High efficiency filters and filter media for removing particles from air — Part 1: Classification, performance, testing and marking

ISO 29463-1 establishes a classification of filters based on their performance, as determined in accordance with ISO 29463‑3, ISO 29463‑4 and ISO 29463‑5. It also provides an overview of the test procedures, and specifies general requirements for assessing and marking the filters, as well as for documenting the test results. It is intended to be used in conjunction with ISO 29463‑2, ISO 29463‑3, ISO 29463‑4 and ISO 29463‑5.

Filtres et media à très haute efficacité pour la rétention particulaire — Partie 1: Classification, essais de performance et marquage

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Status
Published
Publication Date
03-Oct-2017
Current Stage
9092 - International Standard to be revised
Start Date
09-Dec-2021
Completion Date
09-Dec-2021
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INTERNATIONAL ISO
STANDARD 29463-1
Second edition
2017-09
High efficiency filters and filter media
for removing particles from air —
Part 1:
Classification, performance, testing
and marking
Filtres et media à très haute efficacité pour la rétention
particulaire —
Partie 1: Classification, essais de performance et marquage
Reference number
ISO 29463-1:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 29463-1:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

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ii © ISO 2017 – All rights reserved
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ISO 29463-1:2017(E)
Contents Page

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

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

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

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

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

4 Symbols and abbreviated terms ........................................................................................................................................................... 3

5 Classification ............................................................................................................................................................................................................ 3

6 Requirements .......................................................................................................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 Material ......................................................................................................................................................................................................... 4

6.3 Nominal air volume flow rate ..................................................................................................................................................... 5

6.4 Pressure difference ............................................................................................................................................................................. 5

6.5 Filtration performance ..................................................................................................................................................................... 5

7 Test methods — General requirements and test procedures overview ......................................................5

7.1 General ........................................................................................................................................................................................................... 5

7.2 Test rigs ......................................................................................................................................................................................................... 5

7.3 Test conditions ........................................................................................................................................................................................ 5

7.4 Test aerosols .............................................................................................................................................................................................. 6

7.5 Test methods — Principles........................................................................................................................................................... 6

7.5.1 Test method for flat sheet filter media .......................................................................................................... 6

7.5.2 Test method for determining the leakage of filter elements — Scan method ............ 9

7.5.3 Test method for determining the efficiency of filter elements ..............................................10

7.5.4 Remarks ................................................................................................................................................................................11

8 Assessment of the filter, documentation, test reports................................................................................................12

9 Marking .......................................................................................................................................................................................................................12

Annex A (informative) Filtration of nanoparticles .............................................................................................................................13

Annex B (informative) Summary of classification and test methods ...............................................................................14

Bibliography .............................................................................................................................................................................................................................16

© ISO 2017 – All rights reserved iii
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ISO 29463-1:2017(E)
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 on 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 the following

URL: www.iso.org/iso/foreword.html.

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

other gases.

This second edition cancels and replaces the first edition (ISO 29463-1:2011), which has been technically

revised.

This edition includes the following significant changes with respect to the previous edition:

— Table 1 has been split into two tables;
— a definition for "particle diameter" has been added;

— it has been stated that the filter test certificate shall clearly indicate if the filter has been tested

without seal fitted.
A list of all parts in the ISO 29463 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved
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ISO 29463-1:2017(E)
Introduction

ISO 29463 (all parts) is derived from EN 1822 (all parts). It contains requirements, fundamental

principles of testing and the marking for, high-efficiency particulate air filters with efficiencies from

95% to 99,999 995% that can be used for classifying filters in general or for specific use by agreement

between users and suppliers.

ISO 29463 (all parts) establishes a procedure for the determination of the efficiency of all filters on the

basis of a particle counting method using a liquid (or alternatively a solid) test aerosol, and allows a

standardized classification of these filters in terms of their efficiency, both local and overall efficiency,

which actually covers most needs of different applications. The difference between this document

and other national standards lies in the technique used for the determination of the overall efficiency.

Instead of mass relationships or total concentrations, this technique is based on particle counting at

the most penetrating particle size (MPPS), which is for micro-glass filter mediums usually in the range

of 0,12 μm to 0,25 μm. This method also allows testing ultra-low penetration air filters, which was

not possible with the previous test methods because of their inadequate sensitivity. For membrane

filter media, separate rules apply, and are described in ISO 29463-5:2011, Annex B. Although no

equivalent test procedures for testing filters with charged media is prescribed, a method for dealing

with these types of filters is described in ISO 29463-5:2011, Annex C. Specific requirements for testing

method, frequency, and reporting requirements may be modified by agreement between supplier and

customer. For lower efficiency filters (Group H, as described in Clause 5), alternate leak test methods

noted in ISO 29463-4:2011, Annex A may be used by specific agreement between users and suppliers,

but only if the use of these other methods is clearly designated in the filter markings, as noted in the

annex. Although the methods prescribed in this document may be generally used to determine filter

performance for nano-size particles, testing or classification of filters for nano-size particles are beyond

the scope of this document (see Annex A for additional information).

There are differences between ISO 29463 (all parts) and other normative practices common in

several countries. For example, many of these rely on total aerosol concentrations rather than

individual particles. A brief summary of these methods and their reference standards is provided in

ISO 29463-5:2011, Annex A.
© ISO 2017 – All rights reserved v
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INTERNATIONAL STANDARD ISO 29463-1:2017(E)
High efficiency filters and filter media for removing
particles from air —
Part 1:
Classification, performance, testing and marking
1 Scope

This document establishes a classification of filters based on their performance, as determined in

accordance with ISO 29463-3, ISO 29463-4 and ISO 29463-5. It also provides an overview of the test

procedures, and specifies general requirements for assessing and marking the filters, as well as for

documenting the test results. It is intended to be used in conjunction with ISO 29463-2, ISO 29463-3,

ISO 29463-4 and ISO 29463-5.
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 29463-2:2011, High-efficiency filters and filter media for removing particles in air — Part 2: Aerosol

production, measuring equipment and particle-counting statistics

ISO 29463-3:2011, High-efficiency filters and filter media for removing particles in air — Part 3: Testing

flat sheet filter media

ISO 29463-4:2011, High-efficiency filters and filter media for removing particles in air — Part 4: Test

method for determining leakage of filter elements-Scan method

ISO 29463-5:2011, High-efficiency filters and filter media for removing particles in air — Part 5: Test

method for filter elements
ISO 29464:2017, Cleaning equipment for air and other gases — Terminology
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 29464 and the following apply.

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

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
filter medium
material used for filtering
3.2
folded pack
pack of the filter medium (3.1) formed by uniform individual folds
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ISO 29463-1:2017(E)
3.3
filter element
filter
folded pack (3.2) enclosed by a frame
3.4
efficiency

ratio of the number of particles retained by the filter to the number of the particles entering it

3.5
particle size efficiency
efficiency (3.4) for a specific particle diameter (3.6)

Note 1 to entry: The efficiency plotted as a function of the particle diameter gives the fractional efficiency curve.

3.6
particle diameter

geometric diameter (equivalent spherical, optical or aerodynamic, depending on context) of the

particles of an aerosol

Note 1 to entry: Particle diameter is often referred to simply as "particle size".

[SOURCE: ISO 29464:2017, 3.2.124]
3.7
overall efficiency

efficiency (3.4), averaged over the whole superficial face area (3.11) of a filter element (3.3) under given

operating conditions of the filter
3.8
local efficiency

efficiency (3.4) at a specific point of the filter element (3.3) under given operating conditions of the filter

3.9
nominal air volume flow rate

air volume flow rate at which the filter element (3.3) shall be tested as specified by the manufacturer

3.10
filter face area
cross-sectional area of the filter element (3.3) including the frame
3.11
superficial face area

cross-sectional area of the filter element (3.3) through which the air flow passed

3.12
effective filter medium area

area of the filter medium (3.1) contained in the filter element (3.3) (without areas covered by sealant,

spacers, struts, etc.) which the air flow passes
3.13
nominal filter medium face velocity

nominal air volume flow rate (3.9) divided by the effective filter medium (3.1) area

3.14
quasi–monodisperse aerosol

aerosols whose distribution has a geometric standard deviation between σ = 1,15 and σ = 1,5

g g
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ISO 29463-1:2017(E)
4 Symbols and abbreviated terms
d particle diameter
E efficiency
P penetration
p pressure
σ geometric standard deviation
CPC condensation particle counter

DEHS Sebacic acid-bis (2 ethyl hexyl-) ester (trivial name: di-ethyl-hexyl-sebacate)

DMA differential electric mobility analyser
DMPS differential mobility particle sizer

MPPS most penetrating particle size, that is the particle size for which the filtration efficiency

is a minimum
OPC optical particle counter

PAO poly-alpha-olefin, mineral oil with Chemical Abstract Service Registry number

of 68649-12-7
PSL poly-styrene latex (solid spheres)
5 Classification

Filters and filter elements are classified in groups and classes based on their efficiency or penetration

for the MPPS particles by testing as prescribed in Clause 6 and in ISO 29463-5. According to this

document, filter elements fall into one of the following groups.

a) Group E: EPA filters (efficient particulate air filter), also commonly referred to as sub-HEPA.

The efficiency of the filters is determined by statistical sample testing only in accordance with

ISO 29463-5. Group E filters cannot and shall not be leak tested.
b) Group H: HEPA filters (high-efficiency particle air filter)

Filters are individually tested and their efficiency is determined at MPPS in accordance with

ISO 29463-5. The filter is leak tested in accordance with ISO 29463-4, where, in addition to the

reference leak scan method, four alternate methods for leak testing are allowed. Alternate norms

used for leak testing should be clearly identified on the filter and certifications.

c) Group U: ULPA filters (ultra-low penetration air filter)

Filters are individually tested and their efficiency is determined at MPPS in accordance with

ISO 29463-5. Filters are leak tested according to scan method in accordance with ISO 29463-4. No

alternate leak testing is allowed.

A detailed specification for each filter group and class is given in Tables 1 and 2. Either of them can be

used for filter classification purposes.

Detailed information about the permissible test methods in accordance with ISO 29463 (all parts) for

each filter group and class of filters is given in Table B.1.
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ISO 29463-1:2017(E)

Table 1 — Filter classification: Allowed filter classes (5/10th filter efficiency)

a,b
Filter class and group Overall value Local value
Efficiency (%) Penetration (%) Efficiency (%) Penetration (%)
c c
ISO 15 E ≥95 ≤5 — —
c c
ISO 25 E ≥99,5 ≤0,5 — —
ISO 35 H ≥99,95 ≤0,05 ≥99,75 ≤0,25
ISO 45 H ≥99,995 ≤0,005 ≥99,975 ≤0,025
ISO 55 U ≥99,999 5 ≤0,000 5 ≥99,997 5 ≤0,002 5
ISO 65 U ≥99,999 95 ≤0,000 05 ≥99,999 75 ≤0,000 25
ISO 75 U ≥99,999 995 ≤0,000 005 ≥99,999 9 ≤0,000 1
See 7.5.2.4 and ISO 29463-4.

Local penetration values lower than those given in this table may be agreed upon between the supplier and customer.

Filters of Group E cannot and shall not be leak tested for classification purposes.

For Group H filters, local penetration is given for reference MPPS particle scanning method. Alternate limits may be

specified when photometer or oil thread leak testing is used.

Table 2 — Filter classification: Allowed filter classes (1/10th filter efficiency)

a,b
Filter class and group Overall value Local value
Efficiency (%) Penetration (%) Efficiency (%) Penetration (%)
c c
ISO 20 E ≥99 ≤1 — —
c c
ISO 30 E ≥99,90 ≤0,1 — —
ISO 40 H ≥99,99 ≤0,01 ≥99,95 ≤0,05
ISO 50 U ≥99,999 ≤0,001 ≥99,995 ≤0,005
ISO 60 U ≥99,999 9 ≤0,000 1 ≥99,999 5 ≤0,000 5
ISO 70 U ≥99,999 99 ≤0,000 01 ≥99,999 9 ≤0,000 1
See 7.5.2.4 and ISO 29463-4.

Local penetration values lower than those given in this table may be agreed upon between the supplier and customer.

Filters of Group E cannot and shall not be leak tested for classification purposes.

For Group H filters, local penetration is given for reference MPPS particle scanning method. Alternate limits may be

specified when photometer or oil thread leak testing is used.
6 Requirements
6.1 General

The filter element shall be designed or marked so as to prevent incorrect mounting.

The filter element shall be designed so that when correctly mounted in the ventilation duct, no leak

occurs along the sealing edge.

If, for any reason, dimensions do not allow testing of a filter under standard test conditions, assembly of

two or more filters of the same type or model is permitted, provided no leaks occur in the resulting filter.

If the filter is tested without the filter seal fitted, and if designed to have a filter seal, then the filter test

certificate shall be clearly marked “filter efficiency tested without filter seal fitted”.

6.2 Material

The filter element shall be made of suitable material to withstand normal usage and exposures to those

temperatures, humidity and corrosive environments that are likely to be encountered.

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ISO 29463-1:2017(E)

The filter element shall be designed so that it will withstand mechanical constraints that are likely to

be encountered during normal use.

Dust or fibres released from the filter media by the air flow through the filter element shall not

constitute a hazard or nuisance for the people (or devices) exposed to filtered air.

6.3 Nominal air volume flow rate

The filter element shall be tested at its nominal air volume flow rate for which the filter has been

designed by the manufacturer.
6.4 Pressure difference

The pressure difference across the filter element is recorded at the nominal air volume flow rate.

6.5 Filtration performance

The filtration performance is expressed by the efficiency or the penetration as measured by the

prescribed procedures in ISO 29463-5. After testing in accordance with Clause 7, filter elements are

classified in accordance with Tables 1 and 2.

Filters with filter media having an electrostatic charge are classified in accordance with Tables 1 and

2, on the basis of their discharged efficiency or penetration in accordance with ISO 29463-5:2011,

Annex C.
7 Test methods — General requirements and test procedures overview
7.1 General

The complete test method comprises the following three steps, which can be performed independently:

— test for flat sheet filter media, in accordance with ISO 29463-3;

— test for determining the leakage of filter elements (scan method), in accordance with ISO 29463-4;

— test for determining the efficiency of filters, in accordance with ISO 29463-5.

Clause 7 provides the general requirements for the features common to all tests, as well as an overview

of the test procedures.

Detailed information about the permissible test methods for filter elements in accordance with

ISO 29463 (all parts) for each filter group and class of filters is given in Table B.1.

7.2 Test rigs

Test rigs shall be in accordance with ISO 29463-3, ISO 29463-4 and ISO 29463-5 for the respective

tests. The measuring equipment shall be in accordance with ISO 29463-2.
7.3 Test conditions

The air in the test channel used for testing shall comply with the following requirements:

— temperature: 23 °C ± 5 °C;
— relative humidity <75 %.

The temperature shall remain constant during the entire test procedure within ±2 °C, the relative

humidity within ±5 %.
© ISO 2017 – All rights reserved 5
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ISO 29463-1:2017(E)

The cleanliness of the test air shall be ensured by appropriate pre-filtering, so that in operation without

addition of aerosol the particle number concentration measured with the particle counting method is

less than 352 000 particles/m . The test specimen shall have the same temperature as the test air and

hence shall be conditioned at test requirements (temperature and relative humidity) long enough to be

in equilibrium.
7.4 Test aerosols

For the testing of filters in accordance with this document, a liquid test aerosol shall be used as the

reference test method. Alternatively, a solid aerosol may be used for leak testing (see ISO 29463-4:2011,

Annex E). Possible aerosol substances include, but are not limited to, DEHS, PAO and PSL. For further

details, see ISO 29463-2:2011, 4.1.

The use of alternative materials for challenge aerosols shall be agreed between supplier and customer

when the materials specified in this document are unacceptable.

The concentration and the size distribution of the aerosol shall be constant, within experimental limits,

over time. Details of aerosol generation for testing is addressed in the other parts of ISO 29463. For

the leak test and the efficiency test of the filter element, the count mean particle diameter of the test

aerosol shall correspond to the most penetrating particle size (MPPS) for the filter medium.

7.5 Test methods — Principles
7.5.1 Test method for flat sheet filter media
7.5.1.1 General

The fractional efficiency curve of flat sheet filter medium samples is determined in new condition

(material as supplied by the medium manufacturer) and in discharged condition (see ISO 29463-5:2011,

Annex C). If these measurements reveal that the filter medium is having a significant charge, the

filter elements shall be classified on the basis of the discharged flat sheet efficiency or penetration

measurements in accordance with ISO 29463-5:2011, Annex C.

From the fractional efficiency curve generated this way, the most penetrating particle size (MPPS) shall

be determined.
7.5.1.2 Test samples

The testing procedure requires at least five flat sheet samples of the filter material that will make up

the filter elements.

The test samples shall be free of folds, creases, holes and other irregularities. The test samples shall

have a minimum size of 200 mm × 200 mm.
7.5.1.3 Test apparatus

The arrangement of the test apparatus is shown in Figure 1. The test rig is described in detail in

ISO 29463-3. The individual measuring instruments and other devices are described in ISO 29463-2.

An aerosol is produced in the aerosol generator, then passed through a conditioner (for example, to

evaporate a solvent) and neutralised, before being brought together with the particle-free mixing air to

the test filter medium mounting assembly.

Sampling points are positioned upstream and downstream from the test filter medium mounting

assembly from which a part of the flow is led to the particle counter. The upstream sampling point is

connected with a known ratio dilution circuit to reduce the high particle concentration down to the

actual measuring range of the particle counter.
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ISO 29463-1:2017(E)

When using the total count counting method (CPC), a differential electric mobility analyser (DMA) is

included before the aerosol neutralizer to separate out a quasi-monodisperse fraction of the required

particle size from the initial polydisperse aerosol.

If a counting method with particle size analysis (OPC) is used, the size distribution of a polydisperse

aerosol can be measured before and after the test specimen.

Instead of using a single particle counter, which measures the unfiltered and filtered air consecutively,

it is also permissible to use two particle counters of equal optical design (wavelength of light source,

light scattering angle, etc.) simultaneously for both measurements. When using two particle counters,

the two counters shall be correlated by measuring the same aerosol to correct for any response

differences.” It is known that OPCs of the same model can give different responses.

After the downstream sampling point, the test aerosol is led through an exhaust filter and extracted by

a pump. The apparatus is completed by devices to measure (and regulate) the air volume flow rate and

the differential pressure across the filter under test.
The measurement data is recorded and evaluated by a computer.

The test apparatus can also be operated in an overpressure mode. In this case, the extraction pump is

not required and the mixing air is supplied from a compressed air line. If so desired, the measurement

and regulation of the air volume flow rate can then be carried out on the upstream side.

Figure 1 — Arrangement of apparatus for testing the filter medium
7.5.1.4 Measurement procedure

The performance of the filter medium is determined by testing a circular sample with an exposed area

of 100 cm² at the nominal filter medium face velocity. Details of the measurements are described in

ISO 29463-3. In order to establish the penetration versus particle size curve, the penetration values for

at least six logarithmically, approximately equidistant particle size points are determined.

For this measurement, quasi-monodisperse test aerosol from a DMA with appropriate median values

of the particle diameter is used, and their concentrations determined upstream and downstream of

the test sample. Alternately, the size distribution of a polydisperse aerosol may be determined by OPC’s

upstream and downstream of the test sample in at least six particle size classes. In each case, it shall

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ISO 29463-1:2017(E)

be ensured that the measuring range of the particle counter and the range of produced particle sizes

envelopes the minimum of the efficiency curve (MPPS).
7.5.1.5 Evaluation of test results

From the measurements on the five test samples, the efficiency versus particle size curve shall be

drawn (see Figure 2 for an example) from which the position and value of the minimum efficiency shall

be determined.
Arithmetic mean values shall be determined for
— the minimum efficiency,
— the particle size at the m
...

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