ISO TS 24498-2022 pdf free download – Paper, board and pulps — Estimation of uncertainty for test methods by interlaboratory comparisons.
5Preparation of an interlaboratory study
5.1 Laboratories
5.1.1Qualification of laboratories
Any laboratory that would be considered qualified to run the test is permitted and encouraged toparticipate in the interlaboratory study.
Laboratories shall be properly equipped to follow all details of the procedure, including climateconditions when specified, and be willing to assign the work to a skilled operator on a timely basis withcompetent personnel having knowledge of the materials and of the property to be tested.
ln many situations it is preferable that participating laboratories meet the requirements ofISO/IEC 170254] or equivalent, or that at least they participate in a comparative testing service andhave been shown to be competent in the test for which the precision data is being obtained.
The decision on permitting a laboratory to participate should be based on information provided tothe working group, including information as to the required time for calibrating the apparatus and fortesting all of the materials.
5.1.2 Number of participating laboratories
lt is recommended to include at least eight laboratories to obtain a valid estimate of the uncertaintyassociated with the test method.
No interlaboratory round robin test should be performed with less than five laboratories.5.2Sample preparation and distribution
5.2.1 Number and type of material
The number and types of materials to be included in the interlaboratory study should cover the rangeof the values of the property being measured and be representative of the number of types or classesof materials to which the test method is to be applied. lt also should cover each scale of the instrument(e.g. Scott Bond) if applicable.
lf the interlaboratory study is restricted in any of these areas, the omitted information should bereported in the precision statement.
5.2.2 Selection of the material5.2.2.1 General
The sampling procedure shall be appropriate to the property to be assessed and the type of material(pulp, paper, board or cellulosic nanomaterial].
lt is up to the person responsible for the interlaboratory study to check if the material selected issuitable or not.if not, the material shall be changed.
lt is also up to the person responsible for the interlaboratory study to check if the property is normallydistributed. When normality of distribution cannot be proven, it is advised to group the data.One canalso use comparability techniques, i.e. to compare the average mean differences between laboratories,once the consistency of data coming from these laboratories is also proven graphically.
Each selected product shall be sampled so that the variability among the specimens of that material will be minimized. In this way, several basic considerations shall be kept in mind. There are always cross- machine variations in properties, and the rate of change on the edges of the web may be significantly greater than in the middle. The changes in the machine direction are usually less severe. Since paper is anisotropic and two-sided, care shall be taken when the reel is split into sheets to ensure that the machine direction is differentiated from the cross direction and that the two sides of the paper are identified if relevant.ISO TS 24498 pdf download.