ISO 20492-3:2010

Glass in buildings — Insulating glass — Part 3: Gas concentration and gas leakage

ISO 20492-3:2010 specifies two methods of test for insulating glass units, including a determination of the gas leakage rate and a determination of gas concentration tolerances. The two methods designated as approach 1, which is intended for use in markets such as North America, and approach 2, which is intended for use in markets such as Europe.

Verre dans la construction — Verre isolant — Partie 3: Concentration de gaz et fuite de gaz

General Information

• Status: Published
• Publication Date: 28-Jul-2010
• ICS: 81.040.20 - Glass in building
• Technical Committee: ISO/TC 160/SC 1 - Product considerations
• Drafting Committee: ISO/TC 160/SC 1 - Product considerations
• Current Stage: 9092 - International Standard to be revised
• Completion Date: 01-Sep-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 20492-3
First edition
2010-08-15

Glass in buildings — Insulating glass —
Part 3:
Gas concentration and gas leakage
Verre dans la construction — Verre isolant —
Partie 3: Concentration de gaz et fuite de gaz




Reference number
ISO 20492-3:2010(E)
©
ISO 2010

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ISO 20492-3:2010(E)
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ISO 20492-3:2010(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Requirements.3
4.1 Approach 1.3
4.2 Approach 2.3
5 Principle.4
5.1 Approach 1.4
5.2 Approach 2.4
6 Apparatus.4
6.1 Approach 1.4
6.2 Approach 2.4
7 Reagents and materials .5
7.1 Approach 1.5
7.2 Approach 2.5
8 Test specimens.5
8.1 Approach 1.5
8.2 Approach 2.7
9 Procedure.8
9.1 Approach 1.8
9.2 Approach 2.8
10 Precision of test method.10
10.1 Approach 1.10
10.2 Approach 2.10
11 Test report.10
11.1 Approach 1.10
11.2 Approach 2.10
Annex A (normative) Calibration and standardization of the gas chromatograph for approach 1.12
Annex B (normative) Requirements for other gases for approach 2 .14
Annex C (informative) Relationship between artificial and natural ageing with regard to thermal
and sound insulation .16
Annex D (informative) Determination of the gas leakage rate by gas chromatography for
approach 2 .17
Bibliography.27

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ISO 20492-3:2010(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.
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 20492-3 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: Methods of test for the physical attributes of edge seals
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ISO 20492-3:2010(E)
Introduction
This International Standard 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 International Standard 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 International Standard also covers additional characteristics that are important to the trade, and marking
of the product (i.e. CE marking or other regulatory groups).
There are distinct markets to consider for insulating glass. Within each market there are technical differences
with respect to rebate sizes, vision lines and methods of application; two approaches are included in this
International Standard. 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 durability of edge seals by climate tests.
This International Standard 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 constructions such as in
windows, doors, curtain walling, skylights, roofs and partitions where protection against direct ultraviolet
radiation exists at the edges.
The use of insulating glass in cases where there is no protection against direct ultraviolet radiation at the
edges, such as structural glazing systems, can be suitable. However, it can be 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.
NOTE 1 For more information on the requirements for structural sealant glazing applications, reference can be made to
ASTM C1369, ASTM C1249 and ASTM C1265 and CEN technical specifications.
NOTE 2 IG units whose function is artistic only are not part of this International Standard.
The test methods in this International Standard 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 methods 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.
In certain cases such as insulating glass units containing spandrel glass or absorptive coatings, these
methods might not be applicable, as these products can experience field temperatures that exceed the
temperature limitations of the sealant.

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INTERNATIONAL STANDARD ISO 20492-3:2010(E)

Glass in buildings — Insulating glass —
Part 3:
Gas concentration and gas leakage
1 Scope
This part of ISO 20492 specifies two methods of test for insulating glass units, including a determination of the
gas leakage rate and a determination of gas concentration tolerances. The two methods designated as
approach 1, which is intended for use in markets such as North America, and approach 2, which is intended
for use in markets such as Europe.
2 Normative references
The following referenced documents are indispensable for the application 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 16293-1, Glass in building — Basic soda lime silicate glass products — Part 1: Definitions and general
physical and mechanical properties
ISO 20492-1, Glass in building — Insulating glass —Part 1: Durability of edge seals by climate tests
ISO 20492-4, Glass in building — Insulating glass —Part 4: Methods of test for the physical attributes of edge
seals
EN 1279-6:2002, Glass in building — Insulating glass units — Part 6: Factory production control and periodic
tests
ASTM C1036, Standard Specification for Flat Glass
3 Terms and definitions
For the purposes of this document, the terms and definitions in ISO 20492-1 and the following apply.
3.1
standard laboratory conditions
ambient temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %
3.2
controlled limit environment conditions
environment temperature of 10 °C with a dew point temperature of −5 °C, giving a relative humidity of 32,8 %
3.3
accuracy
precision of the test method within confidence limits of 99 %
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ISO 20492-3:2010(E)
3.4
sealed insulating glass unit
pre-assembled unit, comprising lites (panes) of glass that are sealed at the edges and separated by
dehydrated space(s), intended for vision areas of buildings
NOTE The unit is normally used for windows, window walls, picture windows, sliding doors, patio doors, or other
types of fenestration.
3.5
gas-filled insulating glass units
sealed insulating glass unit in which the cavity contains gas(es) in addition to air, usually for improving thermal
and/or sound insulation
3.6
reference standard mixtures
gas mixtures that contain known percentages of argon, oxygen and nitrogen that are required for calibration
purposes
NOTE Where gases other than argon are used the reference samples shall contain those gases. The concentrations
of each component in the reference samples should encompass the expected concentration range of the corresponding
component in the tested samples. The suitable standard mixtures can be obtained with a certificate of analysis of each
mixture from a reputable commercial supplier.
3.7
gas concentration
c
i
volume of gas i in the cavity
NOTE Gas concentration is expressed in units of volume percentage.
3.8
nominal gas concentration
c
i,o
nominal volume of gas i in the cavity
NOTE 1 The nominal gas concentration is used as the basis for testing sound insulation and/or calculating or testing
thermal insulation to fix R and the U value, respectively.
w
NOTE 2 Nominal gas concentration is expressed in units of volume percentage.
3.9
final gas concentration
c
i,f
estimated final volume of gas i in the cavity
NOTE 1 The final gas concentration is expressed in units of volume percentage.
NOTE 2 See Annex B.
3.10
gas leakage rate
L
i
volume of gas i leaking from a gas-filled unit per year
NOTE The gas leakage rate is expressed in units of volume percentage per year.
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ISO 20492-3:2010(E)
3.11
U value for publication
U
p
thermal transmittance value to be published, normally determined from the gas concentration c
i,o
NOTE See ISO 10292 and Annex B.
3.12
sound insulation measure for publication
R (C/C )
w,p tr
weighted sound reduction index that is published, normally determined with the gas concentration
4 Requirements
4.1 Approach 1
If the specimen is filled with argon, the average minimum fill of eight argon-filled specimens shall be 90 %
when tested in accordance with 5.1.
4.2 Approach 2
4.2.1 Gas leakage rate
The gas leakage rate, L , expressed as a percent per year, for gases with concentrations higher than 15 %,
i
and also for air, measured in accordance with 5.2 shall be as given in Equation (1):

L < 1,00 (1)
i
For most insulating glass units, measured L values are much higher than actual L values would be after
i i
10 years natural ageing. Therefore, the limiting value should not be used for calculating the gas concentration
during the lifetime of the unit. See Annex C.
In the case of sealants based on polysulfide, polyurethane, silicone or polyisobutylene, determining the gas
leakage rate of argon, Ar, may replace the measurement of the gas leakage rate for sulfurhexafluoride, SF ,
6
and air.
4.2.2 Tolerances on gas concentration
Tolerances on gas concentration shall be determined in accordance with EN 1279-6:2002, Annex A.3.
4.2.3 Dew-point and moisture-penetration indices
Dew-point and moisture penetration shall be determined in accordance with ISO 20492-1.
4.2.4 Edge-seal strength
Edge-seal strength shall be determined in accordance with ISO 20492-4.
4.2.5 Additional requirements for gases other than argon, sulfurhexafluoride and air
These requirements shall be determined in accordance with Annex B.
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ISO 20492-3:2010(E)
5 Principle
5.1 Approach 1
Argon, nitrogen and oxygen are physically separated by gas chromatography and compared to corresponding
components separated under similar conditions from a reference standard mixture or a mixture of known
similar composition.
5.2 Approach 2
The gas leakage rate at 20 °C is measured after subjecting the test specimen to a climate as specified in
ISO 20492-1 with the following modifications.
⎯ The number of cycles is reduced to 28.
⎯ The time at a constant temperature of 58 °C is reduced to 4 weeks.
For measuring the gas leakage rate, the unit is placed in a gastight container and, after a given time, the
amount of gas that has leaked from the unit is measured. After this measurement, the gas concentration in the
unit is analysed and the gas leakage rate calculated.
6 Apparatus
6.1 Approach 1
6.1.1 Gas chromatograph
The gas chromatograph is comprised of a gas sampling valve with a capacity of 100 µL to 250 µL, an
adsorption column that is capable of separating argon from other gases, a detector and an integrator.
Chromatograms shall be reproducible so that successive runs of a reference standard agree on each
component peak area within ±0,1 %.
NOTE An example of a detector is a thermal conductivity detector (TCD).
6.2 Approach 2
6.2.1 Climate exposure
The climate exposure should be as specified in ISO 20492-1.
6.2.2 Container for gas leakage rate measurement
A controlled temperature container shall be used for measuring the gas leakage rate. It shall be hermetically
sealable, and capable of surrounding the test specimen while inducing as little stress as possible on the
specimen. The residual volume in the container shall be as small as possible yet still allow the exposure of the
sealed edge zones of the specimen to the circulation of purging gas.
The quantity of ambient air penetrating into the container from outside or the quantity of each constituent
leaking from the container shall be measured in a blank test using a solid glass body of approximately the
same dimensions as the test specimens.
The container shall be deemed to have an adequate degree of tightness if the quantity of gas measured
during the test does not exceed 10 % of the mass of gas leaking from the test specimen.
The container shall have fittings for introducing specific gases and for taking gas specimens.
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ISO 20492-3:2010(E)
For test specimens with at least one outer pane made of organic material, it shall be ensured that the gas
diffusion through this (these) pane(s) is included in the measurement.
6.2.3 Gas analysis equipment
Gas analysis equipment should be capable of the following:
a) analysis of the gaseous constituents essential to the insulation function of the glass unit, for
−6
concentrations of 50 × 10 ;
b) determination of percentages by volume of gas of up to 100 % within ±3 % (relative).
These tasks shall not necessarily be performed using the same equipment.
6.2.4 Gas sampling device
A gas sampling device used for taking gas specimens from the glass unit, ensuring that the result is not
distorted by ingress of air, segregation phenomena, etc.
7 Reagents and materials
7.1 Approach 1
7.1.1 Helium carrier gas cylinder, analytical grade with a purity of 99,9 %.
7.1.2 Compressed air cylinder, for valve actuation.
7.1.3 Liquid CO or N cylinder, with dip tube, or refrigeration system, for cooling the column oven if
2 2
using a column that requires sub-ambient temperatures for operation.
7.1.4 10 ml gas-tight syringe(s), with closure valve and side port needle(s).
7.2 Approach 2
Reagents shall be chosen as needed to meet the requirements in 6.2.3.
8 Test specimens
8.1 Approach 1
Each test specimen shall measure (355 ± 6) mm by (505 ± 6) mm, and shall be composed of two or three
panes of clear, tinted or coated annealed, heat-strengthened, tempered or laminated glass.
The double-glazed test specimens shall be fabricated with at least one pane of clear, uncoated glass. The
triple glazed test specimens shall be fabricated with at least one outer pane of clear, uncoated glass. The
other outer pane shall be fabricated with a glass that allows easy viewing of the frost point.
The glass and airspace thicknesses for qualification under this part of ISO 20492 are 4 mm glass with 12 mm
airspace or 5 mm glass with 6 mm airspace.
Glass and/or airspace thickness(es) may be increased e.g. using 6 mm glass with 12 mm airspace. This can
result in a more rigorous test.
For triple pane units, 4 mm glass with 6 mm airspaces shall be used.
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ISO 20492-3:2010(E)
Tolerance of glass thickness shall be in accordance with ASTM C1036.
Airspace tolerance(s) shall be ±0,8 mm.
A minimum of eight specimens shall be submitted for testing. Extra specimens should be considered in case
of breakage.
Triple-pane units where the intermediate airspace divider is a plastic film shall be acceptable.
Each specimen shall be permanently and legibly marked with the designation of the manufacturer, the date of
fabrication (month or quarter and year) and orientation intended in the field (for units constructed with coated
glass).
During all stages of exposure and storage, hold the units in a vertical position with equal support to all panes
and no compression loading.
Select units for testing at random except for units damaged in transit. Do not test damaged units.
The test specimens representing units that are gas filled shall be fabricated using the same hole sealing and
gas filling techniques as those used for manufacturing. For example, if a gas-filling plug is used in
manufacturing then it shall be used in the test units.
It is not allowed to test the specimens representing units that include tubes.
Test specimens representing units that include muntins shall be fabricated with muntins dividing the sample
into nine equal areas (3 by 3).
NOTE See Figure 1.
It is recommended that the test specimens be sealed a minimum of four weeks after the date of manufacture
before testing begins to allow for stabilization. This is at the discretion of the manufacturer.

Key
1 insulation glass unit
2 muntin bars
Figure 1 — Test specimen with muntin bars
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ISO 20492-3:2010(E)
8.2 Approach 2
8.2.1 Preparation of test specimens
8.2.1.1 With the exception of the condition listed in 8.2.1.2, the test specimens shall consist of two panes
of 4 mm clear float glass in accordance with ISO 16293-1. The length shall be (502 ± 2) mm and the width
(352 ± 2) mm. The gap shall be nominally 12 mm, or if not manufactured, a gap as near to 12 mm as possible.
The test specimens shall be representative of the system description as defined in ISO 20492-1.
8.2.1.2 If the actual insulating glass product contains organic materials in its panes and these panes are
arranged on the unit in such a way that gas leakage out of the unit through the plastic is possible, glass shall
be substituted by plastic.
8.2.1.3 Unless otherwise agreed, the design of the insulating glass unit, including the type and quantity of
desiccant and of gas, shall conform to that which is manufactured in normal production (except for the
measurement of the air loss rate, where 100 % air is allowed). The panes of the test specimen shall be flat
when the unit is sealed. During sealing, measure the temperature, T, expressed in kelvins to the nearest 1 K,
and the absolute pressure, P, expressed in hectopascals, to the nearest 3 hPa.
+10
The test specimens shall be manufactured in such a way that the gas concentration, c , is equal to c %
i,o i,o
−5
absolute for each gas when a gas mixture is used.
8.2.2 Number of test specimens
At least six test specimens shall be prepared, of which at least two shall be tested in accordance with 9.2 after
climate exposure.
It is recommended to take more test specimens to test the gas filling before climate exposure. The gas
leakage can be measured on further units before the climate exposure, at the earliest four weeks after they
have been filled with gas and sealed. This achieves the objective of keeping test costs and time scale to an
acceptable maximum.
8.2.3 Construction and appearance
The test specimens shall be examined visually for the following criteria and/or defects:
a) construction of insulating glass unit;
b) damaged edges;
c) edge cracks;
d) fractures;
e) specking in the cavity;
f) congruence of panes;
g) other visible defects.
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ISO 20492-3:2010(E)
9 Procedure
9.1 Approach 1
Carry out the testing as follows.
a) Standardize and calibrate the gas chromatograph in accordance with Annex A.
b) Condition the insulating glass unit so that at the time of sampling a positive pressure exists inside the unit.
To achieve this, either heat the unit above the sealing temperature or place the unit horizontally on a flat
surface and apply a weight to the centre of the glass.
NOTE If the gas sampling occurs with the unit under negative pressure, contamination of the gas sample can occur.
c) Wrap the shank of the sampling needle with polyisobutylene (PIB) sealant or other sealing mastic.
d) If spacers do not allow a needle to pass through the spacer without damage or obstruction to the needle,
drill or punch a 1,6 mm hole through the edge sealant and the spacer, into one of the long sides of the
unit approximately 75 mm from a corner.
e) Remove the drill or punch and immediately plug the hole with a finger.
f) Slide the finger off the hole and immediately insert the PIB wrapped sampling needle, with the syringe
evacuated (plunger forward).
g) Seal the needle into the hole with the PIB sealant.
h) Fill the syringe with the airspace gas then evacuate its contents back into the airspace to purge any
contaminants that it can have contained. Filling and evacuating of the syringe shall be done at a
controlled rate to ensure proper sample collection.
i) Leave the syringe in place and repeat 9.1 h) at least two more times.
j) Fill the syringe with the gas sample.
k) Close the syringe valve.
l) Carefully grip the needle at its base and pull it out of the gas space.
m) Insert the needle into the gas sampling inlet and open the syringe valve.
n) Inject the contents of the syringe into the column via the septum connected at the inlet of the gas
sampling valve.
o) Record the chromatogram with the integrated percentages of Ar, O and N .
2 2
9.2 Approach 2
9.2.1 Determination of internal volume of a test specimen
Measure the clear distances, s and s , between opposite spacers to the nearest 1 mm, e.g. by means of a
1 2
gauge graduated in millimetres. Determine the clear distance, s , between the inner pane surfaces by
3
measuring the distance between the inner pane surfaces at mid-length on the four edges of the test specimen,
to the nearest 0,1 mm, and calculate the mean. Determine the internal volume, V , expressed in cubic
int
millimetres, by calculating the product s × s × s .
1 2 3
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ISO 20492-3:2010(E)
9.2.2 Climate exposure
Perform the climate exposure in accordance with 5.2 on four test specimens, at least one week after
preparation of the test specimens. On completion of the climate exposure, stabilize the test specimens by
storing them with free circula
...