CEN ISO/TS 12025:2015

SLOVENSKI STANDARD
01-julij-2015
1DQRPDWHULDOL.YDQWLILNDFLMDVSURãþDQMDQDQRREMHNWRYL]SUDKXVSURL]YRGQMR
DHURVROD,6276
Nanomaterials - Quantification of nano-object release from powders by generation of
aerosols (ISO/TS 12025:2012)
Nanomaterialien - Quantifizierung der Freisetzung von Nanoobjekten aus Pulvern durch
Aerosolerzeugung (ISO/TS 12025:2012)
Nanomatériaux - Quantification de la libération de nano-objets par les poudres par
production d'aérosols (ISO/TS 12025:2012)
Ta slovenski standard je istoveten z: CEN ISO/TS 12025:2015
ICS:
07.120 Nanotehnologije Nanotechnologies
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION
CEN ISO/TS 12025
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
May 2015
ICS 07.030
English Version
Nanomaterials - Quantification of nano-object release from
powders by generation of aerosols (ISO/TS 12025:2012)
Nanomatériaux - Quantification de la libération de nano- Nanomaterialien - Quantifizierung der Freisetzung von
objets par les poudres par production d'aérosols (ISO/TS Nanoobjekten aus Pulvern durch Aerosolerzeugung
12025:2012) (ISO/TS 12025:2012)
This Technical Specification (CEN/TS) was approved by CEN on 16 May 2015 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 12025:2015 E
worldwide for CEN national Members.

Contents
Page
Foreword .3

Foreword
The text of ISO/TS 12025:2012 has been prepared by Technical Committee ISO/TC 229 “Nanotechnologies”
of the International Organization for Standardization (ISO) and has been taken over as
held by AFNOR.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus,
Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO/TS 12025:2012 has been approved by CEN as CEN ISO/TS 12025:2015 without any
modification.
TECHNICAL ISO/TS
SPECIFICATION 12025
First edition
2012-11-01
Nanomaterials — Quantification of
nano-object release from powders by
generation of aerosols
Nanomatériaux — Quantification de la libération de nano-objets par
les poudres par production d’aérosols
Reference number
ISO/TS 12025:2012(E)
©
ISO 2012
ISO/TS 12025:2012(E)
© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the
address below or ISO’s member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO/TS 12025:2012(E)
Contents Page
Foreword .iv
Introduction .v
1  Scope . 1
2  Normative references . 1
3  Terms, definitions and abbreviated terms . 1
3.1 General terms . 1
3.2 Terms related to particle properties and measurement . 2
4  Symbols . 4
5  Factors influencing results of nano-object release from powders .5
5.1 Test method selection . 5
5.2 Material properties influencing nano-object release from powder . 5
5.3 Test stages . 6
6 Test requirements . 7
6.1 General . 7
6.2 Safety assessment . 7
6.3 Sample preparation . 8
6.4 Sample treatment . 8
6.5 Measurement of aerosolized nano-objects .10
7  Requirements for test setups and protocols .14
8  Data reporting .15
Annex A (informative) Considerations for the selection of the treatment procedure .16
Annex B (informative) Rotating drum and continuous drop methods .18
Annex C (informative) Vortex shaker method .21
Annex D (informative) Dynamic method .23
Annex E (informative) Disagglomeration principles .26
Annex F (informative) Selection of the nano-object measuring method .27
Bibliography .30
ISO/TS 12025:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of document:
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical
experts in an ISO working group and is accepted for publication if it is approved by more than 50 %
of the members of the parent committee casting a vote;
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a
technical committee and is accepted for publication if it is approved by 2/3 of the members of the
committee casting a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for
a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or
ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must either be
transformed into an International Standard or be withdrawn.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TS 12025 was prepared by Technical Committee ISO/TC 229, Nanotechnologies.
iv © ISO 2012 – All rights reserved

ISO/TS 12025:2012(E)
Introduction
The emissions or release of nano-objects into the surrounding air from powdered nanostructured
materials resulting from handling is an important consideration in the design and operation of many
industrial processes. Released nano-objects may affect human health and the environment, depending
on the nature and quanitity of the nanomaterial. It is therefore important to obtain data about the
propensity of nanomaterials to release nano-objects, thereby allowing exposure to be evaluated,
controlled and minimised.
Three main target groups of experts for the evaluation of the release of nano-objects from powdered
nanostructured materials are:
— material scientists and engineers, who design safe nanomaterials and safe nanomaterial
handling processes;
— occupational, health and safety specialists;
— environmental specialists, who need exposure data in addition to toxicity data for risk assessment
of manufactured nanomaterials (see A.2) and who collect dustiness data (gravimetric as well as
particle concentration and particle size information).
The propensity of nanomaterials to release nano-objects into the air is determined by test methods
devised to apply energy to a sample to stress the intra-particle bonds. This stressing induces abrasion,
erosion or comminution, which causes dissemination of the particles into the gaseous phase, i.e.
generation of aerosols allowing quantification with aerosol instrumentation.
Methods to measure the release of nano-objects from nanomaterials may include dustiness testing
methods but basic differences from conventional dustiness methods should be considered. The
high variability of the flow properties of powders and the influence of the test setup should also be
considered. Conventional dustiness methods for micrometre size particles estimate the amount of dust
generated in terms of dust mass fraction or dustiness indices. The methods of aerosol generation for the
determination of the dustiness of powders containing primary particles of less than 10 μm in diameter
have been found to produce very dissimilar results.
There are a large number of possible combinations of different approaches for the design of dustiness
[1] [2]
methods . The only current standard, EN 15051:2006 , selected two methods: the rotating drum
method and continuous drop method. The measured values are the inhalable, thoracic or respirable
mass fractions, expressed in mg/kg.
[3]
Definitions of the inhalable, thoracic and respirable fractions can be found in EN 481 . Aerodynamic
diameters of 100 µm, 10 µm and 4 µm are the upper limits of the corresponding size fractions. These
mass fractions, which are relevant for inhalation, can be added as measurands in measurement of
aerosolised nano-objects to characterize the complete particle release scenario.
[4]
Schneider and Jensen described approaches using particle size distributions by number to relate
exposure from nano-objects in the indoor environment to source strengths resulting from the release
of nano-objects during the handling of nanostructured powders. They concluded that dustiness testing
combined with online size distribution measurements provides insight into the state of agglomeration
of particles released during handling of bulk powder materials.
Furthermore, the evaluation of the release of nano-objects from powdered nanostructured materials
requires additional methods and measurands compared to the methods assessing the dustiness of
powders. Particle number concentration and size distribution are other measurands necessary for
quantifying the release of nano-objects.
Aerosols of nano-objects are more dynamic than micrometre sized particles because of greater sensitivity
to physical effects such as Brownian diffusion. Porosity and cohesion of the powder can be much higher
than those containing larger particles with more resistance to flow and lower volume-specific surface
area. Nano-objects in powdered materials can dominate relevant properties of the bulk material by
particle-particle interactions that form clusters like agglomerates. There is still a lack of understanding
ISO/TS 12025:2012(E)
in the characterization of these secondary nanostructured particles, consisting of primary nano-objects.
It has been shown for fumed silica, as an example, that the resulting aerosol particle size distribution
[5][6]
depends strongly upon the conditions involved in the different measuring methods .
[7]
Aerosols and powders are also generated by tribological abrasive tests of nano-composites and paints
[8][9]
containing nanoparticles . Such abrasion tests are not addressed by this Technical Specification.
However, the measurement methodology of these publications has been proven for the quantification of
nano-object release from wear powders by generation of aerosols.
vi © ISO 2012 – All rights reserved

TECHNICAL SPECIFICATION ISO/TS 12025:2012(E)
Nanomaterials — Quantification of nano-object release
from powders by generation of aerosols
WARNING — The execution of the provisions of this document should be entrusted only to
appropriately qualified and experienced people, for whose use it has been produced.
1  Scope
This Technical Specification provides methodology for the quantification of nano-object release from
powders as a result of treatment, ranging from handling to high energy dispersion, by measuring aerosols
liberated after a defined aerosolization procedure. In addition to information in terms of mass, the
aerosol is characterized for particle concentrations and size distributions. This Technical Specification
provides information on factors to be considered when selecting from the available methods for powder
sampling and treatment procedures and specifies minimum requirements for test sample preparation,
test protocol development, measuring particle release and reporting data. In order to characterize the
full size range of particles generated, the measurement of nano-objects as well as agglomerates and
aggregates is recommended in this Technical Specification.
This Technical Specification does not include the characterization of particle sizes within the powder.
Tribological methods are excluded where direct mechanical friction is applied to grind or abrade the material.
2  Normative references
The following referenced documents are indispensable for the application of this document. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/TS 27687:2008, Nanotechnologies — Terminology and definitions for nano-objects — nanoparticle,
nanofibre and nanoplate
ISO/TS 80004-1, Nanotechnologies — Vocabulary — Part 1: Core terms
3  Terms, definitions and abbreviated terms
For the purposes of this document, the terms and definitions given in ISO/TS 27687 and ISO/TS 80004-1
and the following apply.
3.1  General terms
3.1.1
release from powder
transfer of material from a powder to a liquid or gas as a consequence of a disturbance
3.1.2
nano-object number release
n
total number of nano-objects, released from a sample as a consequence of a disturbance
3.1.3
nano-object release rate
n
t
total number of nano-objects, released per second as a consequence of a disturbance
ISO/TS 12025:2012(E)
3.1.4
mass-specific nano-object number release
n
m
nano-object number release, divided by the mass of the sample before the disturbance
3.1.5
mass loss-specific nano-object number release
n
∆m
nano-object number release, divided by the mass difference of the sample before and after the disturbance
3.1.6
nano-object aerosol number concentration
c
n
number of nano-objects per aerosol volume unit in the sample treatment zone
3.1.7
aerosol volume flow rate
V
t
volume flow rate through the sample treatment zone
3.2  Terms related to particle properties and measurement
3.2.1
aerosol
system of solid or liquid particles suspended in gas
[ISO 15900:2009, definition 2.1]
3.2.2
intraparticle porosity
ratio of the volume of open pores internal to the particle to the total volume occupied by the solid
[ISO 15901-1:2005, definition 3.9]
3.2.3
interparticle porosity
ratio of the volume of space between particles in a powder to the apparent volume of the particles or powder
[ISO 15901-1:2005, definition 3.10]
3.2.4
equivalent spherical diameter
diameter of a sphere that produces a response by a given particle-sizing instrument, that is equivalent
to the response produced by the particle being measured
NOTE 1 The physical property to which the equivalent diameter refers is indicated using a suitable subscript
(ISO 9276-1:1998).
NOTE 2 For discrete-particle-counting, light-scattering instruments, the equivalent optical diameter is used.
NOTE 3 For inertial instruments, the aerodynamic diameter is used. Aerodynamic diameter is the diameter of
-3
a sphere of density 1 000 kg m that has the same settling velocity as the irregular particle.
NOTE 4 [ISO/TS 27687:2008, definition A.3.3]
2 © ISO 2012 – All rights reserved

ISO/TS 12025:2012(E)
3.2.5
particle size distribution
PSD
cumulative distribution or distribution density of a quantity of particle sizes, represented by equivalent
spherical diameters or other linear dimensions
NOTE Quantity measures and types of distributions are defined in ISO 9276-1:1998.
3.2.6
particulate matter smaller 2,5 µm
PM2,5
mass concentration of fine particulate matter having an aerodynamic diameter less than or equal to a
nominal 2.5 micrometres (PM )
2,5
NOTE See Reference [10].
3.2.7
particulate matter smaller 10 µm
PM10
mass concentration of fine particulate matter having an aerodynamic diameter less than or equal to a
nominal 10 micrometres (PM )
NOTE 1 See Reference [11].
NOTE 2 PM10 is used for the thoracic fraction as explained in EN 481:1993.
3.2.8
condensation particle counter
CPC
instrument that measures the particle number concentration of an aerosol using a condensation effect
to increase the size of the aerosolised particles
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).
NOTE 4 Adapted from ISO 15900:2009, definition 2.5.
3.2.9
differential electrical mobility classifier
DEMC
classifier that is able to select aerosol particles according to their electrical mobility and pass them to its exit
NOTE 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.
3.2.10
differential mobility analysing system
DMAS
system to measure the size distribution of sub-micrometre aerosol particles consisting of a DEMC, flow
meters, a particle detector, interconnecting plumbing, a computer and suitable software
NOTE [ISO 15900:2009, definition 2.8]
ISO/TS 12025:2012(E)
3.2.11
nano-object
material with one, two or three external dimensions in the nanoscale
NOTE 1 Generic term for all discrete nanoscale objects.
NOTE 2 [ISO/TS 27687:2008, definition 2.2]
3.2.12
nanoscale
size range from approximately 1 nm to 100 nm
NOTE 1 Properties that are not extrapolations from a larger size will typically, but not exclusively, be exhibited
in this size range. For such properties the size limits are considered approximate.
NOTE 2 The lower limit in this definition (approximately 1 nm) is introduced to avoid single and small groups
of atoms from being designated as nano-objects or elements of nanostructures, which might be implied by the
absence of a lower limit.
NOTE 3 [ISO/TS 27687:2008, definition 2.1]
3.2.13
agglomerate
collection of loosely bound particles or aggregates or mixtures of the two held together by weak forces where
the resulting external surface area is similar to the sum of the surface areas of the individual components
NOTE 1 The weak forces, for example, are van der Waals forces or simple physical entanglement.
NOTE 2 Agglomerates are secondary particles and the original source particles are primary particles.
NOTE 3 Adapted from ISO/TS 27687:2008, definition 3.2.
3.2.14
aggregate
particle comprising strongly bonded or fused particles held together by strong forces where the
resulting external surface area is significantly smaller than the sum of calculated surface areas of the
individual components
NOTE 1 The strong forces, for example, are covalent bonds, or those resulting from sintering or complex
physical entanglement.
NOTE 2 Aggregates are secondary particles and the original source particles are primary particles.
NOTE 3 Adapted from ISO/TS 27687:2008, definition 3.3.
3.2.15
dustiness
propensity of materials to produce airborne dust during handling
NOTE 1 For the purposes of this document, dustiness is derived from the amount of dust emitted during a
standard test procedure.
NOTE 2 [EN 15051:2006, definition 3.4]
4  Symbols
For the purposes of this document, the following symbols apply:
4 © ISO 2012 – All rights reserved

ISO/TS 12025:2012(E)
Symbol Quantity SI unit
n nano-object number release dimensionless
−1
n nano-object release rate s
t
−3
c nano-object aerosol number concentration m
n
−1
n mass specific nano-object number release kg
m
−1
n mass loss specific nano-object number release from a treated sample kg
∆m
with
a mass loss ∆m
3 −1
V aerosol volume flow rate m s
t
5  Factors influencing results of nano-object release from powders
5.1  Test method selection
The purpose of the planned test or experimental program should be carefully defined during selection.
Selection of the test method depends on the following considerations:
a) powder properties listed in Table 1;
[2]
b) applicability of standardized dustiness test methods or of other powder treatment methods to
simulate the typical powder handling process in practice as well as selection of the appropriate
treatment parameters.
The outcome of the planned test will be dependent on the experimental conditions selected.
EXAMPLE 1 Determination of the nano-object release and of the dustiness of a powder to predict release of
particles during handling in typical industrial processes.
EXAMPLE 2 Estimation of nano-object and agglomerate/aggregate release from powder during very high
energy testing.
5.2  Material properties influencing nano-object release from powder
Properties influencing generation and measurements of aerosolized powders containing nano-objects
are summarized in Table 1. Presently, many of these properties might not be easily measured, however,
they should be considered.
ISO/TS 12025:2012(E)
Table 1 — Representative properties influencing nano-object release from powders
Property Description
Particle size Fundamental property. The value of the particle size depends on the sizing method
and the corresponding equivalent diameter (e.g. aerodynamic diameter, electrical
mobility diameter, equivalent area diameter).
The particle size of primary particles or aggregates will not change during the
handling of nanostructured powders. Particle size of agglomerates will change
under certain process and handling conditions. Therefore it may behave like a
process parameter.
The measured size distribution of particles will depend on the type of instrument.
The instrument might measure aerodynamic or mobility diameters, specific sur-
face areas or other parameters. The exact shape of primary particles will depend
on the manufacturing process. Nano-objects may be a small fraction of the total
mass for some materials.
Particle shape Particle shapes are found in a wide range of geometries depending on the material
and the process. Agglomerates and aggregates of nano-objects may have a fractal
shape. Adhesion forces depend on the particle shape because of the contact geom-
etry.
Crystallinity Some powdered materials can exist in various crystalline states or in amorphous
form. The fraction of the crystalline phase may vary depending on the particle
size.
Hygroscopicity Interaction of the particle with moisture in the air characterized by the relative
humidity will affect the cohesion of the particles. Thus, the history of the relative
humidity of the environmental conditions used to store the powder may be impor-
tant.
The hydrophobic versus hydrophilic characteristics affect dustiness because, as
time goes on, a hydrophilic nanomaterial such as magnesium oxide will become
less dusty as it absorbs water from the air. Some synthetic amorphous silica, on
the other hand, for example, can be easily electrostatically charged and is readily
aerosolized.
Cohesion The magnitude of adhesion forces between particles will affect the detachment of
particles as force is introduced into the system. Cohesion will affect the porosity
between the particles and flow ability of the powder. The tendency of the nanopo-
wders to sinter or agglomerate is also a consideration.
Material density The material density will affect aerosolization. For example some tungsten oxide
has a high density and is not very dusty.
Porosity Porosity is a measure of the void spaces in a material. This includes the porosity of
primary nano-objects, agglomerates and generally the packing density of the bulk
powder.
Electrical The electrical resistance of the powder affects the ability of the system to dissi-
resistivity pate electrical charge.
Triboelectrics The ability of the material to generate static electricity will affect the forces within
the powder.
These material-specific properties of powder are considered in the test design in Clause 6 or in the data
reporting in Clause 8, respectively.
5.3  Test stages
A schematic overview of the test stages necessary for the quantification of nano-object release from
powders is shown in Figure 1. Based on the multitude of factors that influence sample preparation
6 © ISO 2012 – All rights reserved

ISO/TS 12025:2012(E)
and sample treatment, and the current lack of understanding of sample treatment, this Technical
Specification provides normative content on basic conditions for the aerosol measurement stage.
Purpose Test stageExample
sample preparation powder and air humidity
simulation of material state
(subclause 6.3) (data reporting 8 a, b)
rotation speed,
simulation of sample treatment
sedimentation height
application process (subclause 6.4)
(data reporting 8 c, d)
size dependent
quantification of released nano-object
aerosol measurement
number concentration
amount (subclause 6.5)
(data reporting 8 e-k)
Figure 1 — Schematic overview of test stages for the quantification of nano-object release from
powders
Currently, for sample treatment no one general method can be normatively standardized. Nearly all
[12]
powder studies suffer from incomplete determination of the energy input during sample treatment .
For repeatable powder treatment, two devices have been standardized for dustiness measurement (see
Annex B) and further devices are tested and recommended in literature (see Annexes C and D). Annex E
adds continuous treatment in technical disagglomeration principles.
6 Test requirements
6.1  General
6.1.1  Process parameters of the sampling procedure and of the measurement procedure shall be
selected with regard to the purpose of the test and to relevant material properties from Table 1.
6.1.2  The test protocol shall contain these considerations: the purpose, the procedure parameters and
the relevant material properties.
6.1.3  Agreements between buyer and seller should include considerations of the process conditions
simulated, ability to relate to standard methods and the objectives of the study.
6.2  Safety assessment
6.2.1  A safety assessment shall be conducted for the materials before beginning the tests. Guidance is
[47] [13]
given in ISO/TR 13121 and ISO/TR 27628 .
NOTE 1 Some nanomaterials might be toxic. The severity of the toxicity might depend on particle composition,
size, morphology and other physico-chemical properties of the material.
NOTE 2 A nanomaterial that is potentially explosive, pyrophoric or sensitive to ignition might present a fire or
explosive hazard.
6.2.2  Electrical earthing shall be considered to prevent electrostatic charge build-up.
6.2.3  The tests should be tailored according to the hazard. The following examples are not exhaustive
but rather are representative:
ISO/TS 12025:2012(E)
EXAMPLE 1 Inert atmospheres may need to be used for some materials and other control measures to be
applied (e.g. electrical earthing of equipment; use of antistatic mats and shoes).
EXAMPLE 2 Toxic materials need to be tested under appropriate controlled conditions (e.g. glove boxes or
fume cupboards) or should be substituted with a non-toxic or less toxic substance. The substitute material should
exhibit the significant characteristics of the materials of interest. If the substitute material is tested, it should be
specified how the equivalence with the toxic material can be ensured.
6.2.4  Differential electrical mobility analysis for aerosol particles may require radioactive sources
within the measurement device. The function of the particle charge conditioner is to establish a known
size-dependent charge distribution on the sampled aerosol prior to the size classification process. This
bipolar ion concentration can be produced either by radioactive ionization of air from radioactive sources
or by corona discharge ionization. ISO 15900 points out that the use, transportation and disposal of
radioisotopes are regulated by government authorities. Basic international standards and guidelines
are, for example, set by commissions of the United Nations like IAEA, ICRP, ADR, etc. The licensing,
shipping and disposal regulations that govern radioactive sources vary from nation to nation. This
Technical Specification can therefore only advise all users of radioactive material that local, national and
international laws and regulations should be considered and followed.
6.3  Sample preparation
Sample preparation procedures shall be reported, e.g. humidity conditioning of the sample and the test
equipment, sample splitting, electrostatic charging and sieving for limiting maximum agglomerate size
of particles.
Guidance on powder sampling, sample splitting and minimum sample size is given in ISO 14488.
Additional safety precautions for nanomaterials require the sampling and sample splitting in closed
systems or within a fume cupboard.
6.4  Sample treatment
6.4.1  Dustiness methods
6.4.1.1  Selection of methods
Methods with controlled levels of applied energy selected to estimate the dustiness related to
nanomaterials expected in an industrial or user setting shall be based on the established practice
described in 6.4.1. Some selection criteria were published for dustiness measurement of micrometre
sized powders (see Annex A).
6.4.1.2  Reference test methods
The rotating drum method (see Annex B) is one of the two reference test methods for determining a
dustiness index described in EN 15051:2006. The dust is generated by a multiple continuous dropping
process of powder at low speed and is intended to simulate general handling processes, which involve
continuous dropping processes.
The continuous drop reference method (see Annex B) intends to simulate dust generation processes
where there are continuous falling operations (e.g. conveying, discharging, filling) and where dust is
liberated by winnowing during falling. It differs from the rotating drum method in that the bulk material
is dropped only once, but continuously.
6.4.1.3  Vortex shaker method
In the vortex shaker method (see Annex C) a powder is placed in a glass test tube and agitated using a laboratory
vortex shaker while a continuous flow of gas (typically air) is supplied to the tube. The particles released
from the powder are carried out of the tube by the air flow and delivered to measurement instruments
that determine size and/or concentration of the released particles. This technique does not require a large
8 © ISO 2012 – All rights reserved

ISO/TS 12025:2012(E)
amount of sample for testing. Typically the amount of sample is in the range from a few milligrams to a few
hundreds of milligrams. The method needs to be checked for the specific powder for stability.
6.4.1.4  Dynamic method
This method utilizes only milligrams of powdered material per test and is completely self enclosed. Both
of these attributes are useful to evaluate nanoscale materials. The test apparatus consists of a glass
chamber with an aspiration nozzle to disperse milligram quantities of test powder into the chamber,
and two samplers within the chamber to collect the dispersed dust. Airflows and sampling times are
controlled by the tester, which is connected to a vacuum source. The dust is dispersed by pulling the
dust into the glass chamber with a short and rapid application of vacuum (see Annex D).
6.4.2  Dispersion methods
Powder dispersion methods have been developed for a wide range of applications including generating
dust for inhalation studies, filter testing and environmental atmospheres. A number of methods have
been used and are tailored to the dust and the application.
An overview of disagglomeration principles is shown in Annex E. One method cannot cover the wide
range of different industrial applications of powders containing nano-objects, like nanostructured
powders, and the very different flow properties of powders.
6.4.3  Sample treatment execution and report
6.4.3.1  The description of the test method shall include specification of sample aerosolization and
disagglomeration characteristics:
a) duration of test and number of runs;
NOTE 1 In a rotating drum or vortex shaker, agglomeration of fractal powders can occur because of
repeated powder disturbance.
b) type and description of treatment of the powder;
NOTE 2 In the drop test, impact on the bottom, coated or uncoated with powder, will affect the results.
c) inlet design of the test method.
NOTE 3 In the dynamic method, the inlet diameter may influence the agglomerate acceleration and
deceleration within the sampling chamber.
6.4.3.2  The following sample treatment parameters have an influence on the resulting particle release.
They shall be kept constant throughout the tests and between tests to achieve reproducibility of the
results. For comparison between different tests they should be quantified.
a) Sample volume, residence time of the sample in the treatment zone. Both sample volume and sample
mass shall be recorded. To ensure reproducibility, the volume used shall be a ‘tap’ volume rather than
a ‘pour’ volume. Guidance on how to obtain a constant sample volume is given in EN 15051:2006, C.3.
b) Mechanical energy input to the treatment zone (air flow pressure drop or other energy input).
NOTE 1 Research is needed on the measurement of the force or energy acting directly on the sample or
agglomerates, like local shear stress, resulting from velocity gradients or dynamic impact.
c) Humidity, temperature and ion concentration.
NOTE 2 All material is to be tested under the same humidity-controlled environment. The dustiness of a
powder tested under a 50 % humidity atmosphere will be different from the dustiness of the same powder
tested under a 30 % or 80 % humidity atmosphere. Humidity inside the test equipment should be 50 % ± 10 %.
NOTE 3 Temperature also should be kept constant 21 °C ± 3 °C.
ISO/TS 12025:2012(E)
d) Air volume flow through the treatment zone.
e) Particle concentration in the air during treatment (interparticle distances determine the ratio of
disagglomeration/agglomeration).
6.4.3.3  The test equipment should be electrically grounded.
6.4.3.4  The repeatability of the aerosolization and disagglomeration process shall be determined over
three to 10 tests of fresh powder samples and can be reported as minimum and maximum values in
addition to the average values of the particle number release. The repeatability of the measurement shall
also be reported as described in 6.6.6.
6.5  Measurement of aerosolized nano-objects
6.5.1  Transport and sampling parameters
Transport and sampling process parameters are:
a) material, length and diameter of sampling tubes;
NOTE Tubes made of electrically conductive materials are recommended for minimizing particle losses
due to electrostatic deposition. Furthermore diffusion, gravity and inertia can cause losses in tubes, which
should therefore be as short as possible. However, instruments operate on different flow rates and losses will
be different even if the length and size of the tubing is the same.
b) sampling air flow, dilution ratio;
c) shear stress as a result of aerodynamic pre-classification (at the inlet of the measurement device);
d) shear stress within a measurement device (for instance of aerodynamic sample focusing);
−3
e) particle number concentration in the tubes should not be greater than 1 000 000 cm to limit
particle coagulation (agglomeration).
6.5.2  Size and concentration measurement results
6.5.2.1  Nano-object number release
The quantity measure “mass” of a particle size fraction depends on the third power of the particle size,
i.e. if the particle size decreases by a factor of 10, the particle mass reduces by a factor of 1 000. Thus,
the nano-object mass concentration may be too low to be measured alone with current commercially
available instruments. Number-based methods are the most sensitive for the smallest size classes in
broad particle size distributions.
The general measurand, the nano-object number release n, is given by Formula (1). If relevant, the
dilution ratio has to be taken into account.
nn=⋅tc=⋅Vt⋅ (1)
tn t
where
n is the nano-object release rate;
t
c is the measured nano-objects number concentration;
n
t is the measurement time;
V i
...