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)

ISO 29463-4:2011 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. ISO 29463-4:2011 also describes the other normative methods: the oil thread leak test and the photometer leak test, applicable to classes ISO 35 H to ISO 45 H HEPA filters, and the leak test with solid PSL aerosol. ISO 29463-4:2011 is intended for use in conjunction with ISO 29463-1, ISO 29463-2, ISO 29463-3 and ISO 29463-5.

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)

Dieser Teil der ISO 29463 spezifiziert das Prüfverfahren des „Scan-Verfahrens“, das als Referenzmethode zur Bestimmung der Leckage von Filterelementen angesehen wird. Er ist für Filter der Klassen ISO 35 H bis ISO 75 U vorgesehen. Er beschreibt ebenfalls die anderen genormten Methoden, die Ölfadenprüfung (siehe Anhang A) und die Fotometer-Leckprüfung (siehe Anhang B), anwendbar für HEPA-Filter der Klassen ISO 35 H bis ISO 45 H, und die Leckprüfung mit festem PSL-Aerosol (siehe Anhang E). Er sollte in Verbindung mit ISO 29463 1, ISO 29463 2, ISO 29463 3 und ISO 29463 5 verwendet werden.

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)

La présente partie de l'ISO 29463 spécifie le mode opératoire d'essai de la «méthode scan», considérée comme la méthode de référence pour déterminer l'étanchéité des éléments filtrants. Elle s'applique aux filtres appartenant aux classes ISO 35 H à ISO 75 U. Elle décrit également les autres méthodes normatives, l'essai d'étanchéité au brouillard d'huile (voir Annexe A) et l'essai d'étanchéité au photomètre (voir Annexe B), applicable aux filtres HEPA de classes ISO 35 H à ISO 45 H, et l'essai d'étanchéité avec un aérosol solide de latex (PSL) (voir Annexe E). Elle est destinée à être utilisée conjointement avec l'ISO 29463‑1, l'ISO 29463‑2, l'ISO 29463‑3 et l'ISO 29463‑5.

Zelo učinkoviti filtri in filtrirno sredstvo za odstranjevanje delcev iz zraka - 4. del: Preskusne metode za ugotavljanje prepuščanja delcev skozi filtrske elemente - metoda s skeniranjem (ISO 29463-4:2011)

ISO 29463-4:2011 določa preskusni postopek pri »metodi s skeniranjem«, ki se obravnava kot referenčna metoda, za ugotavljanje prepuščanja delcev skozi filtrske elemente. Uporablja se za filtre razredov od ISO 35 H do ISO 75 U. ISO 29463-4:2011 opisuje tudi druge normativne metode: preskus prepuščanja DOP in preskus prepuščanja s fotometrom, ki se uporabljata za filtre HEPA razredov od ISO 35 H do ISO 45 H, ter preskus prepuščanja s trdnim aerosolom PSL. ISO 29463-4:2011 je predviden za uporabo v povezavi s standardi ISO 29463-1, ISO 29463-2, ISO 29463-3 in ISO 29463-5.

General Information

Status
Published
Public Enquiry End Date
31-Mar-2018
Publication Date
24-Oct-2018
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
18-Oct-2018
Due Date
23-Dec-2018
Completion Date
25-Oct-2018

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SLOVENSKI STANDARD
SIST EN ISO 29463-4:2018
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
SIST EN ISO 29463-4:2018 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 29463-4:2018
---------------------- Page: 2 ----------------------
SIST EN ISO 29463-4:2018
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.
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SIST EN ISO 29463-4:2018
EN ISO 29463-4:2018 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

---------------------- Page: 4 ----------------------
SIST EN ISO 29463-4:2018
EN ISO 29463-4:2018 (E)
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.
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SIST EN ISO 29463-4:2018
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SIST EN ISO 29463-4:2018
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
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SIST EN ISO 29463-4:2018
ISO 29463-4:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© 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
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SIST EN ISO 29463-4:2018
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 2011 – All rights reserved iii
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SIST EN ISO 29463-4:2018
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
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SIST EN ISO 29463-4:2018
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.
© ISO 2011 – All rights reserved v
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SIST EN ISO 29463-4:2018
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SIST EN ISO 29463-4:2018
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
ISO 29464 , Cleaning equipment for air and other gases — Terminology
1) To be published.
© ISO 2011 – All rights reserved 1
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SIST EN ISO 29463-4:2018
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
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SIST EN ISO 29463-4:2018
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 2011 – All rights reserved 3
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SIST EN ISO 29463-4:2018
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
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SIST EN ISO 29463-4:2018
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 2011 – All rights reserved 5
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SIST EN ISO 29463-4:2018
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
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SIST EN ISO 29463-4:2018
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 po
...

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