EN ISO 18708:2025

SLOVENSKI STANDARD
01-januar-2026
Nadomešča:
SIST-TS CEN/TS 15401:2010
Trdna alternativna goriva - Določanje nasipne gostote (ISO 18708:2025)
Solid recovered fuels - Determination of bulk density (ISO 18708:2025)
Feste Sekundärbrennstoffe - Bestimmung der Schüttdichte (ISO 18708:2025)
Combustibles solides de récupération - Détermination de la masse volumique apparente
(ISO 18708:2025)
Ta slovenski standard je istoveten z: EN ISO 18708:2025
ICS:
75.160.10 Trda goriva Solid fuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 18708
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2025
EUROPÄISCHE NORM
ICS 75.160.10 Supersedes CEN/TS 15401:2010
English Version
Solid recovered fuels - Determination of bulk density (ISO
18708:2025)
Combustibles solides de récupération - Détermination Feste Sekundärbrennstoffe - Bestimmung der
de la masse volumique apparente (ISO 18708:2025) Schüttdichte (ISO 18708:2025)
This European Standard was approved by CEN on 5 October 2025.

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

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, 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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18708:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 18708:2025) 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 April 2026, and conflicting national standards shall be
withdrawn at the latest by April 2026.
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 CEN/TS 15401:2010.
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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 18708:2025 has been approved by CEN as EN ISO 18708:2025 without any modification.

International
Standard
ISO 18708
First edition
Solid recovered fuels —
2025-10
Determination of bulk density
Combustibles solides de récupération — Détermination de la
masse volumique apparente
Reference number
ISO 18708:2025(en) © ISO 2025
ISO 18708:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 18708:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
5.1 Measurement containers .2
5.1.1 General .2
5.1.2 Large container.2
5.1.3 Medium container .2
5.1.4 Small container .3
5.2 Scale/Balances .3
5.2.1 Scale/Balance 1 .3
5.2.2 Scale/Balance 2 .3
5.3 Scantling .3
5.4 Wooden board .4
6 Sampling and sample preparation . 4
7 Operation . 4
7.1 Determination of the container volume .4
7.2 Combination of container size and dropping height .4
7.2.1 General .4
7.2.2 Fluff .4
7.2.3 Pellet .5
7.3 Measurement procedure .5
8 Calculation of bulk density . 6
8.1 Calculation of bulk density as received .6
8.2 Calculation of bulk density of dry matter .6
9 Performance characteristics . 6
9.1 General .6
9.2 Repeatability limit .6
9.3 Reproducibility limit .6
10 Test reports . 7
Annex A (informative) Example of an apparatus for controlled shock exposure . 8
Annex B (informative) Results of interlaboratory test . 9
Annex C (informative) Report of experimental study on the determination of bulk density .10
Annex D (informative) Environmental aspects .22
Bibliography .24

iii
ISO 18708:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.

iv
ISO 18708:2025(en)
Introduction
Bulk density is one of the main quality parameters of solid recovered fuels (SRF). It is needed e.g. in a
sampling process (volume of sampling tools, volume primary sample), in assessing transport capacity or
storage space required or energy density (MWh/m ) of SRF. Bulk density is not an absolute value, therefore
conditions for its determination are standardised in order to gain comparative measuring results.
This document describes the testing method for determining the bulk density of SRFs to produce solidified
fuels from the combustibles in waste by processing, such as compressing, drying, crushing, moulding and
solidifying, and utilize them as an energy source.

v
International Standard ISO 18708:2025(en)
Solid recovered fuels — Determination of bulk density
1 Scope
This document specifies a method for determining the bulk density of solid recovered fuels (SRF) by the use
of a standard measuring container. This method is applicable to all SRFs with a nominal top size of particle
less than 1/3 of the container diameter specified in this document.
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 21637, Solid recovered fuels — Vocabulary
ISO 21645, Solid recovered fuels — Methods for sampling
ISO 21646, Solid recovered fuels — Sample preparation
ISO 21660-3, Solid recovered fuels — Determination of moisture content using the oven dry method — Part 3:
Moisture in general analysis sample
EN 15415-1, Solid recovered fuels — Determination of particle size distribution - Screen method for small
dimension particles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 21637 and the following apply.
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
bulk density
ρ
mass of a portion (i.e. a large quantity of particulate material) of a solid fuel divided by the volume of the
container which is filled by that portion under specific conditions
[SOURCE: ISO 16559:2022, 3.40, modified — ρ added as the symbol for bulk density and definition revised
adding reference to "solid fuel".]
4 Principle
A standard container is filled with the test portion of a given size and shape, densified by specified shock
exposure and weighed afterwards. The bulk density is calculated from the net weight per standard volume
and reported with the determined moisture content.

ISO 18708:2025(en)
5 Apparatus
5.1 Measurement containers
5.1.1 General
The container shall be cylindrically shaped and manufactured of a shock resistant, smooth-surfaced
material. The container shall be resistant to deformation in order to prevent any variation in shape and
volume. The container shall be waterproof. For easier handling, grips can be fixed externally.
The height-to-diameter ratio shall be in the range from 1,25 to 1,50. The determination of the particle size
shall be performed in accordance with EN 15415-1.
5.1.2 Large container
The large measuring container (see Figure 1) has a filling volume of 50 l (0,05 m ). The volume can deviate
by 1 l (= 2 %). It shall have an effective (inner) diameter of 360 mm and an effective (inner) height of 491 mm
(see Figure 1). Deviations from these dimensions are tolerable, if the height-to-diameter ratio remains as
given in 5.1.1.
Key
d inner diameter 360 mm
h inner height 491 mm
Figure 1 — Large standardized measuring container
5.1.3 Medium container
The medium measuring container (see Figure 2) has a filling volume of 20 l (0,02 m ). The volume can
deviate by 0,4 l (= 2 %). It shall have an effective (inner) diameter of 265 mm and an effective (inner) height
of 362 mm (see Figure 2). Deviations from these dimensions are tolerable, if the height-to- diameter ratio
remains as given in 5.1.1.
ISO 18708:2025(en)
Key
d inner diameter 265 mm
h inner height 362 mm
Figure 2 — Medium standardized measuring container
5.1.4 Small container
The small measuring container (see Figure 3) has a filling volume of 5 l (0,005 m ). The volume can deviate
by 0,1 l (= 2 %). It shall have an effective (inner) diameter of 167 mm and an effective (inner) height of
228 mm (see Figure 3). Deviations from these dimensions are tolerable, if the height-to-diameter ratio
remains as given in 5.1.1.
Key
d inner diameter 167 mm
h inner height 228 mm
Figure 3 — Small standardized measuring container
5.2 Scale/Balances
5.2.1 Scale/Balance 1
Capable of weighing the sample and the large container or medium container to the nearest 10 g.
5.2.2 Scale/Balance 2
Capable of weighing the sample and the small container to the nearest 1 g.
5.3 Scantling
A rigid scantling with a length exceeding the diameter of the measuring container in 5.1 shall be used for
levelling the material in the container by lateral movements of the scantling across the rim of the measuring
container.
ISO 18708:2025(en)
5.4 Wooden board
A flat oriented strand board (OSB), with a thickness of about 15 mm and a sufficient size for the container to
be dropped onto for shock exposure. The board should be replaced when it is not fit for purpose anymore.
6 Sampling and sample preparation
Sampling shall be carried out in accordance with ISO 21645. If necessary, the sample shall be divided into test
portions in accordance with ISO 21646. The test portion volume shall exceed the volume of the measuring
container by a minimum of 30 %.
NOTE Annex D shows an environmental checklist (see Table D.1) that indicates possible environmental aspects to
take into account when undertaking the analysis of solid recovered fuels
7 Operation
7.1 Determination of the container volume
Before use, the mass and filling volume of the container shall be determined. Weigh the empty, clean and
dry container on the scale. Then fill the container with water until maximum capacity; then weigh it again.
Calculate the volume (V) of the container from the net weight of water and the density of the water (1 g/
3 3
cm ) and record the result rounded to the nearest 0,01 l (10 cm ) for the large container or the medium
container or 0,001 l (1 cm ) for the small container.
7.2 Combination of container size and dropping height
7.2.1 General
The large container can be used for larger materials within the scope of this document.
The combination of container size and dropping height is specified separately by fluff and pellets as shown
in the Table 1 below. See C.11 for additional information.
Table 1 — Combination of container size and dropping height
Nominal top size of particle
Material
>12 mm and ≦100 mm ≦12 mm
Fluff 15 cm in large container or 15 cm small container
30 cm in medium container
Pellet 15 cm in large container or 15 cm small container or 30 cm
30 cm in medium container medium container
7.2.2 Fluff
All fluff with a nominal top size of particle of more than 12 mm and less than or equal to 100 mm may be
used by one of the following two combinations of the container size and dropping height:
a) large container (5.1.2) with a dropping height of 15 cm;
b) medium container (5.1.3) with a dropping height of 30 cm.
All fluff with a nominal top size of particle less than or equal to 12 mm may be used in a small container
(5.1.4) with a dropping height of 15 cm. See C.10.1 for additional information.
If there are large particles that cannot fit into the standard container (5.1), it is acceptable to use a larger
container with an open top and a diameter at least three times bigger than the nominal top size (D 95) of

ISO 18708:2025(en)
particle. The
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