EN ISO 8497:1996
(Main)Thermal insulation - Determination of steady-state thermal transmission properties of thermal insulation for circular pipes (ISO 8497:1994)
Thermal insulation - Determination of steady-state thermal transmission properties of thermal insulation for circular pipes (ISO 8497:1994)
Specifies apparatus performance requirements, but does not specify apparatus design. Applies to circular pipes, generally operating at temperatures above ambient. The type of specimen, temperatures and test conditions to which the standard applies are specified in the standard in detail.
Wärmeschutz - Bestimmung der Wärmetransporteigenschaften im stationären Zustand von Wärmedämmungen für Rohrleitungen (ISO 8497:1994)
Diese Internationale Norm beschreibt ein Verfahren zur Bestimmung der stationären Wärmedurchgangseigenschaften von Wärmedämmungen für Rohre, die im allgemeinen bei Temperaturen über der Umgebungstemperatur eingesetzt werden.Sie legt Anforderungen an die Leistungsparameter des Prüfgerätes, jedoch nichtdie Geräteausführung fest. In den Abschnitten 5 und 6 sind die Art des Probekörpers, die Temperaturen und Prüfbedingungen angegeben, in deren für die diese Internationale Norm gilt.
Isolation thermique - Détermination des propriétés relatives au transfert de chaleur en régime stationnaire dans les isolants thermiques pour conduites (ISO 8497:1994)
La présente Norme internationale prescrit une méthode de mesure des propriétés thermiques relatives au transfert de chaleur en régime stationnaire à travers des isolants pour conduites, pour des températures supérieures à la température ambiante. Elle normalise la méthode de mesure, y compris les modes opératoires et le fonctionnement de l'appareillage, mais elle ne normalise pas la conception de l'appareillage. Les types d'éprouvettes, les températures et les conditions d'essai auxquels s'applique la présente Norme internationale sont décrits en détail aux articles 5 et 6.
Toplotna izolacija - Določanje toplotne prevodnosti v stacionarnem stanju pri materialih za izolacijo okroglih cevi (ISO 8497:1994)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-1997
7RSORWQDL]RODFLMD'RORþDQMHWRSORWQHSUHYRGQRVWLYVWDFLRQDUQHPVWDQMXSUL
PDWHULDOLK]DL]RODFLMRRNURJOLKFHYL ,62
Thermal insulation - Determination of steady-state thermal transmission properties of
thermal insulation for circular pipes (ISO 8497:1994)
Wärmeschutz - Bestimmung der Wärmetransporteigenschaften im stationären Zustand
von Wärmedämmungen für Rohrleitungen (ISO 8497:1994)
Isolation thermique - Détermination des propriétés relatives au transfert de chaleur en
régime stationnaire dans les isolants thermiques pour conduites (ISO 8497:1994)
Ta slovenski standard je istoveten z: EN ISO 8497:1996
ICS:
27.220 Rekuperacija toplote. Heat recovery. Thermal
Toplotna izolacija insulation
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 8497
First edition
1994-04-15
Thermal insulation - Determination of
steady-state thermal transmission
properties of thermal insulation for circular
pipes
Isolation thermique - Dbtermina tion des propri&& relatives au trans fert
de chaleur en r6gime stationnaire dans les isolants thermiques pour
conduites
Reference number
ISO 8497:1994(E)
ISO 8497:1994(E)
Contents
Page
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Scope
Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Symbols and units
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Requirements
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General considerations
Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test specimens
Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...............................................................
10 End cap corrections
...........................................................................
11 Calculations
..................................................
12 Test precision and accuracy
..I................................,.........................................
13 Test report
Annex
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A Bibliography
0 ISO 1994
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microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
0 ISO
ISO 8497:1994(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. Esch 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.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 8497 was prepared by Technical Committee
lSO/TC 163, Thermal insulation, Subcommittee SC 1, Test and measure-
ment methods.
Annex A of this International Standard is for information only.
. . .
Ill
@J ISO
ISO 8497: 1994(E)
Introduction
The thermal transmission properties of pipe insulation generally have to
be determined using pipe test apparatus rather than flat specimen appa-
ratus such as the guarded hot plate or the heat flow meter apparatus, if
results are to be representative of end-use Performance. Insulation ma-
terial formed into flat sheets often has different internal geometry from
that of the same material formed into cylindrical shapes. Furthermore,
properties often depend significantly upon the direction of heat flow in
relation to inherent characteristics such as fibre planes or elongated cells:
thus flat specimen one-dimensional heat flow measurements may not
necessarily be representative of the two-dimensional radial heat flow en-
countered in pipe insulation.
Another consideration is that commercial insulations for pipes are often
made with the inside diameter slightly larger than the outside diameter
of the Pipe, otherwise manufacturing tolerantes may result in an imperfect
fit on the Pipe, thus creating an air gap of variable thickness. In those
cases where end-use Performance data rather than material properties are
to be determined, the insulation is mounted on the test pipe in the same
loose manner so that the effect of the air gap will be included in the
measurements. This would not be the case if properties were determined
in a flat plate apparatus where good plate contact is required.
Still another consideration is that natura1 convection currents around insu-
lation installed on a pipe will Cause non-uniform surface temperatures.
Such conditions will not be duplicated in a flat plate apparatus with uniform
plate temperatures.
NOTE 1 Comparison tests on apparently similar material using both pipe appa-
ratus and flat plate apparatus have shown varying degrees of agreement of
measured thermal transmission properties. lt appears that better agreement is of-
ten obtained for heavier density products which tend to be more uniform, homo-
geneous and sometimes more isotropic. For those materials which have
repeatedly shown acceptable agreement in such comparisons, the use of data
from flat plate apparatus to characterize pipe insulation may be justified. As a
general rule, when such agreement has not been shown, the pipe test apparatus
shall be used to obtain thermal transmission data for pipe insulations.
INTERNATIONAL STANDARD 0 ISO ISO 8497: 1994(E)
Thermal insulation - Determination of steady-state
thermal transmission properties of thermal insulation
for circular pipes
of steady-state thermal resistance and related prop-
1 Scope
- Heat flow meter appara tus.
erties
This International Standard specifies a method for the
ISO 8302:1991, Thermal insulation - Determination
determination of steady-state thermal transmission
of steady-sta te thermal resistance and rela ted prop-
properties of thermal insulations for circular pipes
erties - Guarded hot plate apparatus.
generally operating at temperatures above ambient.
lt specifies apparatus Performance requirements, but
it does not specify apparatus design.
3 Definitions
The type of specimen, temperatures and test condi-
NOTE 2 The geometry of pipe insulation requires special
tions to which this International Standard applies are
terms not applicable to flat specimens. The word “linear”
specified in clauses 5 and 6.
is used to denote properties based upon a unit length (in the
pipe axis direction) of a specified insulation size. These lin-
ear properties, identified by the subscript “1 ”, are con-
2 Normative references
venient since the total heat loss tan then be calculated
knowing the pipe length and the applicable temperature.
The following Standards contain provisions which,
through reference in this text, constitute provisions
“Linear” does not denote heat flow in the axial direction. In
of this International Standard. At the time of publica- this International Standard, the direction of heat flow is
predominantly radial.
tion, the editions indicated were valid. All Standards
are subject to revision, and Parties to agreements
For the purposes of this International Standard, the
based on this International Standard are encouraged
following definitions apply. The definitions and sym-
to investigate the possibility of applying the most re-
bols given in the following clauses are based upon
cent editions of the Standards indicated below.
those in ISO 7345 except for the linear thermal
Members of IEC and ISO maintain registers of cur-
transference (3.1).
rently valid International Standards.
3.1 linear thermal transference, K,: Linear density
ISO 7345:1987, Thermal insulation - Physical quan-
of heat flow rate divided by the temperature differ-
tities and de finitions.
ence between the pipe surface and the ambient air in
ISO 8301: 1991, Thermal insulation - Determination
the steady-state condition. lt relates to a specific in-
(6 ISO
ISO 8497: 1994(E)
sulation size and is a measure of the heat transferred
3.6 thermal resistivity, r: Reciprocal of the thermal
through the insulation to the ambient atmosphere.
conductivity, ;1, for a homogeneous material in the
steady-state condition.
w
K, = -
. . .
(1)
To - Ta WTO - Tz) 1
r . . .
(6)
= # In(D,lD,) = T
3.2 linear thermal resistance, R,: Temperature dif-
ference between the pipe surface and the insulation
3.7 areal thermal resistance, R: Temperature dif-
outer surface divided by the linear density of heat flow
ference between the pipe surface and the insulation
rate in the steady-state condition. lt relates to a spe-
outer surface divided by the areal density of heat flow
cific insulation size and is the reciprocal of the pipe
rate in the steady-state condition. lt is the reciprocal
linear thermal conductance, A,.
of the areal thermal conductance, A.
To - Tz 1
=-=- To - Tz 1
. . .
c-------z-
(2)
RI R . . .
(7)
@lL
Al A
@IA
where the surface of area A must be specified (usually
the pipe surface, sometimes the insulation outer sur-
3.3 linear thermal conductance, A,: Reciprocal of
face, or other as Chosen; see note 6 in 3.8).
the linear thermal resistance, R,, from the pipe surface
to the insulation outer surface. lt relates to a specific
NOTE 5 The more common “areal” properties, based
insulation size.
upon unit area, are often confusing when applied to pipe
insulation since the area must be Chosen arbitrarily and may
1 w'
range from that of the pipe surface to that of the insulation
=-
n, =- . . .
(3)
outer surface. If these areal properties are computed, the
RI To - Tz
area and its location used in the computation must be re-
ported.
3.4 surface coefficient of heat transfer, 4: Areal
density of heat flow rate at the surface in the steady-
3.8 areal thermal conductance, A: Reciprocal of
state condition divided by the temperature differente
the areal thermal resistance, R.
between the surface and the surrounding ambient air.
For pipe insulation geometry the following relation
@IA
c-z---------
. . .
applies. A n rF m (8)
K
10 - 12
@
. . .
(4)
h2
= xD2L(T2 - Ta)
where the location of the surface of area A must be
specified (usually the pipe surface, sometimes the in-
sulation outer surface, or other as Chosen).
NOTE 6 The value of A, the areal thermal conductance,
3.5 thermal conductivity, ;1: Defined by the follow-
is arbitrary since it depends upon an arbitrary choice of the
ing relation specifically applicable to the pipe insu-
area, A. For a homogeneous material for which the thermal
lation geometry. lt applies to homogeneous material
conductivity is defined as in 3.5, the areal conductance, A,
in the steady-state condition and is the reciprocal of
is given by
the thermal resistivity, r.
2lrLA.
n= . . .
(9)
0 Wz&)) 1
A 1 n(o,/QJ
A. . . l
(5)
= 27tL(To - Tz) = -F
If the area is specially Chosen to be the “log mean area ”,
NOTES equal to KL(D~ - Do)/In(D,/D,) then A = 21/(0, - D,). Since
(Dz - D,)/Z is equal to the insulation thickness measured
3 In ISO 7345, the thermal conductivity is also defined by
from the pipe surface, this is analogous to the relation be-
the more general relation 4 = - ;1 grad T.
tween conductance and conductivity for flat slab geometry.
Similar relations exist for the areal thermal resistance, R,
Since the pipe surface temperature, T,, is used, the
defined in 3.7. Since these areal coefficients are arbitrary
therm al conductivity will inclu de the effect of any gap that
and since the area used is often not stated, thus leading to
exists between the insulation and the pipe (sec 6.1).
possible confusion, it is recommended that they be used
only if specified.
0 ISO
ISO 8497: 1994(E)
4 Symbols and units
5 Requirements
5.1 Test specimens
For the purposes of this International Standard, the
Spetimens may be rigid,
semirigid or flexible
following Symbols and units apply. (See clause 3.)
(blanket-type), or may be loose-fill, suitably contained.
They may be homogeneous or nonhomogeneous,
isotropic or anisotropic, may incl
...
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