Glass in building — Vacuum insulating glass — Part 3: Test methods for evaluation of performance under temperature differences

This document specifies test methods for evaluation of performance of vacuum insulating glass samples with rigid edge seal when subjected to temperature differences between the glass sheets. This document is not applicable to vacuum insulating glass samples with flexible edge seal.

Verre dans la construction — Vitrage isolant à lame de vide — Partie 3: Méthodes d’essai pour l’évaluation des performances en cas de différences de température

Le présent document spécifie des méthodes d’essai pour évaluer les performances d’échantillons de vitrage isolant à lame de vide présentant un joint de scellement rigide lorsque la température fluctue entre les feuilles de verre. Le présent document ne s’applique pas aux échantillons de vitrage isolant à lame de vide présentant un joint de scellement souple.

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Status
Published
Publication Date
25-Oct-2021
Current Stage
6060 - International Standard published
Start Date
26-Oct-2021
Completion Date
26-Oct-2021
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INTERNATIONAL ISO
STANDARD 19916-3
First edition
2021-10
Glass in building — Vacuum insulating
glass —
Part 3:
Test methods for evaluation of
performance under temperature
differences
Verre dans la construction — Vitrage isolant à lame de vide —
Partie 3: Méthodes d’essai pour l’évaluation des performances en cas
de différences de température
Reference number
ISO 19916-3:2021(E)
© ISO 2021
---------------------- Page: 1 ----------------------
ISO 19916-3:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 19916-3:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Test method ............................................................................................................................................................................................................... 2

4.1 Principle ....................................................................................................................................................................................................... 2

4.2 Test specimens........................................................................................................................................................................................ 2

4.2.1 Number of specimens ........................................................................................................................................... .......... 2

4.2.2 Size of specimens ............................................................................................................................................................... 2

4.2.3 Design of specimens ........................................................................................................................................................ 2

4.3 Apparatus .................................................................................................................................................................................................... 2

4.4 Procedures ................................................................................................................................................................................................. 4

4.4.1 General ........................................................................................................................................................................................ 4

4.4.2 Measurement of U-value .............................................................................................................................................. 5

4.4.3 Setting of thermocouples ............................................................................................................................................ 5

4.4.4 Installation of specimens ............................................................................................................................................ 6

4.4.5 Temperature profile ........................................................................................................................................................ 7

4.4.6 Determination of heat transfer coefficient ................................................................................................. 8

4.4.7 Requirements ........................................................................................................................................................................ 8

5 Test report .................................................................................................................................................................................................................. 9

Annex A (informative) Guideline for the test apparatus .............................................................................................................10

Annex B (informative) Stress induced in the glass sheets of vacuum insulating glass under

temperature differences ..........................................................................................................................................................................12

Bibliography .............................................................................................................................................................................................................................24

iii
© ISO 2021 – All rights reserved
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ISO 19916-3:2021(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.org/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 160, Glass in building, Subcommittee SC 1,

Product considerations.
A list of all parts in the ISO 19916 series can be found on the ISO website.

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.
© ISO 2021 – All rights reserved
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INTERNATIONAL STANDARD ISO 19916-3:2021(E)
Glass in building — Vacuum insulating glass —
Part 3:
Test methods for evaluation of performance under
temperature differences
1 Scope

This document specifies test methods for evaluation of performance of vacuum insulating glass samples

with rigid edge seal when subjected to temperature differences between the glass sheets.

This document is not applicable to vacuum insulating glass samples with flexible edge seal.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 19916-1, Glass in building — Vacuum insulating glass — Part 1: Basic specification of products and

evaluation methods for thermal and sound insulating performance
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 19916-1 and the following

apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
heat transfer control board

board placed in a test chamber for reducing air flow around the vacuum insulating glass specimen

3.2
rigid edge seal

edge seal that prevents lateral relative movement between the glass sheets at the edge of the sheets

where the seal is formed, made from a rigid material such as glass or metal
3.3
flexible edge seal
edge seal structure allowing lateral movement between the two glass sheets
© ISO 2021 – All rights reserved
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ISO 19916-3:2021(E)
4 Test method
4.1 Principle

The evaluation of performance of a vacuum insulating glass specimen when subjected to a temperature

difference shall be performed in the following way:

a) the test conditions should ensure that a well-defined and reproducible temperature is established

in all regions of specimen;

b) stresses in the vacuum insulating glass specimen induced by the testing procedure from sources

other than the temperature difference should be as small as possible.
In order to satisfy these criteria:

— the specimen should be surrounded on each side by air at well-defined temperatures, and

— the specimen shall be oriented vertically; this effectively eliminates stresses due to bending under

gravitational forces.

NOTE Heat transfer on the glass surfaces and the glass edge constraint can have a significant influence on

the stress induced in the glass sheets of vacuum insulating glass under temperature differences. A detailed study

of this is given in Annex B.
4.2 Test specimens
4.2.1 Number of specimens
Three vacuum insulating glass specimens shall be submitted for testing.
4.2.2 Size of specimens

Each test specimen shall measure no less than 300 mm in width and 300 mm in height and no more

than 850 mm in width and 850 mm in height. Size of specimens shall be determined so that distance

between edge of the test specimen and inside wall of chamber is no less than 100 mm.

4.2.3 Design of specimens

In the following, a product range shall consist of specimens having the same edge seal structure and

material.

The specimen design with the lowest U-value in the product range shall be selected for the test. If there

are multiple designs with different thickness, one design shall be selected with the following process.

The specimen design with the minimum total nominal thickness in the product range shall be selected

for the test. If the selected design has different nominal thicknesses for the two glass sheets, the thicker

glass sheet shall face the hot side of the apparatus. If there is more than one specimen design of glass

thickness in the product range with the minimum total nominal thickness, the specimen to be tested

shall be the one for which the nominal thicknesses of the glass sheets differ the least.

EXAMPLE 1 For a product range with thickness in mm of 3 + 3, 3 + 5 and 5 + 5, only 3 + 3 is tested.

EXAMPLE 2 For a product range with thickness in mm of 3 + 5 and 5 + 5, only 3 + 5 is tested. The glass sheet

with 5 mm thickness faces to the hot side of the apparatus.

EXAMPLE 3 For a product range with thickness in mm of 3 + 5, 4 + 4 and 5 + 5, only 4 + 4 is tested.

4.3 Apparatus
The usual laboratory apparatus and, in particular, the following.
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ISO 19916-3:2021(E)

4.3.1 Temperature chamber, in which air temperature in a room can be controlled [see Figure 1, a)]

or in which air temperature in two rooms divided by the specimen and the frame can be controlled [see

Figure 1, b)].

4.3.2 Frame for specimen installation, consisting of frame and insulating board [see Figure 1, c)].

4.3.3 Heat transfer control board, consisting of flat metal plate.
4.3.4 Thermocouples.
4.3.5 Data recorder.
4.3.6 Adhesive tape.
a) Temperature chamber having one room
b) Temperature chamber having two rooms
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ISO 19916-3:2021(E)
c) Frame for specimen installation
Key
1 vacuum insulating glass specimen
2 frame for specimen installation
3 temperature controllable room
4 frame
5 insulating board
Air circulation.
Figure 1 — Examples of apparatus
4.4 Procedures
4.4.1 General

The U-value and the thermal resistance of each vacuum insulating glass specimen shall be determined

with the method described in 4.4.2.

The specimen shall be prepared for the test by attaching thermocouples for temperature measurements

to the surface, as shown in 4.4.3. The temperatures as measured by these thermocouples shall be

continually recorded in a data recorder during the test.

The specimen shall be installed in the test apparatus as shown in 4.4.4. A heat transfer control board

can be inserted between the circulating air and the surface of the specimen.
NOTE Annex A shows guidelines of the apparatus setup.

The test condition of the temperature difference to be applied to the specimen is described in 4.4.5.

The heat transfer coefficients on glass surfaces at the hot and cold sides shall be calculated from

measured temperatures using the method described in 4.4.6.

If one or both of the calculated heat transfer coefficients is outside of the acceptable range defined in

4.4.7.1, the heat transfer control board and/or the cooling/heating system control shall be adjusted to

correct the heat transfer coefficient(s) before continuing the test.

Failure criteria with the test shall be evaluated using measured temperatures as in 4.4.7.2.

The test procedure is shown in Figure 2.
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ISO 19916-3:2021(E)
Figure 2 — Flow of test procedure
4.4.2 Measurement of U-value

Before the specimen is installed in the apparatus, the U-value and the thermal resistance of each

specimen shall be determined with the method defined in Annex A of ISO 19916-1:2018.

4.4.3 Setting of thermocouples

Thermocouples of which accuracy is guaranteed shall be placed to measure temperature at the

following points. The thermocouples shall be applied on the glass and the heat transfer control board

surface in such a way that the thermocouples do not change the temperature at the measuring point.

— Hot and cold side glass surface close to the centre of the specimen.

— Air temperature of hot and cold side at the point facing the centre of the specimen and at 100 mm to

200 mm from the glass surface. When the heat transfer control board is used, thermocouple shall be

placed on the board at the point facing the centre of the specimen.

The diameter of thermocouple wire should be no more than 0,25 mm. The thermocouples should

thermally contact the glass and the board surface for no less than 20 mm in length, using thin adhesive

plastic tape having emissivity close to that of the surface. Metallic tape should not be used. The tip

of the thermocouple on the glass should be positioned at the mid-point between two pillars and the

contacting thermocouple wires should be located along a line mid-way between two adjacent rows of

pillars. An example is shown in Figure 3.
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ISO 19916-3:2021(E)
Key
1 pillar
2 tip of thermocouple
3 plastic adhesive tape
4 thermocouple wire
5 no less than 20 mm
Figure 3 — Example for setting a thermocouple on a glass surface
4.4.4 Installation of specimens

Place a specimen vertically at the opening of the test apparatus, taking care that significant stress is not

induced in the specimen by the method of fastening. In particular, all four edges shall be free to bend

during the test.

EXAMPLE The specimen is placed on two setting blocks at the bottom corners and fixed at four corners. The

setting blocks and fixing materials contact the specimen for a distance of no more than 30 mm from the corner of

the specimen. A diagram of the fixing structure is shown in Figure 4.
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ISO 19916-3:2021(E)
Key
1 vacuum insulating glass specimen
2 frame of the apparatus
3 setting block
4 fixing material
5 maximum 30 mm
Figure 4 — Example for fixing structure of the specimen

The gap between the specimen edge and the frame is sealed with a soft material, such as adhesive tape,

in order to stop air flow through the gap.

NOTE The edge constraints affect stress in the specimen. This document specifies the test method with no

edge constraint condition in order that test results obtained in different laboratories are comparable.

4.4.5 Temperature profile

Air temperature at both sides of the specimen shall be controlled at constant temperature. Temperature

difference of the hot side and cold side glass surfaces Δ T shall be at no less than the value calculated

VIG

with Formula (1), which is derived from condition of circumstance that air-to-air temperature difference

2 2

is 40 °C and heat transfer coefficients are 8 W/(m ·K) and 23 W/(m ·K) on both side of surfaces.

2 2

NOTE 8 W/(m ·K) and 23 W/(m ·K) are the respective values of the reference internal and external heat

transfer coefficients in ISO 10292.
ΔTR ≥×40 /(0,)168 + R (1)
VIG
where

is the temperature difference of the hot side and cold side of the glass surfaces, in °C;

VIG
is the thermal resistance of the specimen, in m ·K/W.

The temperature difference of the hot side and cold side glass surfaces Δ T shall be controlled

VIG

within ±5 % range around average value during the steady-state temperature condition for at least 1 h.

© ISO 2021 – All rights reserved
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ISO 19916-3:2021(E)
4.4.6 Determination of heat transfer coefficient

The heat transfer coefficient at the centre of the specimen on the hot and cold sides shall be calculated

with Formulae (2) and (3):
hT=()ΔΔ//TR (2)
hot 21
hT= ΔΔ//TR (3)
cold 23
where

is the heat transfer coefficient on the hot surface of the specimen, in W/(m2·K);

hot

is the heat transfer coefficient on the cold surface of the specimen, in W/(m2·K);

cold

is the average value, under steady-state temperature condition, of the temperature difference

between hot side air and hot side glass surface in °C, or the average value of temperature

difference between the board and the hot side glass surface in °C when the heat transfer

control board is used on the hot side;

is the average value, under steady-state temperature condition, of the temperature difference

between hot side glass surface and cold side glass surface, in °C;

is the average value, under steady-state temperature condition, of the temperature difference

between cold side air and cold side glass surface in °C, or the average value of temperature

difference between the board and the cold side glass surface in °C when the heat transfer

control board is used on the cold side.

NOTE The heat flow through the specimen Q, in W/m , can be calculated as shown below:

Q = ΔTh//()1 (4)
1 hot
Q =Δ TR/ (5)
Q = ΔTh//()1 (6)
3 cold
Formulae (2) and (3) can be derived from Formulae (4), (5) and (6).
4.4.7 Requirements
4.4.7.1 Heat transfer coefficient

The calculated heat transfer coefficient on the hot surface of the specimen h and heat transfer

hot
2 2

coefficient on the cold surface of the specimen h shall be 8,0 W/(m ·K) ± 2,0 W/(m ·K).

cold

NOTE The value 8,0 W/(m ·K) is selected as a free convection condition as used in Formula (13) of

ISO 10292:1994. The range ± 2,0 W/(m ·K) is to account for variations in the measurement.

4.4.7.2 Proportional change in the temperature difference

The proportional change in the temperature difference at the hot and cold sides of the specimen from

the beginning to the end of the steady-state temperature condition ΔT , in %, shall be calculated using

Formula (7).
ΔΔTT =× 100 − ΔΔTT/ (7)
ce bb
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ISO 19916-3:2021(E)
where

ΔT is the temperature difference between the hot and cold sides of the glass surface at the begin-

ning of the steady-state temperature condition at the test, in °C;

is the temperature difference between the hot and cold sides of the glass surface at the end of

the steady-state temperature condition at the test, in °C.

If the calculated value of ΔT during the test of one or more of the test specimens exceeds 10 %, the

relevant set of specimens shall fail the test. Breakage due to laboratory handling is not considered as

test failure. Specimens broken due to laboratory handling shall be replaced and the measurement shall

be repeated.

NOTE The most likely failure mode under this test is mechanical failure leading to loss of vacuum. This is

detectable as a significant decrease in the temperature difference across the test specimen.

5 Test report
The test report shall contain the following items:
a) the international Standard used (including year of publication);
b) identification of the specimens:

— specimen description (e.g. manufacturer’s name, product name or other reference),

— length (mm),
— width (mm), and
— nominal thickness (mm);
c) description of the test apparatus, including:
— manufacturer’s name and model, if using a commercially-available apparatus,
— inside dimensions of the chamber, i.e. height, width and depth (mm), and

— dimensions and material of the heat transfer control board located inside the chamber, if used

(mm);
d) measurement and calculation results of
2 2
— the U-value [W/(m ·K)] and thermal resistance [m ·K /W] of each specimen,

— the average, the minimum and the maximum temperature difference (°C) between the hot side

and the cold side glass surfaces during the steady-state part of the test,

— the calculated heat transfer coefficient [W/(m ·K)] on the hot side glass surface h and the

hot
cold side of the glass surface h , and
cold

— the calculated proportional change of the temperature difference of the hot and the cold side of

each specimen at the beginning and the end of the steady-state temperature condition ΔT (%);

e) the evaluation result: pass or fail of the tests;
f) any deviations from this document which may have affected the result;
g) the date of the test.
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ISO 19916-3:2021(E)
Annex A
(informative)
Guideline for the test apparatus
A.1 General

This annex provides guidelines to make the test conditions suitable for the requirements in this

document.

Circulating air within the chamber can lead to a large heat transfer coefficient at the surface of the

specimen. This heat transfer coefficient can be controlled by inserting a heat transfer control board

between the circulating air and the specimen so that air does not directly flow against the vacuum

insulating glass specimen.
A.2 Guidelines
A.2.1 Option 1

The heat transfer control board allows a small amount of forced convection at the surface of the

specimen.

The dimensions of the heat transfer control board depend on the nature of the forced convection within

the chamber. For example, in case that circulating air flows from top to bottom, the board should be

sealed against the inside surfaces of the apparatus at the top and bottom so that the air does not flow

easily into the space between the board and the specimen. There should be gaps between the board and

the chamber on both sides.

A possible dimension would be a heat transfer control board having 15 mm to 50 mm gap between

the chamber wall and around 100 mm distant from the vacuum insulating glass specimen surface. An

example of the apparatus is shown in Figure A.1.

The board should be painted black on the surface facing to the specimen so that radiative heat transfer

is enhanced.
© ISO 2021 – All rights reserved
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ISO 19916-3:2021(E)
Key
1 vacuum insulating glass specimen
2 heat transfer control board
3 cooling or heating chamber
4 air circulation
Figure A.1 — Example of option 1
A.2.2 Option 2

For an apparatus in which there is negligible forced air flow at the surface of the specimen and sufficient

natural convective heat transfer is established at this surface, the heat transfer board is not necessary.

© ISO 2021 – All rights reserved
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ISO 19916-3:2021(E)
Annex B
(informative)
Stress induced in the glass sheets of vacuum insulating glass under
temperature differences
B.1 General

A temperature difference across a vacuum insulating glass specimen causes the hot glass sheet to

expand relative to the cold sheet. The rigid edge seal prevents relative movement of the sheets at

the edges. This produces mechanical stresses in the sheets and causes the structure to bend. These

stresses can be analysed using analytic and finite element modelling methods. This Annex presents

results of the nature and magnitude of the stresses obtained with both these modelling approaches and

discusses the different physical mechanisms that affect them. The results of the modelling approaches

were validated through systematic measurements performed on VIG units exposed to a well-defined

thermal load.
B.2 Modelling conditions

The temperature difference across a vacuum insulating glass is established in the modelling

configurations by locating the specimen between a hot environment at temperature T and a cold

environment at temperature T . The heat transfer coefficients between the hot and cold environments

and the corresponding glass surfaces are h and h respectively. Heat transfer between the hot and

1 2

cold environments beyond the vacuum insulating glass is prevented by a surrounding thermally

insulating baffle.

The configuration used to apply the thermal difference across a VIG unit should establish a stress

distribution over the glass panes that is close to that which would be observed in a typical window

installation. Primarily, this means that the heat transfer processes at the glass, on the hot and cold

sides, should at least be a combination of heat flow due to natural convection and radiation. There is

sometimes an extra convective component in practical installations due to forced air flow (wind) on

the cold side. However, in the practical test specified in this document, it is convenient to use equal heat

transfer coefficients on both glass sheets, to within an acceptable limit (that is, 8,0 ± 2,0 W/(m ·K)).

This reduces the complexity in the setup and reduces possible inconsistent outcomes between tests. As

discussed in the following sections, choice of the heat transfer coefficients can, by a significant margin,

affect stress levels. Nevertheless, the variations in stress (including the origin of the stress components)

are well understood and can be well predicted through analytical solutions.

Figure B.1 is a schematic diagram of a vacuum insulating glass specimen defining symbols for the

parameters used in this Annex.
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ISO 19916-3:2021(E)
Key
t glass thickness (mm)
L specimen size (mm)
w width of edge seal (mm)
1 vacuum layer
2 glass sheets
3 edge seal
Figure B.1 — Schematic diagram of a vacuum insulating glass specimen

As is conventional, the surfaces of the glass sheets are denoted Surface 1 to 4 from the cold side to the

hot side. Compressive stress is written as negative and tensile stress as positive.

The numerical results of modelling presented in this Annex are for an unconstrained vacuum insulating

glass specimen having properties given in Table B.1, under the thermal conditions given in Table B.2.

NOTE In both Tables B.1 and B.2, parameters that are denoted * are varied in some of the data presented

below.
Table B.1 — Details of specimen modelled
Glass thickness t (mm) 3*
Specimen size L × L (mm × mm) 350 × ^m350*
Width of edge seal w (mm) 4
Thickness of edge seal (mm) 0,2
Pillar separation (mm) 40
Pillar diameter (mm) 0,5
Corrected emissivity of low E coating 0,03
Glass-to-glass specimen conductance h [W/(m ·K)] 0,46
Coefficient of thermal e
...

NORME ISO
INTERNATIONALE 19916-3
Première édition
2021-10
Verre dans la construction — Vitrage
isolant à lame de vide —
Partie 3:
Méthodes d’essai pour l’évaluation des
performances en cas de différences de
température
Glass in building — Vacuum insulating glass —
Part 3: Test methods for evaluation of performance under
temperature differences
Numéro de référence
ISO 19916-3:2021(F)
© ISO 2021
---------------------- Page: 1 ----------------------
ISO 19916-3:2021(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2021

Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, aucune partie de cette

publication ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique,

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être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.

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Publié en Suisse
© ISO 2021 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO 19916-3:2021(F)
Sommaire Page

Avant-propos .............................................................................................................................................................................................................................iv

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ..................................................................................................................................................................................1

3 Termes et définitions ...................................................................................................................................................................................... 1

4 Méthode d’essai ..................................................................................................................................................................................................... 2

4.1 Principe ......................................................................................................................................................................................................... 2

4.2 Éprouvettes ............................................................................................................................................................................................... 2

4.2.1 Nombre d’éprouvettes ................................................................................................................................................... 2

4.2.2 Taille des éprouvettes .................................................................................................................................................... 2

4.2.3 Modèle des éprouvettes ............................................................................................................................................... 2

4.3 Appareillage .............................................................................................................................................................................................. 3

4.4 Modes opératoires ............................................................................................................................................................................... 4

4.4.1 Généralités ............................................................................................................................................................................... 4

4.4.2 Mesure du coefficient de transmission thermique U ......................................................................... 5

4.4.3 Installation des thermocouples ............................................................................................................................. 5

4.4.4 Installation des éprouvettes .................................................................................................................................... 6

4.4.5 Profil de températures .................................................................................................................................................. 7

4.4.6 Détermination du coefficient de transfert thermique ...................................................................... 8

4.4.7 Exigences ................................................................................................................................................................................... 8

5 Rapport d’essai ...................................................................................................................................................................................................... 9

Annexe A (informative) Ligne directrice relative à l’appareillage d’essai ...............................................................11

Annexe B (informative) Tension induite dans les feuilles de verre isolant à lame de vide en

cas de différences de température ................................................................................................................................................13

Bibliographie ...........................................................................................................................................................................................................................25

iii
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ISO 19916-3:2021(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document

a été rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2

(voir www.iso.org/directives).

L’attention est attirée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www.iso.org/brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion

de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir www.iso.org/avant-propos.

Le présent document a été élaboré par le comité technique ISO/TC 160, Verre dans la construction, sous-

comité SC 1, Produits.

Une liste de toutes les parties de la série ISO 19916 se trouve sur le site internet de l’ISO.

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse www.iso.org/fr/members.html.
© ISO 2021 – Tous droits réservés
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NORME INTERNATIONALE ISO 19916-3:2021(F)
Verre dans la construction — Vitrage isolant à lame de
vide —
Partie 3:
Méthodes d’essai pour l’évaluation des performances en
cas de différences de température
1 Domaine d’application

Le présent document spécifie des méthodes d’essai pour évaluer les performances d’échantillons de

vitrage isolant à lame de vide présentant un joint de scellement rigide lorsque la température fluctue

entre les feuilles de verre.

Le présent document ne s’applique pas aux échantillons de vitrage isolant à lame de vide présentant un

joint de scellement souple.
2 Références normatives

Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur

contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.

Pour les références non datées, la dernière édition du document de référence s’applique (y compris les

éventuels amendements).

ISO 19916-1, Verre dans la construction — Vitrage isolant à lame de vide — Partie 1: Spécification de base

des produits et méthodes d'évaluation des performances d'isolation thermique et acoustique

3 Termes et définitions

Pour les besoins du présent document, les termes et définitions de l’ISO 19916-1 ainsi que les suivants,

s’appliquent.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes:

— ISO Online browsing platform: disponible à l'adresse https:// www .iso .org/ obp

— IEC Electropedia: disponible à l'adresse https:// www .electropedia .org/
3.1
panneau de contrôle de transfert thermique

panneau placé dans la chambre d’essai pour réduire le flux d’air autour de l’éprouvette du vitrage

isolant à lame de vide
3.2
joint de scellement rigide

joint de scellement empêchant les mouvements latéraux relatifs entre les feuilles de verre, posé au bord

de ces dernières et fait d’un matériau rigide comme le verre, le métal, etc
3.3
joint de scellement souple

structure de joint de scellement permettant les mouvements latéraux entre deux feuilles de verre

© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
4 Méthode d’essai
4.1 Principe

L’évaluation de la défaillance d’une éprouvette de vitrage isolant à lame de vide soumise à une différence

de température doit être effectuée de la manière suivante:

a) il convient que les conditions d’essai assurent une température bien définie et reproductible sur

l’intégralité de l’éprouvette;

b) il convient que les tensions exercées sur l’éprouvette de vitrage isolant à lame de vide induites par

le mode opératoire d’essai mais autres que celles induites par la différence de température soient

aussi minimes que possible.
Afin de satisfaire à ces critères:

— il convient que l’éprouvette soit entourée de chaque côté par de l’air à des températures bien définies,

— l’éprouvette doit être positionnée verticalement; cela permet en effet d’éliminer toute tension de

flexion du fait des forces gravitationnelles.

NOTE Le transfert thermique sur les surfaces de vitrage et la contrainte sur le bord du vitrage peuvent avoir

une influence considérable sur les tensions exercées sur les feuilles du vitrage isolant à lame de vide en cas de

différences de température. Une méthode détaillée est donnée dans l’Annexe B.
4.2 Éprouvettes
4.2.1 Nombre d’éprouvettes

Trois éprouvettes de vitrage isolant à lame de vide doivent être soumises à essai.

4.2.2 Taille des éprouvettes

Chaque éprouvette doit mesurer au minimum 300 mm de large et 300 mm de haut et au maximum

850 mm de large et 850 mm de haut. La taille des éprouvettes doit être déterminée de manière que la

distance entre le bord de l’éprouvette et la paroi intérieure de la chambre d’essai soit au moins égale à

100 mm.
4.2.3 Modèle des éprouvettes

Dans ce qui suit, une gamme de produits doit être composée d’éprouvettes présentant la même structure

et le même matériau de joint de scellement.

Le modèle d’éprouvette présentant le coefficient de transmission thermique U le plus faible dans la

gamme de produits doit être sélectionné pour l’essai. S’il existe plusieurs de ces modèles présentant

différentes épaisseurs, le modèle doit être sélectionné en fonction du processus suivant.

Le modèle d’éprouvette présentant l’épaisseur nominale totale la plus faible dans la gamme de produits

doit être sélectionné pour l’essai. Si le modèle sélectionné présente différentes épaisseurs nominales

pour ses deux feuilles de verre, la feuille de verre la plus épaisse doit faire face au côté chaud de

l’appareillage. S’il existe plusieurs modèles d’éprouvette pour l’épaisseur de vitrage dans la gamme de

produits et présentant l’épaisseur nominale totale la plus faible, l’éprouvette à soumettre à essai doit

être celle dont les épaisseurs nominales entre les feuilles de verre diffèrent le moins.

EXEMPLE 1 Pour une gamme de produits présentant des épaisseurs en mm de 3 + 3, 3 + 5 et 5 + 5, seul le

modèle offrant les dimensions 3 + 3 est soumis à essai.
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ISO 19916-3:2021(F)

EXEMPLE 2 Pour une gamme de produits présentant des épaisseurs en mm de 3 + 5 et 5 + 5, seul le modèle

offrant les dimensions de 3 + 5 est soumis à essai. La feuille de verre de 5 mm d’épaisseur fait face au côté chaud

de l’appareillage.

EXEMPLE 3 Pour une gamme de produits présentant des épaisseurs en mm de 3 + 5, 4 + 4 et 5 + 5, seul le

modèle offrant les dimensions de 4+4 est soumis à essai.
4.3 Appareillage
Appareillage de laboratoire habituel et, en particulier, ce qui suit.

4.3.1 Chambre à température, dans laquelle la température de l’air dans un espace peut être

contrôlée [voir Figure 1, a)] ou dans laquelle la température de l’air dans deux espaces séparés par

l’éprouvette et le châssis peut être contrôlée [voir Figure 1, b)].

4.3.2 Châssis pour installer l’éprouvette, composé d’un cadre et d’un panneau isolant [voir

Figure 1, c)].

4.3.3 Panneau de contrôle de transfert thermique, composé d’une plaque de métal plate.

4.3.4 Thermocouples.
4.3.5 Dispositif d’enregistrement des données.
4.3.6 Ruban adhésif.
a) Chambre à température disposant d’un espace
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ISO 19916-3:2021(F)
b) Chambre à température disposant de deux espaces
c) Châssis pour installer l’éprouvette
Légende
1 éprouvette de vitrage isolant à lame de vide
2 châssis pour installer l’éprouvette
3 chambre à température contrôlable
4 châssis
5 panneau isolant
Circulation de l’air.
Figure 1 — Exemple d’appareillage
4.4 Modes opératoires
4.4.1 Généralités

Le coefficient de transmission thermique U et la résistance thermique de chaque éprouvette de vitrage

isolant à lame de vide doivent être déterminés selon la méthode décrite en 4.4.2.

L’éprouvette doit être préparée pour l’essai en installant des thermocouples pour mesurer la

température de surface, comme indiqué en 4.4.3. Les températures mesurées par ces thermocouples

doivent être systématiquement consignées à l’aide d’un dispositif d’enregistrement des données

pendant l’essai.
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)

L’éprouvette doit être installée sur l’appareillage d’essai comme indiqué en 4.4.4. Un panneau de contrôle

de transfert thermique peut être inséré entre l’air en circulation et la surface de l’éprouvette.

NOTE L’Annexe A fournit des lignes directrices pour la configuration de l’appareillage.

Les conditions d’essai relatives à la différence de température à appliquer à l’éprouvette sont décrites

en 4.4.5.

Les coefficients de transfert thermique sur les surfaces du vitrage du côté froid et du côté chaud doivent

être calculés à partir des températures mesurées à l’aide de la méthode décrite en 4.4.6.

Si l’un des coefficients de transfert thermique calculés, ou les deux, est en dehors de la plage acceptable

définie en 4.4.7.1, le panneau de contrôle de transfert thermique et/ou la commande du système de

refroidissement/chauffage doivent être paramétrés pour corriger le ou les coefficients de transfert

thermique avant de poursuivre l’essai.

Les critères d’échec de l’essai doivent être évalués à l’aide des températures mesurées comme indiqué

en 4.4.7.2.
Le mode opératoire d’essai est spécifié à la Figure 2.
Figure 2 — Organigramme du mode opératoire d’essai
4.4.2 Mesure du coefficient de transmission thermique U

Avant d’installer l’éprouvette dans l’appareillage, le coefficient de transmission thermique U et la

résistance thermique de chaque éprouvette doivent être déterminés selon la méthode décrite dans

l’Annexe A de l’ISO 19916-1:2018.
4.4.3 Installation des thermocouples

Des thermocouples dont la précision est garantie doivent être placés pour mesurer la température aux

points suivants. Les thermocouples doivent être appliqués sur la surface du vitrage et du panneau de

contrôle de transfert thermique de manière que les thermocouples ne modifient pas la température au

point de mesure.

— Surface du vitrage du côté chaud et du côté froid près du centre de l’éprouvette.

© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)

— Température de l’air du côté chaud et du côté froid au point faisant face au centre de l’éprouvette et à

100 mm à 200 mm de la surface du vitrage. Lorsque le panneau de contrôle de transfert thermique est

utilisé, le thermocouple doit être placé sur le panneau au point faisant face au centre de l’éprouvette.

Il convient que le diamètre du fil du thermocouple ne soit pas supérieur à 0,25 mm. Il convient que les

thermocouples soient thermiquement en contact avec le vitrage ainsi qu’avec la surface du panneau

sur au moins 20 mm de long, ceci grâce à un ruban adhésif plastique fin offrant une émissivité proche

de celle de la surface. Il convient que les rubans adhésifs métalliques ne soient pas utilisés. Il convient

que la pointe du thermocouple soit positionnée au point milieu entre deux entretoises et il convient que

les fils de contact du thermocouple soient situés le long d’une ligne à mi-chemin entre deux rangées

adjacentes d’entretoises. Un exemple est présenté à la Figure 3.
Légende
1 entretoise
2 pointe du thermocouple
3 ruban adhésif plastique
4 fil de thermocouple
5 20 mm au moins
Figure 3 — Exemple d’installation d’un thermocouple sur une surface du vitrage
4.4.4 Installation des éprouvettes

Placer une éprouvette à la verticale à l’entrée de l’appareillage d’essai en veillant à ce que l’éprouvette

ne subisse aucune tension significative à cause de la méthode de fixation. Les quatre bords doivent

notamment être libres de fléchir pendant l’essai.

EXEMPLE L’éprouvette est placée sur deux cales d’assise situées dans les coins en bas et est fixée en ses

quatre coins. Les cales d’assise et les matériaux de fixation sont en contact avec l’éprouvette sur une distance

de 30 mm maximum à partir de chaque coin de l’éprouvette. Un schéma de la structure de fixation est indiqué à

la Figure 4.
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
Légende
1 éprouvette de vitrage isolant à lame de vide
2 châssis de l’appareillage
3 cale d’assise
4 matériau de fixation
5 30 mm maximum
Figure 4 — Structure de fixation de l’éprouvette

L’écart entre le bord de l’éprouvette et le châssis est comblé avec un matériau souple, comme du ruban

adhésif, afin d’interrompre le flux d’air circulant dans cet écart.

NOTE Les contraintes sur les bords affectent la tension dans l’éprouvette. Le présent document spécifie la

méthode d’essai sans condition de contrainte sur les bords afin que les résultats d’essai obtenus dans différents

laboratoires soient comparables.
4.4.5 Profil de températures

La température de l’air des deux côtés de l’éprouvette doit être contrôlée à une température constante.

La différence de température des surfaces du vitrage du côté chaud et du côté froid Δ T ne doit pas

VIG

être inférieure à la valeur calculée à l’aide de la Formule (1), dérivée de la condition de circonstance

selon laquelle la différence de température air-air est de 40 °C et les coefficients de transfert thermique

2 2
sont de 8 W/(m ·K) et 23 W/(m ·K) sur les deux côtés des surfaces.
2 2

NOTE 8 W/(m ·K) et 23 W/(m ·K) correspondent aux valeurs respectives des coefficients de transfert

[1]
thermique interne et externe de référence dans l’ISO 10292 :
ΔTR ≥×40 /(0,)168 + R (1)
VIG

est la différence de température des surfaces du vitrage du côté chaud et du côté froid [°C];

VIG
est la résistance thermique de l’éprouvette [m ·K/W].

La différence de température des surfaces du vitrage du côté chaud et du côté froid Δ T doit être

VIG

contrôlée dans une plage de ± 5 % par rapport à la valeur moyenne pendant la condition de température

en régime stationnaire durant au moins 1 heure.
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
4.4.6 Détermination du coefficient de transfert thermique

Le coefficient de transfert thermique au centre de l’éprouvette sur les côtés chaud et froid doit être

calculé grâce aux équations suivantes:
hT=()ΔΔ//TR (2)
chaud 21
hT= ΔΔ//TR (3)
froid 23

h est le coefficient de transfert thermique sur la surface chaude de l’éprouvette [W/(m ·K)];

chaud

h est le coefficient de transfert thermique sur la surface froide de l’éprouvette [W/(m ·K)];

froid

ΔT est la valeur moyenne, en condition de température en régime stationnaire, de la différence

de température entre l’air du côté chaud et la surface du vitrage du côté chaud. Si le panneau

de contrôle de transfert thermique est utilisé du côté chaud, valeur moyenne de la différence

de température entre le panneau et la surface du vitrage du côté chaud [°C];

ΔT est la valeur moyenne, en condition de température en régime stationnaire, de la différence

de température entre la surface du vitrage du côté chaud et la surface du vitrage du côté

froid [°C];

ΔT est la valeur moyenne, en condition de température en régime stationnaire, de la différence

de température entre la surface du vitrage du côté froid et l’air du côté froid. Si le panneau

de contrôle de transfert thermique est utilisé du côté froid, valeur moyenne de la différence

de température entre la surface du vitrage du côté froid et le panneau [°C].

NOTE Le flux thermique à travers l’éprouvette Q, en W/m peut être calculé comme démontré ci-dessous:

Q = ΔTh//1 (4)
1 chaud
Q =Δ TR/ (5)
Q = ΔTh//1 (6)
3 froid

Les Formules (2) et (3) peuvent être dérivées à partir des Formules (4), (5) et (6).

4.4.7 Exigences
4.4.7.1 Coefficient de transfert thermique

Le coefficient de transfert thermique calculé sur la surface chaude de l’éprouvette h et le coefficient

chaud

de transfert thermique calculé sur la surface froide de l’éprouvette h doivent être de 8,0 W/

froid
2 2
(m ·K) ± 2,0 W/(m ·K).

NOTE 8,0 W/(m ·K) est choisi en tant que condition de convection libre comme dans l’Équation (13) de

l’ISO 10292:1994 ± 2,0 W/(m ·K) sert à prendre en compte les variations de la mesure.

© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
4.4.7.2 Changement proportionnel dans la différence de température

Le changement proportionnel dans la différence de température sur les côtés chaud et froid de

l’éprouvette du début à la fin de la condition de température en régime stationnaire ΔT , en % doit être

calculé à l’aide de la Formule (7):
ΔΔTT =× 100 − ΔΔTT/ (7)
ce bb

ΔT est la différence de température entre le côté chaud et le côté froid de la surface du vitrage au

début de la condition de température en régime stationnaire pendant l’essai [°C];

ΔT est la différence de température entre le côté chaud et le côté froid de la surface du vitrage à

la fin de la condition de température en régime stationnaire pendant l’essai [°C].

Si la valeur calculée de ΔT durant l’essai d’une ou de plusieurs des éprouvettes dépasse 10 %, l’ensemble

des éprouvettes concernées doit être déclaré comme non conforme à l’essai. Si une éprouvette est

endommagée pendant la manipulation en laboratoire, cela n’est pas considéré comme un échec de

l’essai. Les unités endommagées au cours de la manipulation en laboratoire doivent être remplacées et

les mesurages doivent être répétés.

NOTE Le mode d’échec le plus probable lors de cet essai consiste en un dysfonctionnement mécanique

entraînant la perte du vide. Une diminution significative de la différence de température dans toute l’unité d’essai

permet de détecter ce phénomène.
5 Rapport d’essai
Le rapport d’essai doit inclure les éléments suivants:
a) la norme internationale utilisée (comprenant l’année de publication):
b) l’identification des éprouvettes:

— la description des éprouvettes (par exemple, nom du fabricant, nom du produit ou autre référence,

etc.);
— la longueur (mm);
— la largeur (mm);
— l’épaisseur nominale (mm);
c) une description de l’appareillage d’essai utilisé, notamment:

— le nom du fabricant et le modèle, en cas d’utilisation d’un appareillage disponible dans le commerce;

— les dimensions internes de la chambre (à savoir la hauteur et la profondeur (mm));

— les dimensions et le matériau du panneau de contrôle de transfert thermique situé à l’intérieur de la

chambre, le cas échéant (mm);
d) les résultats des mesurages et des calculs:
2 2

— la valeur de transmission thermique U [W/(m ·K)] et la résistance thermique [m ·K /W] de chaque

éprouvette;

— la différence de température moyenne, minimale et maximale [°C] entre les surfaces du vitrage du

côté chaud et du côté froid pendant la partie en régime stationnaire de l’essai;
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)

— le coefficient de transfert thermique calculé [W/(m ·K)] sur la surface du vitrage du côté chaud

h et sur la surface du vitrage du côté froid h ;
chaud froid

— le changement proportionnel calculé de la différence de température des côtés chaud et froid de

chaque éprouvette au début et à la fin de la condition de température en régime stationnaireΔT (%);

e) le résultat de l’évaluation: la conformité ou non-conformité aux essais;

f) tout écart par rapport au présent document susceptible d’avoir influé sur le résultat;

g) la date de l’essai.
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
Annexe A
(informative)
Ligne directrice relative à l’appareillage d’essai
A.1 Généralités

La présente annexe spécifie les lignes directrices pour rendre les conditions d’essai conformes aux

exigences du présent document.

L’air circulant dans la chambre peut générer un coefficient de transfert thermique important à la

surface de l’éprouvette. Ce coefficient de transfert thermique peut être contrôlé en insérant un panneau

de contrôle de transfert thermique entre l’air en circulation et l’éprouvette de façon que l’air ne circule

pas directement contre l’éprouvette de vitrage isolant à lame de vide.
A.2 Lignes directrices
A.2.1 Option 1

Le panneau de contrôle de transfert thermique permet une convection forcée limitée à la surface de

l’éprouvette.

Les dimensions du panneau de contrôle de transfert thermique dépendent de la nature de la convection

forcée à l’intérieur de la chambre. Par exemple, si l’air circule de haut en bas, il convient que le panneau

soit scellé hermétiquement contre les surfaces internes de l’appareillage en haut et en bas afin que l’air

ne circule pas facilement dans l’espace situé entre le panneau et l’éprouvette. Il convient que des écarts

soient créés entre le panneau et la chambre des deux côtés.

Il est possible pour un panneau de contrôle de transfert thermique de marquer un écart de 15 ~ 50 mm

avec la paroi de la chambre et d’être séparé d’environ 100 mm de la surface de l’éprouvette de vitrage

isolant à lame de vide. La Figure A.1 montre un exemple d’appareillage.

Il convient que la surface du panneau faisant face à l’éprouvette soit peinte en noir de façon à ce que le

transfert thermique radiatif soit optimisé.
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
Légende
1 éprouvette de vitrage isolant à lame de vide
2 panneau de contrôle de transfert thermique
3 chambre de refroidissement ou de chauffage
4 circulation de l’air
Figure A.1 — Exemple pour l’option 1
A.2.2 Option 2

Pour un appareillage dans lequel un flux d’air forcé négligeable circule à la surface de l’éprouvette et un

transfert thermique convectif naturel est établi à sa surface, le panneau de transfert thermique n’est

pas nécessaire.
© ISO 2021 – Tous droits réservés
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ISO 19916-3:2021(F)
Annexe B
(informative)
Tension induite dans les feuilles de verre isolant à lame de vide en
cas d
...

INTERNATIONAL ISO
STANDARD 19916-3
First edition
Glass in building — Vacuum insulating
glass —
Part 3:
Test methods for evaluation of
performance under temperature
differences
Verre dans la construction — Vitrage isolant à lame de vide —
Partie 3: Méthodes d’essai pour l’évaluation des performances en cas
de différences de température
PROOF/ÉPREUVE
Reference number
ISO 19916-3:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 19916-3:2021(E)
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© ISO 2021

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Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
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ISO 19916-3:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test method ............................................................................................................................................................................................................... 2

4.1 Principle ........................................................................................................................................................................................................ 2

4.2 Test specimens ........................................................................................................................................................................................ 2

4.2.1 Number of specimens .................................................................................................................................................. 2

4.2.2 Size of specimens............................................................................................................................................................. 2

4.2.3 Design of specimens ..................................................................................................................................................... 2

4.3 Apparatus .................................................................................................................................................................................................... 2

4.4 Procedures .................................................................................................................................................................................................. 4

4.4.1 General...................................................................................................................................................................................... 4

4.4.2 Measurement of U-value ........................................................................................................................................... 5

4.4.3 Setting of thermocouples ......................................................................................................................................... 5

4.4.4 Installation of specimens .......................................................................................................................................... 6

4.4.5 Temperature profile ...................................................................................................................................................... 7

4.4.6 Determination of heat transfer coefficient ................................................................................................ 8

4.4.7 Requirements ..................................................................................................................................................................... 8

5 Test report ................................................................................................................................................................................................................... 9

Annex A (informative) Guideline for the test apparatus ...............................................................................................................11

Annex B (informative) Stress induced in the glass sheets of vacuum insulating glass under

temperature differences ............................................................................................................................................................................13

Bibliography .............................................................................................................................................................................................................................25

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ISO 19916-3:2021(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 .org/ 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 160, Glass in building, Subcommittee,

SC 1, Product considerations.
A list of all parts in the ISO 19916 series can be found on the ISO website.

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.
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INTERNATIONAL STANDARD ISO 19916-3:2021(E)
Glass in building — Vacuum insulating glass —
Part 3:
Test methods for evaluation of performance under
temperature differences
1 Scope

This document specifies test methods for evaluation of performance of vacuum insulating glass samples

with rigid edge seal when subjected to temperature differences between the glass sheets.

This document is not applicable to vacuum insulating glass samples with flexible edge seal.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 19916-1, Glass in building — Vacuum insulating glass — Part 1: Basic specification of products and

evaluation methods for thermal and sound insulating performance
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 19916-1 and the following

apply.

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 https:// www .electropedia .org/
3.1
heat transfer control board

board placed in a test chamber for reducing air flow around the vacuum insulating glass specimen

3.2
rigid edge seal

edge seal that prevents lateral relative movement between the glass sheets at the edge of the sheets

where the seal is formed, made from a rigid material such as glass or metal
3.3
flexible edge seal
edge seal structure allowing lateral movement between the two glass sheets
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ISO 19916-3:2021(E)
4 Test method
4.1 Principle

The evaluation of performance of a vacuum insulating glass specimen when subjected to a temperature

difference shall be performed in the following way:

a) the test conditions should ensure that a well-defined and reproducible temperature is established

in all regions of specimen;

b) stresses in the vacuum insulating glass specimen induced by the testing procedure from sources

other than the temperature difference should be as small as possible.
In order to satisfy these criteria:

— the specimen should be surrounded on each side by air at well-defined temperatures, and

— the specimen shall be oriented vertically; this effectively eliminates stresses due to bending under

gravitational forces.

NOTE Heat transfer on the glass surfaces and the glass edge constraint can have a significant influence on

the stress induced in the glass sheets of vacuum insulating glass under temperature differences. A detailed study

of this is given in Annex B.
4.2 Test specimens
4.2.1 Number of specimens
Three vacuum insulating glass specimens shall be submitted for testing.
4.2.2 Size of specimens

Each test specimen shall measure no less than 300 mm in width and 300 mm in height and no more

than 850 mm in width and 850 mm in height. Size of specimens shall be determined so that distance

between edge of the test specimen and inside wall of chamber is no less than 100 mm.

4.2.3 Design of specimens

In the following, a product range shall consist of specimens having the same edge seal structure and

material.

The specimen design with the lowest U-value in the product range shall be selected for the test. If there

are multiple designs with different thickness, one design shall be selected with the following process.

The specimen design with the minimum total nominal thickness in the product range shall be selected

for the test. If the selected design has different nominal thicknesses for the two glass sheets, the thicker

glass sheet shall face the hot side of the apparatus. If there is more than one specimen design of glass

thickness in the product range with the minimum total nominal thickness, the specimen to be tested

shall be the one for which the nominal thicknesses of the glass sheets differ the least.

EXAMPLE 1 For a product range with thickness in mm of 3 + 3, 3 + 5 and 5 + 5, only 3 + 3 is tested.

EXAMPLE 2 For a product range with thickness in mm of 3 + 5 and 5 + 5, only 3 + 5 is tested. The glass sheet

with 5 mm thickness faces to the hot side of the apparatus.

EXAMPLE 3 For a product range with thickness in mm of 3 + 5, 4 + 4 and 5 + 5, only 4 + 4 is tested.

4.3 Apparatus
The usual laboratory apparatus and, in particular, the following.
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ISO 19916-3:2021(E)

4.3.1 Temperature chamber, in which air temperature in a room can be controlled [see Figure 1, a)]

or in which air temperature in two rooms divided by the specimen and the frame can be controlled [see

Figure 1, b)].

4.3.2 Frame for specimen installation, consisting of frame and insulating board [see Figure 1, c)].

4.3.3 Heat transfer control board, consisting of flat metal plate.
4.3.4 Thermocouples.
4.3.5 Data recorder.
4.3.6 Adhesive tape.
a) Temperature chamber having one room
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ISO 19916-3:2021(E)
b) Temperature chamber having two rooms
c) Frame for specimen installation
Key
1 vacuum insulating glass specimen
2 frame for specimen installation
3 temperature controllable room
4 frame
5 insulating board
Air circulation.
Figure 1 — Examples of apparatus
4.4 Procedures
4.4.1 General

The U-value and the thermal resistance of each vacuum insulating glass specimen shall be determined

with the method described in 4.4.2.

The specimen shall be prepared for the test by attaching thermocouples for temperature measurements

to the surface, as shown in 4.4.3. The temperatures as measured by these thermocouples shall be

continually recorded in a data recorder during the test.

The specimen shall be installed in the test apparatus as shown in 4.4.4. A heat transfer control board

can be inserted between the circulating air and the surface of the specimen.
NOTE Annex A shows guidelines of the apparatus setup.

The test condition of the temperature difference to be applied to the specimen is described in 4.4.5.

The heat transfer coefficients on glass surfaces at the hot and cold sides shall be calculated from

measured temperatures using the method described in 4.4.6.

If one or both of the calculated heat transfer coefficients is outside of the acceptable range defined in

4.4.7.1, the heat transfer control board and/or the cooling/heating system control shall be adjusted to

correct the heat transfer coefficient(s) before continuing the test.

Failure criteria with the test shall be evaluated using measured temperatures as in 4.4.7.2.

The test procedure is shown in Figure 2.
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ISO 19916-3:2021(E)
Figure 2 — Flow of test procedure
4.4.2 Measurement of U-value

Before the specimen is installed in the apparatus, the U-value and the thermal resistance of each

specimen shall be determined with the method defined in Annex A of ISO 19916-1:2018.

4.4.3 Setting of thermocouples

Thermocouples of which accuracy is guaranteed shall be placed to measure temperature at the

following points. The thermocouples shall be applied on the glass and the heat transfer control board

surface in such a way that the thermocouples do not change the temperature at the measuring point.

— Hot and cold side glass surface close to the centre of the specimen.

— Air temperature of hot and cold side at the point facing the centre of the specimen and at 100 mm to

200 mm from the glass surface. When the heat transfer control board is used, thermocouple shall be

placed on the board at the point facing the centre of the specimen.

The diameter of thermocouple wire should be no more than 0,25 mm. The thermocouples should

thermally contact the glass and the board surface for no less than 20 mm in length, using thin adhesive

plastic tape having emissivity close to that of the surface. Metallic tape should not be used. The tip

of the thermocouple on the glass should be positioned at the mid-point between two pillars and the

contacting thermocouple wires should be located along a line mid-way between two adjacent rows of

pillars. An example is shown in Figure 3.
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ISO 19916-3:2021(E)
Key
1 pillar
2 tip of thermocouple
3 plastic adhesive tape
4 thermocouple wire
5 no less than 20 mm
Figure 3 — Example for setting a thermocouple on a glass surface
4.4.4 Installation of specimens

Place a specimen vertically at the opening of the test apparatus, taking care that significant stress is not

induced in the specimen by the method of fastening. In particular, all four edges shall be free to bend

during the test.

EXAMPLE The specimen is placed on two setting blocks at the bottom corners and fixed at four corners. The

setting blocks and fixing materials contact the specimen for a distance of no more than 30 mm from the corner of

the specimen. A diagram of the fixing structure is shown in Figure 4.
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ISO 19916-3:2021(E)
Key
1 vacuum insulating glass specimen
2 frame of the apparatus
3 setting block
4 fixing material
5 maximum 30 mm
Figure 4 — Example for fixing structure of the specimen

The gap between the specimen edge and the frame is sealed with a soft material, such as adhesive tape,

in order to stop air flow through the gap.

NOTE The edge constraints affect stress in the specimen. This document specifies the test method with no

edge constraint condition in order that test results obtained in different laboratories are comparable.

4.4.5 Temperature profile

Air temperature at both sides of the specimen shall be controlled at constant temperature. Temperature

difference of the hot side and cold side glass surfaces Δ T shall be at no less than the value calculated

VIG

with Formula (1), which is derived from condition of circumstance that air-to-air temperature difference

2 2

is 40 °C and heat transfer coefficients are 8 W/(m ·K) and 23 W/(m ·K) on both side of surfaces.

2 2

NOTE 8 W/(m ·K) and 23 W/(m ·K) are the respective values of the reference internal and external heat

transfer coefficients in ISO 10292.
ΔTR ≥×40 /(0,)168 + R (1)
VIG
where

is the temperature difference of the hot side and cold side of the glass surfaces, in °C;

VIG
is the thermal resistance of the specimen, in m ·K/W.

The temperature difference of the hot side and cold side glass surfaces Δ T shall be controlled

VIG

within ±5 % range around average value during the steady-state temperature condition for at least 1 h.

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ISO 19916-3:2021(E)
4.4.6 Determination of heat transfer coefficient

The heat transfer coefficient at the centre of the specimen on the hot and cold sides shall be calculated

with Formulae (2) and (3):
hT=()ΔΔ//TR (2)
hot 21
hT= ΔΔ//TR (3)
cold 23
where

is the heat transfer coefficient on the hot surface of the specimen, in W/(m2·K);

hot

is the heat transfer coefficient on the cold surface of the specimen, in W/(m2·K);

cold

is the average value, under steady-state temperature condition, of the temperature difference

between hot side air and hot side glass surface in °C, or the average value of temperature

difference between the board and the hot side glass surface in °C when the heat transfer

control board is used on the hot side;

is the average value, under steady-state temperature condition, of the temperature difference

between hot side glass surface and cold side glass surface, in °C;

is the average value, under steady-state temperature condition, of the temperature difference

between cold side air and cold side glass surface in °C, or the average value of temperature

difference between the board and the cold side glass surface in °C when the heat transfer

control board is used on the cold side.

NOTE The heat flow through the specimen Q, in W/m , can be calculated as shown below:

Q = ΔTh//()1 (4)
1 hot
Q =Δ TR/ (5)
Q = ΔTh//()1 (6)
3 cold
Formulae (2) and (3) can be derived from Formulae (4), (5) and (6).
4.4.7 Requirements
4.4.7.1 Heat transfer coefficient

The calculated heat transfer coefficient on the hot surface of the specimen h and heat transfer

hot
2 2

coefficient on the cold surface of the specimen h shall be 8,0 W/(m ·K) ± 2,0 W/(m ·K).

cold

NOTE The value 8,0 W/(m ·K) is selected as a free convection condition as used in Formula (13) of

ISO 10292:1994. The range ± 2,0 W/(m ·K) is to account for variations in the measurement.

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ISO 19916-3:2021(E)
4.4.7.2 Proportional change in the temperature difference

The proportional change in the temperature difference at the hot and cold sides of the specimen from

the beginning to the end of the steady-state temperature condition ΔT , in %, shall be calculated using

Formula (7).
ΔΔTT =× 100 − ΔΔTT/ (7)
ce bb
where

ΔT is the temperature difference between the hot and cold sides of the glass surface at the begin-

ning of the steady-state temperature condition at the test, in °C;

is the temperature difference between the hot and cold sides of the glass surface at the end of

the steady-state temperature condition at the test, in °C.

If the calculated value of ΔT during the test of one or more of the test specimens exceeds 10 %, the

relevant set of specimens shall fail the test. Breakage due to laboratory handling is not considered as

test failure. Specimens broken due to laboratory handling shall be replaced and the measurement shall

be repeated.

NOTE The most likely failure mode under this test is mechanical failure leading to loss of vacuum. This is

detectable as a significant decrease in the temperature difference across the test specimen.

5 Test report
The test report shall contain the following items:
a) the international Standard used (including year of publication);
b) identification of the specimens:

— specimen description (e.g. manufacturer’s name, product name or other reference),

— length (mm),
— width (mm), and
— nominal thickness (mm);
c) description of the test apparatus, including:
— manufacturer’s name and model, if using a commercially-available apparatus,
— inside dimensions of the chamber, i.e. height, width and depth (mm), and

— dimensions and material of the heat transfer control board located inside the chamber, if used

(mm);
d) measurement and calculation results of
2 2
— the U-value [W/(m ·K)] and thermal resistance [m ·K /W] of each specimen,

— the average, the minimum and the maximum temperature difference (°C) between the hot side

and the cold side glass surfaces during the steady-state part of the test,

— the calculated heat transfer coefficient [W/(m ·K)] on the hot side glass surface h and the

hot
cold side of the glass surface h , and
cold

— the calculated proportional change of the temperature difference of the hot and the cold side of

each specimen at the beginning and the end of the steady-state temperature condition ΔT (%);

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ISO 19916-3:2021(E)
e) the evaluation result: pass or fail of the tests;
f) any deviations from this document which may have affected the result;
g) the date of the test.
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ISO 19916-3:2021(E)
Annex A
(informative)
Guideline for the test apparatus
A.1 General

This annex provides guidelines to make the test conditions suitable for the requirements in this

document.

Circulating air within the chamber can lead to a large heat transfer coefficient at the surface of the

specimen. This heat transfer coefficient can be controlled by inserting a heat transfer control board

between the circulating air and the specimen so that air does not directly flow against the vacuum

insulating glass specimen.
A.2 Guidelines
A.2.1 Option 1

The heat transfer control board allows a small amount of forced convection at the surface of the

specimen.

The dimensions of the heat transfer control board depend on the nature of the forced convection within

the chamber. For example, in case that circulating air flows from top to bottom, the board should be

sealed against the inside surfaces of the apparatus at the top and bottom so that the air does not flow

easily into the space between the board and the specimen. There should be gaps between the board and

the chamber on both sides.

A possible dimension would be a heat transfer control board having 15 mm to 50 mm gap between

the chamber wall and around 100 mm distant from the vacuum insulating glass specimen surface. An

example of the apparatus is shown in Figure A.1.

The board should be painted black on the surface facing to the specimen so that radiative heat transfer

is enhanced.
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ISO 19916-3:2021(E)
Key
1 vacuum insulating glass specimen
2 heat transfer control board
3 cooling or heating chamber
4 air circulation
Figure A.1 — Example of option 1
A.2.2 Option 2

For an apparatus in which there is negligible forced air flow at the surface of the specimen and sufficient

natural convective heat transfer is established at this surface, the heat transfer board is not necessary.

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ISO 19916-3:2021(E)
Annex B
(informative)
Stress induced in the glass sheets of vacuum insulating glass under
temperature differences
B.1 General

A temperature difference across a vacuum insulating glass specimen causes the hot glass sheet to

expand relative to the cold sheet. The rigid edge seal prevents relative movement of the sheets at

the edges. This produces mechanical stresses in the sheets and causes the structure to bend. These

stresses can be analysed using analytic and finite element modelling methods. This Annex presents

results of the nature and magnitude of the stresses obtained with both these modelling approaches and

discusses the different physical mechanisms that affect them. The results of the modelling approaches

were validated through systematic measurements performed on VIG units exposed to a well-defined

thermal load.
B.2 Modelling conditions

The temperature difference across a vacuum insulating glass is established in the modelling

configurations by locating the specimen between a hot environment at temperature T and a cold

environment at temperature T . The heat transfer coefficients between the hot and cold environments

and the corresponding glass surfaces are h and h respectively. Heat transfer between the hot and

1 2

cold environments beyond the vacuum insulating glass is prevented by a surrounding thermally

insulating baffle.

The configuration used to apply the thermal difference across a VIG unit should establish a stress

distribution over the glass panes that is close to that which would be observed in a typical window

installation. Primarily, this means that the heat transfer processes at the glass, on the hot and cold

sides, should at least be a combination of heat flow due to natural convection and radiation. There is

sometimes an extra convective component in practical installations due to forced air flow (wind) on

the cold side. However, in the practical test specified in this document, it is convenient to use equal heat

transfer coefficients on both glass sheets, to within an acceptable limit (that is, 8,0 ± 2,0 W/(m ·K)).

This reduces the complexity in the setup and reduces possible inconsistent outcomes between tests. As

discussed in the following sections, choice of the heat transfer coefficients can, by a significant margin,

affect stress levels. Nevertheless, the variations in stress (including the origin of the stress components)

are well understood and can be well predicted through analytical solutions.

Figure B.1 is a schematic diagram of a vacuum insulating glass specimen defining symbols for the

parameters used in this Annex.
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ISO 19916-3:2021(E)
Key
t glass thickness (mm)
L specimen size (mm)
w width of edge seal (mm)
1 vacuum layer
2 glass sheets
3 edge seal
Figure B.1 — Schematic diagram of a vacuum insulating glass specimen

As is conventional, the surfaces of the glass sheets are denoted Surface 1 to 4 from the cold side to the

hot side. Compressive stress is written as negative and tensile stress as positive.

The numerical results of modelling presented in this Annex are for an unconstrained vacuum insulating

glass specimen having properties given in Table B.1, under the thermal conditions given in Table B.2.

NOTE In both Tables B.1 and B.2, parameters that are denoted * are varied in some of the data presented

bel
...

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