Determination of particle size distribution -- Differential electrical mobility analysis for aerosol particles

This document provides guidelines and requirements for the determination of aerosol particle number size distribution by means of the analysis of electrical mobility of aerosol particles. This measurement is usually called "differential electrical mobility analysis for aerosol particles". This analytical method is applicable to particle size measurements ranging from approximately 1 nm to 1 µm. This document does not address the specific instrument design or the specific requirements of particle size distribution measurements for different applications but includes the calculation method of uncertainty. In this document, the complete system for carrying out differential electrical mobility analysis is referred to as DMAS (differential mobility analysing system), while the element within this system that classifies the particles according to their electrical mobility is referred to as DEMC (differential electrical mobility classifier). NOTE This document does not include technical requirements and specifications for the application of DMAS, which are defined in application specific standards or guidelines, e.g. for road vehicle applications (ISO/TC 22), environmental measurements (ISO/TC 146) or nanotechnologies (ISO/TC 229).

Détermination de la distribution granulométrique -- Analyse de mobilité électrique différentielle pour les particules d'aérosol

General Information

Status
Published
Publication Date
19-Oct-2020
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
17-Sep-2020
Completion Date
16-Sep-2020
Ref Project

RELATIONS

Buy Standard

Standard
ISO 15900:2020 - Determination of particle size distribution -- Differential electrical mobility analysis for aerosol particles
English language
92 pages
sale 15% off
Preview
sale 15% off
Preview
Draft
ISO/FDIS 15900:Version 24-apr-2020 - Determination of particle size distribution -- Differential electrical mobility analysis for aerosol particles
English language
92 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (sample)

INTERNATIONAL ISO
STANDARD 15900
Second edition
2020-10
Determination of particle size
distribution — Differential electrical
mobility analysis for aerosol particles
Détermination de la distribution granulométrique — Analyse de
mobilité électrique différentielle pour les particules d'aérosol
Reference number
ISO 15900:2020(E)
ISO 2020
---------------------- Page: 1 ----------------------
ISO 15900:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 15900:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

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

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

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

4 Symbols .......................................................................................................................................................................................................................... 4

5 General principle ................................................................................................................................................................................................. 5

5.1 Particle size classification with the DEMC ...................................................................................................................... 5

5.2 Relationship between electrical mobility and particle size ............................................................................. 6

5.3 Measurement and data inversion ........................................................................................................................................... 7

5.4 Transfer function of the DEMC .................................................................................................................................................. 8

5.5 Charge distribution function ....................................................................................................................................................... 9

5.5.1 General...................................................................................................................................................................................... 9

5.5.2 Charge distribution function for radioactive bipolar charge conditioners ................... 9

5.5.3 Charge distribution functions for other bipolar and unipolar charge

conditioners ......................................................................................................................................................................10

5.6 Particle losses in the DMAS .......................................................................................................................................................11

5.7 Effects due to non-spherical particles..............................................................................................................................11

5.8 Measurement of particle sizes below 10 nm .............................................................................................................11

5.9 Traceability of measurement results ................................................................................................................................11

6 System and apparatus ..................................................................................................................................................................................13

6.1 General configuration ....................................................................................................................................................................13

6.2 Components ............................................................................................................................................................................................14

6.2.1 Pre-conditioner ..............................................................................................................................................................14

6.2.2 Charge conditioner .....................................................................................................................................................14

6.2.3 DEMC .......................................................................................................................................................................................15

6.2.4 Aerosol particle detector .......................................................................................................................................15

6.2.5 System controller, data acquisition and analysis ..............................................................................15

7 Measurement procedures ........................................................................................................................................................................16

7.1 Setup and preparation of the instrument .....................................................................................................................16

7.1.1 General...................................................................................................................................................................................16

7.1.2 Aerosol pre-conditioning: Adapting the aerosol to be measured to the

requirements of the DMAS ...................................................................................................................................16

7.1.3 Aerosol pre-conditioning: Separation of large particles ............................................................16

7.1.4 Charge conditioning ...................................................................................................................................................17

7.1.5 DEMC: Flows .....................................................................................................................................................................17

7.1.6 DEMC: Voltage .................................................................................................................................................................18

7.1.7 DEMC: Temperature and pressure ................................................................................................................18

7.1.8 Particle detection: CPC .................. ......................................................................................................................... ..18

7.1.9 Particle detection: FCAE .........................................................................................................................................18

7.1.10 Data acquisition .............................................................................................................................................................18

7.2 Pre-measurement checks............................................................................................................................................................18

7.2.1 General...................................................................................................................................................................................18

7.2.2 Overall DMAS check ...................................................................................................................................................19

7.2.3 Data acquisition check .............................................................................................................................................19

7.3 Measurement .........................................................................................................................................................................................19

7.4 Maintenance ...........................................................................................................................................................................................19

8 Periodic tests and calibrations ...........................................................................................................................................................20

8.1 Overview ...................................................................................................................................................................................................20

8.2 Zero tests ...................................................................................................................................................................................................21

8.2.1 General...................................................................................................................................................................................21

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 15900:2020(E)

8.2.2 Particle detector zero test .....................................................................................................................................21

8.2.3 Overall DMAS zero test with inlet filter .....................................................................................................21

8.2.4 Overall DMAS zero test with DEMC voltage set to 0 V ..................................................................21

8.3 Flow rate tests ......................................................................................................................................................................................21

8.4 Voltage calibration ............................................................................................................................................................................22

8.5 Charge conditioner test ................................................................................................................................................................22

8.6 Calibration for size measurement .......................................................................................................................................22

8.6.1 General...................................................................................................................................................................................22

8.6.2 Purpose of calibration ..............................................................................................................................................22

8.6.3 Particle size standards .............................................................................................................................................22

8.6.4 Dynamic DMAS particle size calibration procedure .......................................................................23

8.6.5 Static DMAS particle size calibration procedure ...............................................................................24

8.7 Size resolution test ...........................................................................................................................................................................28

8.8 Number concentration calibration .....................................................................................................................................28

9 Using a DEMC at a fixed voltage to generate particles of a chosen size ....................................................29

9.1 General ........................................................................................................................................................................................................29

9.2 Multiply-charged particles .........................................................................................................................................................30

9.3 Size calibration with certified spheres ............................................................................................................................30

9.4 Sheath flow ..............................................................................................................................................................................................30

9.5 Slip correction (if applicable) ..................................................................................................................................................31

9.6 Voltage (if applicable) ....................................................................................................................................................................31

9.7 Calculation of overall uncertainty .......................................................................................................................................31

10 Reporting of results ........................................................................................................................................................................................31

Annex A (informative) Charge conditioners and charge distributions .........................................................................33

Annex B (informative) Particle detectors .....................................................................................................................................................44

Annex C (informative) Slip correction factor ............................................................................................................................................48

Annex D (informative) Data inversion .............................................................................................................................................................51

Annex E (informative) Cylindrical DEMC .......................................................................................................................................................67

Annex F (informative) Example certificate for a DMAS particle size calibration ................................................72

Annex G (informative) Good practice for measurements at particle sizes below 10 nm ............................75

Annex H (informative) Examples for overall system tests ..........................................................................................................77

Annex I (informative) Comparison of different approaches to calculate diffusion loss in

laminar tube flow..............................................................................................................................................................................................83

Annex J (informative) Corrections for effects due to non-spherical particles........................................................87

Bibliography .............................................................................................................................................................................................................................88

iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 15900:2020(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 Technical Committee ISO/TC 24, Particle characterization including

sieving, Subcommittee SC 4, Particle characterization.

This second edition cancels and replaces the first edition (ISO 15900:2009), which has been technically

revised.
The main changes compared to the previous edition are as follows:

— subclauses on particle losses due to Brownian diffusion, effects due to non-spherical particles, and

measurement of particles below 10 nm have been added in Clause 5;
— traceability diagrams for DEMC and DMAS have been added in Clause 5;
— calibration for size measurement in Clause 8 has been refined;

— Clause 9 for “Using a DEMC at a fixed voltage to generate particles of a chosen size” has been added;

— Annex D for “Data inversion” has been rewritten completely;

— Annex F for “Example certificate for a DMAS particle size calibration” has been added;

— former Annex G for “Uncertainty” in the previous edition has been deleted;

— new Annex G for “Good practice for measurements at particle sizes below 10 nm” has been added;

— Annex H for “Examples for overall system tests” has been added;

— Annex I for “Comparison of different approaches to calculate diffusion loss in laminar tube flow” has

been added;

— Annex J for “Corrections for effects due to non-spherical particles” has been added.

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 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 15900:2020(E)
Introduction

Differential electrical mobility classification and analysis of airborne particles has been widely used

to measure a variety of aerosol particles ranging from nanometre-size to micrometre-size in the gas

phase. In addition, the electrical mobility classification of charged particles can be used to generate

mono-disperse particles of known size for calibration of other instruments. One notable feature of these

techniques is that they are based on simple physical principles. The techniques have become important

in many fields of aerosol science and technology, e.g. aerosol instrumentation, production of materials

from aerosols, contamination control in the semiconductor industry, atmospheric aerosol science,

characterization of engineered nanoparticles, and so on. However, in order to use electrical mobility

classification and analysis correctly, several issues, such as the slip correction factor, the ion-aerosol

attachment coefficients, the size-dependent charge distribution on aerosol particles and the method

used for inversion of the measured mobility distribution to the aerosol particle size distribution, need

due caution.

There is, therefore, a need to establish an International Standard for the use of differential electrical

mobility analysis for classifying aerosol particles. Its purpose is to provide a methodology for adequate

quality control in particle size and number concentration measurement with this method.

vi © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 15900:2020(E)
Determination of particle size distribution — Differential
electrical mobility analysis for aerosol particles
1 Scope

This document provides guidelines and requirements for the determination of aerosol particle number

size distribution by means of the analysis of electrical mobility of aerosol particles. This measurement

is usually called “differential electrical mobility analysis for aerosol particles”. This analytical method

is applicable to particle size measurements ranging from approximately 1 nm to 1 µm. This document

does not address the specific instrument design or the specific requirements of particle size distribution

measurements for different applications but includes the calculation method of uncertainty. In this

document, the complete system for carrying out differential electrical mobility analysis is referred to as

DMAS (differential mobility analysing system), while the element within this system that classifies the

particles according to their electrical mobility is referred to as DEMC (differential electrical mobility

classifier).

NOTE This document does not include technical requirements and specifications for the application of DMAS,

which are defined in application specific standards or guidelines, e.g. for road vehicle applications (ISO/TC 22),

environmental measurements (ISO/TC 146) or nanotechnologies (ISO/TC 229).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

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

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
aerosol
system of solid and/or liquid particles suspended in gas
3.2
attachment coefficient
attachment probability of ions and aerosol particles
3.3
bipolar charging

process which attains a conditioned charge distribution of both positive and negative charges on

aerosol particles
3.4
bipolar charge conditioner

device which attains a conditioned charge distribution of both positive and negative charges on aerosol

particles
© ISO 2020 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO 15900:2020(E)
3.5
charging

processes that leave aerosol particles with size dependent specific distributions of unipolar or bipolar

electrical charges
3.6
charge conditioner

device (or component of a DMAS) which establishes a known conditioned size dependent charge

distribution on aerosol particles which are passed through it
3.7
charge distribution function

mathematical and/or empirical description of a conditioned particle size dependent charge distribution

3.8
condensation particle counter
CPC
instrument that measures the particle number concentration of an aerosol

Note 1 to entry: The sizes of particles detected are usually smaller than several hundred nanometres and larger

than a few nanometres.
Note 2 to entry: A CPC is one possible detector for use with a DEMC.

Note 3 to entry: In some cases, a condensation particle counter may be called a condensation nucleus counter (CNC).

3.9
conditioned charge distribution

distribution of unipolar or bipolar electrical charges on aerosol particles defined by a charge

distribution function, which is in a steady state for a sufficiently long period of time in an aerosol

instrument downstream of a unipolar or bipolar charge conditioner
3.10
critical mobility

instrument parameter of a DEMC (3.11) that defines the electrical mobility of aerosol particles that exit

the DEMC in aerosol form, which may be defined by the geometry, sample and sheath flow rates, and

electrical field intensity

Note 1 to entry: Particles larger or smaller than the critical mobility migrate to an electrode or exit with the

excess flow and do not exit from the DEMC in aerosol form.
3.11
differential electrical mobility classifier
DEMC

classifier able to select aerosol particles according to their electrical mobility and pass them to its exit

Note 1 to entry: A DEMC classifies aerosol particles by balancing the electrical force on each particle with its

aerodynamic drag force in an electrical field. Classified particles are in a narrow range of electrical mobility

determined by the operating conditions and physical dimensions of the DEMC, while they can have different sizes

due to difference in the number of charges that they have.
Note 2 to entry: Another common acronym for the DEMC is DMA.
3.12
differential mobility analysing system
DMAS

system to measure the size distribution of submicrometre aerosol particles consisting of a charge

conditioner, a DEMC, flow meters, a particle detector, interconnecting plumbing, a computer and

suitable software

Note 1 to entry: Another common acronym for the DMAS is MPSS (mobility particle size spectrometer).

2 © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 15900:2020(E)
3.13
electrical mobility

ratio of migration velocity (3.18) to electrical field for particles and ions in a gas

3.14
equivalent diameter

diameter of a sphere with defined characteristics which behaves under defined conditions in exactly

the same way as the particle being described

Note 1 to entry: Particle diameter (or simply diameter) used throughout this document always refers to the

electrical mobility equivalent diameter, which defines the size of charged particles with the same electrical

mobility or the same terminal migration velocity in still air under the influence of a constant electrical field.

3.15
Faraday cup aerosol electrometer
FCAE

electrometer designed for the measurement of electrical charge concentration carried by an aerosol

Note 1 to entry: A Faraday cup aerosol electrometer consists of an electrically conducting and electrically grounded

cup as a guard to cover the sensing element that includes aerosol filtering media to capture charged aerosol

particles, an electrical connection between the sensing element and an electrometer circuit, and a flow meter. An

FCAE measures electrical current ranging from about one femtoampere (fA) to about ten picoamperes (pA).

3.16
Knudsen number

ratio of gas molecular mean free path to the radius of the particle, which is an indicator of free molecular

flow versus continuum gas flow
3.17
laminar flow

gas flow with no temporally or spatially irregular activity or turbulent eddy flow

3.18
migration velocity

steady-state velocity of a charged airborne particle within an externally applied electric field

3.19
particle diameter
electrical mobility equivalent diameter
Note 1 to entry: Also, just called diameter.
3.20
plateau detection efficiency

mean detection efficiency of a CPC in the size range which is not biased by particle size

[SOURCE: ISO 27891:2015, 3.27, modified — term “plateau efficiency” has been changed to "plateau

detection efficiency.]
3.21
Reynolds number

dimensionless number expressed as the ratio of the inertial force to the viscous force

Note 1 to entry: For example, applied to an aerosol particle or a tube carrying aerosol particles

© ISO 2020 – All rights reserved 3
---------------------- Page: 9 ----------------------
ISO 15900:2020(E)
3.22
slip correction

dimensionless factor used to correct the drag force acting on a particle for non-continuum effects that

become important when the particle size is comparable to or smaller than the mean free path of the gas

molecules
3.23
Stokes's drag

drag force acting on a particle that is moving relative to a continuum fluid in the creeping flow limit

(low Reynolds number)
3.24
transfer function

ratio of particle concentration at the outlet of a DEMC to the particle concentration at the inlet of the DEMC

Note 1 to entry: It is normally expressed as a function of electrical mobility.
3.25
unipolar charge conditioner

device which attains a conditioned charge distribution of either positive or negative charges on aerosol

particles
3.26
unipolar charging
process which attains a condition
...

DRAFT INTERNATIONAL STANDARD
ISO/DIS 15900
ISO/TC 24/SC 4 Secretariat: BSI
Voting begins on: Voting terminates on:
2019-07-08 2019-09-30
Determination of particle size distribution — Differential
electrical mobility analysis for aerosol particles

Détermination de la distribution granulométrique — Analyse de mobilité électrique différentielle pour les

particules d'aérosol
ICS: 19.120
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 15900:2019(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. ISO 2019
---------------------- Page: 1 ----------------------
ISO/DIS 15900:2019(E)
ISO/DIS 15900:2019(E)
Contents Page

Foreword ........................................................................................................................................................................... v

Introduction ................................................................................................................................................................... vi

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

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

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

4 Symbols ............................................................................................................................................................... 5

5 General Principle ............................................................................................................................................. 6

5.1 Particle size classification with the DEMC .............................................................................................. 6

5.2 Relationship between electrical mobility and particle size ............................................................. 7

5.3 Measurement and data inversion .............................................................................................................. 8

5.4 Transfer function of the DEMC .................................................................................................................... 9

5.5 The charge distribution function ............................................................................................................ 10

5.6 Particle losses in the DMAS ....................................................................................................................... 12

5.7 Effects due to non‐spherical particles ................................................................................................... 13

6 System and apparatus ................................................................................................................................. 13

6.1 General configuration ................................................................................................................................. 13

6.2 Components .................................................................................................................................................... 14

7 Measurement procedures ......................................................................................................................... 16

7.1 Setup and preparation of the instrument ............................................................................................ 16

7.2 Pre‐measurement checks .......................................................................................................................... 19

7.3 Measurement ................................................................................................................................................. 19

7.4 Maintenance ................................................................................................................................................... 20

8 Periodic tests and calibrations ................................................................................................................ 20

8.1 Overview .......................................................................................................................................................... 20

8.2 Zero tests ......................................................................................................................................................... 21

8.3 Flow rate tests ................................................................................................................................................ 22

8.4 Voltage calibration ....................................................................................................................................... 22

8.5 Charge conditioner test .............................................................................................................................. 22

8.6 Calibration for size measurement .......................................................................................................... 22

8.7 Size resolution test ....................................................................................................................................... 28

8.8 Number concentration calibration......................................................................................................... 29

9 Using a DEMC at a fixed voltage to generate particles of a chosen size ..................................... 29

9.1 General ............................................................................................................................................................. 29

9.2 Multiply‐charged particles ........................................................................................................................ 30

9.3 Size calibration with certified spheres ................................................................................................. 31

COPYRIGHT PROTECTED DOCUMENT

9.4 Sheath flow ...................................................................................................................................................... 31

9.5 Slip correction (if applicable) .................................................................................................................. 31

© ISO 2019

9.6 Voltage (if applicable) ................................................................................................................................. 31

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

9.7 Calculation of overall uncertainty .......................................................................................................... 32

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. 10 Reporting of results ..................................................................................................................................... 32

ISO copyright office

Annex A (informative) Charge conditioners and charge distributions .................................................. 33

CP 401 • Ch. de Blandonnet 8

CH-1214 Vernier, Geneva A.1 General ............................................................................................................................................................. 33

Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org © ISO 2019 – All rights reserved
iii
Published in Switzerland
ii © ISO 2019 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 15900:2019(E)
Contents Page

Foreword ........................................................................................................................................................................... v

Introduction ................................................................................................................................................................... vi

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

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

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

4 Symbols ............................................................................................................................................................... 5

5 General Principle ............................................................................................................................................. 6

5.1 Particle size classification with the DEMC .............................................................................................. 6

5.2 Relationship between electrical mobility and particle size ............................................................. 7

5.3 Measurement and data inversion .............................................................................................................. 8

5.4 Transfer function of the DEMC .................................................................................................................... 9

5.5 The charge distribution function ............................................................................................................ 10

5.6 Particle losses in the DMAS ....................................................................................................................... 12

5.7 Effects due to non‐spherical particles ................................................................................................... 13

6 System and apparatus ................................................................................................................................. 13

6.1 General configuration ................................................................................................................................. 13

6.2 Components .................................................................................................................................................... 14

7 Measurement procedures ......................................................................................................................... 16

7.1 Setup and preparation of the instrument ............................................................................................ 16

7.2 Pre‐measurement checks .......................................................................................................................... 19

7.3 Measurement ................................................................................................................................................. 19

7.4 Maintenance ................................................................................................................................................... 20

8 Periodic tests and calibrations ................................................................................................................ 20

8.1 Overview .......................................................................................................................................................... 20

8.2 Zero tests ......................................................................................................................................................... 21

8.3 Flow rate tests ................................................................................................................................................ 22

8.4 Voltage calibration ....................................................................................................................................... 22

8.5 Charge conditioner test .............................................................................................................................. 22

8.6 Calibration for size measurement .......................................................................................................... 22

8.7 Size resolution test ....................................................................................................................................... 28

8.8 Number concentration calibration......................................................................................................... 29

9 Using a DEMC at a fixed voltage to generate particles of a chosen size ..................................... 29

9.1 General ............................................................................................................................................................. 29

9.2 Multiply‐charged particles ........................................................................................................................ 30

9.3 Size calibration with certified spheres ................................................................................................. 31

9.4 Sheath flow ...................................................................................................................................................... 31

9.5 Slip correction (if applicable) .................................................................................................................. 31

9.6 Voltage (if applicable) ................................................................................................................................. 31

9.7 Calculation of overall uncertainty .......................................................................................................... 32

10 Reporting of results ..................................................................................................................................... 32

Annex A (informative) Charge conditioners and charge distributions .................................................. 33

A.1 General ............................................................................................................................................................. 33

© ISO 2019 – All rights reserved
iii
---------------------- Page: 3 ----------------------
ISO/DIS 15900:2019(E)

A.2 Ionization sources ........................................................................................................................................ 33

A.3 Charge conditioning .................................................................................................................................... 35

A.4 Implementation of bipolar steady‐state charging ............................................................................ 37

A.5 Implementation of unipolar charge conditioning ............................................................................ 44

Annex B (informative) Particle detectors......................................................................................................... 46

B.1 General ............................................................................................................................................................. 46

B.2 Condensation particle counter ................................................................................................................ 46

B.3 Faraday cup aerosol electrometer ......................................................................................................... 47

Annex C (informative) Slip correction factor .................................................................................................. 50

C.1 General ............................................................................................................................................................. 50

C.2 Historical investigation of the slip correction factor ...................................................................... 50

C.3 Recommended coefficients for the slip correction factor ............................................................. 51

Annex D (informative) Data inversion .............................................................................................................. 53

D.1 General ............................................................................................................................................................. 53

D.2 Step‐by‐step DMAS calculation example.............................................................................................. 53

Annex E (informative) Cylindrical DEMC .......................................................................................................... 67

E.1 Geometry of cylindrical DEMC ................................................................................................................. 67

E.2 Transfer function ......................................................................................................................................... 68

E.3 Uncertainty calculation for Z* ................................................................................................................. 70

Annex F (informative) Example certificate for a DMAS particle size calibration............................... 72

Annex G (informative) Good practice for measurements at particle sizes below 10 nm ................ 75

G.1 General ............................................................................................................................................................. 75

G.2 Using optimized measurement equipment ........................................................................................ 75

G.3 Detector calibration considerations ..................................................................................................... 76

Annex H (informative) Examples for overall system tests ......................................................................... 77

H.1 Example for an overall system test with PSL particles ................................................................... 77

H.2 Example for an overall system test with polydisperse aerosol ................................................... 79

Annex I (informative) Comparison of different approaches to calculate diffusion loss in

laminar tube flow ......................................................................................................................................... 82

I.1 General ............................................................................................................................................................. 82

I.2 Emprical calculation of the particle penetration for laminar tube flow .................................. 82

I.3 Comparison of the different sets of empirical equations .............................................................. 83

I.4 Equivalent tube length ............................................................................................................................... 84

I.5 Overall particle losses in the DMAS ....................................................................................................... 84

I.6 Example calculation .................................................................................................................................... 85

Annex J (informative) Corrections for effects due to non‐spherical particles .................................... 86

Bibliography ................................................................................................................................................................. 87

© ISO 2019 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/DIS 15900:2019(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national

standards bodies (ISO member bodies). The work of preparing International Standards is normally

carried out through ISO technical committees. Each member body interested in a subject for which a

technical committee has been established has the right to be represented on that committee.

International organizations, governmental and non‐governmental, in liaison with ISO, also take part in

the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all

matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the meaning of ISO specific terms and expressions related to conformity

assessment, as well as information about ISO's adherence to the World Trade Organization (WTO)

principles in the Technical Barriers to Trade (TBT) see the following URL:

www.iso.org/iso/foreword.html.

The committee responsible for this document is ISO/TC 24/SC 4 Particle characterization.

This second edition cancels and replaces the first edition (ISO 15900:2009), which has been technically

revised.
The main changes compared to the previous edition are as follows:
[to be completed]

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 2019 – All rights reserved
---------------------- Page: 5 ----------------------
ISO/DIS 15900:2019(E)
Introduction

Differential electrical mobility classification and analysis of airborne particles has been widely used to

measure a variety of aerosol particles ranging from nanometre‐size to micrometre‐size in the gas phase.

In addition, the electrical mobility classification of charged particles can be used to generate mono‐

disperse particles of known size for calibration of other instruments. One notable feature of these

techniques is that they are based on simple physical principles. The techniques have become important

in many fields of aerosol science and technology, e.g. aerosol instrumentation, production of materials

from aerosols, contamination control in the semiconductor industry, atmospheric aerosol science,

characterization of engineered nanoparticles, and so on. However, in order to use electrical mobility

classification and analysis correctly, several issues, such as the slip correction factor, the ion‐aerosol

attachment coefficients, the size‐dependent charge distribution on aerosol particles and the method

used for inversion of the measured mobility distribution to the aerosol size distribution, need due

caution.

There is, therefore, a need to establish an International Standard for the use of differential electrical

mobility analysis for classifying aerosol particles. Its purpose is to provide a methodology for adequate

quality control in particle size and number concentration measurement with this method.

© ISO 2019 – All rights reserved
---------------------- Page: 6 ----------------------
DRAFT INTERNATIONAL STANDARD ISO/DIS 15900:2019(E)
Determination of particle size distribution — Differential
electrical mobility analysis for aerosol particles
1 Scope

This International Standard provides guidelines on the determination of aerosol particle size

distribution by means of the analysis of electrical mobility of aerosol particles. This measurement is

usually called “differential electrical mobility analysis for aerosol particles”. This analytical method is

applicable to particle size measurements ranging from approximately 1 nm to 1 µm. This International

Standard does not address the specific instrument design or the specific requirements of particle size

distribution measurements for different applications, but includes the calculation method of

uncertainty. In this International Standard, the complete system for carrying out differential electrical

mobility analysis is referred to as DMAS (differential mobility analysing system), while the

element within this system that classifies the particles according to their electrical mobility is referred

to as DEMC (differential electrical mobility classifier).

NOTE This International Standard does not include technical requirements and specifications for the

application of DMAS, which should be defined in application specific standards or guidelines, e.g. for road vehicle

applications (ISO/TC 22), environmental measurements (ISO/TC 146, CEN/TC 264) or nanotechnologies (ISO/TC

229).
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/IEC Guide 98: 2008, Guide to the Expression of Uncertainty in Measurement (GUM)

ISO 27891: 2015, Aerosol particle number concentration – Calibration of condensation particle

counters
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
3.2
attachment coefficient
attachment probability of ions and aerosol particles
3.3
bipolar charging

process which attains a conditioned charge distribution of both positive and negative charges on

aerosol particles
© ISO 2019 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/DIS 15900:2019(E)
3.4
bipolar charge conditioner

device which attains a conditioned charge distribution of both positive and negative charges on aerosol

particles
3.5
charging

processes that leave aerosol particles with size dependent specific distributions of unipolar or bipolar

electrical charges
3.6
charge conditioner

device (or component of a DMAS) which establishes a known conditioned size dependent charge

distribution on aerosol particles which are passed through it
3.7
charge distribution function

mathematical and/or empirical description of a conditioned particle size dependent charge distribution

3.8
condensation particle counter
CPC
instrument that measures the particle number concentration of an aerosol

NOTE 1 The sizes of particles detected are usually smaller than several hundred nanometres and larger than a

few nanometres.
NOTE 2 A CPC is one possible detector for use with a DEMC.

NOTE 3 In some cases, a condensation particle counter may be called a condensation nucleus counter (CNC).

3.9
conditioned charge distribution

distribution of unipolar or bipolar electrical charges on aerosol particles defined by a charge

distribution function, which is in a steady state for a sufficiently long period of time in an aerosol

instrument downstream of a unipolar or bipolar charge conditioner
3.10
critical mobility

instrument parameter of a DEMC that defines the electrical mobility of aerosol particles that exit the

DEMC in aerosol form, which may be defined by the geometry, sample and sheath flow rates, and

electrical field intensity

NOTE Particles larger or smaller than the critical mobility migrate to an electrode or exit with the excess flow

and do not exit from the DEMC in aerosol form.
3.11
differential electrical mobility classifier
DEMC

classifier that is able to select aerosol particles according to their electrical mobility and pass them to its

exit
© ISO 2019 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/DIS 15900:2019(E)

NOTE 1 A DEMC classifies aerosol particles by balancing the electrical force on each particle with its

aerodynamic drag force in an electrical field. Classified particles are in a narrow range of electrical mobility

determined by the operating conditions and physical dimensions of the DEMC, while they can have different sizes

due to differen
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.