EN ISO 8990:1996
(Main)Thermal insulation - Determination of steady-state thermal transmission properties - Calibrated and guarded hot box (ISO 8990:1994)
Thermal insulation - Determination of steady-state thermal transmission properties - Calibrated and guarded hot box (ISO 8990:1994)
Lays down the principles for the design of the apparatus and minimum requirement that shall be met for determination of the laboratory steady-state thermal transmission properties of building components and similar components for industrial use. Does not specify a particular design. Describes also the apparatus, measurement technique and necessary data reporting. Primarily intended for laboratory measurements of large, inhomogeneous specimens. Does not provide for measurements where there is mass transfer through the specimen during the test.
Wärmeschutz - Bestimmung der Wärmedurchgangseigenschaften im stationären Zustand-Verfahren mit dem geregelten Heizkasten (ISO 8990:1994)
Diese Internationale Norm legt die Grundlagen für den Aufbau des Gerätes und Mindestanforderungen fest, die für die Bestimmung der stationären Wärmedurchgangseigenschaften von Bauteilen und ähnlichen Ausrüstungen für technische Zwecke im Laboratorium einzuhalten sind. Sie legt jedoch keinen speziellen Aufbau fest, da die Anforderungen, speziell an die Dimensionierung, zu einem geringeren Teil auch in bezug auf die Betriebsbedingungen, ausgesprochen vershieden sind.
Isolation thermique - Détermination des propriétés de transmission thermique en régime stationnaire - Méthodes à la boîte chaude gardée et calibrée (ISO 8990:1994)
La présente Norme internationale établit les principes de conception de l'appareillage et donne les critères minimaux à suivre pour déterminer en laboratoire les propriétés de transmission thermique en régime stationnaire, les composants de bâtiment et les composants similaires à usage industriel. Elle ne spécifie cependant pas de conception particulière, étant donné que les exigences varient, particulièrement les dimensions, et, dans une moindre mesure, les conditions de fonctionnement. La présente Norme internationale décrit également l'appareillage, la technique de mesurage et la consignation des données nécessaires. Les composants spéciaux, par exemple les fenêtres, nécessitent des procédures supplémentaires qui ne sont pas incluses dans la présente Norme internationale. Sont également exclus les mesurages de l'effet du transfert ou de la redistribution de l'humidité sur le flux thermique, mais il faut tenir compte dans la conception et le fonctionnement de l'équipement, de l'effet possible du transfert d'humidité sur l'exactitude et la pertinence des résultats d'essai. Les propriétés que l'on peut mesurer sont le coefficient de transmission thermique et la résistance thermique. Deux méthodes possibles sont spécifiées, à savoir la méthode de la boîte chaude gardée et la méthode de la boîte chaude calibrée. Ces deux méthodes conviennent à des éprouvettes horizontales telles que des plafonds et planchers. L'appareillage peut être suffisamment grand pour étudier de 1159s composants à l'échelle réelle. Les méthodes sont initialement prévues pour des mesurages en laboratoire de grandes éprouvettes non homogènes; des éprouvettes homogènes peuvent bien entendu aussi être essayées, et sont nécessaires pour l'étalonnage et la validation. L'expérience montre que pour des essais effectués sur des éprouvettes homogènes conformément à la présente Norme internationale, l'exactitude se situe dans la fourchette de + 5 %. Toutefois, l'exactitude d'un appareillage par
Toplotna izolacija - Določanje toplotne prehodnosti v stacionarnem stanju - Metoda kalibrirane in zaščitene komore (ISO 8990:1994)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-1997
7RSORWQDL]RODFLMD'RORþDQMHWRSORWQHSUHKRGQRVWLYVWDFLRQDUQHPVWDQMX
0HWRGDNDOLEULUDQHLQ]DãþLWHQHNRPRUH ,62
Thermal insulation - Determination of steady-state thermal transmission properties -
Calibrated and guarded hot box (ISO 8990:1994)
Wärmeschutz - Bestimmung der Wärmedurchgangseigenschaften im stationären
Zustand-Verfahren mit dem geregelten Heizkasten (ISO 8990:1994)
Isolation thermique - Détermination des propriétés de transmission thermique en régime
stationnaire - Méthodes a la boîte chaude gardée et calibrée (ISO 8990:1994)
Ta slovenski standard je istoveten z: EN ISO 8990:1996
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
IS0
STANDARD
First edition
1994-09-01
Thermal insulation - Determination of
steady-state thermal transmission
properties - Calibrated and guarded hot
box
lsola tion thermique - 06 termination des proprig tt% de transmission
thermique en r6gime s ta tionnaire - M&hodes ;i la boife chaude gardge
et calibr6e
Reference number
IS0 8990:1994(E)
IS0 8990: 1994(E)
Contents
Page
General .
Section 1
1.1 Scope .
1.2 Normative reference .
1.3 Definitions .
........................................... 2
1.4 Symbols, units and relationships
..................................................................................
1.5 Principle
..........................................
1.6 Limitations and sources of errors
.....................................................................
Section 2 Apparatus
a
............................................................................
2.1 Introduction
..............................................................
2.2 Design requirements
..........................................................................
2.3 Metering box
...............................................................................
2.4 Guard box
...................................................................
2.5 Specimen frame
2.6 Cold side chamber .
................................................ 10
2.7 Temperature measurements
....................................................................
2.8 Instrumentation
...............................
2.9 Performance evaluation and calibration
...........................................................
Section 3 Test procedure
..........................................................................
3.1 Introduction
....................................................
3.2 Conditioning of specimen
....................................... 13
3.3 Specimen selection and mounting
.....................................................................
3.4 Test conditions
..........................................................
3.5 Measurement periods
3.6 Calculations .
............................................................................
3.7 Test report
0 IS0 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
lisher.
microfilm, without permission in writing from the pub
International Organization for Standardization
and
Case Postale 56 l CH-1211 Geneve 20 l Switzerl
Printed in Switzerland
ii
0 IS0
IS0 8990: 1994(E)
Annexes
A Heat transfer at surfaces and environmental temperatures
. 16
B Bibliography
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
0 IS0
IS0 8990: 1994(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
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 IS0 8990 was prepared by Technical Committee
lSO/TC 163, Therma/ insulation, Subcommittee SC 1, Test and measure-
ment methods.
Annex A forms an integral part of this International Standard. Annex B is
for information only.
0 IS0
IS0 8990: 1994(E)
Introduction
Data on the thermal transmission properties of insulants and insulated
structures are needed for various purposes including judging compliance
with regulations and specifications, for design guidance, for research into
the performance of materials and constructions and for verification of
simulation models.
Many thermal insulating materials and systems are such that the heat
transfer through them is a complex combination of conduction, convection
and radiation. The methods described in this International Standard
measure the total amount of heat transferred from one side of the speci-
men to the other for a given temperature difference, irrespective of the
individual modes of heat transfer, and the test results can therefore be
applied to situations when that is the property required. However, the
thermal transmission properties often depend on the specimen itself and
on the boundary conditions, specimen dimensions, direction of heat
transfer, temperatures, temperature differences, air velocities, and relative
humidity. In consequence, the test conditions must replicate those of the
intended application, or be evaluated if the result is to be meaningful.
It should also be borne in mind that a property can only be assessed as
useful to characterize a material, product or system if the measurement
of the steady-state thermal transmission properties of the specimen and
the calculation or interpretation of the thermal transmission characteristics
represent the actual performance of the product or system.
Further, a property can only be characteristic of a material, product or
system if the results of a series of measurements on a number of speci-
mens from several samples provide sufficient reproducibility.
The design and operation of the guarded or calibrated hot box is a complex
subject. It is essential that the designer and user of such apparatus has a
thorough background knowledge of heat transfer, and has experience of
precision measurement techniques.
Many different designs of the calibrated and the guarded hot box exist
worldwide conforming to national standards. Continuing research and de-
velopment is in progress to improve apparatus and measurement tech-
niques. Also the variation of structures to be tested may be so great, and
the requirements for test conditions so different, that it would be a mis-
take to restrict the test method unnecessarily and to confine all measure-
ments to a single arrangement. Thus it is not practical to mandate a
specific design or size of apparatus.
This page intentionally left blank
INTERNATIONAL STANDARD 0 IS0 IS0 8990:1994(E)
Thermal insulation - Determination of steady-state
thermal transmission properties - Calibrated and
guarded hot box
Section 1: General
also be tested, and these are necessary for calibration
1.1 Scope
and validation.
When testing homogeneous specimens in accord-
This International Standard lays down the principles
ance with this International Standard, experience has
for the design of the apparatus and minimum re-
shown that an accuracy within + 5 % can generally
quirement that shall be met for determination of the
be achieved. However, the accuracy of each individual
laboratory steady-state thermal transmission proper-
apparatus shall be estimated with reference homo-
ties of building components and similar components
geneous specimens of thermal conductance extend-
for industrial use. It does not, however, specify a
ing over the range to be measured using the
particular design since requirements vary, particularly
apparatus.
in terms of size, and also to a lesser extent in terms
The estimation of accuracy for nonhomogeneous
of operating conditions.
specimens will be more complex and involve an
analysis of the heat flow mechanism in the particular
This International Standard describes also the appara-
types of inhomogeneous specimens being tested.
tus, measurement technique and necessary data re-
Such analyses are not covered by this International
porting. Special components, for example windows,
Standard.
need additional procedures which are not included in
this International Standard. Also excluded are meas-
The method does not provide for measurements
urements of the effect on heat flow of moisture
where there is mass transfer through the specimen
transfer or redistribution but consideration shall be
during the test.
given in the design and operation of the equipment
as to the possible effect of moisture transfer on the
accuracy and the relevance of test results. The
properties which can be measured are thermal
1.2 Normative reference
transmittance and thermal resistance. Two alternative
The following standard contains provisions which,
methods are included: the calibrated hot box method
and the guarded hot box method. Both are suitable for through reference in this text, constitute provisions
vertical specimens such as walls and for horizontal of this International Standard. At the time of publi-
specimens such as ceilings and floors. The apparatus cation, the edition indicated was valid. All standards
can be sufficiently large to study full-scale compo- are subject to revision, and parties to agreements
based on this International Standard are encouraged
nents.
to investigate the possibility of applying the most re-
The methods are primarily intended for laboratory cent edition of the standard indicated below. Mem-
measurements of large, inhomogeneous specimens, bers of IEC and IS0 maintain registers of currently
although homogeneous specimens can, of course, valid International Standards.
SIST EN ,SO 8990:1997
IS0 8990: 1994(E)
IS0 7345:1987, Thermal insulation - Physical quan-
A Area perpendicular to heat
Cm21
CI
tities and definitions.
tlow
Density of heat flow rate
[W/m*]
m
d Specimen thickness
c 1
1.3 Definitions
Air temperature
t-u
G
For the purposes of this International Standard, the Mean radiant temperature
t-u
Tr
following definitions apply.
Environmental temperature
t-u
T”
Surface temperature
CKI
Ts
1.3.1 mean radiant temperature, T,: Appropriate
weighting of the temperatures of surfaces “seen” by R, = A(T,i - T,,)I@,
the specimen for the purpose of determining the ra-
R, = 1 /h
diant heat flow rate to the surface of the specimen
Rsi = A(Tni - Tsi)/@l
(see annex A).
R
se = ACT se - Tne) I@1
1.3.2 environmental temperature, 7’“: Appropriate
Ru = l/U
weighting of air and radiant temperatures, for the
u = al/A(Tni - Tne)
purpose of determining the heat flow rate to the sur-
= q) - t& - @, [for guarded hot box]
@l
face of the specimen (see annex A).
= a$ - a3 - a4 [for calibrated hot box]
@l
NOTE 1 This method does not directly measure the
thermal conductivity although it can be derived in case of
opaque, homogeneous, flat specimens using the relation-
ship ;1 = d/R,.
1.4 Symbols, units and relationships
The following recommended symbols are used:
i Interior, usually hot side
e Exterior, usually cold side
1.5 Principle
Surface
S
n Environmental
1.5.1 General
R Thermal conductivity
[W/h-K)]
Both types of apparatus, the guarded hot box (GHB)
R Thermal resistance
[h*-U/W]
and the calibrated hot box (CHB), are intended to re-
u Thermal transmittance
[W/h*- U]
produce conventional boundary conditions of a speci-
men between two fluids, usually atmospheric air,
h Surface coefficient of heat
[W/(m2-K)]
each at uniform temperature.
transfer
@ Heat flow rate
WI
The specimen is placed between a hot and a cold
chamber in which environmental temperatures are
Total power input, heating or
iwl
@P
known.
cooling
Heat flow rate through speci-
@I Iv1
Measurements are made at steady-state of air and
men
surface temperatures and of the power input to the
Imbalance, heat flow rate par-
hot side chamber. From these measurements the
@2 cw
allel to specimen
thermal transfer properties of the specimen are cal-
culated. Heat exchange at the surfaces of the test
Heat flow rate through meter-
@3 WI
specimen involves both convective and radiative
ing box walls
components. The former depends upon air tempera-
Flanking loss, heat flow rate
@4 WI
ture and air velocity, and the latter depends upon the
flanking specimen
temperatures and the total hemispherical emittances
Peripheral loss, heat flow rate,
of specimen sur
...
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