ASTM E1594-16

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: 14-May-2016
• ICS: 17.200.20 - Temperature-measuring instruments
• Technical Committee: E20 - Temperature Measurement
• Drafting Committee: E20.91 - Editorial and Terminology

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 − 16
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 5.1.1 By international agreement, the theoretical tempera-
ture scale to which all temperature values should be ultimately
1.1 This guide covers uniform methods for expressing
referable is the Kelvin Thermodynamic Temperature Scale
temperature, temperature values, and temperature differences.
(KTTS). A value of temperature expressed on the KTTS is
1.2 This guide is intended as a supplement to IEEE/ASTM
known as a thermodynamic temperature, symbol T.
SI-10.
5.1.2 The unit of thermodynamic temperature is the kelvin,
symbolK.ThekelvinisabaseunitintheInternationalSystem
2. Referenced Documents
of Units (SI). Note that the symbol for the kelvin is the capital
2
2.1 ASTM Standards:
letter K only; the degree sign (°) is not used.
E344Terminology Relating to Thermometry and Hydrom-
5.1.3 The expression of a value of thermodynamic tempera-
etry
ture is written:
IEEE/ASTM SI-10Standard for Use of the International
T 5 n K (1)
System of Units (SI): The Modern Metric System k
where:
3. Terminology
n = a numerical value designating the magnitude,
k
3.1 General—Standard terms used in this guide are defined
K = the symbol for the unit kelvin.
in Terminology E344 and in IEEE/ASTM SI-10.
The magnitude may also be represented by the notation T/K.
4. Basic Concepts
5.1.4 Athermodynamic temperature may be expressed as a
Celsius temperature. The symbol t is to be used to designate a
4.1 Temperature is a fundamental measurable quantity des-
Celsius temperature, but if this symbol leads to a conflict in
ignated by the symbol T or the symbol t (see 5.1).
notation in a given context, it is acceptable to use the symbol
4.2 Atemperature value is expressed in terms of a tempera-
T instead to designate a Celsius temperature.
ture scale. The complete description consists of a numerical
5.1.5 The unit of Celsius temperature is the degree Celsius,
value designating the magnitude, a unit, and, where
symbol °C. The degree Celsius is a derived SI unit. Note that
appropriate, a tolerance or uncertainty. Both the numerical
thesymbolforthedegreeCelsiusconsistsofthedegreesign(°)
value and the unit depend upon the scale.
followedbythecapitalletterC.Neitherthedegreesignnorthe
4.3 Aunit of temperature is understood to mean an interval
letterCalonerepresentsthedegreeCelsius.TheUnicodevalue
on a temperature scale.
for the degree sign is 176 (00B0 in hexadecimal). The symbol
mayberepresentedbythetwoseparateUnicodecharacters,the
4.4 A temperature difference, interval, or increment is also
degree sign (°) followed by the capital letter C. The Unicode
described by a numerical value designating the magnitude, a
character“°C”withthevalue8451(2103inhexadecimal)may
unit, and, where appropriate, a tolerance or uncertainty.
also be used as the degree Celsius symbol.
5. Temperature Scales
5.1.6 The expression of a value of Celsius temperature is
5.1 Thermodynamic Temperature Scales: written:
t 5 n °C (2)
c
1
This guide is under the jurisdiction ofASTM Committee E20 on Temperature
where:
Measurement and is the direct responsibility of Subcommittee E20.91 on Editorial
and Terminology.
n = a numerical value designating the magnitude,
c
Current edition approved May 15, 2016. Published May 2016. Originally
°C = the symbol for the unit degree Celsius.
approved in 1994. Last previous edition approved in 2011 as E1594–11. DOI:
10.1520/E1594-16. Themagnitudemayalsoberepresentedbythenotation t/°C.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.1.7 Bydefinition,atanytemperature,atemperatureincre-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
mentofonedegreeCelsiusisequaltoatemperatureincrement
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. of one kelvin.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E1594 − 16
5.1.8 By definition, the Celsius temperature t=0 °C is the 6.1.4 A scale may also be identified by a subscript associ-
same as the thermodynamic temperature T =273.15 K. The ated with a quantity symbol; for example, T and t for
Th Th
relationbetweennumericalvaluesassociatedwithbothexpres- thermodynamic temperatures, T and t for temperature
90 90
sions of a temperature is therefore given by: values on ITS-90, and T for temperature values on PLTS-
20
...

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. 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 − 11 E1594 − 16
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. A number 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 θ 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
designating the magnitude, a unit, and, where appropriate, a tolerance or uncertainty. Both the numerical value and the unit depend
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). A value 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). 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 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.
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, 2011May 15, 2016. Published December 2011May 2016. Originally approved in 1994. Last previous edition approved in 20062011 as
E1594 – 06.E1594 – 11. DOI: 10.1520/E1594-11.10.1520/E1594-16.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For 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 − 16
5.1.4 A thermodynamic temperature may be expressed as a Celsius temperature. The symbol t is to be used to designate a
Celsius temperature, but if this symbol leads to a conflict in notation in a given context, it is acceptable to use the symbol T 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 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. The Unicode value for the degree sign is 176 (00B0 in hexadecimal). The symbol may be
represented 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) may also be used as the degree Celsius symbol.
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 inc
...