EN ISO 21660-2:2025

Solid recovered fuels - Determination of moisture content using the oven dry method - Part 2: Determination of total moisture by a simplified method (ISO 21660-2:2025)

This document specifies a method for determination of the moisture content in a test portion of the laboratory sample by drying the test portion in an oven. This method is applicable for routine production control on site, e.g. if a high precision of the determination of moisture content is not required. It is applicable to all solid recovered fuels.
If the solid recovered fuel contains large amounts of oil-fractions, a lower temperature is advisable (e.g. 50 °C ± 10 °C) and a longer drying time until constant mass is achieved. As an alternative, the Karl-Fischer-Titration-Method (see ISO 760[1]) is advisable.
NOTE 1        The total moisture content of recovered fuels is not an absolute value and therefore standardised conditions for its determination are indispensable to enable comparative determinations.
NOTE 2        The term moisture content when used with recovered materials can be misleading since solid recovered materials, e.g. biomass, frequently contain varying amounts of volatile compounds (extractives) which can evaporate when determining the moisture content of the general analyses sample by oven drying.

Feste Sekundärbrennstoffe - Bestimmung des Wassergehaltes unter Verwendung des Verfahrens der Ofentrocknung - Teil 2: Bestimmung des Gesamtgehaltes an Wasser mittels eines vereinfachten Verfahrens (ISO 21660-1:2025)

Dieses Dokument legt ein Verfahren zur Bestimmung des Wassergehaltes in einer Prüfmenge der Laboratoriumsprobe durch Trocknung der Prüfmenge in einem Ofen fest. Dieses Verfahren ist anwendbar für die routinemäßige Produktionskontrolle im Betrieb, z. B. wenn eine Bestimmung des Wassergehaltes nicht mit hoher Präzision erforderlich ist. Es ist anwendbar für alle festen Sekundärbrennstoffe.
Wenn der feste Sekundärbrennstoff große Mengen an Ölfraktionen enthält, sind eine niedrigere Temperatur (z. B. 50 °C ± 10 °C) und eine längere Trocknungszeit ratsam, bis die Massekonstanz erreicht ist. Alternativ wird geraten, die Karl-Fischer-Titration (siehe ISO 760 [1]) anzuwenden.
ANMERKUNG 1   Der Gesamtgehalt an Wasser von Sekundärbrennstoffen ist kein Absolutwert, weshalb Normbedingungen bei dessen Bestimmung unerlässlich sind, um vergleichbare Bestimmungen zu ermöglichen.
ANMERKUNG 2   Der Begriff Feuchte kann bei der Anwendung im Zusammenhang mit Sekundärrohstoffen irreführend sein, weil Sekundärrohstoffe, z. B. Biomasse, oft unterschiedliche Mengen an flüchtigen Verbindungen (Extraktstoffen) enthalten, die bei der Bestimmung des Wassergehaltes einer allgemeinen Analysenprobe durch Ofentrocknung verdampfen können.

Combustibles solides de récupération - Détermination de l'humidité par la méthode de séchage à l'étuve - Partie 2: Détermination de l’humidité totale à l’aide d’une méthode simplifiée (ISO 21660‑2:2025)

Le présent document spécifie une méthode de détermination de la teneur en humidité d'une prise d’essai de l'échantillon pour laboratoire en la séchant dans une étuve. Cette méthode est applicable pour un contrôle de la production en routine réalisé in situ, par exemple lorsqu’une fidélité élevée de la détermination de la teneur en humidité n’est pas nécessaire. Elle est applicable à tous les combustibles solides de récupération.
Si le combustible solide de récupération contient de grandes quantités de fractions d'huile, une température plus faible est conseillée (par exemple 50 °C ± 10 °C), ainsi qu'une durée de séchage plus importante jusqu'à l'obtention d'une masse constante. Sinon, il est conseillé d’utiliser la méthode de titrage Karl Fischer (voir l'ISO 760[1]).
NOTE 1        La teneur en humidité totale des combustibles de récupération n'est pas une valeur absolue et il donc nécessaire de normaliser les conditions de sa détermination afin de permettre la réalisation de déterminations comparables.
NOTE 2        Le terme teneur en humidité, lorsqu'il est utilisé avec matière de récupération, peut induire en erreur puisque des matières solides de récupération, par exemple de la biomasse, contiennent fréquemment diverses quantités de composés volatils (extractibles) qui peuvent s'évaporer lors de la détermination de la teneur en humidité de l'échantillon pour analyses générales par séchage en étuve.

Trdna alternativna goriva - Določanje vlage z metodo sušenja v sušilni komori - 2. del: Določanje celotne vlage s poenostavljeno metodo (ISO 21660-2:2025)

Ta dokument določa metodo za določanje vlage v preskusnem deležu laboratorijskega vzorca s sušenjem v sušilni komori. Metoda se uporablja za rutinsko kontrolo proizvodnje na mestu uporabe, npr. kadar določanje vlage z visoko natančnostjo ni potrebno. Uporablja se za vsa trdna alternativna goriva. Če trdno alternativno gorivo vsebuje velike količine oljnih frakcij, sta priporočljiva nižja temperatura (npr. 50 °C ± 10 °C) in daljši čas sušenja, dokler se ne doseže konstantna masa. Kot alternativna možnost je priporočljiva metoda Karl-Fischerjeve titracije (glej standard ISO 760 [1]). OPOMBA 1:         Skupna vsebnost vlage alternativnih goriv ni absolutna vrednost, zato so za zagotavljanje primerljivih rezultatov nujni standardizirani pogoji. OPOMBA 2:         Izraz »vsebnost vlage« je lahko pri uporabi za alternativne materiale zavajajoč, saj trdni alternativni materiali (npr. biomasa) pogosto vsebujejo različne količine hlapnih snovi (ekstraktov),​ki lahko pri določevanju vlage s sušenjem vzorca v sušilni komori izhlapijo.

General Information

• Status: Published
• Publication Date: 04-Nov-2025
• ICS: 75.160.10 - Solid fuels
• ICS: 75.160.40 - Biofuels
• Technical Committee: CEN/TC 343 - Solid Recovered Fuels
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 05-Nov-2025
• Completion Date: 05-Nov-2025
• Ref Project: SIST EN ISO 21660-2:2026 - Solid recovered fuels - Determination of moisture content using the oven dry method - Part 2: Determination of total moisture by a simplified method (ISO 21660-2:2025)

Relations

• Replaces: CEN/TS 15414-2:2010 - Solid recovered fuels - Determination of moisture content using the oven dry method - Part 2: Determination of total moisture content by a simplified method
• Effective Date: 11-Mar-2026
• Refers: ISO 21646:2022 - Solid recovered fuels — Sample preparation
• Effective Date: 11-Mar-2026
• Refers: ISO 21645:2021 - Solid recovered fuels — Methods for sampling
• Effective Date: 11-Mar-2026
• Refers: ISO 21637:2020 - Solid recovered fuels — Vocabulary
• Effective Date: 11-Mar-2026
• Refers: EN 45545-3:2024 - Railway applications - Fire protection on railway vehicles - Part 3: Fire resistance requirements for fire barriers
• Effective Date: 28-Jan-2026
• Refers: EN 45545-6:2024 - Railway applications - Fire protection on railway vehicles - Part 6: Fire control and management systems
• Effective Date: 28-Jan-2026
• Refers: EN ISO 14083:2023 - Greenhouse gases - Quantification and reporting of greenhouse gas emissions arising from transport chain operations (ISO 14083:2023)
• Effective Date: 28-Jan-2026
• Referred By: CEN/TS 15639:2010 - Solid recovered fuels - Determination of mechanical durability of pellets
• Effective Date: 11-Mar-2026
• Referred By: EN ISO 21646:2022 - Solid recovered fuels - Sample preparation (ISO 21646:2022)
• Effective Date: 11-Mar-2026
• Referred By: CEN/TS 15401:2010 - Solid recovered fuels - Determination of bulk density
• Effective Date: 11-Mar-2026
• Referred By: EN ISO 21645:2021 - Solid recovered fuels - Methods for sampling (ISO 21645:2021)
• Effective Date: 11-Mar-2026
• Referred By: CEN/TS 15406:2010 - Solid recovered fuels - Determination of bridging properties of bulk material
• Effective Date: 11-Mar-2026
• Referred By: EN 15415-1:2011 - Solid recovered fuels - Determination of particle size distribution - Part 1: Screen method for small dimension particles
• Effective Date: 11-Mar-2026
• Consolidated By: ISO 21660-2:2025 - Solid recovered fuels — Determination of moisture content using the oven dry method — Part 2: Determination of total moisture by a simplified method
• Effective Date: 12-Feb-2026

Overview

EN ISO 21660-2:2025 specifies a standardized oven dry method to determine the total moisture content in solid recovered fuels (SRF) through a simplified on-site approach. Developed by CEN and ISO/TC 300, this standard is tailored for routine production control scenarios where acquiring a highly precise moisture value is not essential. Its protocol ensures that determinations are comparable across different facilities and fuel types.

The method involves drying a test portion of the laboratory sample in an oven at 105 ± 2°C until a constant mass is reached, then calculating the moisture lost as a percentage of the initial mass. The procedure has been designed for efficiency, reproducibility, and broad applicability across all types of solid recovered fuels, including those used in power generation and industrial processes.

Key Topics

• Moisture Content Determination: Outlines a standardized protocol for measuring total moisture levels in SRF, crucial for reporting fuel quality and energy content.
• Applicability: Intended for all types of solid recovered fuels, regardless of origin or composition. This includes materials like processed municipal waste, biomass, and industrial by-products.
• Equipment Requirements: Specifies essential apparatus, including an oven capable of controlled temperature, suitable drying containers, and a highly accurate balance.
• Sample Handling: Emphasizes representative sampling, prompt weighing, and careful handling of hygroscopic materials to ensure valid results.
• Precautions: Recommends alternative methods-such as lower oven temperatures or the Karl-Fischer titration (ISO 760)-for SRFs with high oil content or volatile compounds.
• Reporting: Details requirements for the test report to ensure traceability, transparency, and comparability of results.
• Environmental Considerations: Encourages environmentally responsible procedures throughout the analysis and highlights potential environmental impacts of fuel analysis activities.

Applications

This standard provides practical and reliable procedures for determining the moisture content of solid recovered fuels in:

• Production and Quality Control: Used on-site at fuel processing plants for routine monitoring, helping producers and users assess fuel quality and optimize processing parameters.
• Fuel Trading and Documentation: Ensures consistent reporting of fuel properties for regulatory compliance, contract fulfillment, and customer information.
• Energy Generation: Supports power plant operators in predicting combustion characteristics, adjusting process operations, and improving efficiency by understanding fuel moisture content.
• Laboratory Analysis: Offers a robust method for labs conducting compliance and reference testing according to international standards.

Using a harmonized method like EN ISO 21660-2:2025 enables accurate benchmarking, regulatory adherence, and international trade of solid recovered fuels.

Related Standards

• ISO 21637: Vocabulary for solid recovered fuels, providing definitions crucial for proper interpretation of test results.
• ISO 21645: Standard on sampling methods for solid recovered fuels, ensuring sample representativeness.
• ISO 21646: Procedures for the preparation of samples prior to analysis.
• ISO 21660-3: Oven dry method for moisture content determination in the general analysis sample.
• CEN/TS 15414-1: Reference method for determining total moisture in solid recovered fuels using the oven dry method.
• ISO 760: Karl Fischer titration method for precise water content determination, offered as an alternative for samples with high oil or volatile content.

By aligning with EN ISO 21660-2:2025, stakeholders in biofuels, waste-derived fuel production, and energy generation can ensure reliable, consistent, and internationally recognized moisture measurement outcomes. This supports quality management, regulatory compliance, and safe, efficient fuel utilization.

Standards Content (Sample)

SLOVENSKI STANDARD
01-januar-2026
Trdna alternativna goriva - Določanje vlage z metodo sušenja v sušilni komori - 2.
del: Določanje celotne vlage s poenostavljeno metodo (ISO 21660-2:2025)
Solid recovered fuels - Determination of moisture content using the oven dry method -
Part 2: Determination of total moisture by a simplified method (ISO 21660-2:2025)
Feste Sekundärbrennstoffe - Bestimmung des Wassergehaltes unter Verwendung des
Verfahrens der Ofentrocknung - Teil 2: Bestimmung des Gesamtgehaltes an Wasser
mittels eines vereinfachten Verfahrens (ISO 21660-1:2025)
Combustibles solides de récupération - Détermination de l'humidité par la méthode de
séchage à l'étuve - Partie 2: Détermination de l'humidité totale par une méthode
simplifiée (ISO 21660-2:2025)
Ta slovenski standard je istoveten z: EN ISO 21660-2:2025
ICS:
75.160.40 Biogoriva Biofuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 21660-2
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2025
EUROPÄISCHE NORM
ICS 75.160.10
English Version
Solid recovered fuels - Determination of moisture content
using the oven dry method - Part 2: Determination of total
moisture by a simplified method (ISO 21660-2:2025)
Combustibles solides de récupération - Détermination Feste Sekundärbrennstoffe - Bestimmung des
de l'humidité par la méthode de séchage à l'étuve - Wassergehaltes unter Verwendung des Verfahrens der
Partie 2: Détermination de l'humidité totale par une Ofentrocknung - Teil 2: Bestimmung des
méthode simplifiée (ISO 21660-2:2025) Gesamtgehaltes an Wasser mittels eines vereinfachten
Verfahrens (ISO 21660-1:2025)
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 21660-2:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 21660-2:2025) 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 May 2026, and conflicting national standards shall be
withdrawn at the latest by May 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.
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 21660-2:2025 has been approved by CEN as EN ISO 21660-2:2025 without any
modification.
International
Standard
ISO 21660-2
First edition
Solid recovered fuels —
2025-10
Determination of moisture content
using the oven dry method —
Part 2:
Determination of total moisture by
a simplified method
Combustibles solides de récupération — Détermination de
l'humidité par la méthode de séchage à l'étuve —
Partie 2: Détermination de l’humidité totale à l’aide d’une
méthode simplifiée
Reference number
ISO 21660-2:2025(en) © ISO 2025

ISO 21660-2:2025(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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 21660-2:2025(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
6 Sample preparation . 2
7 Procedure . 2
8 Calculation . 3
9 Precision . 3
10 Test report . 3
Annex A (informative) Environmental aspects . 5
Bibliography . 7

iii
ISO 21660-2:2025(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).
A list of all parts in the ISO 21660 series can be found on the ISO website.
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 21660-2:2025(en)
Introduction
International Standards facilitate the production, trade and use of solid recovered materials including solid
recovered fuels. Solid recovered fuels are a major source of renewable energy. For the determination of total
[2]
moisture, ISO 21660-3 and this document can be used (in conjunction) by different types of organizations,
including but not limited to:
— solid recovered fuel production and trading companies
...