EN ISO 80000-5:2019

SLOVENSKI STANDARD
01-december-2019
Nadomešča:
SIST EN ISO 80000-5:2013
Veličine in enote - 5. del: Termodinamika (ISO 80000-5:2019)
Quantities and units - Part 5: Thermodynamics (ISO 80000-5:2019)
Größen und Einheiten - Teil 5: Thermodynamik (ISO 80000-5:2019)
Grandeurs et unités - Partie 5: Thermodynamique (ISO 80000-5:2019)
Ta slovenski standard je istoveten z: EN ISO 80000-5:2019
ICS:
01.060 Veličine in enote Quantities and units
17.200.01 Termodinamika na splošno Thermodynamics in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 80000-5
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2019
EUROPÄISCHE NORM
ICS 01.060; 17.200.01 Supersedes EN ISO 80000-5:2013
English Version
Quantities and units - Part 5: Thermodynamics (ISO
80000-5:2019)
Grandeurs et unités - Partie 5: Thermodynamique (ISO Größen und Einheiten - Teil 5: Thermodynamik (ISO
80000-5:2019) 80000-5:2019)
This European Standard was approved by CEN on 5 May 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 80000-5:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 80000-5:2019) has been prepared by Technical Committee ISO/TC 12
"Quantities and units" in collaboration with Technical Committee CEN/SS F02 “Units and symbols” the
secretariat of which is held by CCMC.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2020, and conflicting national standards shall be
withdrawn at the latest by April 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 80000-5:2013.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 80000-5:2019 has been approved by CEN as EN ISO 80000-5:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 80000-5
Second edition
2019-08
Quantities and units —
Part 5:
Thermodynamics
Grandeurs et unités —
Partie 5: Thermodynamique
Reference number
ISO 80000-5:2019(E)
©
ISO 2019
ISO 80000-5:2019(E)
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 80000-5:2019(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
Bibliography .14
Alphabetical index .15
ISO 80000-5:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www. iso. org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www. iso.o rg/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www. iso
.org/iso/foreword. html.
This document was prepared by Technical Committee ISO/TC 12, Quantities and units, in collaboration
with Technical Committee IEC/TC 25, Quantities and units.
This second edition cancels and replaces the first edition of (ISO 80000-5:2007), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— the table giving the quantities and units has been simplified;
— some definitions and the remarks have been stated physically more precisely.
A list of all parts in the ISO 80000 and IEC 80000 series can be found on the ISO and IEC websites.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www. iso. org/members. html.
iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 80000-5:2019(E)
Quantities and units —
Part 5:
Thermodynamics
1 Scope
This document gives names, symbols, definitions and units for quantities of thermodynamics. Where
appropriate, conversion factors are also given.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
Names, symbols, definitions and units for quantities used in thermodynamics are given in Table 1.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
ISO 80000-5:2019(E)
2 © ISO 2019 – All rights reserved
Table 1 — Quantities and units used in thermodynamics
Item No. Quantity Unit Remarks
Name Symbol Definition
5-1 thermodynamic tem- T, Θ partial derivative of internal energy with K It is measured with a primary thermometer,
perature respect to entropy at constant volume and con- examples of which are gas thermometers of
stant number of particles in the system: different kinds, noise thermometers, or radia-
tion thermometers.
¶U
 
T =
The Boltzmann constant (ISO 80000-1) relates
 
¶S 
VN,
energy at the individual particle level with
thermodynamic temperature.
where U is internal energy (item 5-20.2), S is
entropy (item 5-18), V is volume (ISO 80000-3),
Differences of thermodynamic temperatures
and N is number of particles
or changes may be expressed either in kelvin,
symbol K, or in de grees Celsius, symbol °C
(item 5-2).
Thermodynamic temperature is one of the
seven base quantities in the International Sys-
tem of Quantities, ISQ (see ISO 80000-1).
The International Temperature Scale of
For the purpose of practical measurements,
the International Temperature Scale of 1990,
ITS-90, was adopted by CIPM in 1989, which is
a close approximation to the thermodynamic
temperature scale.
The quantities defined by this scale are de-
noted T and t , respectively (replacing T
90 90 68
and t defined by the International Practical
Temperature Scale of 1968, IPTS-68), where
tT
90 90
=−273,15
11°CK
ISO 80000-5:2019(E)
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition
5-1   The units of T and t are the kelvin, symbol
90 90
(cont.) K, and the degree Celsius, symbol °C (item 5-2),
respectively.
[ ] [ ]
For further information, see References 5 , 6 .
For ready conversion between temperatures
reported on the International Temperature
Scale and thermodynamic temperatures the
systematic deviations can be found in Refer-
[ ]
ence 7 .
5-2 Celsius temperature temperature difference from the thermody- °C The unit degree Celsius is a special name for
t ,ϑ
namic temperature of the ice point is called the the kelvin for use in stating values of Celsius
Celsius temperature t, which is defined by the temperature. The unit degree Celsius is by
quantity equation: definition equal in magnitude to the kelvin. A
difference or interval of temperature may be
tT=−T
expressed in kelvin or in degrees Celsius.
where T is thermodynamic temperature (item
The thermodynamic temperature T is 0,01 K
below the thermodynamic temperature of the
5-1) and T =273,K15
triple point of water.
The symbol °C for the degree Celsius shall be
preceded by a space (see ISO 80000-1).
Prefixes are not allowed in combination with
the unit °C.
−1
5-3.1 linear expansion relative change of length with temperature: K The subscripts in the symbols may be omitted
α
l
coefficient when there is no risk of confusion.
1dl
α =
l
l dT
where l is length (ISO 80000-3) and T is thermo-
dynamic temperature (item 5-1)
−1
5-3.2 cubic expansion relative change of volume with temperature: K Also called volumetric expansion coefficient.
α ,γ
V
coefficient
The subscripts in the symbols may be omitted
1dV
α =
when there is no risk of confusion.
V
V dT
where V is volume (ISO 80000-3) and T is ther-
modynamic temperature (item 5-1)

ISO 80000-5:2019(E)
4 © ISO 2019 – All rights reserved
Table 1 (continued)
Item No. Quantity Unit Remarks
Name Symbol Definition
−1
5-3.3 relative pressure relative change of pressure with temperature at K The subscripts in the symbols may be omitted
α
p
coefficient constant volume: when there is no risk of confusion.
1 ¶p
 
α =
 
p
p¶T
V
where p is pressure (ISO 80000-4), T is ther-
modynamic temperature (item 5-1), and V is
volume (ISO 80000-3)
5-4 pressure coefficient change of pressure with temperature at con- Pa/K
β
stant volume:
−1 −2 −1
kg m s K
¶p
 
β =
 
¶T 
V
where p is
...