ISO 20492-1:2008

INTERNATIONAL ISO
STANDARD 20492-1
First edition
2008-10-01
Glass in buildings — Insulating glass —
Part 1:
Durability of edge seals by climate tests
Verre dans la construction — Verre isolant —
Partie 1: Résistance des fermetures de côté par essais climatiques

Reference number
©
ISO 2008
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©  ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols and abbreviated terms .2
5 Requirements.3
6 Test methods .4
7 Methods of measurement.14
8 Test report.15
Annex A (normative) Reference method for frost/dew point temperature measurement.18
Annex B (normative) Moisture content measurement according to the 950 °C drying method.20
Annex C (normative) Moisture content measurement by the Karl Fischer method .24
Annex D (normative) Establishing the standard moisture adsorption capacity of desiccants.30
Bibliography.32

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
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.
ISO 20492-1 was prepared by Technical Committee ISO/TC 160, Glass in building, Subcommittee SC 1,
Product considerations.
ISO 20492 consists of the following parts, under the general title Glass in buildings — Insulating glass:
⎯ Part 1: Durability of edge seals by climate tests
⎯ Part 2: Chemical fogging tests
⎯ Part 3: Gas concentration and gas leakage
⎯ Part 4: Test methods for the physical attributes of edge seals

iv © ISO 2008 – All rights reserved

Introduction
This part of ISO 20492 consists of a series of procedures for testing the performance of pre-assembled,
permanently sealed insulating glass units or insulating glass units with capillary tubes that have been
intentionally left open. This part of ISO 20492 is intended to help ensure that
⎯ energy savings are made, as the U-value and solar factor (solar-heat gain coefficient) do not change
significantly;
⎯ health is preserved, because sound-reduction and vision do not change significantly;
⎯ safety is provided, because mechanical resistance does not change significantly.
This part of ISO 20492 also covers additional characteristics that are important to the trade and includes the
marking of the product (i.e., the CE marking or markings of other regulatory groups).
It is necessary to consider distinct markets for insulating glass. As within each market there are technical
differences with respect to rebate sizes, vision lines and methods of application, two approaches are included
in this part of ISO 20492. Approach 1 addresses requirements for markets such as North America. Approach 2
addresses requirements for markets such as Europe. Each approach includes separate test methods and
specifications pertaining to minimum requirements for the durability of edge seals as determined by climate
tests.
This part of ISO 20492 does not cover physical requirements of sealed-glass insulating units such as
appearance, thermo-physical properties, heat and light transmission and glass displacement.
The main intended uses of the insulating glass units are installations in buildings and construction, such as in
windows, doors, curtain walling, skylights, roofs and partitions where protection against direct ultraviolet
radiation exists at the edges.
NOTE In cases where there is no protection against direct ultraviolet radiation at the edges, such as structural-
sealant glazing systems, it is still necessary to review factors such as sealant longevity when exposed to long term
ultraviolet light and the structural properties of the sealant for these applications. For more information on the requirements
[1] [2]
for structural-sealant glazing applications, reference can be made to ASTM C1369 , ASTM C1249 and
[3]
ASTM C1265 .
The test methods in this part of ISO 20492 are intended to provide a means for testing the performance of the
sealing system and construction of sealed, insulating glass units.
Sealed, insulating glass units tested in accordance with these method are not intended for long-term
immersion in water.
The options for testing apply only to sealed, insulating glass units that are constructed with glass.
The methods of this part of ISO 20492 might not be applicable in certain cases, such as for insulating glass
units containing spandrel glass or absorptive coatings, as these products can experience field temperatures
that exceed the temperature limitations of the sealant.

INTERNATIONAL STANDARD ISO 20492-1:2008(E)

Glass in buildings — Insulating glass —
Part 1:
Durability of edge seals by climate tests
1 Scope
This part of ISO 20492 establishes two methods for testing the durability of edge seals of insulating glass units
by means of climate tests. The two methods are designated as Approach 1 for markets such as North
America and Approach 2 for markets such as Europe.
This part of ISO 20492 is applicable to pre-assembled, permanently sealed, insulating glass units with one or
two airspaces, and with capillary tubes that are intentionally left open to equalize pressure inside the unit with
the surrounding atmosphere.
This part of ISO 20492 is not applicable to sealed, insulating glass units that contain a spandrel glass coating.
This part of ISO 20492 does not apply to insulating glass (IG) units whose function is decorative only.
2 Normative references
The following reference documents are indispensable for the application of this document. For dated
references, only the cited edition applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 760, Determination of water — Karl Fischer method (General method)
EN 572-1, Glass in building — Basic soda lime silicate glass products — Definitions and general physical and
mechanical properties
EN 572-2, Glass in building — Basic soda lime silicate glass products — Float glass
EN 1279-1, Glass in building — Insulating glass units — Part 1: Generalities, dimensional tolerances and
rules for the system description
ASTM E546, Standard Test Method for Frost Dew Point of Sealed Insulating Glass Units
ASTM E631, Standard Terminology of Building Constructions
ASTM C1036, Standard Specification for Flat Glass
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1279-1, ASTM E631 and the
following apply.
3.1
standard laboratory conditions
ambient temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %
3.2
standard moisture-adsorption capacity
capacity of a desiccant material to adsorb a quantity of moisture under controlled limit environmental
conditions
3.3
controlled limit environmental conditions
environment temperature of 10 °C with a dew-point temperature of − 5 °C, giving a relative humidity of 32,8 %
3.4
moisture penetration index
amount of drying capacity consumed after standardized ageing conditions
3.5
accuracy
accuracy of the test method itself within statistical confidence limits of 99 %
3.6
frost/dew point
temperature at which water, organic vapour or other chemicals begin to appear on the interior glass surface of
a sealed, insulating glass unit
3.7
sealed, insulating glass unit
pre-assembled unit consisting of panes of glass that are sealed at the edges and separated by dehydrated
space(s), intended for use in buildings
NOTE The unit is normally used for windows, window walls, picture windows, sliding doors, patio doors, or other
types of fenestration.
4 Symbols and abbreviated terms
For the purposes of this document, the following symbols and abbreviations apply.
I moisture penetration index (can be expressed in decimal or in percentage terms)
I average value of the moisture penetration index, I, based on five measurements
av
m mass of dish plus desiccant plus water adsorbed from 32 % r.h. air
c
m mass of dish plus desiccant plus water initially adsorbed plus water adsorbed when subjected to the
f
climate conditions in the chamber
m mass of dish plus desiccant plus water initially adsorbed
i
M mass of desiccant in mixtures with non-desiccant material
m
m mass of dish plus desiccant plus water adsorbed in equilibrium with a defined reference level of relative
r
humidity of air, or dish plus dried desiccant at high temperatures
M total mass of desiccant when, for the purpose of testing, in a mixture with non-desiccant material, the
t
non-desiccant material is replaced by the same volume of desiccant
m mass of dish when empty, clean and dry
o
2 © ISO 2008 – All rights reserved

R ratio between the masses of desiccant M and M
m t
r.h. relative humidity
T standard moisture adsorption capacity of desiccant
c
T average standard moisture adsorption capacity of desiccant, T , obtained over two measurements
c,av c
T final moisture content of desiccant
f
T uncorrected final moisture content of desiccant
f,u
T initial moisture content of desiccant
i
T average initial moisture content of desiccant, T , obtained over four measurements
i,av i
T uncorrected initial moisture content of desiccant
i,u
Θ temperature of test specimens in test chamber
Θ temperature of the central test specimen in test chamber during constant temperature phase
c
Θ high temperature of the central test specimen in the test chamber during the high humidity/temperature
h
cycling phase
Θ low temperature of the central test specimen in the test chamber during the high humidity/temperature
l
cycling phase
Θ temperature of the central test specimen in the test chamber as the cycle moves between high
s
temperature and low temperature and vice versa
5 Requirements
5.1 Approach 1 — Final frost/dew point
The six test specimens that complete the weather cycle and high-humidity phases of the test in 6.1 shall be
unbroken and without deposits in the airspaces.
The final frost/dew points of all airspaces shall be − 40 °C or colder when measured in accordance with
ASTM E546 or equivalent.
5.2 Approach 2 — Moisture-penetration index
The following values shall be verified on test specimens that are submitted to the climate test.
⎯ The
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