ISO/TS 17595

Solid biofuels — Characterization of wood chip fuels — Essential information for producers, suppliers and users

This document compiles information about wood chips produced from raw materials as defined in ISO 17225-4: — quality classes and specifications; — sampling, sample preparation and determination of parameters which can be conducted on site and — practical information about parameters to be determined in external laboratories This document provides additional information related to selection of essential parameters to be determined and the frequency of analyses.

Biocombustibles solides — Caractérisation des combustibles à base de plaquettes de bois — Informations essentielles pour les producteurs, les fournisseurs et les utilisateurs

General Information

• Status: Not Published
• ICS: 75.160.40 - Biofuels
• Technical Committee: ISO/TC 238 - Solid biofuels
• Drafting Committee: ISO/TC 238/WG 2 - Fuel specifications and classes
• Current Stage: 6000 - International Standard under publication
• Start Date: 14-May-2025
• Completion Date: 17-May-2025

Standards Content (Sample)

FINAL DRAFT
Technical
Specification
ISO/DTS 17595
ISO/TC 238
Solid biofuels — Characterization
Secretariat: SIS
of wood chip fuels — Essential
Voting begins on:
information for producers,
2025-03-18
suppliers and users
Voting terminates on:
2025-05-13
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 SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/DTS 17595:2025(en) © ISO 2025

FINAL DRAFT
ISO/DTS 17595:2025(en)
Technical
Specification
ISO/DTS 17595
ISO/TC 238
Solid biofuels — Characterization
Secretariat: SIS
of wood chip fuels — Essential
Voting begins on:
information for producers,
suppliers and users
Voting terminates on:
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 SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ISO/DTS 17595:2025(en) © ISO 2025

ii
ISO/DTS 17595:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Quality specifications for wood chips . 1
4.1 General .1
4.2 Classification of raw material .2
4.3 Normative and informative properties of graded wood chips .3
4.4 Classification of particle size classes and fines fractions.3
4.5 Specifications of graded wood chips in accordance with ISO 17225-4 .4
4.6 Typical ranges for key quality properties .5
4.7 Principles for assessing the quality of wood chip fuel .6
4.8 Procurement approaches .7
5 Standards for on-site characterisation of graded wood chips . 8
5.1 General .8
5.2 Sampling method .9
5.3 Sample preparation . 12
5.4 Bulk density .14
5.5 Moisture content . .17
5.6 Particle size distribution .18
5.7 Heavy extraneous materials .19
6 Additional standards for characterisation of graded wood chips by external laboratories .22
6.1 General . 22
6.2 Ash content . 22
6.3 Calorific value . 23
6.4 Elemental analysis: C, H, N, S, Cl and ash forming elements .24
Annex A (informative) Calculating the net calorific value based on an empirical formula .25
Annex B (informative) Model sampling plan and sampling report .26
Annex C (informative) Examples of Data Logging Tables to Record Test Results .27
Annex D (informative) Basic information included in an external laboratory test report .29
Bibliography .31

iii
ISO/DTS 17595:2025(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 238, Solid biofuels and pyrogenic biocarbon.
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/DTS 17595:2025(en)
Introduction
For effective use of solid biofuels in heating and power facilities, it is crucial to assess fuel quality starting
from the planning stage through daily routine operation. It is equally critical to be familiar with the quality
specifications needed for a particular application and to determine key fuel properties using proven and
well-validated test methods.
Numerous International Standards exist to characterize various types of solid biofuels, including wood
chips, pellets, and briquettes for a variety of residential, commercial, and industrial applications. In addition
to providing detailed information on fuel specifications and classes and test methods, these International
Standards make it possible to draw up clear and unambiguous fuel supply contracts. They also support the
creation of quality assurance and certification systems.
Wood chips are among the most commonly used solid biofuels in space heating applications in commercial
and institutional buildings, district heating, light industry and greenhouses. Wood chips specifications and
test methods are described in a large number of International Standards, either as stand-alone, or as part of
International Standards addressing various types of solid biofuels.
This document is intended primarily for wood chip producers, traders, and owners and operators of energy
facilities in small to medium residential, commercial and public sectors. It is based on relevant International
Standards. The aim of this document is to provide practical guidance and examples on quality specifications
relevant to wood chips, presents guiding principles for assessing the quality of wood chip fuel and gives
common procurement approaches. Only those quality properties and their test methods that are critical
for both internal quality control purposes and smooth and efficient boiler operation are included in this
document.
Clause 4 describes general information about the quality of wood chips. Clause 5 provides guidance on test
methods for the determination of essential physical properties of wood chips. These tests can be performed
on a regular basis at the site of the wood chip fuel producer, fuel supplier or energy facility. Sampling and
sample preparation are also described in Clause 5. A calculation tool, covering the properties described in
1)
Clause 5, is available as an MS Excel document to assist users in recording, calculating and reporting test
results in a consistent manner. Clause 6 provides practical information on essential tests that are carried
out by external laboratories. Annex A gives an empirical formula to calculate energy content of wood chips.
Annex B gives an example of a sampling plan and sampling report. Annex C includes examples of data logging
tables that can be used in reporting test results. Annex D shows key information expected to be found in a
laboratory report of graded wood chips.
The sampling techniques and test methods described in this document are aligned with the methods given
in the corresponding International Standards, with minor modifications to some steps, such as sample size,
sampling frequency, number of replicates, or measurement time. This is done to make them more practical
for routine testing. As such, the methods described in this document can lead to minor differences in the
results when compared with the corresponding International Standards. These differences will not impact
the reliability of assessing changes to the properties of wood chips when measured on a relative, day-to-day
basis. Boiler operators, owners and fuel producers are encouraged to incorporate them into their regular
quality monitoring and control routines.
1) Accessible at: https://standards.iso.org/iso/ts/17595/ed-1/en
...

ISO/DTS 17595 (E:2025(en)
ISO/TC 238
Date: 2024-10-18
Solid Biofuels — Characterization of wood chip fuel — Essential information for producers,
suppliers and users
DTS stage
Warning for WDs and CDs
This document is not an ISO International Technical Report. It is distributed for review and comment. It is subject
to change without notice and may not be referred to as an International Technical Report.
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.

UNCLASSIFIED - NON CLASSIFIÉ
ISO/DTS 17595 (E)
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.orgwww.iso.org
Published in Switzerland
ii © ISO 2024 – All rights reserved

ISO/DTS 17595 (E:2025(en)
Contents
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Quality specifications for wood chips . 2
General . 2
Classification of raw material . 4
Normative and informative properties of graded wood chips . 4
Classification of particle size classes and fines fractions . 5
Specifications of graded wood chips in accordance with ISO 17225-4 . 6
Typical ranges for key quality properties . 8
Principles for assessing the quality of wood chip fuel . 8
Procurement approaches . 11
5 Standards for on-site characterisation of graded wood chips . 12
General . 12
Sampling method . 12
Sample preparation . 17
Bulk density . 23
Moisture content . 25
Particle size distribution . 27
5.7 Heavy extraneous materials . 29
6 Additional standards for characterisation of graded wood chips by external
laboratories . 32
General . 32
Ash content . 33
Calorific value . 34
Elemental analysis: C, H, N, S, Cl and ash forming elements . 36
Annex A (informative) . 37
Annex B (informative) . 39
Annex C . 40
(informative) . 40
Examples of Data Logging Tables to Record Test Results . 41
Annex D (informative) Basic information included in an external laboratory test report. 44
Bibliography . 46
Foreword . iv
Introduction . v
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Quality specifications for wood chips . 6
4.1 General . 6
iii
ISO/DTS 17595 (E)
4.2 Classification of raw material . 7
4.3 Normative and informative properties of graded wood chips . 7
4.4 Classification of particle size classes and fines fractions . 8
4.5 Specifications of graded wood chips in accordance with ISO 17225-4 . 9
4.6 Typical ranges for key quality properties .10
4.7 Principles for assessing the quality of wood chip fuel .11
4.8 Procurement approaches .13
5 Standards for on-site characterisation of graded wood chips .14
5.1 General .14
5.2 Sampling method .14
5.3 Sample preparation .17
5.4 Bulk density .20
5.5 Moisture content .21
5.6 Particle size distribution .23
5.7 Heavy extraneous materials .24
6 Additional standards for characterisation of graded wood chips by external
laboratories .26
6.1 General .26
6.2 Ash content .27
6.3 Calorific value .27
6.4 Elemental analysis: C, H, N, S, Cl and ash forming elements .28
Annex A (informative) .30
Annex B (informative) .31
Annex C .32
(informative) .32
Examples of Data Logging Tables to Record Test Results .32
Annex D (informative) Basic information included in an external laboratory test report .34
Bibliography .35

iv © ISO 2024 – All rights reserved

ISO/DTS 17595 (E: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 documentsdocument should be noted. This document was drafted in accordance
with the editorial rules of the ISO/IEC Directives, Part 2 (see
www.iso.org/directiveswww.iso.org/directives).
Attention is drawnISO draws attention to the possibility that some of the elementsimplementation of this
document may beinvolve the subjectuse 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. 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.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee 238, Solid biofuels and pyrogenic biocarbon.
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.www.iso.org/members.html.

v
ISO/DTS 17595 (E)
Introduction
For effective use of solid biofuels in heating and power facilities, it is crucial to assess fuel quality starting
from the planning stage through daily routine operation. It is equally critical to be familia
...