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UDC 53.081
IS0
FOR STAND A RD IZATl ON
I N TE RN AT1 O N A L ORGANIZATION
IS0 RECOMMENDATION
R 31
PART IV
QUANTITIES AND UNITS OF HEAT
1st EDITION
December 1960
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs. to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of 1SO.
For each individual country the only valid standard is the national standard of that country.
Printed in Denmark
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
'l'lie IS0 I\ecoiiiiiiendatioii 11 31, Part IV, Qritrritities triid Units of Heat, was drawn
up by Technical Cominittee ISO/'l'C 12, Qriuiitit ifs, Units, Symbols, Coituersion
1:crctors arid Conversion Tubles, the Secretariat or which is held by the Danish
Standards Association, Dansk Staiidardiseringsr~d (DS).
lhc ISO/'l'C 1'2 Secretariat tire\\. up two clrafts in succession, the second of which
\vas studicd by the Technical Committee during its fourth meeting, held in Copen-
hagen in Noveniher 1957. The Sccretariat then prepared a third draft proposal,
\\ hich \\ as submitted hy correspondence to the Mcmbers of the Technical Con-
niittee and \\ as approved as a Ilraft IS0 Hecornmendation.
It should be noted that the following international organizations have had these
draft proposals scnt to them and have taken part in the discussions at the meeting\
of Technical Committee ISO/'l'C 12 :
International Commission on Illumination
International Committee on \\'eights and Measures
Iiiternational Electrotcchnical Commission
International Union of Pure and Applied Chemistry
Interriational Gnion of Pure and Applied Physics
and its Sub-Committee SUN
Organi4ation Internationale tie Sldtrolngie Ikgale
On 31 March 1959, the Ilraft IS0 Reconinieridation (No. 277) was distributed
to all the IS0 SIemher I3odies and \vas approyed, subject to small niodifications,
by the follo\viny ;\lember I3odics:
Greece Pakistan
Hungary Poland
India Portugal
R o m a n i a
I re1 and
Israel Sweden
Japan Switzerland
Se 111 erlands United Kingdom
New Zealand U. S. A.
Y
Norway U. S. S. R.
One Slcnihcr I3ody opposed the approval of the draft : Italy.
The Ilraft IS0 Recommendation \\.as submitted by correspondence to the I SO
Council, which decided, in Deceniber 1960, to accept it as an IS0 ItECOMhlEND-
AT I O K.
-2-
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lSO/R 31/Part IV - 1960(E)
I nt roduct ion
General remarks
This document, containing a table of Quantities and I’niis of Heat, is pal t of
a more comprehensive publication dealing with quantities and units in various
fields of science and technology.
IS0 Recoinmendation
Parts of this more coinpreliensive publication are the
R 31/Part I (2nd edition):
The Iriternniioriul Siptern of Units nrid
Quantities and C‘nits of Space and Time1)>
the IS0 Recommendation R 31/l’art II :
Quantities and Units of Periodic and Related Phenonleria
and the IS0 Recoinmendation R 31/I’art III:
Quuntities und C‘nits of Mechnnics.
General information regarding the arrangement of thc tables and the symhols
and abbreviations used is to be found in the introduction to ISO/R 31/Part I,
where the full definitions of basic units are given as an appendix.
The statements in the definition column for quantities are given merely for
identification; they are not intended to be complete definition\.
Special remarks
Attention is drawm to the remarks 4-4.a and 4-5.a. Quantities involving heat
in the present document can be expressed in units based on the various units
of energy, given in Part III “hIechanics” item 3-22.
For simplicity, the present document includes only a selection of units.
l) The title of the first edition of this document was: “Fundamental Quantities and T’nits of
the hlKSA System and Quantities and [-nits of Space and Time”.
-3-
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lSO/R 31jPart IV - 1960(E)
Quantities
4-1 .I . . .4-6.1
Item
Symbol Definition ') Remarks
Quantity
No.
The thermodynamic temperature is de-
t-1.1 I thermodynamic tempera- T, 0
ture. absolute temperature fined according to the principles of ther-
1 modynamics.
l
customary temperature ' t=T T"
1-2.1
where t and I' are the customary and
absolute (thermodynamic) temperatures,
1 of the same system, and To is fixed by
convention.
~
These quantities are not completely
4-3.1 ~ linear expansion coefficient a, I
defined unless the type of change is
I
specified.
4-3.2 cubic expansion coefficient ~ a, ,8, y
The quantity, pressure coefficient, as
4-3.3 1 pressure coefficient IB
here defined is used only for gases.
1- ~ ~~ ~
-
I
4-4.1 I heat, quantity of heat
IQ
-- -~~ -- ~~~
~~ -~ __ -
1 Heat crossing a surface divided by time.
4-5.1 1 heat flow rate
1 @* (4
--
I
flow rate divided by area.
4-6.1 1 density of heat flow rate Heat
q, (9)
, I l
1
') 'The statements in this column are given merely for identification, and they are not intended to be complete definitions.
-4-
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ISO/R 31/Part IV - 1960(E)
4. Heat
Units
4-ta. .4-6.a
Name of unit International
symbolic
Item ’ and in certain
Definition Conversion factors Remarks
N~. cases abbreviation abbreviation
for this name for unit
,
The entries in the 2nd and 3rd
4-l.a degree ’ OK
columns are more than names of
unlts and symbolic abbreviations
Kelvin
ture as defined by the Con- 1
1 for unies. They imply also the
férenceGBnerale des Poids et
zero point used.
Mesures. (See IS0 Recom-
The units of Kelvin and Celsius
mendation R 3i/Part I).
temperature interval or diffe-
rence are identical. The Con-
i ference GBn6rale des Poids et
Mesures has recommended that
........ the name“degr6”or its abbrevia-
............................................................... .............................................................................
tion deg should be used for tem-
4-1.b 1 degree Rankine
perature interval or difference.
1
In English the name “degree” is
used.
The abbreviations OK and OC are
still often used.
Similarly, the units for interval
of Rankine and Fahrenheit tem-
I
Ferature are identical. For this
common unit the names “Ran-
kine degree” and “Fahrenheit
degree” have been proposed and
used with the abbreviations,
degR and degF.
~~
The “lnternational Temperature
Srale of 1848”
For purposes of practical measure-
ments the Conférence GCnCraledes
Poids et Mesures has adopted a
The Celsius temperature f
4-2.a I degree Celsius OC
temperature scale based on a
of a system is given by ex-
number of fixed points (that can
pressing in , be reproduced with high accuracy)
and on certain procedures for in-
t=T-To
ternolation
This scale is called the Interna-
the absolute (thermodyna-
tional Temperature Scale of 1948.
~ mic) temperature T in
Temperatures on it are indicated
, degrees Kelvin and putting “C(Int.1948).
bh T e tint Comitb International des
T,, = 273.15 OK
If fc OC. ti. OF, TK OK and TI\ OR Poids et Mesures has adopted an
~ relate to one and the Same international Kelvin temperature
scale, indication Tint “1<(Int.l94R)
physicalstate,then the numerical
This is defined by
values fc, tl;. TKand Titare
...