ISO 23766:2022
(Main)Thermal insulating products for industrial installations — Determination of the coefficient of linear thermal expansion at sub-ambient temperatures
Thermal insulating products for industrial installations — Determination of the coefficient of linear thermal expansion at sub-ambient temperatures
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.
Produits isolants thermiques pour les installations industrielles — Détermination du coefficient de dilatation thermique linéique à des températures inférieures à la température ambiante
Produits isolants thermiques pour les installations industrielles — Détermination du coefficient de dilatation thermique linéique à des températures inférieures à la température ambiante
General Information
Standards Content (Sample)
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.
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.
iv
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 chamber with liquid nitrogen cooling
system above and heating elements below the sample is usually fit to optical dilatometry. There should
be two holes on the test chamber to let the light beam go through. The dimension is fit to the sample
and light beam to ensure good temperature distribution.
NOTE Liquid nitrogen has been found in practice to be the most satisfactory coolant. The cooling system can
consist of pressure-controlled valve and nitrogen source (e.g. a dewar) feeds liquid nitrogen to a heat exchanger.
4.2.4 Temperature-measuring instruments
Calibrated thermocouples suitable for the test with an accuracy of ± 0,5 K.
The thermocouples are connected to a stepwise recording device. If only the mean coefficient of linear
thermal expansion, α , between two temperatures is needed, the measurements shall only be carried
m
out at these temperatures. If the full curve over a temperature range is needed, it shall be done in a
continuous way.
4.2.5 Equipment to prepare the test specimen
Suitable saw or thin-walled steel tube to prepare the test specimen. The thin-walled steel tube is a steel
tube with a thin wall, and one side is sharp, which can be used to cut a cylinder-shaped specimen.
4.3 Test specimen
4.3.1 Dimensions of test specimens
The dimensions shall be appropriate for the dimensions of the apparatus and smaller than the
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