ISO 20393:2007

INTERNATIONAL ISO
STANDARD 20393
First edition
2007-06-15
Thermal-insulating materials —
Determination of long-term water
absorption by diffusion
Matériaux d'isolation thermique — Détermination de l'absorption d'eau à
long terme par diffusion
Reference number
©
ISO 2007
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Foreword
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ISO 20393 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 10, Cellular plastics.

INTERNATIONAL STANDARD ISO 20393:2007(E)

Thermal-insulating materials — Determination of long-term
water absorption by diffusion
1 Scope
This International Standard specifies equipment and procedures for determining the long-term water
absorption of test specimens by diffusion. It is intended for use with thermal-insulation products. It is designed
to simulate the absorption of water by products subjected for a long period of time not only to high relative
humidity, approximating to 100 %, on both sides, but also to a water vapour pressure gradient, as experienced
by e.g. inverted roof or unprotected ground insulation.
The test is not applicable to all types of thermal-insulation product. The product standard should normally
state whether this test is applicable to a particular product.
NOTE For unprotected ground insulation, a lower temperature might, when more data is available, replace the test
temperature of 50 °C currently specified in this International Standard.
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 472, Plastics — Vocabulary
ISO 1923, Cellular plastics and rubbers — Determination of linear dimensions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 apply.
4 Principle
The long-term water absorption by diffusion is determined by measuring the increase in mass of a test
specimen when it is subjected to a water vapour pressure difference and temperature gradient between its
upper and lower surfaces for a period of 28 days.
5 Apparatus and materials
5.1 Balance, capable of determining the mass of the test specimen to within 0,1 g.
5.2 Corrosion-resistant container, with a frame supporting the test specimen.
5.3 Heating device, with a thermostat capable of controlling the water temperature at (50 ± 1) °C.
5.4 Cooling plate, thermally insulated on the outside, operating at a temperature of (1 ± 0,
...