ISO 22031:2021

INTERNATIONAL ISO
STANDARD 22031
First edition
2021-01
Sampling and test method for
cleanable filter media taken from
filters of systems in operation
Échantillonnage et méthode d'essai pour médias filtrants
décolmatables prélevés sur des filtres de systèmes en exploitation
Reference number
©
ISO 2021
© ISO 2021
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 the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
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 Sampling of a representative filter element . 2
4.1 General . 2
4.2 Selection of the sampling block in the system . 3
4.2.1 Sampling block . 3
4.2.2 Number of filter elements to be sampled . 5
4.2.3 Sampling time and interval . 5
4.3 Procedure for sampling . 5
4.3.1 General. 5
4.3.2 Preparation . 5
4.3.3 Sampling of filter element. 5
4.3.4 Installation of new fabric filters . 6
4.3.5 Transportation of sampled filter elements to the test lab . 6
5 Test method for the sampled filter fabric . 6
5.1 General . 6
5.2 Appearance inspection. 7
5.3 Photography . 7
5.4 Cutting out of the test specimen . 7
5.5 Testing . 7
5.5.1 General. 7
5.5.2 Tensile strength . 7
5.5.3 Elongation ratio . 7
5.5.4 Air permeability . 8
5.5.5 Observation with a microscope . 8
5.5.6 Optional characteristics for measurement . 8
5.6 Handling of the sampled filter after the test . 8
6 Precautions for handling samples . 9
7 Test report .10
Annex A (informative) Analysing filter media damage through fault tree analysis (FTA) .11
Annex B (informative) Example of test report .14
Annex C (informative) Example of test results .18
Bibliography .22
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 142, Cleaning equipment for air and
other gases.
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 main purpose of using dust collector systems is to remove dust particles from dirty gases. The
dry type filtering dust collectors, known as bag filters, are one of the most widespread industrial dust
collectors and are used in applications such as municipal garbage incinerators, coal fired boilers, iron
making, cement factories, power plants, etc. Especially, in municipal garbage incinerators, bag filters
[1],[2]
have been used frequently to overcome dioxin emission .
Since filter media are used under various gas and dust conditions for a long time, their physical and
[3]-[12]
chemical properties change (deteriorate) with operating time due to various causes . The
important filter characteristics such as collection performance and residual pressure drop change with
the operation period. Since users of bag filter systems have usually evaluated the parameters associated
with the change in the filter properties with their own methods, the results obtained were not easily
compared with each other. For this reason, the establishment of a standard for operation, management,
and maintenance of filter systems is important to allow prediction of the timing of replacement and/or
service life time of filter media.
Changes in the physical and chemical properties of the filter medium, i.e., physical and chemical
degradation are caused by many factors, such as heat, particle accumulation, reaction with corrosive
gases and deposited particles, and mechanical reasons like clogged weave openings and increasing
size of weave openings, the combination of those factors and so on. The filter medium damage can be
analysed through the fault tree analysis in Annex A. Clogged weave openings reduce the permeability
of the filter medium; and increasing the size of weave openings lessens the collection performance of
the filter medium. The reaction with corrosive gases and deposited particles changes properties of the
filter fibre material itself and decreases the tensile strength, tenacity, flexibility of the filter medium
and so on. These changes cause mostly adverse effects to the filter medium. This can result in the
breakage of filter media and leakage of dust to the atmosphere.
Therefore, since it is important to evaluate the property changes of filter media in order to predict the
timing of replacement and/or service life time, ISO 16891, which specifies test methods for evaluating
degradation of tensile stress of cleanable filter media, has been published. However, test methods for
other evaluation parameters such as permeability, collection efficiency, fibre diameter of used filter
media, mass and size distribution of deposited particles, have not yet been specified.
Industrial bag filter systems, in general, handle large amounts of dirty gas so that a system with a large
number of filter elements in parallel is needed to remove the dust. The degree of degradation of filter
properties depends on the location of the filter in the system because the dirty gas usually enters the
system in an irregular flow pattern. Furthermore, the method used for sampling and storage of the
used filter, and the preparation method of the test specimen should be defined. By standardizing these
test methods, it is possible to accurately assess the deterioration of individual filter media.
This document provides a standard method for sampling filter elements from a dust collector system
in operation, and a test method for monitoring sampled filter elements and the system through
measurement of basic filter properties.
INTERNATIONAL STANDARD ISO 22031:2021(E)
Sampling and test method for cleanable filter media taken
from filters of systems in operation
1 Scope
This document specifies a method for sampling fabric filter medium from a filter system in operation,
and a test method for evaluating the degradation of the sampled filter medium. It applies to both woven
and nonwoven fabric filter media.
This document specifies a method for removing used filter medium from a dry type filtering dust
collector, a method for removing dust from the sampled filter medium as part of preparation for testing,
and measurement parameters for the test specimen. The number of filter elements to be sampled,
their positions in the blocks of filter elements in the dust collector, the position and the size of the test
specimens to be cut out from the filter element, measurement parameters and their test methods are
also specified.
This document also sp
...