SIST-TS CEN/TS 17274:2019
(Main)Nanotechnologies - Guidelines for determining protocols for the explosivity and flammability of powders containing nano-objects (for transport, handling and storage)
Nanotechnologies - Guidelines for determining protocols for the explosivity and flammability of powders containing nano-objects (for transport, handling and storage)
This document provides protocol guidelines for determining explosivity and flammability characteristics of powders containing manufactured nano-objects. These explosivity and flammability characteristics are needed for safety data sheets for safe storage, handling and transport of any powder.
In particular, this document will provide protocol guidelines concerning:
- the determination of flammability characteristics of powders containing nano-objects with regard to sensitivity to ignition sources;
- the ability of a powder containing nano-objects to generate an explosive atmosphere and the assessment of its explosion characteristics.
This document is not suitable for use with recognized explosives, such as gunpowder and dynamite, explosives which do not require oxygen for combustion, or substances or mixtures of substances which may under some circumstances behave in a similar manner. Where any doubt exists about the existence of hazard due to explosive properties, it is best to seek expert advice.
Nanotechnologien - Leitfaden für Protokolle zur Bestimmung des Brand- und Explosionsverhaltens von Pulvern, die Nano-Objekte beinhalten (für Transport, Handhabung und Lagerung)
Dieses Dokument stellt einen Leitfaden für Protokolle zur Bestimmung des Explosions- und Brandverhaltens von Pulvern, die industriell hergestellte Nanoobjekte enthalten, bereit. Diese Informationen zum Explosions- und Brandverhalten werden für Sicherheitsdatenblätter zur sicheren Lagerung und zum sicheren Umschlag und Transport aller Arten von Pulvern benötigt.
Im Besonderen stellt dieses Dokument einen Leitfaden für Protokolle zu Folgendem zur Verfügung:
- Bestimmung des Brandverhaltens von Pulvern, die Nanoobjekte enthalten, im Hinblick auf die Sensibilität gegenüber Zündquellen;
- Fähigkeit eines Pulvers, das Nanoobjekte enthält, eine explosionsfähige Atmosphäre zu erzeugen, und Beurteilung seines Explosionsverhaltens.
Dieses Dokument ist nicht für die Anwendung auf anerkannte Explosivstoffe, wie z. B. Schießpulver und Dynamit, auf Explosivstoffe, die zur Verbrennung keinen Sauerstoff benötigen, oder auf Substanzen oder Stoffgemische, die sich unter bestimmten Umständen ähnlich wie diese verhalten, geeignet. Bestehen Zweifel über das Vorliegen einer Gefährdung aufgrund von Explosionsfähigkeit, ist es ratsam, sich an einen Sachverständigen zu wenden.
Nanotechnologies - Lignes directrices pour la détermination de protocoles pour l’explosivité et l’inflammabilité de poudre contenant des nano-objets (pour le transport, la manipulation et le stockage) central
Le présent document spécifie des lignes directrices sur les protocoles permettant de déterminer les caractéristiques d’explosivité et d’inflammabilité des poudres contenant des nano-objets manufacturés. Ces caractéristiques d’explosivité et d’inflammabilité sont nécessaires pour établir les fiches de données de sécurité utiles pour la sécurité du stockage, la mise en oeuvre et le transport des poudres.
Le présent document fournit notamment des lignes directrices sur les protocoles concernant :
- la détermination des caractéristiques d’inflammabilité des poudres contenant des nano-objets au regard de leur sensibilité aux sources d’inflammation ;
- la capacité d’une poudre contenant des nano-objets à générer une atmosphère explosive et l’évaluation des caractéristiques d’explosion de cette poudre.
Le présent document ne s’applique ni aux explosifs reconnus tels que la poudre noire et la dynamite, ni aux explosifs dont la combustion ne nécessite pas la présence d’oxygène, ni aux substances ou mélanges de substances susceptibles d’avoir un comportement analogue dans certaines circonstances. En cas de doute sur l’existence d’un danger dû aux propriétés explosives, il est fortement recommandé de solliciter l’avis d’un expert.
Nanotehnologija - Smernice za določanje protokolov za eksplozivnost in vnetljivost praškov, ki vsebujejo nanomateriale (za transport, ravnanje z njimi in shranjevanje)
Ta dokument vsebuje smernice za določanje protokolov za lastnosti eksplozivnosti in vnetljivosti praškov, ki vsebujejo proizvedene nanomateriale. Te lastnosti eksplozivnosti in vnetljivosti so potrebne za varnostne tehnične liste pri varnem skladiščenju, rokovanju in prevozu prahu.
Ta dokument bo zlasti zagotovil smernice za protokole glede:
– določanja lastnosti vnetljivosti praškov, ki vsebujejo nanomateriale, glede na občutljivost virov vžiga;
– zmožnost nanomaterialov, ki vsebujejo prašek, da ustvarijo eksplozivno okolje, in oceno lastnosti eksplozivnosti.
Ta dokument ni primeren za uporabo z znanimi eksplozivi, kot sta smodnik in dinamit, z eksplozivnimi materiali, ki za zgorevanje ne potrebujejo kisika, s snovmi ali mešanicami snovi, ki lahko v nekaterih okoliščinah delujejo na podoben način. Kadar obstaja kakršen koli dvom o obstoju nevarnosti zaradi eksplozivnih lastnosti, je najbolje poiskati nasvet strokovnjaka.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN/TS 17274:2019
01-marec-2019
1DQRWHKQRORJLMD6PHUQLFH]DGRORþDQMHSURWRNRORY]DHNVSOR]LYQRVWLQ
YQHWOMLYRVWSUDãNRYNLYVHEXMHMRQDQRPDWHULDOH ]DWUDQVSRUWUDYQDQMH]QMLPLLQ
VKUDQMHYDQMH
Nanotechnologies - Guidelines for determining protocols for the explosivity and
flammability of powders containing nano-objects (for transport, handling and storage)
Nanotechnologien - Leitfaden für Protokolle zur Bestimmung des Brand- und
Explosionsverhaltens von Pulvern, die Nano-Objekte beinhalten (für Transport,
Handhabung und Lagerung)
Nanotechnologies - Lignes directrices pour la détermination de protocoles pour
l’explosivité et l’inflammabilité de poudre contenant des nano-objets (pour le transport, la
manipulation et le stockage) central
Ta slovenski standard je istoveten z: CEN/TS 17274:2018
ICS:
07.120 Nanotehnologije Nanotechnologies
13.220.40 Sposobnost vžiga in Ignitability and burning
obnašanje materialov in behaviour of materials and
proizvodov pri gorenju products
13.230 Varstvo pred eksplozijo Explosion protection
SIST-TS CEN/TS 17274:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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CEN/TS 17274
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
December 2018
TECHNISCHE SPEZIFIKATION
ICS 07.120
English Version
Nanotechnologies - Guidelines for determining protocols
for the explosivity and flammability of powders containing
nano-objects (for transport, handling and storage)
Nanotechnologies - Lignes directrices sur les Nanotechnologien - Leitfaden für Protokolle zur
protocoles permettant de déterminer les Bestimmung des Brand- und Explosionsverhaltens von
caractéristiques d'explosivité et d'inflammabilité des Pulvern, die Nano-Objekte beinhalten (für Transport,
poudres contenant des nano-objets (en vue de leur Handhabung und Lagerung)
transport, manipulation et stockage)
This Technical Specification (CEN/TS) was approved by CEN on 28 September 2018 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17274:2018 E
worldwide for CEN national Members.
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Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Safe handling of powders containing nano-objects . 7
5 Preparation and characterization of samples . 7
5.1 Receipt of sample . 7
5.2 Characterization of the sample . 7
5.3 Preparation of sample . 8
6 Flammability characteristics - Test methods to characterize the sensitivity to ignition
sources . 8
6.1 Test for pyrophoricity of a powder containing nano-objects . 8
6.2 Flammability characteristics in layers and accumulations . 9
6.3 Flammability characteristics in clouds . 12
7 Test methods for the determination of explosion characteristics . 13
7.1 Explosivity . 13
7.2 Determination of Minimum Ignition Energy (MIE) . 15
7.3 Determination of explosion characteristics . 15
8 Test report . 18
Annex A (informative) Figures of test equipment . 20
Annex B (informative) Example of test report for the explosivity of aluminum nanoparticles
. 29
Bibliography . 31
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European foreword
This document (CEN/TS 17274:2018) has been prepared by Technical Committee CEN/TC 352
"Nanotechnologies", the secretariat of which is 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 shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN/CENELEC Internal Regulations, the national standards organisations 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, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
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1 Scope
This document provides protocol guidelines for determining explosivity and flammability characteristics
of powders containing manufactured nano-objects. These explosivity and flammability characteristics
are needed for safety data sheets for safe storage, handling and transport of any powder.
In particular, this document will provide protocol guidelines concerning:
— the determination of flammability characteristics of powders containing nano-objects with regard to
sensitivity to ignition sources;
— the ability of a powder containing nano-objects to generate an explosive atmosphere and the
assessment of its explosion characteristics.
This document is not suitable for use with recognized explosives, such as gunpowder and dynamite,
explosives which do not require oxygen for combustion, or substances or mixtures of substances which
may under some circumstances behave in a similar manner. Where any doubt exists about the existence
of hazard due to explosive properties, it is best to seek expert advice.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 14034-1:2004+A1:2011, Determination of explosion characteristics of dust clouds — Part 1:
Determination of the maximum explosion pressure p of dust clouds
max
EN 14034-2:2006+A1:2011, Determination of explosion characteristics of dust clouds — Part 2:
Determination of the maximum rate of explosion pressure rise (dp/dt) of dust clouds
max
EN 14034-3:2006+A1:2011, Determination of explosion characteristics of dust clouds — Part 3:
Determination of the lower explosion limit LEL of dust clouds
EN 14034-4:2004+A1:2011, Determination of explosion characteristics of dust clouds — Part 4:
Determination of the limiting oxygen concentration LOC of dust clouds
EN ISO/IEC 80079-20-2:2016, Explosive atmospheres — Part 20-2: Material characteristics —
Combustible dusts test methods (ISO/IEC 80079-20-2:2016)
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:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
powder
assembly of discrete particles usually less than 1 mm in size
[SOURCE: EN ISO 3252:2000, 1001]
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3.2
nano-object
discrete piece of material with one, two or three external dimensions in the nanoscale
Note 1 to entry: The second and third external dimensions are orthogonal to the first dimension and to each
other.
[SOURCE: CEN ISO/TS 80004-1:2015, 2.5]
3.3
powder containing nano-objects
powder containing a specific relative amount of nano-objects in number, or displaying a specific surface
area per volume, above a specific threshold value
3.4
smouldering temperature
describes the flammability behaviour of a flat dust layer on a hot surface. It is defined as the lowest
temperature of a heated, free-standing surface which is capable of igniting a powder containing
nano-objects
3.5
cloud
solids dispersed in a gaseous phase
3.6
flammable powder containing nano-objects
combustible powder containing nano-objects which ignites and burns, under effective ignition sources
(see Clause 6)
Note 1 to entry: For the purpose of this document, the flammability characteristics of a powder containing
nano-objects will be viewed as its sensitivity to thermal ignition sources.
3.7
pyrophoric solid
solid substance or mixture which, even in small quantities, is liable to ignite after coming into contact
with air at ambient conditions.
Note 1 to entry: For the purpose of this document, pyrophoric powder containing nano-objects are considered to
be flammable and may yield explosive atmospheres.
3.8
combustible powder
powder able to undergo an exothermic oxidation reaction with air when ignited
3.9
explosive atmosphere containing nano-objects
combustible powder containing nano-objects which may form an explosive mixture with air at
atmospheric conditions
3.10
explosivity of an atmosphere containing nano-objects
aptitude of an explosive atmosphere containing nano-objects to explode.
Note 1 to entry: For the purpose of this document, the explosivity of a combustible powder will reside in its
ability to form an explosive atmosphere in which a combustion reaction can propagate
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3.11 Flammability characteristics
3.11.1
minimum ignition temperature (MIT) in layer of a powder containing nano-objects
lowest temperature of a hot surface at which ignition occurs in air in a layer of combustible powder
containing nano-objects under specified test conditions
3.11.2
minimum ignition temperature (MIT) in cloud of a powder containing nano-objects
lowest temperature of a hot surface on which the most ignitable mixture of dispersed combustible nano-
objects and air is ignited under specified test conditions
3.11.3
self-ignition temperature of accumulations of powders containing nano-objects
highest temperature of a given volume of an accumulation of a powder containing nano-objects which
does not ignite
3.12 Explosion characteristics
3.12.1
minimum ignition energy (MIE) of an atmosphere containing nano-objects
smallest electrical energy stored in a capacitor, which is sufficient enough to ignite an explosive mixture
in its most critical composition when discharged via a spark gap
3.12.2
lower explosion limit
LEL
highest concentration at which an explosion is not detected in three successive tests (see Clause 7)
3.12.3
initial pressure
P
i
pressure inside the explosion vessel at the moment of ignition
3.12.4
initial air temperature
T
i
temperature inside the explosion vessel at the moment of ignition
3.12.5
explosion pressure
p
ex
highest over pressure relative to the initial pressure occurring in a closed vessel during the explosion of
a specific mixture of flammable powder containing nano-objects with air or air and inert substances
determined under specified test conditions
3.12.6
maximum explosion pressure
p
max
maximum explosion overpressure (pressure above initial pressure conditions) during explosions of all
explosive atmospheres in the explosion range of a combustible substance in a closed vessel under
specified test conditions and ambient atmospheric conditions
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3.12.7
maximum rate of pressure rise
(dp/dt)
max
maximum rate of explosion pressure rise is the maximum value of the pressure rise per unit time during
explosions of all explosive atmospheres in the explosion range of a combustible substance in a closed
vessel under specified test conditions and standard atmospheric conditions
3.12.8
normalized maximum rate of pressure rise
Kst, Kmax
K and K are equivalent and defined as the maximum rate of pressure rise normalized for a container
st max
3
size of 1 m (see 7.3.4.3)
Note 1 to entry: In K , st (staub) means dust in German.
st
3.12.9
limiting oxygen concentration
LOC
highest oxygen concentration in a mixture of a combustible dust and air and an inert gas, in which an
explosion will not occur.
4 Safe handling of powders containing nano-objects
Preventive and protective safety measures, described as for example in ISO/TR 12885:2008 should be
taken in carrying out all the tests discussed in this document. It is nevertheless advised to avoid using
pyrophoric powders in the explosivity and flammability tests. Usual fire and explosion safety measures
should be taken.
In the following, various tests of characterization related to the flammability and explosivity of powders
containing nano-objects are presented. The choice of the tests to be conducted will depend upon the
specific application of the user.
5 Preparation and characterization of samples
5.1 Receipt of sample
For very reactive powders containing nano-objects, samples can be received in suitable containers of
small sizes (e.g.: 100 g/200 g), prepared under partial vacuum conditions or under argon or any inert
preferably nontoxic fluid that can easily be separated from the solids.
The type of package used to store and transport the powder should be reported since it may alter the
product specification and modify the explosivity and flammability characteristics of the powder
containing nano-objects.
To be most representative of the material being used in the process, standardized sampling procedures
should be followed, as the one described, for example, in the ISO 10725:2000. If no standardized sampling
procedures are followed, the sample provider should mention that no sampling procedures were
followed in providing the sample.
5.2 Characterization of the sample
The powder containing nano-objects shall be at least characterized in terms of particle size distribution
and moisture content as:
— particle size distribution (d , median d , d ) by any suitable methods in terms of volume,
10% 50% 90%
number (e.g. CEN ISO/TS 12025:2015, ISO 13320:2009, CEN/TS 17010:2016);
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— moisture content (e.g. EN 14346:2006).
NOTE Additional characteristics may prove useful for interpretation of test results. These may include:
— nano-object size and shape of constituent or primary particles, possibly by TEM or SEM methods
(e.g. CEN ISO/TS 17200:2015, ISO 13322-1:2014 and ISO 13322-2:2006);
— specific Surface Area, possibly by BET method (e.g. ISO 9277:2010).
These techniques may help assess whether the powder containing nano-objects exceeds a given
threshold in terms of number size distribution or specific surface area per volume (e.g. 50 % in number
2 3
size distribution or 60 m /cm in specific surface area per volume). For such typical cases, increased
vigilance on safety measures in handling and testing reactive powders should be given (see Clause 4).
Each method used for sample characterization should be mentioned in the report (e.g. use of Electron
microscopy for particle size distribution measurements, protocol for measuring moisture content,…).
5.3 Preparation of sample
If it is not possible to test the sample as received (for example if the particle sizes are too large to be
tested), or if the sample is to be tested under most conservative conditions, it may then be necessary to
prepare specifically the sample for testing. This may include:
— Drying:
Drying should be performed without significantly decreasing the reactivity of the material.
— Sieving and/or milling/grinding (< 63 µm object size, to remove large objects):
If sieving does not yield the desired results, milling/grinding should be considered.
If milling, grinding or sieving is required, the samples should be prepared in a safe manner.
The sample preparation steps should be reported because the sample explosivity/flammability
characteristics may be altered during these procedures. Pre-conditioning status of the sample received
(e.g. use of inert gas) should be mentioned. If the samples are tested as received, the test report should
mention it.
NOTE Sample preparation such as grinding and sieving, or drying may alter the material characteristics. For
mixtures of powders, sample preparation can result in changes to the sample composition, which in turn can result
in changes to the experimentally determined parameters.
Characterization of the powder to be tested shall be reported.
6 Flammability characteristics - Test methods to characterize the sensitivity to
ignition sources
6.1 Test for pyrophoricity of a powder containing nano-objects
6.1.1 Test Equipment
Inert (non electrically charged) spoon, non combustible support.
6.1.2 Test Procedure and reporting results
A sufficient amount of the test substance (e.g.: 1 ml to 2 ml ) is dropped from a height of 1 m through air
onto a non-combustible support. It is observed whether the substance starts burning during the fall or
within 5 min after the complete fall.
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Six trials are made. A substance is considered as "pyrophoric" if ignition occurs at least in one trial. In this
case, there is no need to further test flammability characterisitics.
6.2 Flammability characteristics in layers and accumulations
6.2.1 Burning tests
6.2.1.1 General
The aim of the test is to determine if and to what extent a fire started by an external source will propagate
in a layer consisting of a powder containing nano-objects.
Two tests should be considered. The first one is a screening test so as to qualify the burning behaviour of
the powder, and the second one is to quantify the degree of flammability (burning rate) of the powder.
6.2.1.2 Determination of the burning behaviour as a screening procedure
6.2.1.2.1 Test equipment
Ceramic plate, electrically heated glowing platinum wire at approximately 1 000 °C (diameter 1 mm,
length 86 mm, intensity 30 A).
6.2.1.2.2 Test procedure and reporting results
3
At room temperature, the prepared sample (approximately 5 cm ) is deposited on the ceramic plate as a
strip approximately 2 cm wide and 4 cm long (Annex A, Figure A.1). One tries to ignite, within 15 s to 30 s,
the sample from one end of the strip with the glowing platinum wire. In case of no ignition with the
platinum wire, one can use a gas burner (minimum diameter 5 mm, at least 1 000 °C).
This screening test is carried out in a laminar flow hood. The burning characteristics are observed and
rated as follows (Combustibility Indices 1 to 6, as follows):
1) No ignition
2) Extinction after short burning
3) Local burning or glowing, limited spread of the flame
4) Smouldering fire or slow flameless decomposition
5) Complete combustion of the heap
6) Very fast combustion or fast flameless decomposition
NOTE For metallic powders, ignition with a gas burner is advised.
6.2.1.3 Determination of burning rate of a layer of a powder containing nano-objects
6.2.1.3.1 Test equipment
Mould, gas flame micro burner or electrically heated glowing platinum wire (1 000 °C), placed into a
laminar flow fume hood.
6.2.1.3.2 Test procedure and reporting results
Using a mould, a powder train of 250 mm length, 20 mm width and 10 mm height (Annex A, Figure A.2)
is produced on an impervious, low heat-conducting base plate. The powder train is ignited at one end
with the glowing platinum wire. In case of no ignition with the platinum wire, one can use a gas burner
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(minimum diameter 5 mm, at least 1 000 °C). The ignition time is generally set up to 2 min, and up
to 5 min for metal powders.
In a preliminary test, it is observed, whether the combustion propagates over a distance of 200 mm
within 4 minutes. If the time is longer than 4 minutes (and 40 minutes for metal powders), the substance
is considered as not "highly flammable solid". No further testing is required. In all other cases, the burning
rate is determined by measuring the combustion time for over a distance of 100 mm after an initial
burning distance of 80 mm from the ignition point.
A substance is classified a "highly flammable solid" if the combustion time over 100 mm is less than 45 s
(or 10 min for metal powders) in one of six trials.
6.2.2 Determination of MIT of a layer of powder containing nano-objects
6.2.2.1 Test equipment
The apparatus consists of a heated plate and a powder ring (A suitable system is given in Annex A,
Figure A.3).
Electrically heated circular plate made out of stainless steel, diameter 200 mm, thickness
approximately 20 mm, electric power 2 kW to 3 kW, temperature controller and temperature recorder
for the plate and sample temperature.
6.2.2.2 Test procedure and reporting results
For the determination of the minimum ignition temperature a layer of 5 mm thickness and with a
diameter of 10 cm is prepared on a heating plate. Then it is exposed during at least 30 min (within
a 2 h limit) to a constant elevated temperature of the plate. The Minimum Ignition Temperature (MIT) of
the layer is the lowest temperature of the plate, at which the layer ignites, smoulders or self-heats to a
temperature of 450 °C or 250 °C above the temperature of the plate. If none of these three conditions are
met during four trials of at least 30 min (within a 2 h limit) each, the result of the plate temperature test
is considered negative and the test is carried out at higher temperatures. In practice, the lowest
temperature rounded down to an even 10 °C which will just result in a smouldering appearance or
ignition will be defined as the MIT of the layer.
For further details, refer to EN ISO/IEC 80079-20-2:2016.
6.2.3 Determination of the spontaneous ignition behaviour of accumulations of powder
containing nano-objects
NOTE These are powders which, in contact with air, are liable to self-heating.
6.2.3.1 Screening test procedure for self-ignition temperature and reporting results
6.2.3.1.1 Test equipment
Oven
A temperature-programmed laboratory oven (volume about 2 l) fitted with natural air circulation and
explosion relief system (A suitable equipment is given in Annex A, Figure A.4).
Wire mesh cube
Stainless steel wire mesh basket.
6.2.3.1.2 Test procedure and reporting of the results
The size of the wire mesh has to be chosen in such a way that the powder cannot fall through the mesh
and the diffusion of oxygen from the oven air should not be hindered. This test can only be applicable if
the powder can be kept in the basket during the experiment.
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Approximately 8 ml of the test substance are filled into the small wire basket of 2 cm × 2 cm × 2 cm and
then heated in an oven at a constant rate of approximately 0,5 °C/min. up to 400 °C. The temperatures in
the centre of the sample and in the oven are recorded (Annex A, Figure A.4). The test can be carried out
only up to the melting point of the sample.
When the sample thermocouple measures a temperature rise above the oven temperature, the sample is
self-heating.
The temperature in the oven, for which the temperature of the sample reaches 400 °C, is indicative of the
self-ignition temperature in air for this sample volume. This screening test can provide self-ignition
temperature ranges that can be used for a more precise evaluation of the self-ignition temperature
through an isothermal procedure as described in EN 15188:2007.
6.2.3.2 Spontaneous combustion properties of accumulations of powders containing nano-
objects
6.2.3.2.1 Self-heating substance: Test procedure and reporting results
6.2.3.2.1.1 Test equipment
The test substance (sample) is filled into a stainless steel wire basket and then put into a ventilated
heating chamber with fresh air inlet (approximately 2 L/min), where it is exposed to a defined constant
temperature.
6.2.3.2.1.2 Reporting results
A substance is to be regarded as self-heating substance, if the ΔT-signal (Temperature difference between
the sample and the air in the oven) for a 10 cm × 10 cm × 10 cm cubic wire basket exceeds + 60 °C
within 24 h at a heating chamber temperature of 140 °C.
6.2.3.2.2 Self -ignition temperature of a powder accumulation
6.2.3.2.2.1 Test equipment
The test substance (sample) is filled into stainless steel wire baskets and then put into a heating chamber
3
(e.g. oven) of natural or forced convection. Volumes of these baskets can range from 10 cm to more
3
than 1 000 cm .
6.2.3.2.2.2 Reporting results
The temperature difference between the sample and the air in the chamber (i.e. the ΔT-signal) is recorded
and plotted against time (Annex A, Figure A.4).
If during the test a positive ΔT-signal is observed, it indicates an exothermic reaction. The most probable
cause for this is oxidation. In some cases, the exothermic reaction occurs only after a certain induction
time. Such reactions are called "autocatalytic". A positive ΔT indicates that the sample is self-heating.
Once the self-ignition temperature range has been determined by the screening procedure discussed
in 6.2.3.1, the self-ignition temperature for a powder accumulation can be defined as the oven
temperature at which the sample rises 60 °C above the oven temperature. This self-ignition temperature
is sample volume dependent and should be reported as function of the sample volume and sample
external surface area. Further details can be found in EN 15188:2007.
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6.3 Flammability characteristics in clouds
6.3.1 General
Two methods for measuring the MIT (Minimum Ignition Temperature) of an atmosphere containing
nano-objects are described:
— the GG (Godbert-Greenwald) oven;
— or the BAM (Bundesanstalt für Materialforschung und prüfung) oven method.
6.3.2 Determination of MIT in cloud of a powder containing nano-objects - Godbert Greenwald
Oven
6.3.2.1 Test equipment
A detailed description o
...
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Nanotechnologies - Guidelines for determining protocols for the explosivity and
flammability of powders containing nano-objects (for transport, handling and storage)
Nanotechnologien - Leitfaden für Protokolle zur Bestimmung des Brand- und
Explosionsverhaltens von Pulvern, die Nano-Objekte beinhalten (für Transport,
Handhabung und Lagerung)
Nanotechnologies - Lignes directrices pour la détermination de protocoles pour
l’explosivité et l’inflammabilité de poudre contenant des nano-objets (pour le transport, la
manipulation et le stockage) central
Ta slovenski standard je istoveten z: FprCEN/TS 17274
ICS:
07.120 Nanotehnologije Nanotechnologies
13.220.40 Sposobnost vžiga in Ignitability and burning
obnašanje materialov in behaviour of materials and
proizvodov pri gorenju products
13.230 Varstvo pred eksplozijo Explosion protection
kSIST-TS FprCEN/TS 17274:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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kSIST-TS FprCEN/TS 17274:2018
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kSIST-TS FprCEN/TS 17274:2018
FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17274
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
June 2018
ICS 07.120
English Version
Nanotechnologies - Guidelines for determining protocols
for the explosivity and flammability of powders containing
nano-objects (for transport, handling and storage)
Nanotechnologies - Lignes directrices pour la Nanotechnologien - Leitfaden für Protokolle zur
détermination de protocoles pour l'explosivité et Bestimmung des Brand- und Explosionsverhaltens von
l'inflammabilité de poudre contenant des nano-objets Pulvern, die Nano-Objekte beinhalten (für Transport,
(pour le transport, la manipulation et le stockage) Handhabung und Lagerung)
central
This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/TC 352.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
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.
Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change
without notice and shall not be referred to as a Technical Specification.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 17274:2018 E
worldwide for CEN national Members.
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Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Safe handling of powders containing nano-objects . 7
5 Preparation and characterization of samples . 7
5.1 Receipt of sample . 7
5.2 Characterization of the sample . 7
5.3 Preparation of sample . 8
6 Flammability characteristics - Test methods to characterize the sensitivity to ignition
sources . 8
6.1 Test for pyrophoricity of a powder containing nano-objects . 8
6.2 Flammability characteristics in layers and accumulations . 9
6.3 Flammability characteristics in clouds . 12
7 Test methods for the determination of explosion characteristics . 13
7.1 Explosivity . 13
7.2 Determination of Minimum Ignition Energy (MIE) . 15
7.3 Determination of explosion characteristics . 15
8 Test report . 18
Annex A (informative) Figures of test equipment . 20
Annex B (informative) Example of test report for the explosivity of aluminum nanoparticles
. 29
Bibliography . 31
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European foreword
This document (FprCEN/TS 17274:2018) has been prepared by Technical Committee CEN/TC 352
"Nanotechnologies", the secretariat of which is held by AFNOR.
This document is currently submitted to the Vote on TS.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
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1 Scope
This document provides protocol guidelines for determining explosivity and flammability characteristics
of powders containing manufactured nano-objects. These explosivity and flammability characteristics
are needed for safety data sheets for safe storage, handling and transport of any powder.
In particular, this document will provide protocol guidelines concerning:
— the determination of flammability characteristics of powders containing nano-objects with regard to
sensitivity to ignition sources;
— the ability of a powder containing nano-objects to generate an explosive atmosphere and the
assessment of its explosion characteristics.
This document is not suitable for use with recognized explosives, such as gunpowder and dynamite,
explosives which do not require oxygen for combustion, or substances or mixtures of substances which
may under some circumstances behave in a similar manner. Where any doubt exists about the existence
of hazard due to explosive properties, it is best to seek expert advice.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 14034-1:2004+A1:2011, Determination of explosion characteristics of dust clouds - Part 1:
Determination of the maximum explosion pressure pmax of dust clouds
EN 14034-2:2006+A1:2011, Determination of explosion characteristics of dust clouds - Part 2:
Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds
EN 14034-3:2006+A1:2011, Determination of explosion characteristics of dust clouds - Part 3:
Determination of the lower explosion limit LEL of dust clouds
EN 14034-4:2004+A1:2011, Determination of explosion characteristics of dust clouds - Part 4:
Determination of the limiting oxygen concentration LOC of dust clouds
EN ISO/IEC 80079-20-2:2016, Explosive atmospheres - Part 20-2: Material characteristics - Combustible
dusts test methods
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:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
powder
assembly of discrete particles usually less than 1 mm in size
[SOURCE: EN ISO 3252:2000, 1001]
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3.2
nano-object
discrete piece of material with one, two or three external dimensions in the nanoscale
Note 1 to entry: The second and third external dimensions are orthogonal to the first dimension and to each
other.
[SOURCE: CEN ISO/TS 80004-1:2015, 2.5]
3.3
powder containing nano-objects
powder containing a specific relative amount of nano-objects in number, or displaying a specific surface
area per volume, above a specific threshold value
3.4
smouldering temperature
describes the flammability behaviour of a flat dust layer on a hot surface. It is defined as the lowest
temperature of a heated, free-standing surface which is capable of igniting a powder containing
nano-objects
3.5
cloud
solids dispersed in a gaseous phase
3.6
flammable powder containing nano-objects
combustible powder containing nano-objects which ignites and burns, under effective ignition sources
(see Clause 6)
Note 1 to entry: For the purpose of this document, the flammability characteristics of a powder containing
nano-objects will be viewed as its sensitivity to thermal ignition sources.
3.7
pyrophoric solid
solid substance or mixture which, even in small quantities, is liable to ignite after coming into contact
with air at ambient conditions.
Note 1 to entry: For the purpose of this document, pyrophoric powder containing nano-objects are considered to
be flammable and may yield explosive atmospheres.
3.8
combustible powder
powder able to undergo an exothermic oxidation reaction with air when ignited
3.9
explosive atmosphere containing nano-objects
combustible powder containing nano-objects which may form an explosive mixture with air at
atmospheric conditions
3.10
explosivity of an atmosphere containing nano-objects
aptitude of an explosive atmosphere containing nano-objects to explode.
Note 1 to entry: For the purpose of this document, the explosivity of a combustible powder will reside in its
ability to form an explosive atmosphere in which a combustion reaction can propagate
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3.11 Flammability characteristics
3.11.1
minimum ignition temperature (MIT) in layer of a powder containing nano-objects
lowest temperature of a hot surface at which ignition occurs in air in a layer of combustible powder
containing nano-objects under specified test conditions
3.11.2
minimum ignition temperature (MIT) in cloud of a powder containing nano-objects
lowest temperature of a hot surface on which the most ignitable mixture of dispersed combustible nano-
objects and air is ignited under specified test conditions
3.11.3
self-ignition temperature of accumulations of powders containing nano-objects
highest temperature of a given volume of an accumulation of a powder containing nano-objects which
does not ignite
3.12 Explosion characteristics
3.12.1
minimum ignition energy (MIE) of an atmosphere containing nano-objects
smallest electrical energy stored in a capacitor, which is sufficient enough to ignite an explosive mixture
in its most critical composition when discharged via a spark gap
3.12.2
lower explosion limit
LEL
highest concentration at which an explosion is not detected in three successive tests (see Clause 7)
3.12.3
initial pressure
P
i
pressure inside the explosion vessel at the moment of ignition
3.12.4
initial air temperature
T
i
temperature inside the explosion vessel at the moment of ignition
3.12.5
explosion pressure
p
ex
highest over pressure relative to the initial pressure occurring in a closed vessel during the explosion of
a specific mixture of flammable powder containing nano-objects with air or air and inert substances
determined under specified test conditions
3.12.6
maximum explosion pressure
p
max
maximum explosion overpressure (pressure above initial pressure conditions) during explosions of all
explosive atmospheres in the explosion range of a combustible substance in a closed vessel under
specified test conditions and ambient atmospheric conditions
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3.12.7
maximum rate of pressure rise
(dp/dt)
max
maximum rate of explosion pressure rise is the maximum value of the pressure rise per unit time during
explosions of all explosive atmospheres in the explosion range of a combustible substance in a closed
vessel under specified test conditions and standard atmospheric conditions
3.12.8
normalized maximum rate of pressure rise
Kst, Kmax
K and K are equivalent and defined as the maximum rate of pressure rise normalized for a container
st max
3
size of 1 m (see 7.3.4.3)
Note 1 to entry: In K , st (staub) means dust in German.
st
3.12.9
limiting oxygen concentration
LOC
highest oxygen concentration in a mixture of a combustible dust and air and an inert gas, in which an
explosion will not occur.
4 Safe handling of powders containing nano-objects
Preventive and protective safety measures, described as for example in ISO/TR 12885:2008 should be
taken in carrying out all the tests discussed in this document. It is nevertheless advised to avoid using
pyrophoric powders in the explosivity and flammability tests. Usual fire and explosion safety measures
should be taken.
In the following, various tests of characterization related to the flammability and explosivity of powders
containing nano-objects are presented. The choice of the tests to be conducted will depend upon the
specific application of the user.
5 Preparation and characterization of samples
5.1 Receipt of sample
For very reactive powders containing nano-objects, samples can be received in suitable containers of
small sizes (e.g.: 100 g/200 g), prepared under partial vacuum conditions or under argon or any inert
preferably nontoxic fluid that can easily be separated from the solids.
The type of package used to store and transport the powder should be reported since it may alter the
product specification and modify the explosivity and flammability characteristics of the powder
containing nano-objects.
To be most representative of the material being used in the process, standardized sampling procedures
should be followed, as the one described, for example, in the ISO 10725:2000. If no standardized sampling
procedures are followed, the sample provider should mention that no sampling procedures were
followed in providing the sample.
5.2 Characterization of the sample
The powder containing nano-objects shall be at least characterized in terms of particle size distribution
and moisture content as:
— particle size distribution (d , median d , d ) by any suitable methods in terms of volume,
10% 50% 90%
number (e.g. CEN ISO/TS 12025:2015, ISO 13320:2009, CEN/TS 17010:2016);
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— moisture content (e.g. EN 14346:2006).
NOTE Additional characteristics may prove useful for interpretation of test results. These may include:
— nano-object size and shape of constituent or primary particles, possibly by TEM or SEM methods
(e.g. CEN ISO/TS 17200:2015, ISO 13322-1:2014 and ISO 13322-2:2006);
— specific Surface Area, possibly by BET method (e.g. ISO 9277:2010).
These techniques may help assess whether the powder containing nano-objects exceeds a given
threshold in terms of number size distribution or specific surface area per volume (e.g. 50 % in number
2 3
size distribution or 60 m /cm in specific surface area per volume). For such typical cases, increased
vigilance on safety measures in handling and testing reactive powders should be given (see Clause 4).
Each method used for sample characterization should be mentioned in the report (e.g. use of Electron
microscopy for particle size distribution measurements, protocol for measuring moisture content,…).
5.3 Preparation of sample
If it is not possible to test the sample as received (for example if the particle sizes are too large to be
tested), or if the sample is to be tested under most conservative conditions, it may then be necessary to
prepare specifically the sample for testing. This may include:
— Drying:
Drying should be performed without significantly decreasing the reactivity of the material.
— Sieving and/or milling/grinding (< 63 µm object size, to remove large objects):
If sieving does not yield the desired results, milling/grinding should be considered.
If milling, grinding or sieving is required, the samples should be prepared in a safe manner.
The sample preparation steps should be reported because the sample explosivity/flammability
characteristics may be altered during these procedures. Pre-conditioning status of the sample received
(e.g. use of inert gas) should be mentioned. If the samples are tested as received, the test report should
mention it.
NOTE Sample preparation such as grinding and sieving, or drying may alter the material characteristics. For
mixtures of powders, sample preparation can result in changes to the sample composition, which in turn can result
in changes to the experimentally determined parameters.
Characterization of the powder to be tested shall be reported.
6 Flammability characteristics - Test methods to characterize the sensitivity to
ignition sources
6.1 Test for pyrophoricity of a powder containing nano-objects
6.1.1 Test Equipment
Inert (non electrically charged) spoon, non combustible support.
6.1.2 Test Procedure and reporting results
A sufficient amount of the test substance (e.g.: 1 ml to 2 ml ) is dropped from a height of 1 m through air
onto a non-combustible support. It is observed whether the substance starts burning during the fall or
within 5 min after the complete fall.
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Six trials are made. A substance is considered as "pyrophoric" if ignition occurs at least in one trial. In this
case, there is no need to further test flammability characterisitics.
6.2 Flammability characteristics in layers and accumulations
6.2.1 Burning tests
6.2.1.1 General
The aim of the test is to determine if and to what extent a fire started by an external source will propagate
in a layer consisting of a powder containing nano-objects.
Two tests should be considered. The first one is a screening test so as to qualify the burning behaviour of
the powder, and the second one is to quantify the degree of flammability (burning rate) of the powder.
6.2.1.2 Determination of the burning behaviour as a screening procedure
6.2.1.2.1 Test equipment
Ceramic plate, electrically heated glowing platinum wire at approximately 1 000 °C (diameter 1 mm,
length 86 mm, intensity 30 A).
6.2.1.2.2 Test procedure and reporting results
3
At room temperature, the prepared sample (approximately 5 cm ) is deposited on the ceramic plate as a
strip approximately 2 cm wide and 4 cm long (Annex A, Figure A.1). One tries to ignite, within 15 s to 30 s,
the sample from one end of the strip with the glowing platinum wire. In case of no ignition with the
platinum wire, one can use a gas burner (minimum diameter 5 mm, at least 1 000 °C).
This screening test is carried out in a laminar flow hood. The burning characteristics are observed and
rated as follows (Combustibility Indices 1 to 6, as follows):
1) No ignition
2) Extinction after short burning
3) Local burning or glowing, limited spread of the flame
4) Smouldering fire or slow flameless decomposition
5) Complete combustion of the heap
6) Very fast combustion or fast flameless decomposition
NOTE For metallic powders, ignition with a gas burner is advised.
6.2.1.3 Determination of burning rate of a layer of a powder containing nano-objects
6.2.1.3.1 Test equipment
Mould, gas flame micro burner or electrically heated glowing platinum wire (1 000 °C), placed into a
laminar flow fume hood.
6.2.1.3.2 Test procedure and reporting results
Using a mould, a powder train of 250 mm length, 20 mm width and 10 mm height (Annex A, Figure A.2)
is produced on an impervious, low heat-conducting base plate. The powder train is ignited at one end
with the glowing platinum wire. In case of no ignition with the platinum wire, one can use a gas burner
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(minimum diameter 5 mm, at least 1 000 °C). The ignition time is generally set up to 2 min, and up
to 5 min for metal powders.
In a preliminary test, it is observed, whether the combustion propagates over a distance of 200 mm
within 4 minutes. If the time is longer than 4 minutes (and 40 minutes for metal powders), the substance
is considered as not "highly flammable solid". No further testing is required. In all other cases, the burning
rate is determined by measuring the combustion time for over a distance of 100 mm after an initial
burning distance of 80 mm from the ignition point.
A substance is classified a "highly flammable solid" if the combustion time over 100 mm is less than 45 s
(or 10 min for metal powders) in one of six trials.
6.2.2 Determination of MIT of a layer of powder containing nano-objects
6.2.2.1 Test equipment
The apparatus consists of a heated plate and a powder ring (A suitable system is given in Annex A,
Figure A.3).
Electrically heated circular plate made out of stainless steel, diameter 200 mm, thickness
approximately 20 mm, electric power 2 kW to 3 kW, temperature controller and temperature recorder
for the plate and sample temperature.
6.2.2.2 Test procedure and reporting results
For the determination of the minimum ignition temperature a layer of 5 mm thickness and with a
diameter of 10 cm is prepared on a heating plate. Then it is exposed during at least 30 min (within
a 2 h limit) to a constant elevated temperature of the plate. The Minimum Ignition Temperature (MIT) of
the layer is the lowest temperature of the plate, at which the layer ignites, smoulders or self-heats to a
temperature of 450 °C or 250 °C above the temperature of the plate. If none of these three conditions are
met during four trials of at least 30 min (within a 2 h limit) each, the result of the plate temperature test
is considered negative and the test is carried out at higher temperatures. In practice, the lowest
temperature rounded down to an even 10 °C which will just result in a smouldering appearance or
ignition will be defined as the MIT of the layer.
For further details, refer to EN ISO/IEC 80079-20-2:2016.
6.2.3 Determination of the spontaneous ignition behaviour of accumulations of powder
containing nano-objects
NOTE These are powders which, in contact with air, are liable to self-heating.
6.2.3.1 Screening test procedure for self-ignition temperature and reporting results
6.2.3.1.1 Test equipment
Oven
A temperature-programmed laboratory oven (volume about 2 l) fitted with natural air circulation and
explosion relief system (A suitable equipment is given in Annex A, Figure A.4).
Wire mesh cube
Stainless steel wire mesh basket.
6.2.3.1.2 Test procedure and reporting of the results
The size of the wire mesh has to be chosen in such a way that the powder cannot fall through the mesh
and the diffusion of oxygen from the oven air should not be hindered. This test can only be applicable if
the powder can be kept in the basket during the experiment.
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Approximately 8 ml of the test substance are filled into the small wire basket of 2 cm × 2 cm × 2 cm and
then heated in an oven at a constant rate of approximately 0,5 °C/min. up to 400 °C. The temperatures in
the centre of the sample and in the oven are recorded (Annex A, Figure A.4). The test can be carried out
only up to the melting point of the sample.
When the sample thermocouple measures a temperature rise above the oven temperature, the sample is
self-heating.
The temperature in the oven, for which the temperature of the sample reaches 400 °C, is indicative of the
self-ignition temperature in air for this sample volume. This screening test can provide self-ignition
temperature ranges that can be used for a more precise evaluation of the self-ignition temperature
through an isothermal procedure as described in EN 15188:2007.
6.2.3.2 Spontaneous combustion properties of accumulations of powders containing nano-
objects
6.2.3.2.1 Self-heating substance: Test procedure and reporting results
6.2.3.2.1.1 Test equipment
The test substance (sample) is filled into a stainless steel wire basket and then put into a ventilated
heating chamber with fresh air inlet (approximately 2 L/min), where it is exposed to a defined constant
temperature.
6.2.3.2.1.2 Reporting results
A substance is to be regarded as self-heating substance, if the ΔT-signal (Temperature difference between
the sample and the air in the oven) for a 10 cm × 10 cm × 10 cm cubic wire basket exceeds + 60 °C
within 24 h at a heating chamber temperature of 140 °C.
6.2.3.2.2 Self -ignition temperature of a powder accumulation
6.2.3.2.2.1 Test equipment
The test substance (sample) is filled into stainless steel wire baskets and then put into a heating chamber
3
(e.g. oven) of natural or forced convection. Volumes of these baskets can range from 10 cm to more
3
than 1 000 cm .
6.2.3.2.2.2 Reporting results
The temperature difference between the sample and the air in the chamber (i.e. the ΔT-signal) is recorded
and plotted against time (Annex A, Figure A.4).
If during the test a positive ΔT-signal is observed, it indicates an exothermic reaction. The most probable
cause for this is oxidation. In some cases, the exothermic reaction occurs only after a certain induction
time. Such reactions are called "autocatalytic". A positive ΔT indicates that the sample is self-heating.
Once the self-ignition temperature range has been determined by the screening procedure discussed
in 6.2.3.1, the self-ignition temperature for a powder accumulation can be defined as the oven
temperature at which the sample rises 60 °C above the oven temperature. This self-ignition temperature
is sample volume dependent and should be reported as function of the sample volume and sample
external surface area. Further details can be found in EN 15188:2007.
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6.3 Flammability characteristics in clouds
6.3.1 General
Two methods for measuring the MIT (Minimum Ignition Temperature) of an atmosphere containing
nano-objects are described:
— the GG (Godbert-Greenwald) oven;
— or the BAM (Bundesanstalt für Materialforschung und prüfung) oven method.
6.3.2 Determination of MIT in cloud of a powder containing nano-objects - Godbert Greenwald
Oven
6.3.2.1 Test equipment
A detailed description of suitable equipment can be found in Annex A, Figure A.5.
6.3.2.2 Test procedure and reporting results
For the determination of MIT using the Godbert-Grenwald oven, the powder is initially blown, at 10 kPa
(gauge pressure) through a hot glass tube mounted vertically in a heating chamber.
Starting at 500 °C, if an ignition is observed, the test is repeated with fresh samples decreasing the
temperatures by intervals of 20 °C. If not, the temperature is increased by intervals of 50 °C until an
ignition is observed. In addition, to obtain the most severe ignition conditions, the amount of powder
injected into the tube and the blowing gauge pressure (from 2 kPa to 50 kPa (gauge pressure)) are varied,
because the flammability depends on the dust concentration and the residence time in the tube.
Once an ignition is observed, the temper
...
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