EN ISO 21646:2022

SLOVENSKI STANDARD
01-julij-2022
Nadomešča:
SIST EN 15413:2011
SIST EN 15443:2011
Trdna alternativna goriva - Priprava vzorca (ISO 21646:2022)
Solid recovered fuels - Sample preparation (ISO 21646:2022)
Feste Sekundärbrennstoffe - Probenvorbereitung (ISO 21646:2022)
Combustibles solides de récupération - Préparation des échantillons (ISO 21646:2022)
Ta slovenski standard je istoveten z: EN ISO 21646:2022
ICS:
75.160.10 Trda goriva Solid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 21646
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2022
EUROPÄISCHE NORM
ICS 75.160.10 Supersedes EN 15443:2011, EN 15413:2011
English Version
Solid recovered fuels - Sample preparation (ISO
21646:2022)
Combustibles solides de récupération - Préparation des Feste Sekundärbrennstoffe - Probenvorbereitung (ISO
échantillons (ISO 21646:2022) 21646:2022)
This European Standard was approved by CEN on 25 March 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

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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
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21646:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 21646:2022) has been prepared by Technical Committee ISO/TC 300 "Solid
recovered materials, including solid recovered fuels" in collaboration with Technical Committee
CEN/TC 343 “Solid recovered materials, including solid recovered fuels” the secretariat of which is held
by SFS.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by November 2022, and conflicting national standards
shall be withdrawn at the latest by November 2022.
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 supersedes EN 15443:2011 and EN 15413:2011.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 21646:2022 has been approved by CEN as EN ISO 21646:2022 without any modification.

INTERNATIONAL ISO
STANDARD 21646
First edition
2022-05
Solid recovered fuels — Sample
preparation
Combustibles solides de récupération — Préparation des échantillons
Reference number
ISO 21646:2022(E)
ISO 21646:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Email: copyright@iso.org
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Published in Switzerland
ii
ISO 21646:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 4
5 Safety remarks . 4
6 Principles of correct sample preparation . 4
7 Quality control and sources of error .6
8 Apparatus . 7
8.1 Selection of equipment . 7
8.2 Apparatus for sample division . 8
8.2.1 Scoops and shovels (sampling tools) . 8
8.2.2 Riffle boxes . 9
8.2.3 Rotary sample dividers . 10
8.3 Apparatus for particle size reduction . 11
8.3.1 Shredder . 11
8.3.2 Coarse cutting mill . 11
8.3.3 Cutting mill . 11
8.4 Sieves . 11
8.5 Balance . 11
9 Sample preparation procedure .12
9.1 General .12
9.2 Step 1: Collecting the relevant information of the material for sample preparation .12
9.3 Step 2: Making a sample preparation plan .12
9.3.1 General .12
9.3.2 Sample division . . .12
9.3.3 Particle size reduction of a sample .12
9.3.4 Retaining the minimum (sub-)sample mass . 15
9.4 Step 3: Performing the sample preparation plan . 16
10 Methods for homogenization and sample division .16
10.1 General . 16
10.2 Homogenization. 16
10.3 Sample division methods . 16
10.3.1 General . 16
10.3.2 Riffling . 16
10.3.3 Strip division . . 17
10.3.4 Long strip . 18
10.3.5 Manual increment division . 18
10.3.6 Rotary sample divider . 19
10.3.7 Fractional shovelling . 19
10.3.8 Quartering . 20
11 Methods for mass and particle size reduction of laboratory samples and general
analysis samples .21
11.1 General . 21
11.2 Initial sample division . 21
11.3 Initial mass determination . 21
11.4 Pre-drying . 21
11.5 Particle size reduction to < 30 mm. 22
11.6 Sample division of < 30 mm material . 23
iii
ISO 21646:2022(E)
11.7 Particle size reduction of < 30 mm material to < 1 mm . 23
11.8 Sample division of < 1 mm material . 24
11.9 Particle size reduction of < 1 mm material to < 0,25 mm . 24
12 Handling considerations of the general analysis sample and the test portion .25
12.1 Key concepts . 25
12.2 Sequence of preparation procedures . 26
13 Storage, preservation and labelling of samples .26
14 Sample preparation report .26
15 Precision .27
Annex A (normative) Determination of the shape factor .28
Annex B (normative) Determination of the changing shape factor .29
Annex C (informative) Examples of sample preparation procedures .31
Annex D (normative) Guidelines for choosing sample preparation procedures .35
Annex E (informative) Relationship between minimum amount of sample and particle
size – Formula for the estimation of the minimum amount of sample . 44
Annex F (normative) Sample preparation equipment .47
Annex G (normative) Characteristics of the laboratory sample for chemical analysis of solid
recovered fuel .48
Annex H (informative) Data on the precision of sample preparation .50
Annex I (informative) Results of ruggedness testing .53
Bibliography .61
iv
ISO 21646:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 300, Solid recovered materials, including
solid recovered fuels, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 343, Solid recovered materials, including solid recovered fuels, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO 21646:2022(E)
Introduction
Solid recovered fuels are a major source of renewable energy. International Standards facilitate
the production, trade and use of solid recovered fuels. For sampling and sample preparation of solid
recovered fuels, ISO 21645 and this document, respectively, can be used (in conjunction) by different
types of organizations, including but not limited to:
— solid recovered fuel production and trading companies;
— energy companies;
— regulatory bodies;
— conformity assessment bodies;
— laboratories.
The sample preparation technique adopted depends on a combination of different characteristics of the
material and circumstances encountered at the sampling location. The determining factors are:
— the type of solid recovered fuel;
— the physical behaviour of the specific solid recovered fuel;
— the (expected) degree of heterogeneity (e.g. monostreams, mixed fuels, blended fuels).
In laboratory practice, different analytical procedures often need to be applied to the laboratory
sample that has been taken according to the sampling plan. For this purpose, sub-sampling is applied
in a way that the different test portions are representative of the laboratory sample with respect to the
compounds of interest and the specific analytical procedures. The representativeness of the laboratory
sample and of the test portions is of major importance to guarantee the quality and accuracy of
analytical results. The representativeness of the laboratory sample is specified by the sampling plan.
This document is largely based on the work done by CEN/TC 343, Solid recovered fuels, and CEN/
TC 292, Characterization of waste (now integrated in CEN/TC 444, Environmental characterization of
solid matrices), and in particular EN 15002, which was developed for the majority of waste samples.
Most of its concepts and specifications are also applicable to solid recovered fuel samples. However,
the foundations of EN 15002 are not completely applicable to solid recovered fuel, as the nature of this
material is substantially different and can lead to misrepresentation of the fuel quality.
The main characteristic that makes solid recovered fuel samples significantly different from other
kinds of waste is that very often solid recovered fuels are solid, but neither ‘granular’ nor monolithic.
It often happens that solid recovered fuel samples are fibrous-like materials, so that the statistical
formula for sampling as defined in EN 15002 is not applicable. One additional term in the statistical
formula is needed, namely the ‘shape factor’ ( f ).
This document is part of the testing programme for solid recovered fuels. This programme consists of
various steps leading to the analysis sample for fuel quality testing as outlined in Figure 1.
vi
ISO 21646:2022(E)
a
ISO 21645:2021, B.2, steps 5) and 6).
Figure 1 — Links between the essential elements of a testing programme
vii
INTERNATIONAL STANDARD ISO 21646:2022(E)
Solid recovered fuels — Sample preparation
1 Scope
This document specifies methods for sample preparation to ensure representativeness of the samples
throughout the preparation procedures to produce general analysis samples. Suitable test portions can
be taken from the laboratory or general analysis samples and used for analysis according to the specific
requirements defined in the corresponding analytical procedures.
This document specifies the correct sample preparation sequence to be applied to:
a) the composite sample, in order to produce a laboratory sample (taking into account large pieces of
solid recovered fuel);
b) each sub-sampling step throughout the testing programme;
c) the laboratory sample, in order to obtain suitable test portions;
d) ensure the representativeness of the test portions that have been taken according to the sample
preparation plan, prior to physical analysis, chemical analysis or both (e.g. extractions, digestion,
analytical determinations).
The methods specified in this document can be used for sample preparation, for example, when the
samples are to be tested for bulk density, biomass content determination, mechanical durability,
particle size distribution, moisture content, ash content, ash melting behaviour, calorific value, chemical
composition, impurities and self-heating properties. The methods are not intended to be applied to the
very large samples required for the testing of bridging properties.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3310-2, Test sieves — Technical requirements and testing — Part 2: Test sieves of perforated metal
plate
ISO 21637:2020, Solid recovered fuels — Vocabulary
ISO 21660-3, Solid recovered fuels — Determination of moisture content using the oven dry method — Part
3: Moisture in general analysis sample
CEN/TS 15414-1, Solid recovered fuels —Determination of moisture content using the oven dry method —
Part 1: Determination of total moisture by a reference method
CEN/TS 15414-2, Solid recovered fuels — Determination of moisture content using the oven dry method —
Part 2: Determination of total moisture by a simplified method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21637 and the following apply.
ISO 21646:2022(E)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
composite sample
sample (3.12) consisting of all the increments (3.6) taken from a lot (3.8) or a sub-lot
Note 1 to entry: The increments can be reduced by division before being added to the composite sample.
Note 2 to entry: The minimum sample mass shall be retained during the collection of increments to form the
composite sample.
3.2
drying
process of removing water from a sample (3.12)
Note 1 to entry: For the purpose of test portion (3.16) preparation, it can be useful to remove just the amount
of water that can possibly interfere with other processes involved (e.g. during crushing or milling). In order
to minimize the alteration of the sample during test portion preparation, removing the total amount of water
present in the sample is not necessarily needed.
[SOURCE: ISO 21637:2020, 3.19, modified — “solid fuel” was replaced with “sample” in Note 1 to entry.]
3.3
fraction separation
process of dividing components, particles or layers if homogenization (3.5) of the sample (3.12) is
practically not applicable and/or the analyses of different fractions or phases are appropriate
[SOURCE: ISO 21637:2020, 3.32]
3.4
general analysis sample
sub-sample (3.14) of a laboratory sample (3.7) having a nominal top size (3.10) of 1 mm or less and used
for a number of chemical and physical analyses
3.5
homogenization
process of combining of increments (3.16) making up a combined sample, components, particles or
layers into a more homogeneous state than in the samples (in the case of composite samples) or pre-
treated fractions of samples in order to ensure equal distribution of substances in and properties of the
sample (3.12)
3.6
increment
portion of solid recovered fuel extracted from a lot (3.8) or sub-lot in a single operation of the sampling
device
[SOURCE: ISO 21637:2020, 3.39]
3.7
laboratory sample
composite sample (3.1) received by the laboratory on which sample (3.12) preparation procedures are
undertaken
Note 1 to entry: When the laboratory sample is further prepared (reduced) by subdividing, mixing, grinding or
by combinations of these operations, leading to a nominal top size (3.10) ≤ 1 mm, the result is the general analysis
sample (3.4). A test portion (3.16) is removed from the general analysis sample for the performance of the test or
for analysis. When no preparation of the laboratory sample is required, the laboratory sample may become the
test portion.
ISO 21646:2022(E)
Note 2 to entry: The composite sample becomes the laboratory sample when it is delivered into the laboratory for
commencement of the sample preparation procedures.
3.8
lot
defined quantity of fuel for which the quality is to be determined
[SOURCE: ISO 21637:2020, 3.40]
3.9
minimum sample mass
minimum amount or dimension of the sample (3.12) required during sampling and sample preparation
from the point of view of preserving its representativeness
Note 1 to entry: The minimum sample mass is at least equal to the increment mass multiplied by the number of
increments (3.6) and is linked directly to the nominal top size (3.10).
[SOURCE: ISO 21645:2021, 3.14]
3.10
nominal top size
smallest aperture size of the sieve used for determining the particle size distribution of solid recovered
fuels through which at least 95 % by mass of the total material passes through the sieve
[SOURCE: ISO 21637:2020, 3.48]
3.11
particle size reduction
reduction of the nominal top size (3.10) of a sample (3.12) or sub-sample (3.14)
3.12
sample
quantity of material, representative of a larger quantity for which the quality is to be determined
3.13
sample division
reduction of the mass of a sample (3.12) or sub-sample (3.14)
[SOURCE: ISO 21637:2020, 3.64, modified — “by mass” was deleted from the term.]
3.14
sub-sample
portion of a sample (3.12)
Note 1 to entry: A sub-sample is obtained by procedures in which the particles are randomly distributed in parts
of equal or unequal size.
Note 2 to entry: A sub-sample may be either a portion of the sample obtained by selection, or division of the
sample itself, or the final sample of a multistage sample preparation procedure.
[SOURCE: ISO 21637:2020, 3.82, modified — “items of interest” was replaced by “particles” in Note 1 to
entry and Note 2 to entry was added.]
3.15
sub-sampling
process of selecting one or more sub-samples (3.14) from a sample (3.12)
ISO 21646:2022(E)
3.16
test portion
sub-sample (3.14) of a laboratory sample (3.7) or general analysis sample (3.4) consisting of the quantity
of material required for a single execution of a test method
Note 1 to entry: The test portion may be taken from the laboratory sample directly if no preparation of sample
(3.12) is required (e.g. for bulk density determination or particle size distribution).
3.17
total moisture sample
sample (3.12) taken specifically for the purpose of determining the total moisture content
4 Symbols
For the purposes of this document, the following symbols apply.
α constant in third power law, in g/mm
d nominal minimum particle size (a mass fraction of 5 % of the particles are smaller than d ), in mm
05 05
d nominal top size of a particle (a mass fraction of 95 % of the particles are smaller than d ), in mm
95 95
3 3
f shape factor, in mm /mm
M moisture, in per cent by mass
m mass of a sample, in g
5 Safety remarks
Safety issues relating to the handling of potentially hazardous materials are dealt with in relevant
national and international regulations, to which every laboratory should refer.
In addition, the following applies:
a) The apparatus for grinding, cutting, milling and homogenization shall be operated by skilled
persons strictly according to the manufacturer's instructions.
b) All operations shall be performed in a hood or in closed force-ventilated equipment, due to the
possibility of generation of fine particles.
6 Principles of correct sample preparation
The main purpose of sample preparation is to reduce the mass and/or the particle size of a sample to
obtain one or more test samples that are in general smaller than the laboratory sample. The principle
of correct sample preparation is that the composition of the composite sample collected does not
change during each step of the sample preparation procedures. When correct sample preparation is
performed, any sub-sample or test portion is representative of the laboratory sample and every particle
in that sample has then an equal probability of being included in any sub-sample retained. Also, the
loss of moisture and other volatile components is minimized following the procedures described in
this document. Equally, any contamination of the sample during the sample preparation processes is
addressed and measures are taken to avoid contamination.
Three basic methods are used during the sample preparation:
— homogenization;
— sample division;
ISO 21646:2022(E)
— particle size reduction of the sample.
For granular materials generally, the principle of the third-power law is accepted and respected at each
sample division step. Formula (1) shows this third-power law:
md>×α (1)
where
m is the mass retained after each sample division step in g;
d is the nominal top size in mm;
α is a constant over the whole sample preparation procedure for a particular material, in g/mm .
The value and unit of constant α is fixed by the particle nominal top size, d , and the sample mass, m, of
the sample collected following the sampling plan and before sample preparation.
The minimum amount of sample for each step of sample preparation and sub-sampling can be directly
estimated by Formula (E.1) in Annex E, including Table E.2.
EXAMPLE A sample of 10 kg of solid recovered fuel has d of 50 mm. For the analysis, a test portion of 5 g
3 3
is required. The third-power law results in α = 10 000 g/(50 mm) = 0,08 g/mm . Using this value in Formula (1)
for a reduced sample mass results in a nominal top size for the particles in the test portion of 3,97 mm [i.e.
∛ (5,0 g / 0,08 g/mm )]. The resultant figures are shown in the following table.
m α d
g g/mm mm
10 000 0,08 50
5 0,08 3,97
Table 1 shows the resulting reduction factors for the minimum (sub-)sample mass, if a certain reduction
of the nominal top size is chosen and the third-power law is respected. The reduction factor of the
nominal top size can be calculated by dividing the current nominal top size by the proposed nominal
top size after mass reduction.
Table 2 shows the desired reduction factors for the minimum nominal top size, if a certain reduction
of the (sub-)sample mass is chosen and the third-power law is respected. The reduction factor of the
minimum (sub-)sample mass can be calculated by dividing the current minimum (sub-)sample mass by
the proposed minimum (sub-)sample top size after mass reduction.
Formula (1) can be used to calculate the exact values for each specific situation.
Table 1 — Common values for desired reduction factor minimum (sub-)sample mass
Chosen reduction factor of the nominal Resulting reduction factor for the minimum
top size (sub-)sample mass
1,5 3,4
2 8
3 27
4 64
5 125
6 216
7 343
8 512
9 729
ISO 21646:2022(E)
Table 1 (continued)
Chosen reduction factor of the nominal Resulting reduction factor for the minimum
top size (sub-)sample mass
10 1 000
20 8 000
30 27 000
Table 2 — Common values for desired reduction factor nominal top size
Desired reduction factor for the minimum Necessary reduction factor of the nominal
(sub-)sample mass top size
2 1,3
3 1,4
4 1,6
5 1,7
10 2,2
20 2,7
50 3,7
80 4,3
100 4,6
200 5,8
500 7,9
1 000 10,0
For solid recovered fuels, many materials turn out to be far from granular (e.g. in fluff the particles turn
out to be predominantly flat). Therefore, for solid recovered fuels, a correction can be made for non-
granular materials.
If a sub-sample is required for the determination of total moisture content, the sub-sample is prepared
by a procedure that does not conflict with the requirements of CEN/TS 15414-1 and CEN/TS 15414-2.
If the total moisture content of the material (as sampled) is to be determined, it is recommended that
a separate total moisture sample is taken as there is a risk of reducing the moisture content by sample
preparation procedures.
If mercury content of the material (as sampled) is to be determined, it is recommended that a separate
mercury analysis sample is taken, as there is a risk of reducing the mercury content by sample
preparation operations if it is assumed that the material contains elemental mercury.
For materials that are examined for moisture and mercury content, significant heat build-up and risk of
loss of moisture and mercury can occur.
If samples are to be tested for substances that volatilize (e.g. mercury), care shall be taken during the
sample preparation procedures, in particular the stages of particle size reduction, to minimize any
increase in temperature.
7 Quality control and sources of error
Quality control during sample preparation procedures shall be demonstrated by carrying out at least
the following everyday laboratory practices:
a) all balances used for weighing sample masses shall be calibrated by an external calibration body on
a regular basis;
NOTE 1 This can be undertaken in accordance with the quality control procedures of the laboratory at
6-month or 12-month intervals, for example.
ISO 21646:2022(E)
b) a weight check on each balance shall be undertaken at a regular basis, preferably at the
commencement of each working day and by using calibrated weights that fall within the typical
weighing range of the balances in use, and the readings of this weight check shall be recorded;
c) the operating temperature of drying oven(s) shall be checked, preferably at the commencement
of each working day and in addition at a 6-month or 12-month frequency by using a calibrated
temperature recorder, to ensure that samples are dried at the correct temperature (within the
acceptable range permitted by the test method), and the reading(s) of the operating temperature
shall be recorded;
d) the milled product (i.e. the general analysis sample from which the test portion is taken) shall be
checked for oversize (i.e. > 1 mm) on a regularly basis, preferably on a weekly basis, or following
any mechanical changes (e.g. new screens, hammers) to ensure that the particle size is within
specification, and the results are recorded;
NOTE 2 This check also confirms that there is no problem with the operation of the milling equipment.
e) the sieves used in the laboratory shall be manufactured according to the specifications in ISO 3310-1
and ISO 3310-2 and their apertures shall be checked as described according to the manufacturer’s
instructions at an agreed periodicity;
f) all balances, ovens, milling and sieving equipment shall have unique identification and shall exhibit
the date of any calibrations undertaken as well as the 'next due' date.
The sub-sample shall be re-homogenized after any operation that can result in segregation of different
sized particles.
Loss of material (e.g. fine particles) and volatile components, such as moisture and mercury during
milling, and contamination of the sample via the air, by dust or by the use of the apparatus (e.g. from the
ambient laboratory atmosphere or between samples stored or processed close to one another) shall be
avoided.
The following types of contamination can occur from the sample preparation apparatus:
— abrasion;
— cross-contamination;
— chemical release;
— chemical reaction due to generated heat (which can be a source of error and can cause material
alteration).
Treatment of samples should be performed in a separate room that is used only for this purpose,
especially for crushing or sieving.
If the sample has a dust-like consistency or contains (semi-)volatile compounds, losses shall be
minimized as these can alter its physical-chemical properties.
Tests shall be carried out to detect possible contamination from the apparatus used during sample
preparation.
8 Apparatus
8.1 Selection of equipment
For the purpose of preparation of the general analysis sample, test portions from the laboratory sample,
or both, appropriate equipment shall be chosen depending on the procedures selected according to
Annex D. In the selection of the type of treatment techniques, it should be taken into account that each
of them has potential impact on analytical results, due to introducing contamination or altering the
physical-chemical properties of the sample.
ISO 21646:2022(E)
All materials that come into contact with the sample shall be:
a) made from suitable materials;
b) chemically compatible with the sample;
c) selected in order to minimize contamination.
Good cleaning shall be ensured to avoid cross-contamination of samples.
The equipment to be used for the sample preparation procedures shall be in accordance with Annex F.
8.2 Apparatus for sample division
8.2.1 Scoops and shovels (sampling tools)
8.2.1.1 Scoops
A scoop being used for manual sampling shall have:
a) dimensions and an opening at least three times greater than the nominal top size of the material to
be processed;
b) a flat bottom with edges raised high enough to prevent losing particles.
Figure 2 shows examples of scoops.
EXAMPLE 1 For a granular solid recovered fuel with a d of 20 mm, the minimum dimensions (l × b × h) of the
sampling scoop are 60 mm × 60 mm × 60 mm. A sampling scoop like the one illustrated in Figure 2a can be used
for this type of solid recovered fuel.
EXAMPLE 2 For a solid recovered fuel, which consists almost entirely of flat parts, the dimensions of the
sampling scoop are at least equal to three times d , where d is the maximum length of a fluff particle (a mass
95,l 95,l
fraction of 95 % of the particles are smaller than d ). Therefore, for fluff with a d of 200 mm, the dimensions
95,l 95,l
of the sampling scoop (l × b × h) are at least 600 mm × 600 mm × 600 mm. For sampling fluff-type solid recovered
fuels, it is advisable to use a sampling scoop that has a sharp point underneath and upright walls, as illustrated in
Figure 2b.
a) Example of scoop for granular solid b) Example of scoop for solid recovered fuel
a b
recovered fuel almost entirely consisting of flat parts
a
See Example 1.
b
See Example 2.
Figure 2 — E
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