ISO 9932 pdf download – Paper and board – Determinationof water vapour transmission rate of sheet materials – Dynamic sweep and static gas methods

ISO 9932 pdf download – Paper and board – Determinationof water vapour transmission rate of sheet materials – Dynamic sweep and static gas methods.
4.2.4 Inert dry gas (as required by the specific apparatus to be used). for purging on the dry side. NOTE The gas is normally desiccated air or dry nitrogen.
4.2.5 Sensor, with rapid response and high sensitivity capable of detecting levels In the moisture content ni the sweep gas equivalent to 0,05% rebtive humidity or less. The sensor may take a number of forms: an electrical resistance element, an electrolytic cell, or an Infrared detector.
4,2.6 Means to convert the output from the sensor Into a signal that can be used to calculate the amount of moisture passing through the test piece being tested in unit time.
4.2.7 Means of maintaining the test chamber and the sweep gas and the sensor at the required temperature.
NOTE The normal test temperature is either 23 C ± 1 C or 38 C ± 1 C, but other temperatures can be used.
4.2.8 Specimen of stated water vapour transmission rate supplied by the instrument manufacturer for standardization of the test cell.
5 Method B: Static gas method
5.1 Principle
The test piece is mounted in a cell containing an electrolytic element and the cell placed in a humidity cabinet at the required temperature and relative humidity. The water vapour penetrating the cell is electrolyzed and consequently the relative humidity within the cell remains very low (<1 %). After equilibrium, the electric current is a direct measure of the rate of electrolysis (according to Faraday’5 law of electrolysis) and the water vapour transmission rate. 5.2 Apparatus 5.2.1 Control box, containing a) an electric power supply; b) a microammeter, graduated directly in grants per square metre per 24 h [g/(m’d)J; c) selector and range switches; d) connection points for cells and, if desired, a recorder. See Figure 2. 8.4Creased material For some purposes it may be necessary to determine the transmission rate of creased material; insuch cases carry out the creasing procedure described in IS0 2528:2017,Annex A and then follow theprocedure of method A or method B as appropriate. 9Expression of results Calculate the mean and standard deviation of the separate determinations carried out with face oneand face two facing the wet side respectively. Express the results in grams per square metre per 24 h [g/[m2-d)] for each side, tested to two significantfigures. 10 Precision 10.1 General statement of the precision There is scepticism that a proper seal can be done for paperboard and some nonwovens. There is also alack of good repeatability data for these two types. 10.2 Method A No firm statement about precision can be made at the time of publication.But work in the USA usingsimilar principles gave a repeatability within the range from 2 % to 8 % of the test value and areproducibility within the range from 7 % to 13 % of the test value based on samples within the rangefrom 2,3 g/([m2.d) to 24g/(m2-d) when tested at 38 C and 90 %relative humidity. 10.3 Method B There is no precise information for this method at the time of publication.According to the experiencein the Netherlands, a repeatability of about 5 % of the test value and a reproducibllity of 10 % to 15 %of the test value can be expected from materials with WVTR in the range from 2 g/(m2-d) to 5 g/[m2-d). 11 Test report The test report shall include the following: a) reference to this document, i.e. ISO 9932:2021; b)the date and place of testing; c)all information necessary for the complete identification of the sample; d)the type of apparatus and the type of dry gas used; e)the temperature and relative humidity used as the test conditions; f)the arithmetic mean of the result for each face tested; g)the standard deviation for each face tested; h)if necessary, the results after creasing; i)any deviation from the procedure specified.