, within a given context. Where there is a possibility of misunderstanding, thetemperature scale should be explicitly identified.7.2 A small temperature difference, interval, or increment may be expressed in terms of a s
36、ubmultiple of the appropriate unitof temperature. The use of unit prefixes to indicate submultiples should follow the guidelines in IEEE/ASTM SI-10. The preferredsubmultiple is 0.001 (prefix “milli,” symbol m).7.3 The magnitude of a temperature increment at a particular temperature is sometimes expr
37、essed as a relative fraction or apercentage of the numerical value (on a particular temperature scale) of the temperature. Such usage should be carefully explainedso that the expression is meaningful and unambiguous.7.4 When a tolerance or uncertainty is associated with the magnitude of a temperatur
38、e difference, interval, or increment, boththe magnitude and tolerance or uncertainty should be expressed in the same numerical format and with the same unit. Anappropriate unit prefix may be used (see 7.2). The resulting unit symbol should follow each numerical value in the expression. Forexample:t
39、510.00 C60.01 Cdescribes atemperature interval of (7)about 10 CT 59.8 mK60.2 mK describes atemperature interval of (8)about 9.8 mK7.5 In the expression of derived quantities the unit of temperature should be the kelvin. For example, the preferred expressionfor heat capacity is joules per kelvin, JK1
40、 or J/K; for temperature gradient, kelvins per metre, Km 1 or K/m.8. Units Other Than SI8.1 Values of temperature are sometimes expressed in degrees Rankine, symbol R, instead of kelvins, or in degrees Fahrenheit,symbol F, instead of degrees Celsius. Neither the degree Rankine nor the degree Fahrenh
41、eit are part of the SI.8.2 At any temperature, a temperature increment of one degree Rankine is equal to a temperature increment of 5/9 kelvin. Therelation between numerical values associated with both expressions of a temperature is given by:nr 59nk /5 (9)where:T = nr R is the same temperature as T
42、 = nk K.E1594 1638.3 At any temperature, a temperature increment of one degree Fahrenheit is equal to a temperature increment of 5/9 degreeCelsius. The relation between numerical values associated with both expressions of a temperature is given by:nf 59nc /5132 (10)where:t = nfF is the same temperat
43、ure as t = nc C.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 one degree Rankine is equal to a temperature increment of one degreeFahrenheit.8.4.2 If T = nr R and t = nf F are the same temperature, then the relation between the nume
44、rical values is given by:nr 5nf1459.67 (11)8.4.3 If a temperature interval expressed in degrees Rankine or degrees Fahrenheit has a magnitude n 1, and the sametemperature interval expressed in kelvins or degrees Celsius has a magnitude n2, then the relation between n1 and n2 is given by:n159n2/5 (12
45、)8.5 Both thermodynamic temperatures and values of temperature on a practical temperature scale may be expressed in degreesRankine or degrees Fahrenheit. In both cases the considerations of Section 6 apply.8.6 The use of multiple or submultiple prefixes with the degree Rankine or the degree Fahrenhe
46、it is not recommended.9. Keywords9.1 degree Celsius; degree Fahrenheit; degree Rankine; kelvin; SI; temperature; temperature difference; temperature increment;temperature interval; temperature scales; temperature value; thermodynamic temperatureASTM International takes no position respecting the val
47、idity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is sub
48、ject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquar
49、ters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This 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 o
