EN ISO 16170:2016

SLOVENSKI STANDARD
01-oktober-2016
Metode za preskušanje vgrajenih visoko učinkovitih zračnih filtrskih sistemov v
industrijskih postrojenjih (ISO 16170:2016, popravljena različica 2017-04)
In situ test methods for high efficiency filter systems in industrial facilities (ISO
16170:2016, Corrected version 2017-04)
Verfahren zur Prüfung von Luftfiltersystemen mit sehr hohen Wirkungsgraden im
eingebauten Zustand (ISO 16170:2016, korrigierte Fassung 2017-04)
Méthodes d'essai in situ pour les systèmes filtrants à très haute efficacité dans les
installations industrielles (ISO 16170:2016, Version corrigée 2017-04)
Ta slovenski standard je istoveten z: EN ISO 16170:2016
ICS:
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 16170
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2016
EUROPÄISCHE NORM
ICS 91.140.30
English Version
In situ test methods for high efficiency filter systems in
industrial facilities (ISO 16170:2016, Corrected version
2017-04)
Méthodes d'essai in situ pour les systèmes filtrants à Verfahren zur Prüfung von Luftfiltersystemen mit sehr
très haute efficacité dans les installations industrielles hohen Wirkungsgraden im eingebauten Zustand (ISO
(ISO 16170:2016, Version corrigée 2017-04) 16170:2016, korrigierte Fassung 2017-04)
This European Standard was approved by CEN on 5 May 2016.

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: Avenue Marnix 17, B-1000 Brussels
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16170:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 16170:2016) has been prepared by Technical Committee ISO/TC 142 “Cleaning
equipment for air and other gases” in collaboration with 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 January 2017, and conflicting national standards shall
be withdrawn at the latest by January 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
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, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16170:2016, Corrected version 2017-04 has been approved by CEN as
INTERNATIONAL ISO
STANDARD 16170
First edition
2016-07-01
Corrected version
2017-04
In situ test methods for high efficiency
filter systems in industrial facilities
Méthodes d’essai in situ pour les systèmes filtrants à très haute
efficacité dans les installations industrielles
Reference number
ISO 16170:2016(E)
©
ISO 2016
ISO 16170:2016(E)
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
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ii © ISO 2016 – All rights reserved

ISO 16170:2016(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Principle of the method . 4
5 Prerequisites . 6
5.1 Filter initial characterization . 6
5.2 Preparatory conditions . 6
5.2.1 General. 6
5.2.2 Choice of injection and sampling locations. 7
5.2.3 Conditions for the ventilation systems on which the test is performed . 7
5.2.4 Climatic conditions in the rooms where the injection/sampling is performed . 7
5.2.5 Apparatus selection and preparation . 8
5.2.6 Qualification of the test personnel .10
5.2.7 Health and safety .10
5.2.8 Test conditions.11
6 Test sequence .11
6.1 Evaluation of filtration system under test .11
6.2 Preparation of test equipment .12
6.3 Preparation of log sheets .12
6.4 Monitoring of climatic conditions .12
6.5 Aerosol generation setup .12
6.6 Sampling equipment setup .12
6.7 Monitoring of upstream challenge .12
6.8 Monitoring of downstream .13
6.9 Test performance .13
6.10 Calculations .13
7 Evaluation and report .14
Annex A (informative) Aerosol candidates for in situ testing .16
Annex B (normative) Integrity testing — Typical methodology using dispersed oil test aerosols .17
Annex C (normative) Efficiency accountancy testing — Uranine test method .26
Annex D (informative) Leakage test methods .33
Annex E (informative) Guideline for representative sampling .34
Bibliography .36
ISO 16170:2016(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/d irectives).
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/p atents).
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 WTO
principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary
information.
This document was prepared by Technical Committee ISO/TC 142, Cleaning equipment for air and other
gases.
This corrected version of ISO 16170:2016 incorporates the following corrections.
All figures have been replaced with higher quality diagrams.
In C.3.2 the key and cross-references within the text to Figure C.3 have been corrected.
iv © ISO 2016 – All rights reserved

ISO 16170:2016(E)
Introduction
Methods for measuring the performance of high efficiency gas cleaning devices are described in a
number of existing standards. These specify procedures for quality assurance following manufacture
(e.g. ISO 29463 and EN 1822).
Some other standards specify the filter medium used in such devices, how they are constructed and
how they are installed within industrial facilities.
Installations of high efficiency particulate filters are extensively used within nuclear and toxic material
processing plants and laboratories to confine these materials within the facility and prevent their
discharge to the environment.
Radioactive and other toxic materials are confined within processing facilities inside containment zones
bordered by barriers. Air and gases vented from these zones are decontaminated by passage through
a series of highly efficient particulate filters before final discharge to the environment. The membrane
(filter medium) of the filters acts as part of the containment barrier. In view of its perceived fragility,
confirmation of its integrity is required on a periodic basis because operational safety cases depend on
the knowledge that the effectiveness of these filters is maintained at all times. These periodic checks
are made by the procedure(s) known as “in-situ” or “in-place” testing.
The basic principles of in situ tests on installed filters are the same as for laboratory tests, such as those
described in EN 1822 and ISO 29463, insofar as known quantities of a challenge aerosol are dispersed
into the airstream upstream of the filter installation; the particulate contents of the unfiltered
and filtered air are sampled and analysed to determine whether the integrity of the filters has been
compromised.
In the case of testing a single unit (manufacturer’s production test or in the case of a laboratory testing
on a single filter unit), the purpose is to confirm that the unit performance [efficiency/penetration at
Most Penetrating Particle Size (MPPS) and other parameters] lies within specified limits, and further,
that the results are globally reproducible. To achieve this requires the use of a laboratory test rig
setup with full dispersion of a challenge aerosol, prescribed geometry of the test rig, and to obtain
and analyse fully representative particulate samples both upstream and downstream of the test filter.
Some ventilation systems are highly complex and it should be noted that many facilities use ventilation
systems in which a high percentage of the air is recirculated.
The purpose of an in situ test is to detect any adverse change in the filtration performance of the
installation and to compare it with the expected efficiency or decontamination factor. Such a change
might be caused by deterioration of a unit or units or a faulty sealing system and would be manifested
by the appearance of a proportion of unfiltered aerosol in the effluent airstream. Testing methodologies
developed in this International Standard do not cover the other requirements that relate to filters in
terms of mechanical resistance, burst strength or temperature and moisture resistance.
It is neither fully necessary nor useful for the results of an in situ test to replicate the results of
production tests on the individual filters in the installation, nor is it necessary to confine the test
aerosol size distribution to one which replicates that used in production tests.
No International Standard for general in situ testing of high efficiency filters has been produced before,
explaining the needs for such an International Standard.
This International Standard describes the requirements for test equipment, data interpretation and
reporting for the in situ testing of HEPA and ULPA air cleaning installations designed for the removal of
airborne particulate contamination in high-integrity ventilation systems.
This International Standard includes specification of the test interval, aerosol type, aerosol mixing and
measurement methods, i.e. the following:
— aerosol: solid or liquid, monodisperse or polydisperse;
— mixing: degree of mixing, mixing lengths, etc.;
ISO 16170:2016(E)
— method: injection, detection.
This International Standard proposes an outline testing philosophy to highlight the following:
— principle of the method;
— prerequisites;
— preparatory conditions;
— injected aerosol properties;
— qualification and selection of measuring devices;
— qualification of test personnel;
— test setup;
— test sequence;
— evaluation and reporting.
vi © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 16170:2016(E)
In situ test methods for high efficiency filter systems in
industrial facilities
1 Scope
This International Standard specifies in situ test methods for high efficiency particulate air filters used
to limit releases towards the environment (e.g. from nuclear facilities or facilities with aerosol toxic or
biological releases). This applies where installations of these filters are used to clean effluent air before
discharge to the environment from industrial (including nuclear) installations where toxic/radioactive/
biological materials are handled or processed.
This International Standard excludes the application already covered by ISO 14644-3.
The scope of this International Standard includes detail of two methods, either of which applies to the
periodic testing of high efficiency filters which are used in demanding applications aiming at protecting
the environment, such as the nuclear industry.
In the case of nuclear applications, this International Standard is applicable to installations covered by
ISO 17873 (applications other than nuclear reactors) and ISO 26802 (nuclear reactors).
The two reference methods specified in this International Standard are not equivalent, but related to,
the requirements to be addressed by the test results. The choice of which of the two methods is adopted
in any specific case depends on whether the outcome requires an integrity test or a statutory efficiency
accountancy test.
For industries handling or processing radioactive or toxic materials giving rise to a risk of possible
release, the main goal of the tests is to confirm that the filter installation is fit for purpose. In the case
of integrity tests (Annex B), this is to confirm that no significant leakage of toxic aerosols through the
filter installation is possible.
In the case of efficiency accountancy tests (Annex C), the test is designed to make an accurate
measurement of decontamination factor with respect to the MPPS size range of particles.
The reference method described in Annex B (integrity test) requires a test aerosol of dispersed oil
particles mainly submicrometre in size range, which is stable during the test procedure and compatible
with other installation components. Particle concentrations are measured in real time by light
scattering instrumentation (optical detectors).
The reference method described in Annex C (efficiency accountancy test) requires a test aerosol
of particles having a narrow size range centred on MPPS size range for HEPA filter media. Their
concentration both upstream and downstream the filters is measured by fluorimetric analysis of
aqueous solution obtained by washing the membrane sampling filters.
It should be noted that the requirements for an efficiency accountancy test also cover the requirements
of an integrity test, which is considered to be a minimum requirement.
Test methods developed in this International Standard do not cover the other in situ performance
requirements, such as mechanical resistance, bursting resistance or humidity resistance. Specific
systems operating at high temperature or with specific gaseous effluents might require specific test
methods.
ISO 16170:2016(E)
The engineering design of HEPA and ULPA filter installations does not fall within the scope of this
International Standard.
NOTE In the field of filters for general ventilation applications, ISO 29462 is a detailed and comprehensive
description of a method which uses scanning and particle counting methods to evaluate the performance of a filter
in terms of particle grade efficiency, as well as pressure drop. Such a method and procedure would not be applicable
in those nuclear installations where quantification of the decontamination factor at MPPS size is needed.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 29463-1, High-efficiency filters and filter media for removing particles in air — Part 1: Classification,
performance testing and marking
ISO 14644-3:2005, Cleanrooms and associated controlled environments — Part 3: Test methods
ISO 17873, Nuclear facilities — Criteria for the design and operation of ventilation systems for nuclear
installations other than nuclear reactors
ISO 26802, Nuclear facilities — Criteria for the design and the operation of containment and ventilation
systems for nuclear reactors
ISO 2889, Sampling airborne radioactive materials from the stacks and ducts of nuclear facilities
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
aerosol
system of solid or liquid particles suspended in gas
Note 1 to entry: In general, one divides the atmospheric aerosol into three size categories: the ultrafine range
x ≤ 0,1 μm, the fine range 0,1 μm < x ≤ 1 μm, and the coarse range x > 1 μm, where x is the particle diameter.
[SOURCE: ISO 29464:2011, 3.1.1]
3.1.1
monodisperse aerosol
aerosol (3.1), the width of whose distribution function, described by the geometric standard deviation
σ , is less than 1,15 μm
g
[SOURCE: ISO 29464:2011, 3.1.2]
3.1.2
polydisperse aerosol
aerosol (3.1), the width of whose distribution function, described by the geometric standard deviation
σ , exceeds 1,5 μm
g
[SOURCE: ISO 29464:2011, 3.1.3]
3.1.3
quasi-monodisperse aerosol
aerosol (3.1), the width of whose distribution function, described by the geometric standard deviation
σ , is between 1,15 μm and 1,5 μm
g
[SOURCE: ISO 29464:2011, 3.1.4]
2 © ISO 2016 – All rights reserved

ISO 16170:2016(E)
3.1.4
test aerosol
aerosol (3.1) used for determining filter efficiency
3.2
decontamination factor
ratio between the concentration or particles number upstream the filter and the concentration or
particles number contamination downstream the filter
Note 1 to entry: This ratio is also defined by 1/(1- overall efficiency (3.13)).
3.3
effective filter media area
area of the media contained in the filter (without adhesive spaces or ligament) and passed by air during
operation
[SOURCE: ISO 29464:2011, 3.1.11]
3.4
efficiency
E
fraction of contaminant entering the filter which is retained
[SOURCE: ISO 29464:2011, 3.1.55]
3.5
efficiency accountancy test
in-situ test procedure meeting a requirement for an accurate system overall efficiency (3.13)
determination at MPPS (3.11)
3.6
integrity test
in-situ test procedure meeting the requirement for confirming the absence of unfiltered leakage of
the system
3.7
filter element
filtering material in a preformed shape being a part of a complete filter
[SOURCE: ISO 29464:2011, 3.1.67]
3.8
filter face area
frontal face area of the filter including the header frame
[SOURCE: ISO 29464:2011, 3.1.83]
3.9
HEPA filter
filter with performance complying with requirements of filter class ISO 35 – ISO 45 as per ISO 29463-1
[SOURCE: ISO 29464:2011, 3.1.88]
3.10
filter medium
material used for filtering
[SOURCE: ISO 29464:2011, 3.1.90]
ISO 16170:2016(E)
3.11
most penetrating particle size
MPPS
particle size at which the minimum of the particle size efficiency (3.14) curve occurs under test
conditions
Note 1 to entry: This MPPS is media and ventilation conditions dependent. This MPPS is in the 0,1 µm to 0,2 µm
medium aerodynamic size range for fibreglass type filters commonly used in nuclear applications.
[SOURCE: ISO 29464:2011, 3.1.129]
3.12
user nominal air volume flow rate
q
v,nom
air volume flow rate specified by the user, at which the filter element (3.7) is tested in situ
Note 1 to entry: This flow rate may be different from the one specified by the manufacturer.
3.13
overall efficiency
efficiency averaged over the whole superficial face area (3.15) of a filter element (3.7) under given
operating conditions of the filter
Note 1 to entry: It is expressed in percentage (%).
3.14
particle size efficiency
efficiency for a specific particle diameter
Note 1 to entry: The efficiency plotted as a function of the particle diameter gives the fractional efficiency curve.
Note 2 to entry: It is expressed in percentage (%).
3.15
superficial face area
cross-sectional area of the filter element (3.7) through which the air flow passes
3.16
ULPA filter
filters with performance complying with requirements of filter class ISO 55 – ISO 75 as per ISO 29463-1
[SOURCE: ISO 29464:2011, 3.1.100]
3.17
user nominal filter medium face velocity
nominal air volume flow rate divided by the effective filter medium (3.10) area
4 Principle of the method
For industries handling radioactive and/or toxic materials, the main goals of the tests are the following.
a) For efficiency accountancy tests: to confirm that the overall filtration efficiency, in particular the
decontamination factor for the MPPS size range and other performance parameters, remain within
the operating envelope criteria authorized in the site operating licence.
b) For integrity tests: to detect any significant leakages of airborne particles bypassing the filter media.
The test procedure follows the following sequence:
— measure the main ventilation parameters (e.g. flow rates, pressure drops, temperature and
humidity) of the system under test;
4 © ISO 2016 – All rights reserved

ISO 16170:2016(E)
— inject the appropriate quantity/quantities and type of the test aerosol into the airstream(s) upstream
of the filter installation with a size distribution covering the MPPS range;
— measure the concentration of aerosol challenging the filter installation upstream of the filters;
— measure the quantity of aerosol present in the airflow downstream of the filter installation;
— calculate the efficiency or decontamination factor(s) within a size range covering the most
penetrating particle size (MPPS);
— compare the measured value(s) against the required regulatory value(s) or other criteria, such as
MPPS filter classification.
Figure 1 shows one general principle of the method, which is then further refined for the different
methods.
Key
1 injected particles injection
2 provisions for homogenization
3 upstream representative sampling
4 downstream representative sampling
5 representative samples (this is done using different techniques in Annex B and Annex C)
6 mobile or fixed unit
7 filter(s) to be tested
8 fan (in many nuclear installations, it is customary to return the sample to the duct from which it was originally
withdrawn downstream of the original sampling point)
Figure 1 — Principle of the method for representative sampling
According to ISO 29463-1, the MPPS range value should be obtainable from the media manufacturer
for the typical media that are installed (e.g. 0,1 µm to 0,2 µm for HEPA filters constructed with glass
microfibre media).
For efficiency accountancy tests, the chosen method shall be capable of measuring values within the
range of 10 to 100 000 (efficiency range 90 % to 99,999 %), for particles sizes covering the MPPS range.
For integrity tests, an accurate measurement is not as important as for efficiency accountancy tests but
the method shall cover ranges of efficiency between 90 % and 99,99 %.
ISO 16170:2016(E)
If it is needed to compare further the efficiency results, the parameters having an impact on the filter
efficiency results should be reliably known for the test (e.g. flow rates, pressure drop, temperature,
humidity).
Specific limitations on the applicability of the test results shall be detailed on the results sheet(s); for
example, limitations on access to ideal sampling locations because of high dose rates, or difficulty in
ensuring design flow rates, temperature, humidity, etc. within the ventilation system.
The results of the tests are provided only for the ventilation regime at which the test has been
performed.
NOTE The specific case of continuous efficiency monitoring is rarely implemented in industrial facilities but
obeys to the same principles.
5 Prerequisites
5.1 Filter initial characterization
The filter, bank of filters or filters in series to be tested shall have been initially certified in the
manufacture according to a given standard (e.g. ISO 29463) for new filters or for filters already installed
in the facilities according to relevant national standards.
ISO 29463-1 provides a classification of all filters with efficiencies ranging from 95 % to 99,999 999 5 %.
Since the efficiencies are measured at the MPPS of the filter, the efficiency of a filter at any particle size
is better than at the filter class. That is, these filters provide particle removal at, or better than, the
filter class efficiency at all particle sizes. In addition, in this classification, filters with efficiencies higher
than 99,95 % are tested for leaks. Although this document deliberately avoids prescribing specific filter
classes for specific end use, the classification scheme provides a sound basis for selecting filters for
nuclear protection where a minimum decontamination safety factor is required. For this end use, ISO
Class 35H to 45H, and 50U (99,95 %, 99,995 % and 99,999 %, respectively at MPPS) generally provides
commonly acceptable decontamination safety factors. For some specific applications where higher
safety factors are required, ISO Class 55 to 75U filters may be specified for the last filtration stage.
NOTE The selection of the filter to be tested considers that the filter operating flow rate (user nominal
flowrate) is as close as possible, or lower than, the nominal flow rate specified by the manufacturer in order to
ensure that the filter performs as classified.
5.2 Preparatory conditions
5.2.1 General
To obtain the most valuable and useful in-situ test results, the test procedure shall be carried out when
the plant is operating either at or as close as possible to its normal operating conditions.
Unlike production testing in industrial environments, access limitations may be created by factors
such as radiation levels or even straightforward physical obstruction, preventing access to otherwise
best possible sampling locations. These considerations should be addressed in advance to the best
possible extent, e.g., by carrying out full system characterization tests before the introduction of
radioactive/toxic materials, i.e., the following:
— qualification of injection and sampling locations to ensure fully mixed aerosol both upstream and
downstream of the filter;
— conditions in the ventilation system and its operation during the test;
— apparatus selection and preparation;
— qualification of test personnel;
— test conditions;
6 © ISO 2016 – All rights reserved

ISO 16170:2016(E)
— climatic conditions of the air and rooms during the tests, if needed;
— aerosol preparation;
— health and safety.
Where this is no longer possible, more specialized means of addressing the problem need to be
developed and implemented.
5.2.2 Choice of injection and sampling locations
The sampling location shall provide the ability to extract a representative sample. For existing plants,
where it is not possible, sampling locations should be selected to provide representative samples to the
best feasible extent. The injection and sampling locations shall be located in a way to ensure the optimum
possible homogeneity of concentrations at sampling locations (ISO 14644-3 and ISO 2889) according to
the guidelines defined in the annexes, particularly Annex C and Annex E. The expected homogeneity at
the sampling point depends on the expected accuracy of the filter’s decontamination factor.
The design of new injection and sampling ports/probes should, as far as possible, ensure that a
suitable cross section of the duct can be accessed to extract representative samples to the best feasible
extent and that sampling points are appropriately placed to assist fault identification. Representative
sample(s) shall be extracted from location(s) where the contributing airstreams are blended to the
greatest prevailing extent. If the sample is extracted from another location (e.g., because of accessibility
conditions), then the uncertainties that are induced shall be assessed. The sample probe shall be located
at the best available location (see Annex E). Consideration may be given to installing a device or devices
to improve mixing. In this case, the sampling probe may contain a single or multiple sampling points. In
circumstances where the well-mixed criteria are not achieved, a multi-sampling probe may be used or
needed to get a representative sample.
For facilities that could not characterize fully the filtration system after careful evaluation, one or
more of the following steps should be taken in circumstances where these previous criteria cannot be
satisfied in effluent systems designed and constructed prior to the publication of this International
Standard:
a) select another well mixed location for the sampling probe;
b) install features that promote mixing;
c) perform an in situ test or simulation demonstrating that a representative sample is being collected.
The values of the properties that signify a well-mixed location for sample extraction can be characterized
by certain parameters that are specified in 5.2.5.
5.2.3 Conditions for the ventilation systems on which the test is performed
The ventilation systems on which the in situ test is performed should be under normal operating
conditions (e.g. not in degraded mode) when the test is performed. If normal conditions are not achieved
when the test is performed, then the effects on the tests results shall be evaluated. The results’ validity
depends on the chosen test conditions. Generally, for the filters meeting the specifications described in
5.1, the tests results show greater decontamination factors for lower flow rates.
5.2.4 Climatic conditions in the rooms where the injection/sampling is performed
Room air temperature and air humidity should be established under nominal conditions where the
sampling is performed.
The conditions in the ventilation system during normal operations shall not exceed the following:
— during normal operations: the stated maximum rating for any component contained within the
system;
ISO 16170:2016(E)
— during testing: the stated maximum rating of any apparatus used to undertake the test.
Additionally, if it is necessary to compare further the efficiency results,
— the climatic conditions of the air and rooms during the test should be compatible with the materials
used for the test, and
— the background particulate levels in the air should be low enough to ensure sufficient detection
sensitivity to the challenge aerosol (see Annex B).
5.2.5 Apparatus selection and preparation
5.2.5.1 General
The apparatus should be able to operate at the climatic conditions of the filtration system under test
(5.2.4). The sampling flow rates for upstream and downstream shall not differ by greater than 5 %
when connected to the system under test.
The tubing connecting the sampling probes (either installed or otherwise) to the sampling apparatus
shall be as short as possible and the length for upstream and downstream shall be the same to minimize
transit time and line losses.
All apparatus used for performing tests as described in this International Standard shall have a valid
calibration certificate.
For the efficiency accountancy test, defined in Annex C, any apparatus shall be selected to work
covering the MPPS range of the particular filtration system under test, and be able to determine, at a
sufficient confidence level, the required efficiency/decontamination factor to satisfy the regulations or
users’ acceptance criterion.
5.2.5.2 Injected aerosol properties
The efficiency of filters varies with particle size and exhibits a minimum efficiency at a particle size
which is typically close to 0,15 μm for HEPA filters made with glass microfibre media due to the
influence of particle inertia and diffusivity, as well as other parameters of usually lesser influence such
as fibre size and electrostatics.
In order to ensure that the filter is stringently tested, they are usually challenged with particles at, or
close to, the MPPS. While the majority of clean new filters which use standard glass fibre filter media
have an MPPS to test aerosols in the 0,1 μm to 0,2 μm range, this is not always the case and this changes
as filters age, as local and average flow rates vary, and as lifetime conditions change.
While injecting a narrow range covering the MPPS is fundamental for the efficiency accountancy test
method (in Annex C), this is less important for the integrity test.
It is nevertheless important that the test aerosol is carefully controlled with regards to its
— type,
— size (mass median diameter),
— standard deviation,
— generation method,
— electrostatic charge
— toxicity.
8 © ISO 2016 – All rights reserved

ISO 16170:2016(E)
A list of suitable candidates is mentioned in Annex A (e.g. uranine, dispersed oil particulates such as
di-2-ethyl hexyl sebacate (DEHS), Ondina oil or poly-alpha olefin (PAO)). Any other aerosol (e.g. sodium
produced in a flame) would be suitable if it meets the requirements given in this International Standard.
The use of aerosols that would create other physical phenomena, such as electrostatic properties, that
can interfere with the results shall be avoided. Test aerosols shall not carry significant electrostatic
charge. In particular, aerosols with electrostatic properties (e.g. polystyrene latex) shall be avoided.
When an aerosol is generated from aqueous or other polar solution or suspension, consideration should
be given for diluting air through a neutralizer, i.e. a source of bipolar ions, immediately before mixing
with the output from the aerosol generator.
The aerosol to be injected shall, therefore, be at a size that shall cover MPPS range (generally 0,1 µm
to 0,2 µm, depending on flow rates and media). A broader range (typically 0,1 µm to 0,5 µm) should be
accepted, in accordance with national agreement with the national regulations in force, if both aerosol
selection and chosen method are proven to give adequate results with regards to the results needs.
NOTE Generally, a safety margin is already applied; a margin is implemented between the criteria used in
the safety case and the results.
Key
1 MPPS range
2 acceptable aerosols range to inject
Figure 2 — Efficiency of a filter depending on an aerosol injection range (covering MPPS range)
The geometrical standard deviation of the challenge particle size distribution generated should be less
than 2 for the method described in Annex C, and less than 2,5 for the method described in Annex B (see
ISO 29463-2).
The quantity of injected particles at MPPS shall be enough to minimize uncertainties for the calculation
of the efficiency/decontamination factor, taking into account the expected efficiency/decontamination
factor. The total quantity of injected particles shall also minimize uncertainties for the calculation of
the decontamination factors.
ISO 16170:2016(E)
The following conditions should be met:
a) the median mass particle diameter should be close to MPPS range, preferably around 0,15 μm; but a
higher median mass particle diameter is acceptable if the apparatus and the methods are adequate
to achieve the required conservative result;
b) the particles to be injected shall be measurable by the monitoring apparatus, otherwise, the test
cannot be performed;
c) the concentration of the aerosol challenge upstream of the filter should be sufficiently high to
achieve acceptable and measurable concentration downstream the filter.
5.2.5.3 Qualification and selection of testing apparatus
The devices used for the efficiency measurement (samplers, injectors, flow meters, particle counters)
shall be qualified prior to the test measurements and should meet the requirements of ISO 14644-3:2005,
Annex
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