ISO 9932:2021

INTERNATIONAL ISO
STANDARD 9932
Second edition
2021-03
Paper and board — Determination
of water vapour transmission rate of
sheet materials — Dynamic sweep and
static gas methods
Papier et carton — Détermination du coefficient de transmission de
la vapeur d'eau des matériaux en feuille — Méthode dynamique par
balayage de gaz et méthode statique
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Method A: Dynamic sweep gas method . 1
4.1 Principle . 1
4.2 Apparatus . 2
5 Method B: Static gas method . 3
5.1 Principle . 3
5.2 Apparatus . 3
6 Sampling . 4
7 Preparation of test pieces . 5
8 Procedure. 5
8.1 Method A . 5
8.2 Method B . 5
8.3 Barrier material having one face of uncoated paper . 5
8.4 Creased material . 6
9 Expression of results . 6
10 Precision . 6
10.1 General statement of the precision . 6
10.2 Method A . 6
10.3 Method B . 6
11 Test report . 6
Annex A (normative) Saturated saline solutions . 7
Annex B (normative) Calibration . 8
Annex C (informative) Comparison of dynamic method with gravimetric method .9
Bibliography .10
Foreword
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www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee
SC 2, Test methods and quality specifications for paper and board.
This second edition cancels and replaces the first edition (ISO 9932:1990), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— update of the normative references;
— removal of footnotes listing instruments in Clauses 4 and 5;
— addition of a general statement of the precision.
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 © ISO 2021 – All rights reserved

Introduction
The rate of water vapour penetration through a barrier is an important property in many applications,
for example, in building and in packaging. ISO 2528 describes a dish method for the determination of
the transmission rate and this method has wide acceptance. It does, however, have three disadvantages.
Results take several days to obtain, it is not suitable for transmission rates less than 1 g/(m ·d) and it is
not recommended for materials thicker than 3 mm.
The methods described in this document can, depending on the material being tested, produce results
in a matter of hours and are suitable for materials with transmission rates considerably less than 1 g/
(m ·d). Depending on the specific apparatus, they are also suitable for materials up to 38 mm thick.
INTERNATIONAL STANDARD ISO 9932:2021(E)
Paper and board — Determination of water vapour
transmission rate of sheet materials — Dynamic sweep and
static gas methods
1 Scope
This document describes general test methods for determining the water vapour transmission rate of
sheet materials by means of a dynamic gas method or a static gas method. Depending on the method
and specific apparatus employed, materials up to 38 mm thick and with water vapour transmission
2 2
rates in the range from 0,05 g/(m ·d) to 65 g/(m ·d) can be tested. The basis of the function of the
instrumental techniques is briefly described. Advice on calibration is given in Annex B.
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 186:2002, Paper and board — Sampling to determine average quality
ISO 2528:2017, Sheet materials — Determination of water vapour transmission rate (WVTR) —
Gravimetric (dish) method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
water vapour transmission rate
mass of water vapour transmitted through unit area in unit time under specified conditions of
temperature and humidity. It is expressed in grams per square metre per 24 h [g/(m ·d)]
3.2
dry side
side of the test cell which is exposed to low humidity
3.3
wet side
side of the test cell which is exposed to high humidity
4 Method A: Dynamic sweep gas method
4.1 Principle
The test piece is mounted between two chambers. One at a known relative humidity and the other
swept by a dry gas. The amount of water vapour picked up by the dry gas stream is detected by an
electrical sensor and converted to a reading which directly, or after calculation, is a measure of the rate
of water vapour transmission through the test piece.
4.2 Apparatus
4.2.1 Test cell, designed to clamp a test piece having a defined area, between two chambers, one swept
by a dry gas (the dry side) and the other containing an atmosphere of high relative humidity (the wet
side) (see Figure 1).
Key
1 flowmeter 8 by-pass
2 desiccant column or electrolytic cell 9 recorder or display
3 test piece 10 sensor (infra-red, electrolytic cell or electrical
4 dry side resistance element)
5 test cell A gas recirculation in some systems
6 enclosure maintained at required temperature B dry gas in
7 water or saline solution
Figure 1 — Schematic diagram of dynamic system
4.2.2 Clamping arrangements, to allow rapid insertion and removal of the test piece, equipped with
s
...