ASTM E1594-11

Standard Guide for Expression of Temperature

ABSTRACT
This guide presents the uniform methods for expressing temperature, temperature values, and temperature differences. Also covered here are the practical scales, numerical formats, and unit symbol formats used in representing temperature.
SCOPE
1.1 This guide covers uniform methods for expressing temperature, temperature values, and temperature differences.
1.2 This guide is intended as a supplement to IEEE/ASTM SI-10.

General Information

• Status: Historical
• Publication Date: 31-Oct-2011
• ICS: 17.200.20 - Temperature-measuring instruments
• Technical Committee: E20 - Temperature Measurement
• Drafting Committee: E20.91 - Editorial and Terminology

Relations

• Replaces: ASTM E1594-06 - Standard Guide for Expression of Temperature
• Effective Date: 01-Nov-2011
• Referred By: ASTM E344-20 - Terminology Relating to Thermometry and Hydrometry
• Effective Date: 01-Nov-2011
• Referred By: ASTM E1750-10(2016) - Standard Guide for Use of Water Triple Point Cells
• Effective Date: 01-Nov-2011
• Referred By: ASTM E220-19 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
• Effective Date: 01-Nov-2011
• Referred By: ASTM E563-22 - Standard Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature
• Effective Date: 01-Nov-2011

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1594 − 11
StandardGuide for
1
Expression of Temperature
This standard is issued under the fixed designation E1594; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4.4 A temperature difference, interval, or increment is also
described by a numerical value designating the magnitude, a
1.1 This guide covers uniform methods for expressing
unit, and, where appropriate, a tolerance or uncertainty.
temperature, temperature values, and temperature differences.
1.2 This guide is intended as a supplement to IEEE/ASTM
5. Temperature Scales
SI-10.
5.1 Thermodynamic Temperature Scales:
5.1.1 By international agreement, the theoretical tempera-
2. Referenced Documents
ture scale to which all temperature values should be ultimately
2
2.1 ASTM Standards:
referable is the Kelvin Thermodynamic Temperature Scale
E344Terminology Relating to Thermometry and Hydrom-
(KTTS). A value of temperature expressed on the KTTS is
etry
known as a thermodynamic temperature, symbol T.
IEEE/ASTM SI-10Standard for Use of the International
5.1.2 The unit of thermodynamic temperature is the kelvin,
System of Units (SI): The Modern Metric System
symbolK.ThekelvinisabaseunitintheInternationalSystem
of Units (SI). Note that the symbol for the kelvin is the capital
3. Terminology
letter K only; the degree sign (°) is not used.
3.1 General—Standard terms used in this guide are defined 5.1.3 The expression of a value of thermodynamic tempera-
in Terminology E344 and in IEEE/ASTM SI-10. ture is written:
T 5 n K (1)
k
4. Basic Concepts
where:
4.1 Temperature is a fundamental measurable quantity des-
n = a numerical value designating the magnitude,
k
ignated by the symbol T or the symbol t (see 5.1). In
K = the symbol for the unit kelvin.
expressions of dimensions the symbol θ is sometimes used to
The magnitude may also be represented by the notation T/K.
indicate the dimension temperature.
5.1.4 Athermodynamic temperature may be expressed as a
4.2 Atemperature value is expressed in terms of a tempera-
Celsius temperature. The symbol t is to be used to designate a
ture scale. The complete description consists of a numerical
Celsius temperature, but if this symbol leads to a conflict in
value designating the magnitude, a unit, and, where
notation in a given context, it is acceptable to use the symbol
appropriate, a tolerance or uncertainty. Both the numerical
T instead to designate a Celsius temperature.
value and the unit depend upon the scale.
5.1.5 The unit of Celsius temperature is the degree Celsius,
4.3 Aunit of temperature is understood to mean an interval
symbol °C. The degree Celsius is a derived SI unit. Note that
on a temperature scale.
thesymbolforthedegreeCelsiusconsistsofthedegreesign(°)
followedbythecapitalletterC.Neitherthedegreesignnorthe
letter C alone represents the degree Celsius.
1
5.1.6 The expression of a value of Celsius temperature is
This guide is under the jurisdiction ofASTM Committee E20 on Temperature
Measurement and is the direct responsibility of Subcommittee E20.91 on Editorial written:
and Terminology.
t 5 n °C (2)
c
Current edition approved Nov. 1, 2011. Published December 2011. Originally
approved in 1994. Last previous edition approved in 2006 as E1594–06. DOI:
where:
10.1520/E1594-11.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
n = a numerical value designating the magnitude,
c
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
°C = the symbol for the unit degree Celsius.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Themagnitudemayalsoberepresentedbythenotation t/°C.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E1594 − 11
5.1.7 Bydefinition,atanytemperature,atemperatureincre-
mentofonedegreeCelsiusisequaltoatemperatureincrement
of one kelvin.
1

---------------------- Page: 2 ----------------------
E1594 − 11
5.1.8 By definition, the Celsius temperature t=0 °C is the thermodynamic temperatures, T and t for temperature
90 90
same as the thermodynamic temperature T =273.15 K. The values on ITS-90, and T for temperature values on PLTS-
2000
relationbetweennumericalvaluesassociatedwithbothexpres- 2000.
sions of a temperature is therefore given by:
6.2 Numerical Format:
n 5 n 2 273.15 (3)
c k
6.2.1 Numerical values of temperature should be expressed
as decimal numbers.
where:
t = n °C is the same temperature as T= n K.
6.3 Unit Symbol Format:
c k
6.3.1 Theunitsy
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E1594–06 Designation:E1594–11
Standard Guide for
1
Expression of Temperature
This standard is issued under the fixed designation E1594; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide covers uniform methods for expressing temperature, temperature values, and temperature differences.
1.2 This guide is intended as a supplement to IEEE/ASTM SI-10.
2. Referenced Documents
2
2.1 ASTM Standards:
E344 Terminology Relating to Thermometry and Hydrometry
IEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System
3. Terminology
3.1 General—Standard terms used in this guide are defined in Terminology E344 and in IEEE/ASTM SI-10.
4. Basic Concepts
4.1 Temperature is a fundamental measurable quantity designated by the symbol T or the symbol t (see 5.1). In expressions of
dimensions the symbol u is sometimes used to indicate the dimension temperature.
4.2 A temperature value is expressed in terms of a temperature scale. The complete description consists of a numerical value
designatingthemagnitude,aunit,and,whereappropriate,atoleranceoruncertainty.Boththenumericalvalueandtheunitdepend
upon the scale.
4.3 A unit of temperature is understood to mean an interval on a temperature scale.
4.4 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 Scales
5.1 Thermodynamic Temperature Scales:
5.1.1 By international agreement, the theoretical temperature scale to which all temperature values should be ultimately
referable is the Kelvin Thermodynamic Temperature Scale (KTTS).Avalue of temperature expressed on the KTTS is known 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 the International System of
Units (SI). Note1—The 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 5 n K (1)
k
where:
n = a numerical value designating the magnitude,
k
K = the symbol for the unit kelvin.
The magnitude may also be represented by the notation T/K.
5.1.4 A thermodynamic temperature may be expressed as a Celsius temperature. The symbol t is to be used to designate a
Celsiustemperature,butifthissymbolleadstoaconflictinnotationinagivencontext,itisacceptabletousethesymbol Tinstead
to designate a Celsius temperature.
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 and
Terminology.
Current edition approved Nov. 1, 2006.2011. Published December 2006.2011. Originally approved in 1994. Last previous edition approved in 19992006 as
E1594–99.E1594–06. DOI: 10.1520/E1594-06.10.1520/E1594-11.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,[e-mail] Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
E1594–11
5.1.5 The unit of Celsius temperature is the degree Celsius, symbol °C. The degree Celsius is a derived SI unit. Note2—The
that the symbol for the degree Celsius consists of the degree sign (°) followed by the capital letter C. Neither the degree sign nor
the letter C alone represents the degree Celsius.
5.1.6 The expression of a value of Celsius temperature is written:
t 5 n °C (2)
c
where:
n = a numerical value designating the magnitude,
c
°C = the symbol for the unit degree Celsius.
The magnitude may also be represented by the notation t/°C.
5.1.7 By definition, at any temperature, a temperature increment of one degree Celsius is equal to a temperature increment of
one kelvin.
5.1.8 By definition, the Celsius temperature t=0 °C is the same as the thermodynamic temperature T =273.15 K.The relation
between numerical values associated with both expressions of a temperature is therefore given by:
n 5 n 2273.15 (3)
c k
where:
t = n °C is the same temperature as T= n K.
...