SIST EN ISO 21083-1:2019

Test method to measure the efficiency of air filtration media against spherical nanomaterials - Part 1: Size range from 20 nm to 500 nm (ISO 21083-1:2018)

This document specifies the testing instruments and procedure for determining the fractional filtration efficiencies of flat sheet filter medium against airborne nanoparticles in the range of 20 nm to 500 nm. The testing methods in this document are limited to spherical or nearly-spherical particles to avoid uncertainties due to the particle shape.

Prüfverfahren zur Messung der Effizienz von Luftfiltrationsmedien gegen sphärische Nanomaterialien - Teil 1: Partikelgrößenbereich von 20 nm bis 500 nm (ISO 21083-1:2018)

Dieses Dokument legt die Prüfinstrumente und Prüfverfahren für die Bestimmung des Filtrationswirkungsgrads von planen Filtermedien gegen Nanoschwebstoffpartikel im Größenbereich zwischen 20 nm und 500 nm fest. Die Prüfverfahren in diesem Dokument sind auf kugelförmige oder fast kugelförmige Partikel beschränkt, um Unsicherheiten aufgrund der Partikelform zu vermeiden.

Méthode d'essai pour mesurer l'efficacité des médias de filtration d'air par rapport aux nanomatériaux sphériques - Partie 1: Spectre granulométrique de 20 nm à 500 nm (ISO 21083-1:2018)

Le présent document spécifie les instruments et modes opératoires d'essai à utiliser pour la détermination des efficacités fractionnelles de filtration des médias filtrants plans par rapport à des nanoparticules en suspension dans l'air dans la plage granulométrique de 20 nm à 500 nm. Les méthodes d'essai décrites dans le présent document sont limitées aux particules sphériques ou quasi-sphériques afin d'éviter toute incertitude liée à la forme des particules.

Preskusna metoda za merjenje učinkovitosti sredstev za filtriranje zraka, ki vsebuje kroglaste nanomateriale - 1. del: Velikost od 20 nm do 500 nm (ISO 21083-1:2018)

Ta dokument določa preskusne instrumente in postopek za učinkovitost filtracije ploščatih filtrirnih medijev za filtriranje zraka, ki vsebuje kroglaste nanomateriale v obsegu 20–500 nm.

General Information

• Status: Published
• Public Enquiry End Date: 31-Oct-2017
• Publication Date: 08-Jan-2019
• ICS: 91.140.30 - Ventilation and air-conditioning systems
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 21-Dec-2018
• Due Date: 25-Feb-2019
• Completion Date: 09-Jan-2019
• Mandate: M/461 - Mandate addressed to CEN, CENELEC and ETSI for Standardization activities regarding Nanotechnologies and Nanomaterials
• Ref Project: EN ISO 21083-1:2018 - Test method to measure the efficiency of air filtration media against spherical nanomaterials - Part 1: Size range from 20 nm to 500 nm (ISO 21083-1:2018)

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2019
3UHVNXVQDPHWRGD]DPHUMHQMHXþLQNRYLWRVWLVUHGVWHY]DILOWULUDQMH]UDNDNL
YVHEXMHNURJODVWHQDQRPDWHULDOHGHO9HOLNRVWRGQPGRQP,62

Test method to measure the efficiency of air filtration media against spherical
nanomaterials - Part 1: Size range from 20 nm to 500 nm (ISO 21083-1:2018)
Prüfverfahren zur Messung der Effizienz von Luftfiltrationsmedien gegen sphärische
Nanomaterialien - Teil 1: Partikelgrößenbereich von 20 nm bis 500 nm (ISO 21083-
1:2018)
Méthode d'essai pour mesurer l'efficacité des médias de filtration d'air par rapport aux
nanomatériaux sphériques - Partie 1: Spectre granulométrique de 20 nm à 500 nm (ISO
21083-1:2018)
Ta slovenski standard je istoveten z: EN ISO 21083-1:2018
ICS:
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 21083-1
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2018
EUROPÄISCHE NORM
ICS 91.140.30
English Version
Test method to measure the efficiency of air filtration
media against spherical nanomaterials - Part 1: Size range
from 20 nm to 500 nm (ISO 21083-1:2018)
Méthode d'essai pour mesurer l'efficacité des médias Prüfverfahren zur Messung der Effizienz von
de filtration d'air par rapport aux nanomatériaux Luftfiltrationsmedien gegen sphärische
sphériques - Partie 1: Spectre granulométrique de 20 Nanomaterialien - Teil 1: Partikelgrößenbereich von
nm à 500 nm (ISO 21083-1:2018) 20 nm bis 500 nm (ISO 21083-1:2018)
This European Standard was approved by CEN on 19 November 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 21083-1:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 21083-1:2018) 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 June 2019, and conflicting national standards shall be
withdrawn at the latest by June 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 has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
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 21083-1:2018 has been approved by CEN as EN ISO 21083-1:2018 without any
modification.
INTERNATIONAL ISO
STANDARD 21083-1
First edition
2018-11
Test method to measure the efficiency
of air filtration media against
spherical nanomaterials —
Part 1:
Size range from 20 nm to 500 nm
Méthode d'essai pour mesurer l'efficacité des médias de filtration
d'air par rapport aux nanomatériaux sphériques —
Partie 1: Spectre granulométrique de 20 nm à 500 nm
Reference number
ISO 21083-1:2018(E)
©
ISO 2018
ISO 21083-1:2018(E)
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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 written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 21083-1:2018(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms. 2
4 Principle . 3
5 Test materials . 4
5.1 General . 4
5.2 Liquid phase aerosol . 4
5.2.1 DEHS test aerosol . 4
5.2.2 Liquid phase aerosol generation . 5
6 Test setup . 6
6.1 General . 6
6.2 Specification of setup . 8
6.2.1 Aerosol generation system . 8
6.2.2 Tubing . 8
6.2.3 Dryer. 8
6.2.4 DEMC . 9
6.2.5 Equilibrium charge distribution and neutralization of aerosol particles .11
6.2.6 Neutralization of aerosol particles .11
6.2.7 Make-up air line .12
6.2.8 Test filter medium mounting assembly .13
6.2.9 CPC .14
6.2.10 Final filter .16
6.3 Detailed setup for test using DEHS particles .16
6.4 Determination of the filter medium velocity .17
7 Qualification of the test rig and apparatus.17
7.1 CPC tests .17
7.1.1 CPC — Air flow rate stability test .17
7.1.2 CPC — Zero test .18
7.1.3 CPC — Overload test . .18
7.1.4 Counting accuracy calibration .18
7.2 DEMC tests .21
7.3 Qualification of aerosol neutralization .21
7.3.1 General.21
7.3.2 Qualification of neutralization by checking the multiple charge fraction on
the particles passing through the neutralizer .21
7.3.3 Qualification of the aerosol neutralizer using corona discharge balanced
output .21
7.3.4 Qualification of neutralization according to ISO/TS 19713-1 .22
7.4 System leak checks .22
7.4.1 Air leakage tests .22
7.4.2 Visual detection by cold smoke .22
7.4.3 Pressurization of the test system .22
7.4.4 Use of high efficiency filter media .22
7.5 Uniformity of the test aerosol concentration.22
8 Test procedure .23
8.1 Determination of the correlation ratio/zero efficiency test .23
8.2 Protocol of filtration efficiency measurement .24
ISO 21083-1:2018(E)
8.2.1 Preparatory checks .24
8.2.2 Equipment preparation .24
8.2.3 Aerosol generator .24
8.2.4 Aerosol generator — Neutralizer .25
8.2.5 Filter medium neutralization .26
8.2.6 Filter medium neutralization according to ISO 29461-1 .26
8.2.7 Air flow measurement .28
8.2.8 Measurement of the pressure drop .29
8.2.9 Zero count test .29
8.2.10 Air leakage test .29
8.2.11 Loading effect test .29
8.2.12 Reported values .29
8.2.13 Measurement of filtration efficiency — DEHS particles .29
8.3 Test evaluation .31
8.4 Measurement protocol for one sample — Summary .31
8.4.1 Using one CPC to measure the upstream and downstream particle
concentrations .31
8.4.2 Using two CPCs to measure the upstream and downstream particle
concentrations .32
9 Maintenance items .33
10 Measurement uncertainties .34
11 Reporting results .35
11.1 General .35
11.2 Required reporting elements .35
11.2.1 General.35
11.2.2 Report summary .35
11.2.3 Report Details .36
Annex A (informative) Instruments specifications .40
Annex B (informative) Statistical analysis for precision of an experiment (according to
ISO 5725-2) .44
Annex C (informative) Safe use of IPA .49
Annex D (informative) Safe handling of radioactive devices .50
Bibliography .51
iv © ISO 2018 – All rights reserved

ISO 21083-1:2018(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by the European Committee for Standardization (CEN) Technical
Committee CEN/TC 195, Air filters for general cleaning, in collaboration with ISO Technical Committee
TC 142, Cleaning equipment for air and other gases, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 21083 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
ISO 21083-1:2018(E)
Introduction
Nano-objects are discrete piece of material with one, two or three external dimensions in the nanoscale
(see ISO/TS 80004-2) and are building blocks of nanomaterials. Nanoparticles, referring to particles
with at least one dimension below 100 nm, generally have a higher mobility than larger particles.
Because of their higher mobility and larger specific surface area, available for surface chemical
reactions, they can pose a more serious health risk than larger particles. Thus, particulate air pollution
with large concentrations of nanoparticles can result in an increased adverse effect on human health
and an increased mortality (see Reference [17]).
With the increased focus on nanomaterials and nanoparticles, the filtration of airborne nanoparticles
is also subject to growing attention. Aerosol filtration can be used in diverse applications, such as air
pollution control, emission reduction, respiratory protection for human and processing of hazardous
materials. The filter efficiency can be determined by measuring the testing particle concentrations
upstream and downstream of the filter. The particle concentration may be based on mass, surface area
or number. Among these, the number concentration is the most sensitive parameter for nanoparticle
measurement. State-of-the-art instruments enable accurate measurement of the particle number
concentration in air and therefore precise fractional filtration efficiency. Understanding filtration
efficiency for nanoparticles is crucial in schemes to remove nanoparticles, and thus, in a wider context,
improve the general quality of the environment, including the working environment.
A large number of standards for testing air filters exist such as the ISO 29463 series and the ISO 16890
series. The test particle range in the ISO 29463 series is between 0,04 µm and 0,8 µm, and the focus is on
measurement of the minimum efficiency at the most penetrating particle size (MPPS). The test particle
range in the ISO 16890 series is between 0,3 µm and 10 µm. The ISO 21083 series aims to standardize
the methods of determining the efficiencies of filter media, of all classes, used in most common air
filtration products and it focuses on filtration efficiency of airborne nanoparticles, especially for
particle size down to single-digit nanometres.
vi © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 21083-1:2018(E)
Test method to measure the efficiency of air filtration
media against spherical nanomaterials —
Part 1:
Size range from 20 nm to 500 nm
1 Scope
This document specifies the testing instruments and procedure for determining the fractional filtration
efficiencies of flat sheet filter medium against airborne nanoparticles in the range of 20 nm to 500 nm.
The testing methods in this document are limited to spherical or nearly-spherical particles to avoid
uncertainties due to the particle shape.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5167 (all parts), Measurement of fluid flow by means of pressure differential devices inserted in circular
cross-section conduits running full
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 15900, Determination of particle size distribution — Differential electrical mobility analysis for aerosol
particles
ISO 27891, Aerosol particle number concentration — Calibration of condensation particle counters
ISO 29463-1, High efficiency filters and filter media for removing particles from air — Part 1: Classification,
performance, testing and marking
ISO 29464, Cleaning of air and other gases — Terminology
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5725-2, ISO 15900, ISO 27891
and ISO 29464 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
ISO 21083-1:2018(E)
3.2 Symbols and abbreviated terms
3.2.1 Symbols
Symbol Definition
A Source strength of the radioactive source
A Original source strength of the radioactive source
A Effective filtration surface area
f
C Particle concentration upstream of the filter medium
up
C Concentration of particles with the i monodisperse size upstream of the filter medium
up,i th
C Particle concentration downstream of the filter medium
down
C Concentration of particles with the i monodisperse size downstream of the filter medium
down,i th
C Concentration of particles after the second DEMC for the particles with i charge(s)
ni
d Diameter of the initial droplet including the solvent
d
d Diameter of the testing particle after complete evaporation of the solvent
p
E Filtration efficiency of the test filter medium
E Filtration efficiency of the test filter medium against the particles with the i monodisperse size
i th
e Charge of an electron
φ Volume fraction of DEHS in the solution
v
t Half-life of the radioactive source
0,5
N Total count of particles upstream of the filter medium in a certain user-defined time interval
up
Counts of particles with the i monodisperse size upstream of the filter medium in a certain user-
th
N
up,i
defined time interval
N Total count of particles downstream of the filter medium in a certain user-defined time interval
down
Counts of particles with the i monodisperse size downstream of the filter medium in a certain
th
N
down,i
used-defined time interval
N Total count of particles after the second DEMC for the particles with i charge(s)
ni
n Number of elementary charges
p
P Fractional penetration of the test filter medium
P Fractional penetration of particles with the i monodisperse size for the test filter medium
i th
P Penetration with the filter medium, before applying the correlation ratio
m
Measured penetration against particles with the i monodisperse size when the filter medium is
th
P
m,i
installed in the filter medium holder, before applying the correlation ratio
q Flow rate through the filter medium
q Air flow rate through the electrometer
e
R Correlation ratio
Correlation ratio for the i monodisperse particle size, obtained as the penetration without the
th
R
i
filter media
R Resistance of resistor
es
t Time
v Filter medium velocity
f
V Voltage
x Volume of the sampled air
α Angle for the transition section in the filter medium holder
∆p Pressure drop across the filter medium
E Initial particulate efficiency of media sample
∆E Difference in particulate efficiency between E and conditioned efficiency of the media sample
c 0
λ Radioactive decay constant equal to 0,693/t
0,5
2 © ISO 2018 – All rights reserved

ISO 21083-1:2018(E)
3.2.2 Abbreviated terms
AC Alternating current
CAS Chemical abstracts service
CL Concentration limit
CPC Condensation particle counter
DEHS Di(2-ethylhexyl) sebacate
DEMC Differential electrical mobility classifier
DMAS Differential mobility analysing system
HEPA High efficiency particulate air
Kr Krypton
IPA Isopropyl alcohol
MPPS Most penetrating particle size
Po Polonium
PSL Polystyrene latex
RH Relative humidity
SRM Standard reference material
4 Principle
The filtration efficiency of the filter medium is determined by measuring the particle number
concentrations upstream and downstream of the filter medium. The fractional penetration, P,
represents the fraction of aerosol particles which can go through the filter medium, defined as:
PC= /C (1)
down up
where C and C are the particle concentrations downstream and upstream of the filter medium,
down up
respectively. Another way is to measure the particle counts upstream and downstream of the filter
medium for a certain same user-defined time interval and sampling volume rate. Then the penetration
is the ratio between the downstream count N and upstream count N :
down up
PN= /N (2)
down up
ISO 21083-1:2018(E)
The filter medium efficiency, E, is the fraction of aerosol particles removed by the filter medium:
EP=−1 (3)
The filter medium efficiency is dependent on the challenge particle size. If the test is performed with a
number of monodisperse particles with different sizes, the expression for the penetration of particles
with the i monodisperse size P can be written as:
th i
PC= /C (4)
iidown,up,i
where C and C are the concentrations of particles with the i monodisperse size upstream
up,i down,i th
and downstream of the filter medium, respectively. If the measurement is performed with the particle
number count, P can be written as:
i
PN= /N (5)
iidown,,up i
where N and N are the counts of particles with the i monodisperse size upstream and
up,i down,i th
downstream of the filter medium in the same user-defined time interval and sampling volume rate,
respectively. Correspondingly, the filtration efficiency E of the test filter medium against the particles
i
with the i monodisperse size is:
th
EP=−1 (6)
ii
The test aerosol from the aerosol generator is conditioned (e.g. evaporation of the solvent) and then
neutralized. The particles are mixed homogeneously with filtered test air if necessary to achieve
desired concentration and flow rate, before they are used to challenge the test filter medium.
A specimen of the sheet filter medium is fixed in a test filter assembly and subject to the test air flow
corresponding to the prescribed filter medium velocity. Partial flow, which is the flow that the CPC
operates with, of the test aerosol is sampled upstream and downstream of the filter medium, and the
fractional penetration is determined from the upstream and downstream number concentrations or
total numbers in user-defined time intervals. Furthermore, the measurement of the pressure drop
across the filter medium is made at the prescribed filter medium velocity.
Additional equipment is required to measure the absolute pressure, temperature and RH of the test air.
It is also needed to measure and control the air volume flow rate.
5 Test materials
5.1 General
Any aerosol used to test the filtration performance according to this test method shall only be
introduced to the test section as long as needed to test the filtration performance properties of the test
filter medium without changing the filtration performance properties of the subject filter medium due
to loading, charge neutralization or other physical or chemical reaction.
5.2 Liquid phase aerosol
5.2.1 DEHS test aerosol
Test liquid aerosol of DEHS, as an example, is widely used in the testing of filters. DEHS aerosols are
spherical in shape. Experiments conducted by comparing DEHS droplets and solid silver nanoparticles
in the range of 20 nm to 30 nm demonstrated similar filtration efficiencies with the differences below
[19]
8 % .
4 © ISO 2018 – All rights reserved

ISO 21083-1:2018(E)
DEHS/DES/DOS – formula:
C H O or CH (CH ) CH(C H )CH OOC(CH ) COOCH CH(C H )(CH )3CH
26 50 4 3 2 3 2 5 2 2 8 2 2 5 2 3
DEHS properties:
Density 912 kg/m
Melting point 225 K
Boiling point 529 K
Flash point >473 K
−6
Vapour pressure 1,9 × 10 Pa at 273 K
−9
Refractive index 1,450 at 600 · 10 m wavelength
Dynamic viscosity 0,022 Pa·s to 0,024 Pa·s
CAS number 122-62-3
5.2.2 Liquid phase aerosol generation
5.2.2.1 Principles and specifications
The test aerosol shall consist of pure DEHS in a suitable solvent (for example IPA), or other liquid phase
test aerosols in accordance with the producer’s specification.
Figure 1 gives an example of a system for generating the aerosol. Into more details, compressed air
expands through an orifice to form a high-velocity jet. The liquid is drawn into the atomizing section
through a vertical passage and is then atomized by the jet. Large droplets are removed by impaction on
the wall opposite the jet and excess liquid is drained at the bottom of the atomizer assembly block. Fine
spray leaves the atomizer through a fitting at the top.
Any other generator capable of producing droplets with a minimum concentration of about
1 000 particles per cubic centimetre in the particle size range of 20 nm to 500 nm can be used. The
specifications of different atomizers, as examples, are presented in Annex A, Table A.1.
Before testing, regulation of the upstream concentration, to reach a steady state and to have a
concentration in the range that the particle counter can measure, shall be carried out.
ISO 21083-1:2018(E)
Key
1 aerosol out
2 compressed air in
3 liquid in
4 excess liquid to closed reservoir
5 hole
6 O-ring
Figure 1 — Schematic of the atomizer assembly block
5.2.2.2 Atomizer maintenance
The atomizer shall be kept clean and free of rust. Even though most of the atomizer parts are made
of stainless steel, solutes such as sodium chloride will eventually corrode them. In that case, it is
recommended to clean and dry the atomizer assembly.
6 Test setup
6.1 General
The test setup is shown in Figure 2 for monodisperse challenge particles and in Figure 3 for
polydisperse challenge particles. When the challenge particles are monodisperse the setup consists of
the three sections: the one that produces the aerosol particles (which contains the aerosol generator),
the particle classification section (which contains the DEMC) and the particle measuring section (which
contains the CPC). When the challenging particles are polydisperse, the particle classification shall be
performed after sampling the aerosol from the upstream or downstream section.
6 © ISO 2018 – All rights reserved

ISO 21083-1:2018(E)
Key
1 atomizer 7 make-up air with HEPA filter
2 diffusion dryer 8 CPC
3 excess flow with HEPA filter 9 filter medium holder
4 DEMC 10 HEPA filter on the exhaust line
5 neutralizer 11 vacuum
6 flow controller
Figure 2 — Test setup for monodisperse challenge particles
Key
1 atomizer 6 CPC
2 diffusion dryer 7 filter medium holder
3 flow compensation through HEPA filter 8 HEPA filter on the exhaust line
4 neutralizer 9 flow controller
5 DEMC 10 vacuum
Figure 3 — Test setup using polydisperse particles to obtain size resolved fractional filtration
efficiency
ISO 21083-1:2018(E)
6.2 Specification of setup
6.2.1 Aerosol generation system
The aerosol generation system is described in 5.2.2.
6.2.2 Tubing
Tubes shall be made of electrically conductive material (stainless steel, carbon embedded silicon tubing,
etc.) in order to minimize particle losses due to electrostatic deposition. Furthermore, the tubing length
shall be minimized so as to minimize particle losses due to diffusion. The upstream and downstream
sample lines shall be nominally identical in geometry and material.
6.2.3 Dryer
6.2.3.1 Principles
In the case of generated aerosol from atomization, the particles coming out of the atomizer may have
solvent attached and the solvent shall be evaporated. One approach is to pass the aerosol through a
diffusion dryer. The dryer in this document refers to a device which can reduce the vapour pressure of
the solvent in the test aerosol flow coming from the atomization process. The diffusion dryer consists
of a porous tube for air flow passing through a bed of adsorptive materials, e.g. silica gel. The solvent
vapour in the air has high diffusivity and can be adsorbed by the material in the diffusion dryer. For
example, silica gel can adsorb IPA which may be used as the solvent for DEHS in the atomizer (see
Reference [26]). A diffusion dryer is shown in Figure 4.
Key
1 aerosol in
2 annular space filled with an adsorptive material to reduce the vapour pressure of the solvent, for example silica gel
3 inner tube made of wire screen
4 aerosol flow with reduced amount of the solvent vapour
Figure 4 — Diffusion dryer
6.2.3.2 Maintenance
In order to ensure a partial pressure reduction for the solvent, the adsorptive material shall not
be saturated. If silica gel is used, it shall be regenerated periodically until it loses its function after
extensive use and regeneration cycles.
8 © ISO 2018 – All rights reserved

ISO 21083-1:2018(E)
6.2.4 DEMC
6.2.4.1 Principles and specifications
The DMAS consists primarily of a bipolar charger to neutralize the charges on particles, a controller to
control flows and high-voltage, a DEMC (see Figure 5) which separates particles based on their electrical
mobilities, a particle detector, interconnecting plumbing, a computer and suitable software. The DEMC
shall be able to classify particles in the size range of 20 nm to 500 nm and fulfil the qualification
procedure described in 7.2. In case of the unipolar charger based instrument, the manufacturer shall be
contacted for suitable size range, in order to avoid errors due to multiple charge effect. The losses of the
smallest particles due to diffusion within the challenge range shall be considered as well.
NOTE For more information, see ISO 15900.
DEMC principles are as follows.
Particles are introduced at the circumference of a hollow tube. A radial electric field is maintained
across the outer walls of this tube and a central electrode. As the charged particles flow through the
tube, they are attracted towards the central electrode due to the electric field. These are removed
through openings in the central electrode.
Small particles require weak electric fields to move them towards the central electrode. Larger particles
require stronger fields. By adjusting the electric field, particles of a known size are attracted towards
the opening in the central rod and are removed for measurements. Thus particles with a narrow
range of sizes can be extracted for each voltage setting. The narrowness is mainly determined by the
geometry and uniformity of air flow in the device. By stepping through a range of voltages, or electric
field strength, the number of particles in different sizes in the sample can be measured and the particle
size distribution of the sample determined.
Alternately, since the DEMC separates particles according to their electrical mobilities, if one knows the
number of charges on a particle, it can be used to separate monodisperse particles from a polydisperse
aerosol. In this measurement method test particles are first generated and then sent through a
neutralizer. Afterwards, the test particles have the Boltzmann equilibrium charge distribution. In this
case the singly charged particles represent the largest fraction of the charged particles (see the details
in 7.3.2). In addition the size distribution can be controlled so that the target monodisperse particle
size is on the right side of the mode of particle size distribution (see the details in 8.2.13). Under these
carefully controlled conditions it is possible to use a DEMC to classify monodisperse particles in the
range of 20 nm to 500 nm. (See ISO 15900 for more details.)
A DEMC suitable for the prescribed methods in this document shall be able to separate and provide
monodisperse particles in the size range from 20 nm to 500 nm with a geometric standard deviation
less than 1,10. In general, the ratio of the sheath flow rate to the aerosol flow rate into the DEMC
determines the sizing resolution of
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