ISO 23766:2022

INTERNATIONAL ISO
STANDARD 23766
First edition
2022-03
Thermal insulating products
for industrial installations —
Determination of the coefficient of
linear thermal expansion at sub-
ambient temperatures
Produits isolants thermiques pour les installations industrielles —
Détermination du coefficient de dilatation thermique linéique à des
températures inférieures à la température ambiante
Reference number
© ISO 2022
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Method A — Optical method .1
4.1 Principle . 1
4.2 Apparatus . 2
4.2.1 Light source system . 2
4.2.2 Light detector system . 2
4.2.3 Test chamber and cooling system . 2
4.2.4 Temperature-measuring instruments . 3
4.2.5 Equipment to prepare the test specimen . 3
4.3 Test specimen . 3
4.3.1 Dimensions of test specimens . 3
4.3.2 Preparation of test specimens . 3
4.3.3 Number of test specimens . . 3
4.4 Conditioning of test specimens . 3
4.5 Procedure . 4
5 Method B — Displacement method . 4
5.1 Principle . 4
5.2 Apparatus . 5
5.2.1 Sensor for distance . 5
5.2.2 Test chamber and cooling system . 5
5.2.3 Temperature-measuring instruments . 5
5.2.4 Equipment to prepare the test specimen . 5
5.3 Test specimen . 5
5.3.1 Dimensions of test specimens . 5
5.3.2 Preparation of test specimens . 5
5.3.3 Number of test specimens . . 6
5.4 Conditioning of test specimens . 6
5.5 Procedure . 6
6 Calculation and expression of results . 6
7 Accuracy of measurement.7
8 Test report . 7
Bibliography . 9
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment, Subcommittee SC 1, Test and measurement methods.
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INTERNATIONAL STANDARD ISO 23766:2022(E)
Thermal insulating products for industrial installations —
Determination of the coefficient of linear thermal
expansion at sub-ambient temperatures
1 Scope
This document specifies the equipment and procedures for determining the coefficient of linear
thermal expansion at sub-ambient temperatures (−196 °C to 25 °C), subject to the possible temperature
limitation of the test specimens. It is not applicable to products which experience dimensional changes
during the test due to the loss of hydration water or which undergo other phase changes.
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 9229, Thermal insulation — Vocabulary
ISO 18099, Thermal insulating products for building equipment and industrial installations —
Determination of the coefficient of thermal expansion
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 9229, ISO 18099 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/o bp
— IEC Electropedia: available at https:// www.e lectropedia. org/
3.1
sub-ambient temperature
temperature from −196 °C to 25 °C at which the thermal insulation product is used to reduce heat flow
4 Method A — Optical method
4.1 Principle
The changes in a product’s linear dimensions, as its temperature is changed, are measured and
characterized by the optical measurement method (See Figure 1 for an example).
Key
1 light source
2 light
3 collimator lens
4 parallel light beam, wider than the test specimen
5 test specimen, with dimension of 10 mm to 30 mm
6 detector, wider than the light beam
7 test chamber
Figure 1 — Example of an apparatus for optical method
4.2 Apparatus
4.2.1 Light source system
An InGaN-based light source which can project a broad-width planar parallel light beam onto the
sample and detector. The collimator lens should be used to keep the light beam parallel within 2”
(≈ 0,009 696 mrad).
4.2.2 Light detector system
The light beam with the shadow of the sample is detected by a sensor. The signal is then evaluated
by a digital edge-detection processor which provides a sensitive and precise measurement of the
dimensions of the sample before and after expansion. It shall be calibrated over the required range to
−5
within 2 × 10 × l for the length.
4.2.3 Test chamber and cooling system
Capable of maintaining the mean temperature of the test specimen to within ± 0,5 K of the desired test
temperature.
The test chamber shall be capable of limiting the rate of temperature change to 1 °C/min during the
change from one test temperature to another. The disk-shaped chamb
...