ISO/DIS 22031

DRAFT INTERNATIONAL STANDARD
ISO/DIS 22031
ISO/TC 142 Secretariat: UNI
Voting begins on: Voting terminates on:
2019-04-05 2019-06-28
Sampling and test method for cleanable filter media taken
from filters of systems in operation
ICS: 91.140.30
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NATIONAL REGULATIONS.
ISO/DIS 22031:2019(E)
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2019
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ISO/DIS 22031:2019(E)
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© ISO 2019

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Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Sampling of representative filter element ................................................................................................................................. 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Selection of 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 of 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 test lab ..................................................................... 6

5 Test method of the sampled fabric filter ..................................................................................................................................... 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Appearance inspection..................................................................................................................................................................... 6

5.3 Photography .............................................................................................................................................................................................. 7

5.4 Cut out of the test specimen ........................................................................................................................................................ 7

5.5 Testing ............................................................................................................................................................................................................ 7

5.5.1 Tensile strength ................................................................................................................................................................ 7

5.5.2 Elongation ratio ................................................................................................................................................................ 7

5.5.3 Air permeability ............................................................................................................................................................... 8

5.5.4 Observation with microscope ............................................................................................................................... 8

5.5.5 Optional measurement items................................................................................................................................ 8

5.6 Handling of the sampled fabric filter after the end of test ................................................................................ 9

6 Cautions for handling ...................................................................................................................................................................................... 9

7 Test report ................................................................................................................................................................................................................10

Annex A (informative) Example of test report .........................................................................................................................................12

Annex B (informative) Example of test results........................................................................................................................................14

Annex C (informative) Analysing filter media damage through FTA ................................................................................17

Bibliography .............................................................................................................................................................................................................................19

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This document was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and

Any feedback or questions on this document should be directed to the user’s national standards body. A

The main purpose of using dust collector systems is to separate dust particles from dirty gases. The

dry type filtering dust collector, bag filters are one of the most widely used industrial dust collectors

such as municipal garbage incinerators, coal fired boilers, iron makings, cement factories, power plants,

etc. Their important characteristics such as collection performance and residual pressure drop change

with the operation period, because the filter media in them exposed under various gases, dust and

Changes in physical and chemical properties of filter media are caused by many factors, such as

heat, particle accumulation, reaction with corrosive gases and deposited particles, and mechanical

reasons like clogging weave openings and increasing size of weave openings, the combination of those

factors and so on. Clogging weave openings reduces the permeability of the filter media, increasing

size of weave openings also lessens its collection performance. The reaction with corrosive gases and

deposited particles changes properties of filter fibre material itself, and decreases tensile strength,

tenacity, flexibility of filter media and so on. These changes are mostly adverse effects to filter media.

This can result in the breakage of filter media and leakage of dust to the atmosphere.

Therefore, since it is important to evaluate property change of filter media for predicting the timing

of replacement and/or service life time, ISO 16891:2016, test methods for evaluating degradation of

tensile stress of cleanable filter media has been published. However, test method for other evaluation

terms such as permeability, collection efficiency, fibre diameter of used filter media, mass and size

Industrial bag filter systems, in general, handle large amount of dirty gas so that dirty gas is introduced

to the system with large number of filter elements to separate dust. Accordingly, degree of degradation

of filter properties also depends on the location of filter in the system. Furthermore, sampling and

storage method of used filter, preparation method of test specimen should be also determined. By the

standardization of these test method, it is possible to accurately assess the deterioration of filter media

This standard provides the standard sampling method of filter elements from a dust collector system in

operation and test method to monitor sampled filter element and the system through measurement of

This International Standard specifies the sampling method of fabric filter media from filter system in

operation and test method thereof to evaluate the degradation of filter media for dry type filtering

dust collector (hereafter referred to as “bag filters”) used in thermal power plants, municipal waste

Bag filters are one of the most widely used dust collectors in industries such as municipal garbage

incinerators, coal fired boilers, iron makings, cement factories, power plants, etc. Since filter media are

used under various gas and dust circumstances for a long time, its physical and chemical properties

change (deteriorate) with operation time due to various causes . Especially, in the municipal

garbage incinerator, bag filter has been used very popularly to overcome dioxin emission . Since

users of bag filter system usually evaluated the necessary items for the change in the filter properties

with each method by themselves, obtained results were not compatible with each other. For this

reason, the establishment of the standard operation management and maintenance of filter system is

an important issue to predict the timing of replacement and/or service life time of filter media.

It is usually desirable to remove dust from the filter element before sampling. However, it may be

sampled with dust when it is difficult. In any case, special care shall be paid not to scatter too much

dust accompanying sampling work and not to bring out extra dust outside the factory.

Since measured physical and chemical properties of the filter media may differ depending on whether

or not dust adheres to the media, it is recommended to measure with and without attached dust on the

filter media. When dust removal from the filter media is necessary, it shall be carried out using a brush

Sampled filter media may be contaminated with potential hazardous substances so it shall be handled

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 16891:2016, Test methods for evaluating degradation of characteristics of cleanable filter media

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

degradation of chemical properties of filter media by the interaction with test gases

change in physical and chemical performances of filter media by the interaction with corrosive gases

filter media using fabric made from long fibres, bonded together with each other by chemical,

to remove collected particulate from filtration element by injecting compressed air in short time from

a supporting device fixing the fabric filter to perform dust collection, which may be referred to as a cage

To evaluate or monitor the service life time of filter elements, it is essential to sample the representative

filter element, since degree of degradation of filter properties depends not only on causes but also on

the location of filter in the system. Hence, even for a given cause, it is practically difficult to select a

representative filter because of the size and structure of the system, arrangement of filter elements,

gas flow distribution in the system and so on, are different to the individual system. Even in the same

system, the degree of the degradation is different by the element location. Hence it is extremely difficult

to point out the exact location in the system. Hence from the safety point of view, it is preferable to

sample a filter element as the representative element from the area the filter element is assumed to be

Most serious deterioration is expected to appear where dirty gas concentrates. Appearing area depends

on whether the bag filter system has a baffle plate at the dirty gas inlet. When dirty gas flows into

the system without a baffle plate, gas will flow to the opposite side of the system and change the flow

direction as shown in Figure 1 a) so that filter element is recommended to be sampled from a block at

either central or outside in the opposite side of the dirty gas inlet, for instance, block F, C, D. When the

system has a baffle plate, dirty gas flow is divided by the baffle plate and will gather again downstream

as shown in Figure 1 b). Therefore, the filter element is recommended to be sampled from a block at

the block where gas flow concentrates after it is divided by the baffle plate, for instance, block E or F.

The filter element can be sampled from the block identified by the flow analysis, etc. where dirty gas

concentrates, for instance, block E, I, F for left-hand side and G, I, H for right-hand side as shown in

c) Area where dirty gas flow concentrates d) Area where dirty gas flow concentrates

is already identified by flow analysis etc. is already identified by flow analysis etc.

Number of filter elements to be sampled shall be determined in accordance with the number of

b) Bag filter with multi-compartments: At least one filter element per compartment shall be sampled.

The first filter element shall be sampled around one year after its operation. Thereafter, it is preferable

Unused fabric filter shall be stored as reference to create the baseline for comparison.

Though plants installing a bag filter system usually operate continuously, the facility must be shut-

down when sampling the filter media. Therefore, it is preferable to sample filter element during the

Sampling of filter element is carried out by replacing old and new filter elements in the following

a) Stop the dust laden gas flow to the bag filter system and operate the system for more than 10

minutes with clean air alone and repeat pulse cleaning several times to remove dust on the filter

b) The flow rate and pressure drop of the designated filter element to sample shall be measured.

d) Then open the lid of the dirty side of the system and take a picture of the arrangement state of the

b) Remove the retainer holding the filter element. Then remove the filter element by loosening snap

c) Pull down the sampled filter element to dust bin with a rope. It had better be taken out to the clean

NOTE When filter element can be dropped down softly to the dust bin without rope, it does not need

to use the rope. Particularly, pay attention to prevent penetrate of dust inside the filter media and the re-

d) Measure the mass of filter element, if necessary, and record in a gram (g) unit for reference.

e) Put the sampled filter element into a polyethylene bag, etc. and seal the bag tightly.

NOTE This is to prevent absorption of moisture and re-entrainment of dust. Hence, it is desirable to put

the sampled filter element into a double layer polyethylene bag. Furthermore, in order to prevent changes of

the properties of the filter, it shall be kept in a vacuum state or filled with an inert gas, if possible.

f) Record the address of sampled filter element on the polyethylene bag. An example address of the

filter elements in the system is shown in Figure 2. (address of hatched filter element: 1-2-X)

NOTE When the arrangement plan of fabric elements is provided, the address of sampled filter element shall

Install new filter elements at the corresponding addresses of the sampled filter elements.

a) The sampled filter elements shall be put in a card board box not to contact with each other and

sealed tightly to prevent re-entrainment of attached dust, etc. In the case of handling, care shall be

b) The sampled filter elements shall be sent by appropriate mean of transport to arrive at the test

NOTE The sampled filter element is treated as a sample and is not pertinent to an industrial waste.

The sampled filter elements shall be selectively tested from the items shown below by the negotiation

between stakeholders. In the negotiation, it may be considered whether or not there is damage and

Stretch wholly the fabric filter on a flat plate and examine visually the damaged site, measure the

Indicate the head and tail of fabric filter with the filter wholly stretched, and then the pictures of the

fabric filter should be taken for both front and back sides. In addition, if a whole photograph of the fabric

filter is considered unnecessary because of restrictions of space due to circumstances of photograph

site, and presence and absence of damage of the fabric filter, etc., partial photograph may be allowed.

Clean up the fabric filter carefully in an appropriate manner for the measurement item, such as

vacuum cleaner, jet air, brush or scraper. The dust removed from the fabric filter shall be captured and

preserved. Cut out from the fabric filter a test specimen required for the following.

The cut out of the test sample is fundamentally performed at three sites of “upper”, “medium” and

In addition, if it is judged that the three sites are unnecessary in consideration of presence or absence of

damage on the fabric filter, the sample may be cut out at two sites such as a combination of “upper” and

The test specimen cut out longitudinally from the fabric filter shall include the part in contact with the

The test shall be performed as follows according to the type of fabric filter. In addition, the test should

The test shall be performed in accordance with the method specified in 6.2 of ISO 16891.

Cut out three test specimens (30 mm x 250 mm) in lengthwise and lateral directions, respectively, from

the sample, pull each of them at a constant rate (200 mm/min) with width of 25 mm and clamp distance

The test shall be performed in accordance with the cut strip method in the method specified in 6.2 of

Cut out three test specimens (50 mm x 300 mm) in lengthwise and lateral directions, respectively, from

the sample, pull each of them at a constant rate (100 mm/min or 200 mm/min) with width of 50 mm

and clamp distance of 200 mm. calculate the ultimate load (N) and obtain an average value of them.

The test shall be performed as follows according to the type of the fabric filter. In addition, the test

The test shall be performed in accordance with the cut strip method in the method A specified in 7.4 of

Cut out three test specimens (50 mm x 300 mm) in lengthwise and lateral directions, respectively, from

the sample, pull each of them at a constant rate (100 mm/min or 200 mm/min) with width of 50 mm

and clamp distance of 200 mm, calculate the elongation ratio (%) and obtain an average value of them.

The test shall be performed as follows according to the type of the fabric filter. The measurement should

be performed both with the dust attached on the filter and with the dust removed away brushed away

The test shall be performed according to Frazier type method specified in 6.2.3 of ISO 16891 or a similar

method. Sample three test specimens from the sample and obtain their average value.

The test shall be performed according to Frazier type method in the method A specified in 6.2.3

of ISO16891 or a similar method. Sample three test specimens from the sample and obtain their