Paper, board and pulps — Estimation of uncertainty for test methods by interlaboratory comparisons

This document presents guidelines for a methodology for the estimation of the uncertainty of methods for testing lignins and kraft liquors, pulps, paper, board, cellulosic nanomaterials, as well as products thereof containing any portion of recycled material or material intended for recycling.

General Information

Status
Published
Publication Date
20-Jan-2022
Current Stage
9020 - International Standard under periodical review
Start Date
15-Jan-2025
Due Date
15-Jan-2025
Completion Date
15-Jan-2025
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ISO/TS 24498:2022 - Paper, board and pulps — Estimation of uncertainty for test methods by interlaboratory comparisons Released:1/21/2022
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TECHNICAL ISO/TS
SPECIFICATION 24498
First edition
2022-01
Paper, board and pulps — Estimation
of uncertainty for test methods by
interlaboratory comparisons
Reference number
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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or ISO’s member body in the country of the requester.
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Email: copyright@iso.org
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Procedure .2
5 Preparation of an interlaboratory study . 3
5.1 Laboratories . . 3
5.1.1 Qualification of laboratories . 3
5.1.2 Number of participating laboratories . 3
5.2 Sample preparation and distribution . 3
5.2.1 Number and type of material . 3
5.2.2 Selection of the material . 3
5.2.3 Identification and packaging . 5
5.2.4 Additional and specific care . 5
5.3 Documentation for the interlaboratory study . 5
6 Testing. 6
7 Analysis of the results .6
7.1 Calculations . 6
7.2 Case of interlaboratory study organised by the working group . 7
7.2.1 General . 7
7.2.2 Consistency evaluation . 7
7.2.3 Handling of outlying data . 7
7.3 Case of data provided from proficiency testing services . 7
8 Re-evaluation of the uncertainty . 8
9 Report . 8
10 Archiving raw data . 8
Annex A (informative) Tappi and ISO codifications . 9
Annex B (informative) Example of a recommended form to be distributed to participating
laboratories for the collation of results for analysis .10
Annex C (informative) Example of precision statements for physical properties .11
Bibliography .12
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps.
This first edition cancels and replaces the second edition of ISO/TR 24498:2019, which has been
technically revised.
The main changes are as follows:
— ISO/TR 24498 has been changed into ISO/TS 24498 adding normative language
— Lignins and kraft liquors have been introduced in the scope of the document, and a subclause on the
sampling of these materials in 5.2 has been added
— Subclause 7.3 has been updated.
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
Introduction
One step in the development of any new standard test method is to estimate the uncertainty of the
method. After such a procedure, a "Precision statement" is usually included in ISO test methods for pulp,
paper and board and is recommended by ISO/TC 6 for all new and revised ISO/TC 6 standards. This is
normally performed in a precision experiment, in which samples are sent to a number of laboratories
and the results are compared. Such a precision experiment is often referred to as "interlaboratory
comparative testing".
[1]
The procedures for conducting a precision statement are outlined in the ISO 5725 series , which is
general and does not cover the special conditions that apply in the testing of pulp, paper, board and
cellulosic nanomaterials (this is the reason why some countries have published national standards or
[2][3]
test methods dedicated to pulp, paper and board ).
For example, paper and board materials as well as cellulosic nanomaterials are very sensitive to changes
in relative humidity and temperature. Changes in the environmental conditions may induce significant
moisture content variations in paper and board, which may induce changes in physical and mechanical
properties.
Due to product heterogeneity, randomisation of the samples and /or test pieces is essential to minimize
the impact of such variability. For the same reason, the variation in the properties can increase
drastically when the test piece size decreases, for example when measuring grammage or Cobb water
absorptiveness.
These reasons make it necessary to have special instructions for precision experiments for pulp, paper,
board and cellulosic nanomaterials.
One effect of the heterogeneity of the product is that a large number of measurements is required in
order to achieve sufficient precision. Most standardized test methods are therefore based on 10 or
more measurements. The result is generally the average of these measurements.
Uncertainty has multiple components including a random component and a systematic component.
This document focuses on the random component, defined by a repeatability and reproducibility of the
measurements.
There are four main purposes for testing:
— Research, where the main question is whether there is an expected maximum difference between
two samples, for instance, papers produced using different pulp mixtures.
— Verification of conformance with a specification. This can be at the production central testing
laboratory site or in an independent laboratory.
— Evaluation of a new test method, where the aim is to verify that the precision of the test method is
acceptable.
— Determination of a precision statement for an existing test method either where one does not exist
or where it requires revision.
When the uncertainty of a test method is to be expressed, the following aspects should be considered.
— The conditions for the tests. Are the conditions as similar as possible, or as different as possible?
— The uncertainty can be expressed in different statistical measures, as a standard deviation or as a
confidence interval.
— The uncertainty can be expressed either as a variation in the test results themselves, or as the
difference between two test results.
v
TECHNICAL SPECIFICATION ISO/TS 24498:2022(E)
Paper, board and pulps — Estimation of uncertainty for
test methods by interlaboratory comparisons
1 Scope
This document presents guidelines for a methodology for the estimation of the uncertainty of methods
for testing lignins and kraft liquors, pulps, paper, board, cellulosic nanomaterials, as well as products
thereof containing any portion of recycled material or material intended for recycling.
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 187, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for
monitoring the atmosphere and conditioning of samples
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 https:// www .electropedia .org/
3.1
interlaboratory comparison
organization, performance and evaluation of measurements or tests on the same or similar items by
two or more laboratories in accordance with predetermined conditions
[SOURCE: ISO 13528:2015, 3.1]
3.2
interlaboratory test
series of measurements of one or more quantities performed independently by a number of laboratories
on samples of a given material
[SOURCE: ISO 11459:1997, 3.16]
3.3
repeatability condition of measurement
repeatability condition
condition of measurement, out of a set of condit
...

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