EN ISO 29463-4:2018

SLOVENSKI STANDARD
01-december-2018
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SIST EN 1822-4:2010
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High-efficiency filters and filter media for removing particles in air - Part 4: Test method
for determining leakage of filter elements-Scan method (ISO 29463-4:2011)
Schwebstofffilter und Filtermedien zur Abscheidung von Partikeln aus der Luft - Teil 4:
Prüfverfahren zur Ermittlung der Leckage des Filterelementes - Scan-Verfahren (ISO
29463-4:2011)
Filtres à haut rendement et filtres pour l'élimination des particules dans l'air - Partie 4:
Méthode d'essai pour déterminer l'étanchéité de l'élément filtrant (méthode scan) (ISO
29463-4:2011)
Ta slovenski standard je istoveten z: EN ISO 29463-4:2018
ICS:
13.040.99 Drugi standardi v zvezi s Other standards related to air
kakovostjo zraka quality
91.140.30 3UH]UDþHYDOQLLQNOLPDWVNL Ventilation and air-
VLVWHPL conditioning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 29463-4
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2018
EUROPÄISCHE NORM
ICS 91.140.30 Supersedes EN 1822-4:2009
English Version
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-
4:2011)
Filtres à haut rendement et filtres pour l'élimination Schwebstofffilter und Filtermedien zur Abscheidung
des particules dans l'air - Partie 4: Méthode d'essai von Partikeln aus der Luft - Teil 4: Prüfverfahren zur
pour déterminer l'étanchéité de l'élément filtrant Ermittlung der Leckage des Filterelementes - Scan-
(méthode scan) (ISO 29463-4:2011) Verfahren (ISO 29463-4:2011)
This European Standard was approved by CEN on 6 May 2018.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 29463-4:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 29463-4:2011 has been prepared by Technical Committee ISO/TC 142 "Cleaning
equipment for air and other gases” of the International Organization for Standardization (ISO) and has
been taken over as EN ISO 29463-4:2018 by Technical Committee CEN/TC 195 “Air filters for general
air cleaning” the secretariat of which is held by UNI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2019, and conflicting national standards shall be
withdrawn at the latest by April 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 1822-4:2009.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 29463-4:2011 has been approved by CEN as EN ISO 29463-4:2018 without any
modification.
INTERNATIONAL ISO
STANDARD 29463-4
First edition
2011-10-15
High-efficiency filters and filter media for
removing particles in air —
Part 4:
Test method for determining leakage of
filter elements — Scan method
Filtres à haut rendement et filtres pour l'élimination des particules dans
l'air —
Partie 4: Méthode d'essai pour déterminer l'étanchéité de l'élément
filtrant (méthode scan)
Reference number
ISO 29463-4:2011(E)
©
ISO 2011
ISO 29463-4:2011(E)
©  ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 2
4  Principle . 2
5  Test filter . 3
6  Test apparatus . 3
6.1  Set-up of the test apparatus . 3
6.2  Test duct . 6
6.3  Scanning assembly . 7
6.4  Aerosol generation and measurement techniques . 8
7  Test air . 9
8  Procedure . 10
8.1  General . 10
8.2  Preparatory checks . 10
8.3  Starting up the aerosol generator . 11
8.4  Preparing the test filter . 11
8.5  Testing . 11
9  Test report . 12
10  Maintenance and inspection of the test apparatus . 13
Annex A (normative) Oil thread leak test . 15
Annex B (normative) Aerosol photometer filter scan test method . 16
Annex C (normative) Determining the test parameters . 20
Annex D (informative) Example of an application with evaluation . 28
Annex E (informative) Leak test with solid PSL aerosol . 31
Annex F (informative) 0,3 μm to 0,5 μm particle efficiency leak test . 34
Annex G (informative) Calculation of aerosol challenge . 36
Bibliography . 38

ISO 29463-4:2011(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 29463-4 was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and other gases.
ISO 29463 consists of the following parts, under the general title High-efficiency filters and filter media for
removing particles in air:
 Part 1: Classification, performance, testing and marking
 Part 2: Aerosol production, measuring equipment, particle-counting statistics
 Part 3: Testing flat sheet filter media
 Part 4: Test method for determining leakage of filter element — Scan method
 Part 5: Test method for filter elements
iv © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
Introduction
ISO 29463 (all parts) is derived from EN 1822 (all parts) with extensive changes to meet the requests from
non-EU p-members. 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 requirements of different applications. The difference between ISO 29463 (all parts) 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 they
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 test method, frequency, and reporting requirements can be modified by
agreement between supplier and customer. For lower efficiency filters (group H, as described below),
alternate leak test methods described in Annex A of this part of ISO 29463 can 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 described in Annex A of this part of ISO 29463.
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. For
information, a brief summary of these methods and their reference standards are provided in
ISO 29463-5:2011, Annex A.
INTERNATIONAL STANDARD ISO 29463-4:2011(E)

High-efficiency filters and filter media for removing particles in
air —
Part 4:
Test method for determining leakage of filter elements — Scan
method
1 Scope
This part of ISO 29463 specifies the test procedure of the “scan method”, considered to be the reference
method, for determining the leakage of filter elements. It is applicable to filters ranging from classes ISO 35 H
to ISO 75 U. It also describes the other normative methods, the oil thread leak test (see Annex A) and the
photometer leak test (see Annex B), applicable to classes ISO 35 H to ISO 45 H HEPA filters, and the leak
test with solid PSL aerosol (see Annex E). It is intended for use in conjunction with ISO 29463-1, ISO 29463-2,
ISO 29463-3 and ISO 29463-5.
2 Normative references
The following referenced documents are indispensable for the application 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 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
ISO 29463-1:2011, High-efficiency filters and filter media for removing particles in air — Part 1: Classification,
performance, testing and marking
ISO 29463-2:2011, High-efficiency filters and filter media for removing particles in air — Part 2: Aerosol
production, measuring equipment, particle-counting statistics
ISO 29463-3, High-efficiency filters and filter media for removing particles in air — Part 3: Testing flat sheet
filter media
ISO 29463-5:2011, High-efficiency filters and filter media for removing particles in air — Part 5: Test method
for filter elements
1)
ISO 29464 , Cleaning equipment for air and other gases — Terminology

1) To be published.
ISO 29463-4:2011(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 29463-1, ISO 29463-2, ISO 29463-3,
ISO 29463-5, ISO 29464 and the following apply.
3.1
sampling duration
time period during which the particles in the sample are counted upstream and downstream
3.2
total particle count method
particle counting method in which the total number of particles in a certain sample volume is determined
without classification according to size
EXAMPLE By using a condensation nucleus counter.
3.3
particle counting and sizing method
particle counting method which allows both the determination of the number of particles and also the
classification of the particles according to size
EXAMPLE By using an optical particle counter.
3.4
particle flow rate
number of particles that are measured or that flow past a specified cross-section per unit time
3.5
particle flow distribution
distribution of the particle flow over a plane at right angles to the direction of flow
3.6
aerosol photometer
light-scattering airborne particle mass concentration measuring apparatus, which uses a forward-scattering-
light optical chamber to make measurements
4 Principle
For most high-efficiency filter applications, a leak-free filter is essential. The reference leakage test serves to
test the filter element for local penetration values and determine whether it exceeds permissible levels (see
ISO 29463-1). For group H filters, alternatives to the reference scan method provide equivalent filter leakage
determination and are described as alternate methods in Annexes A, B, E and F. Although not considered
equivalent, the particle count method using 0,3 μm to 0,5 μm PSL given in Annex F may be used instead of
the oil thread method (see Annex A).
For leakage testing, the test filter is installed in the mounting assembly and subjected to a test airflow
corresponding to the nominal airflow rate. After measuring the pressure differential at the nominal air flow
volume flow rate, the filter is purged and the test aerosol produced by the aerosol generator is mixed with the
prepared test air along a mixing duct, so that it is spread homogeneously over the cross-section of the duct.
The particle flow rate on the downstream side of the test filter is smaller than the particle flow rate reaching the
filter on the upstream side by the mean penetration factor.
The manufacturing irregularities of the filter media or leaks lead to a variation of the particle flow rate over the
filter face area. In addition, leaks at the boundary areas and within the components of the test filter (sealant,
filter frame, seal of the filter mounting assembly) can lead locally to an increase in the particle flow rate on the
downstream side of the test filter.
2 © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
For the leakage test, the particle flow distribution shall be determined on the downstream side of the filter in
order to check where the limit values are exceeded. The coordinates of these positions shall be recorded.
The scanning tracks shall also cover the area of the filter frame, the corners, the sealant between filter frame
and the gasket, so that possible leaks in these areas can also be detected. It is advisable to scan filters for
leaks with their original gasket mounted and in the same mounting position and airflow direction as they are
installed on site.
In order to measure the downstream particle flow distribution, a probe with defined geometry shall be used on
the downstream side to take a specified partial flow as sample. From this partial flow, a sample volume flow
rate shall be directed to a particle counter, which counts the particles and displays the results as a function of
time. During the testing, the probe moves at a defined speed in adjoining or overlapping tracks without gaps
(see C.3.2 and C.3.3) close to the downstream side of the filter element. The measuring period for the
downstream particle flow distribution can be shortened by using several measuring systems (partial flow
extractors/particle counters) operating in parallel.
The measurement of the coordinates of the probe, a defined probe speed, and measurement of the particle
flow rate at sufficiently short intervals allow the localization of leaks. In a further test step, the local penetration
shall be measured at this position using a stationary probe.
The leakage tests shall always be conducted using MPPS particles (see ISO 29463-3), except for filters with
membrane medium in accordance with Annex E. The size distribution of the aerosol particles can be checked
using a particle size analysis system (for example, a differential mobility particle sizer, DMPS).
The leakage testing can be carried out using either a mono-disperse or poly-disperse test aerosol. It shall be
ensured that the mean particle diameter corresponds to the most penetrating particle size (MPPS) particle
diameter, at which the filter medium has its minimum efficiency.
When testing with a mono-disperse aerosol, the total particle counting method may be used with a
condensation particle counter (CPC) or an optical particle counter (OPC; e.g. a laser particle counter).
When using a poly-disperse aerosol, an optical particle counter that counts the particles and measures their
size distribution shall be used.
5 Test filter
A test filter shall be used for the leak testing that does not show any visible signs of damage or other
irregularities and that can be sealed in position and subjected to air flow in accordance with requirements. The
temperature of the test filter during the tests shall correspond to the temperature of the test air. The test filter
element shall be handled with care and shall be clearly and permanently marked with the following details:
a) designation of the test filter element;
b) upstream side of the filter element.
6 Test apparatus
6.1 Set-up of the test apparatus
Figure 1 shows the set-up of the test apparatus. This layout is valid for tests with a mono-disperse or with a
poly-disperse aerosol. The only differences between these lie in the technique used to measure the particles
and the way the aerosol is generated.
ISO 29463-4:2011(E)
Key
1 pre-filter for the test air
2 fan with speed regulator
3 air heater
4 aerosol inlet in the duct
5 aerosol generator with conditioning of supply air and aerosol flow regulator
6 measurement of atmospheric pressure, temperature and relative humidity
7 upstream side mixing section
8 sampling point for upstream particle counting
9 dilution system (optional)
10 particle counter, upstream
11 sheath flow (optional)
12 test filter
13 sampling point and partial flow extraction, downstream
14 traversing system for probe
15 volume flow rate measurement
16 particle counter, downstream
17 computer for control and data storage
18 measuring system to check the test aerosol
19 measurement of differential pressure
Figure 1 — Diagram of test apparatus
4 © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
An example of a test rig, without particle measuring equipment, is shown in Figure 2.

Key
1 coarse dust filter
2 fine dust filter
3 fan
4 air heater
5 dampers to adjust test and sheath air
6 high-efficiency air filter for the test air
7 aerosol inlet in the duct
8 test airflow
9 sheath airflow
10 effective pressure measuring device
11 differential pressure
12 atmospheric pressure
13 temperature measurement
14 hygrometer
15 sampling point for particle size analysis
16 sampling point, upstream
17 high-efficiency air filter for the sheath air
18 measurement of pressure drop
19 measurement of sheath air speed
20 test filter
21 flow equalizer for the sheath airflow
22 filter mounting assembly
23 screening (linked to the filter mounting assembly during the testing)
24 traversing probe arm with downstream sampling probe
25 probe traversing system
26 downstream sampling point
Figure 2 — Test duct for scan testing
ISO 29463-4:2011(E)
The basic details for the generation and neutralization of the aerosol, together with the details of suitable types
of equipment and detailed descriptions of measuring instruments needed for the testing, are given in
ISO 29463-2.
6.2 Test duct
6.2.1 Test air conditioning
The test air conditioning unit contains the equipment required to condition the test airflow (see Clause 7).
The test airflow shall be so prepared that it is in accordance with Clause 7 and does not exceed the limit
values specified during the course of the efficiency testing.
6.2.2 Adjustment of the volume flow rate
It shall be possible by means of a suitable provision (e.g. changes to the speed of the fan, or by dampers) to
produce the volume flow rate with a reproducibility of 3 %. The nominal volume flow rate shall then remain in
this range throughout the testing.
6.2.3 Measurement of the volume flow rate
The volume flow rate shall be measured using a standardized or calibrated method (e.g. measurement of the
pressure drop using standardized damper equipment such as orifice plates, nozzles, Venturi tubes in
accordance with ISO 5167-1).
The limit error of measurement shall not exceed 5 % of the measured value.
6.2.4 Aerosol mixing duct
The aerosol input and the mixing duct (see example in Figure 2) shall be so constructed that the aerosol
concentration measured at individual points of the duct cross-section directly in front of the test filter does not
deviate by more than 10 % from the mean value obtained from at least 10 measuring points spread evenly
over the duct cross-section.
6.2.5 Test filter mounting assembly
The test filter mounting assembly shall ensure that the test filter can be sealed and subjected to flow in
accordance with requirements. It shall not obstruct any part of the media area of the filter.
It is advisable to scan filters for leaks in the same mounting position and airflow direction as they are installed
on site.
6.2.6 Measuring points for the pressure difference
The measuring points for pressure shall be so arranged that the mean value of the difference between static
pressure in the upstream flow and the pressure of the surrounding air can be measured. The plane of the
pressure measurements shall be positioned in a region of uniform flow.
In rectangular or square test ducts, smooth holes with a diameter of 1 mm to 2 mm for the pressure
measurements shall be bored in the middle of the duct walls, normal to the direction of flow. The four
measurement holes shall be interconnected with a circular pipe.
6 © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
6.2.7 Sampling, upstream
Samples are taken upstream by means of one or more sampling probes in front of the test filter. The probe
diameter shall be chosen such that, at an average flow velocity, isokinetic conditions pertain at the given
volume flow rate for the sample. Sampling errors that arise due to higher or lower flow velocities in the duct
can be disregarded due to the small size of the particles in the test aerosol. The tubing connections to the
particle counter shall be as short as possible.
The sampling shall be representative, i.e. the aerosol concentration measured from the sample shall not
deviate by more than 10 % from the mean value determined in accordance with 6.2.4.
The mean aerosol concentrations determined at the upstream and downstream sampling points without the
test filter in position shall not differ from each other by more than 5 %.
6.2.8 Screening
The downstream side of the test filter shall be completely screened from impurities in the surrounding air.
Furthermore, for the correct detection and localization of leaks in the edges of the filter, in the gasket, the filter
frame or the sealant, the particles emitted in these sections shall be swept away from the section that is
covered by scanning. This can be achieved, for example, if the outer sides of the filter frame are enclosed by
a shrouding flow of particle-free air flowing in the downstream direction.
The scanning tracks shall also cover the area of the filter frame, the corners, and the sealant between filter
frame and the gasket so that possible leaks in these areas are detected. A validation of the test rig shall be
performed to verify that leaks in these areas are detected with the same probability and sensitivity as media
leaks, being located in the middle of the filter.
6.3 Scanning assembly
In addition to the automated testing for leaks, manual scanning is also permitted, provided that there is
adherence to the most important parameters for the test procedure.
However, when the probe is moved manually, it is not possible to avoid irregularities, since the movement
over the filter surface cannot be smooth and even. As a result, quantitative assessments are usually possible
only to a limited extent, if at all. Furthermore, it is extremely time-consuming to keep a record of the
coordinates of leaks and particularly to evaluate the particle counts.
The remainder of 6.3 describes an automatic scanning apparatus.
6.3.1 Sampling — Downstream
The sampling conditions affect the local resolution for the determination of the particle flow distribution on the
downstream side. In order to ensure the comparability of the measurements for the local value of the
penetration, the sampling shall be carried out under standardized conditions.
The geometry of the probe aperture may be rectangular or circular. The relationship between the sides of a
rectangular probe shall not exceed 15 to 1. The inlet area of the probe shall be 9 cm  1 cm . The volume
flow rate in the probe shall be chosen so that the speed at the probe aperture does not differ by more than
25 % from the face velocity of the filter (see C.5).
If the probes have a rectangular aperture, then the measuring time can be shortened by using several probes
next to each other (for several particle counters).
The probe shall be positioned at a distance of 10 mm to 50 mm from the downstream face of the filter element.
For specially constructed filter forms and extremely high face velocities, it is permissible to deviate from the
dimensional requirements specified here. However, it is then possible to arrive at only a conditional
determination of the local efficiency within the meaning of this part of ISO 29463.
The alternative method of testing with the aerosol photometer is found in Annex B.
ISO 29463-4:2011(E)
6.3.2 Probe arm
The partial flow probe on the downstream side shall be fixed to a moveable probe arm. This probe arm shall
be designed in such a way that neither the arm nor the provisions made to move the arm disturb the airflow in
the proximity of the filter.
6.3.3 Aerosol transport lines
The aerosol transport lines downstream shall lead the particles to the measuring chamber of the particle
counter with the least possible delay and without losses. The lines shall, therefore, be as short as possible
and without tight bends. They shall be made of a conductive material and have smooth surfaces that do not
emit particles.
6.3.4 Provisions to move the probe
These provisions include drive, guidance and control to move the probe arm at right angles to the direction of
flow with a constant probe speed.
The speed of the probe may be selected and shall not exceed a maximum of 10 cm/s (see C.6). During a run,
the speed shall not deviate from the set value by more than 10 %.
Suitable provisions shall also be made to measure the position of the probe in the coordinates X, Y and Z
during the probe run, and also to reposition the probe over a leak determined during a run. The accuracy of
repositioning to any point in the downstream cross-section of the test filter shall be at least 1 mm.
6.4 Aerosol generation and measurement techniques
6.4.1 General
For a poly-disperse test aerosol, the operating parameters of the aerosol generator shall be adjusted to
produce a test aerosol whose mean diameter does not deviate by more than 50 % from the MPPS for the
plane filter medium. For a mono-disperse test aerosol, the operating parameters of the aerosol generator shall
be adjusted to produce a test aerosol whose mean diameter does not deviate by more than 10 % from the
MPPS for the plane filter medium.
It shall be possible to set the mean value of the number distribution of the test aerosol within 10 %.
The particle generation rate of the aerosol generator shall be adjusted according to the test volume flow rate
and the filter efficiency so that the counting rates on the upstream and downstream sides lie under the
coincidence limits of the counters, and significantly above the zero count rate of the instruments.
The number distribution of the test aerosol may be determined using a suitable particle size analysis system
(e.g. a DMPS) or with a laser particle counter suitable for these test purposes. The limit error of the
measurement method used to determine the mean value shall not exceed 10 % relative to the measured
value.
The number of particles counted upstream and downstream shall be sufficiently large to provide statistically
meaningful results, without the concentration exceeding the coincidence limit of the upstream particle counter.
If the upstream number concentration exceeds the limit of the particle counter (in the counting mode), then a
dilution system shall be switched between the sampling point and the counter.
The maximum measurable concentration can also be limited by the maximum possible processing speed of
the evaluation electronics of the test apparatus. The measuring uncertainties involved in determining the
sample volume flow rate and the duration of measurement can also influence the concentration
measurements. The result for the particle concentration, including all sources of error at the interface of the
apparatus responsible for the recording, shall not differ by more than 10 % from the true value.
The particle flow rate shall be registered at time intervals (counting intervals t ) that correspond, at least, to
i
the time taken by the probe to traverse the width of its own aperture (a ). The transmission characteristics of
p
the particle counter and the evaluation electronics shall satisfy these requirements. The uncertainty in
determining the duration of the counting interval shall be less than 10 %.
8 © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
6.4.2 Set-up for testing with a mono-disperse test aerosol
For technical reasons, the particle size distribution produced by the aerosol generator is usually quasi-mono-
disperse.
When using a mono-disperse aerosol for the leakage testing of the filter element, either optical particle
counters or condensation nucleus counters may be used to determine the particle number concentration.
When using a condensation nucleus counter, it shall be ensured that the test aerosol does not produce
appreciable numbers of particles that are very much smaller than the MPPS. Such particles, which can be
produced by an aerosol generator that is no longer working properly, for example, are also counted by a
condensation nucleus counter and can lead to a considerable error in the determination of the local efficiency.
Therefore, when using a condensation nucleus counter, the number distribution of the test aerosol shall be
determined with a measuring procedure that stretches over a range from the lower range limit of the
condensation nucleus counter up to a particle size of approximately 1 µm. The geometric distribution thus
determined shall be 1,5 (quasi-mono-disperse).
6.4.3 Set-up for testing with a poly-disperse test aerosol
When testing a filter element for leaks using a poly-disperse test aerosol, the particle concentration and size
distribution by number shall be determined using an optical particle counter (e.g. laser particle counters).
The measuring range of the optical particle counter used in testing efficiency shall comply with the following
requirements.
S
MPPS
a) The measuring range shall cover the particle size range to 1,5 S , where S is the most
MPPS MPPS
1,5
penetrating particle size, in accordance with ISO 29463-5:2011, Figure 4, range I.
b) The distribution of the size classes shall be such that one class limit, C , meets the condition:
L
S S
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C (ISO 29463-5:2011, Figure 4, range IIa).
L
21,5
c) A further class limit shall be the condition: 1,5SC 2S (ISO 29463-5:2011, Figure 4,
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range IIb).
All classes between these two limits are evaluated to determine the efficiency. There is no requirement for a
minimum number of classes in this range, so that in the extreme case the conditions in a) to c) may be met by
only one size class.
7 Test air
The test air shall be prepared before mixing it with the test aerosol. The purity of the test air (particle number
concentration 352 000 particles/m ) shall be ensured by suitable pre-filtering (for example using
commercially available coarse and fine dust filters and high-efficiency particulate air filters).
The temperature and relative humidity of the test air in the test duct shall be measured on the upstream side
and can be adapted to meet the following requirements using an air heating system:
 temperature: (23  5) °C:
 relative humidity: 75 %.
ISO 29463-4:2011(E)
8 Procedure
8.1 General
Before beginning the scan test, the test parameters shall be determined or calculated, if this has not already
been done for earlier tests, and the appropriate adjustments made.
On the basis of the dimensions of the filter and the probe, the following parameters for the probe tracking shall
be determined:
 distance between the probe aperture and the filter element (10 mm to 50 mm; see 6.3.1);
 speed of the probe (determined in accordance with C.6);
 number and position of the probe tracks.
The other test parameters shall be determined on the basis of the nominal air volume flow rate and the
anticipated penetration for the test filter. Additional test parameters are the aerosol concentration on the
upstream side, the volume flow rate in the probe, the speed of the probe and the signal value for the counting
rate. The parameters shall be determined in accordance with Annex C and the adjustments made to the test
apparatus. An example of this determination is given in Annex D.
Before beginning a test with newly determined test parameters, the interaction of the test parameters shall be
checked as well as the ability to recognize limit-values for leakages. Reference filters for which defined
leakages have already been determined may be used for this purpose.
Testing shall not commence until it has been shown that leaks can be detected adequately.
8.2 Preparatory checks
After switching on the test apparatus the following parameters shall be checked.
 Operational readiness of the measuring instruments:
 The warming-up times specified by the instrument manufacturers shall be observed.
 The condensation nucleus counters shall be filled with operating liquid.
 If the instrument manufacturers recommend further regular checks before taking measurements,
then these checks shall also be carried out.
 Zero count rate of the particle counter:
 The measurement of the zero count rate may be carried out using filtered flushing air.
 Zero value of the test apparatus:
 The test shall be carried out using a reference filter with the aerosol generator switched off.
 If the measured particle flow rate on the downstream side, either locally or as the mean value, is
significantly higher than the long-term zero value of the apparatus, then the cause shall be eliminated
before proceeding further with the test.
 Temperature, relative humidity and purity of the test air:
 These parameters shall be checked to ensure that they comply with the specifications in Clause 7.
Appropriate corrections to achieve the specifications in Clause 7 shall be made, as applicable.
10 © ISO 2011 – All rights reserved

ISO 29463-4:2011(E)
8.3 Starting up the aerosol generator
When starting up the aerosol generator, a standby filter element shall be installed in the test filter mounting
assembly in place of the test filter.
After adjusting the operating parameters of the aerosol generator and observing an appropriate warming-up
period, the particle concentration and the particle-size distribution of the test aerosol shall be checked to
ensure that they comply with the requirements specified in 6.4.
8.4 Preparing the test filter
8.4.1 Installing the test filter
The test filter shall be handled in such a way as to ensure that it is not damaged. It shall be installed
appropriately, oriented to the designed airflow direction, and without by-pass leaks in the test filter mounting
assembly.
The position of the test filter in the mounting assembly shall be recorded in order to allow a determination of
the position of any leaks after the tests. It is advisable to scan filters for leaks with their original gasket
mounted and in the same mounting position and airflow direction as they are installed on site.
8.4.2 Flushing the test filter
In order to reduce the emission of particles by the test filter itself and to equalize the temperature of the test
filter and the test air, the test filter shall be flushed with test air for a suitably long period at the nominal volume
flow rate.
If necessary, the particle self-emission of the test filter shall be measured by scan testing at the nominal
volume flow rate without the generation of test aerosol. If the particle counting rate recorded downstream is
locally higher or th
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