EN ISO 17225-2:2021

Solid biofuels - Fuel specifications and classes - Part 2: Graded wood pellets (ISO 17225-2:2021)

This document determines the fuel quality classes and specifications of graded wood pellets for non-industrial and industrial use. This document covers only wood pellets produced from the following raw materials (see ISO 17225‑1:2021, Table 1):
—    1.1 Forest, plantation and other virgin wood;
—    1.2 By-products and residues from wood processing industry;
—    1.3.1 Chemically untreated used wood.
Thermally treated biomass pellets (e.g. torrefied pellets) are not included in the scope of this document.

Biogene Festbrennstoffe - Brennstoffspezifikationen und -klassen - Teil 2: Klassifizierung von Holzpellets (ISO 17225-2:2021)

Dieses Dokument legt die qualitätsbezogenen Brennstoffklassen und -spezifikationen für klassifizierte Holzpellets für nichtindustrielle und industrielle Verwendung fest. Dieses Dokument umfasst nur Holzpellets, die aus folgenden Rohmaterialien hergestellt wurden (siehe ISO 17225-1:2021, Tabelle 1):
- 1.1 Wald- und Plantagenholz sowie anderes naturbelassenes Holz;
- 1.2 Industrie-Restholz;
- 1.3.1 Chemisch unbehandeltes Gebrauchtholz.
Thermisch behandelte Pellets aus Biomasse (z. B. torrefizierte Pellets) fallen nicht in den Anwendungsbereich dieses Dokuments.

Biocombustibles solides - Classes et spécifications des combustibles - Partie 2: Classes de granulés de bois (ISO 17225-2:2021)

Le présent document détermine les classes et les spécifications de qualité pour les granulés de bois combustibles, à usages non industriel et industriel. Le présent document couvre uniquement les granulés de bois produits à partir des matières premières suivantes (voir ISO 17225-1:2021, Tableau 1) :
—    1.1 Bois de forêt, de plantations et autres bois vierges ;
—    1.2 Sous-produits et résidus de l'industrie de transformation du bois ;
—    1.3.1 Bois usagé, non traité chimiquement.
Les granulés de biomasse traitée thermiquement (par exemple, les granulés torréfiés) ne sont pas couverts par le présent document.

Trdna biogoriva - Specifikacije goriv in razredi - 2. del: Razvrstitev lesnih peletov (ISO 17225-2:2021)

General Information

• Status: Published
• Publication Date: 25-May-2021
• Withdrawal Date: 29-Nov-2021
• ICS: 27.190 - Biological sources and alternative sources of energy
• ICS: 75.160.40 - Biofuels
• Technical Committee: CEN/TC 335 - Solid biofuels
• Drafting Committee: CEN/TC 335 - Solid biofuels
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 26-May-2021
• Completion Date: 26-May-2021
• Ref Project: SIST EN ISO 17225-2:2021 - Solid biofuels - Fuel specifications and classes - Part 2: Graded wood pellets (ISO 17225-2:2021)

Relations

• Replaces: EN ISO 17225-2:2014 - Solid biofuels - Fuel specifications and classes - Part 2: Graded wood pellets (ISO 17225-2:2014)
• Effective Date: 02-Jun-2021

Overview - EN ISO 17225-2:2021 (Graded wood pellets)

EN ISO 17225-2:2021 (CEN adoption of ISO 17225-2:2021) is the international/European standard that defines fuel specifications and quality classes for graded wood pellets used as solid biofuels. It applies to pellets produced from:

• forest, plantation and other virgin wood (1.1),
• by‑products and residues from the wood‑processing industry (1.2), and
• chemically untreated used wood (1.3.1).

Thermally treated biomass pellets (e.g., torrefied pellets) are explicitly excluded. The document supersedes the 2014 edition and aligns classification principles for trading, appliance compatibility and regulatory reporting.

Key topics and technical requirements

This standard focuses on measurable pellet quality attributes and the procedures to determine them. Main technical topics include:

• Fuel quality classes (e.g., A1, A2, I1, I2): defined to match end‑use requirements (A‑classes for higher‑quality residential/commercial use; I‑classes for industrial use).
• Physical properties: pellet diameter, length, bulk density, particle density (informative), coarse pellet fines (informative), and mechanical durability.
• Chemical and combustion properties: moisture, ash content, calorific value, elemental contents (C, H, N, S, Cl), and ash melting behaviour (now normative with threshold DT values).
• Sampling, sample preparation and test methods: references to established ISO test methods (e.g., ISO 18135 sampling, ISO 14780 sample preparation, ISO 18134 moisture, ISO 18125 ash, ISO 18125/18122 calorific/ash tests, ISO 21404 ash melting).
• Specification tables: class limits are provided in tabular form (refer to the standard for numerical thresholds).

Applications and who uses the standard

EN ISO 17225-2:2021 is practical for:

• Pellet manufacturers - to certify product quality and meet buyer specifications.
• Fuel traders and procurement teams - to specify, compare and procure graded wood pellets with confidence.
• Heating appliance and boiler manufacturers - to design and recommend compatible pellet quality classes for stoves, burners and boilers.
• Test laboratories and conformity assessors - to perform standardized sampling and analytical testing.
• Regulators and project owners - for permitting, reporting and ensuring safe, low‑emission operation in residential, commercial and industrial installations.

Practical benefits include improved market transparency, reduced installation/operator problems, and better alignment between pellet quality and appliance performance.

Related standards

• ISO 17225-1:2021 - General requirements for solid biofuels (recommended to use in conjunction).
• Sampling and test method standards referenced in the document: ISO 18135, ISO 14780, ISO 18134, ISO 18125, ISO 21404, etc.

For exact class limits, test procedures and normative tables, consult the full EN ISO 17225-2:2021 publication.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2021
Nadomešča:
SIST EN ISO 17225-2:2014
Trdna biogoriva - Specifikacije goriv in razredi - 2. del: Razvrstitev lesnih peletov
(ISO 17225-2:2021)
Solid biofuels - Fuel specifications and classes - Part 2: Graded wood pellets (ISO 17225
-2:2021)
Biogene Festbrennstoffe - Brennstoffspezifikationen und klassen - Teil 2: Klassifizierung
von Holzpellets (ISO 17225 2:2021)
Biocombustibles solides - Classes et spécifications des combustibles - Partie 2: Classes
de granulés de bois (ISO 17225-2:2021)
Ta slovenski standard je istoveten z: EN ISO 17225-2:2021
ICS:
75.160.40 Biogoriva Biofuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 17225-2
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2021
EUROPÄISCHE NORM
ICS 27.190; 75.160.40 Supersedes EN ISO 17225-2:2014
English Version
Solid biofuels - Fuel specifications and classes - Part 2:
Graded wood pellets (ISO 17225-2:2021)
Biocombustibles solides - Classes et spécifications des Biogene Festbrennstoffe - Brennstoffspezifikationen
combustibles - Partie 2: Classes de granulés de bois und klassen - Teil 2: Klassifizierung von Holzpellets
(ISO 17225-2:2021) (ISO 17225 2:2021)
This European Standard was approved by CEN on 24 January 2021.

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, 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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17225-2:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 17225-2:2021) has been prepared by Technical Committee ISO/TC 238 "Solid
biofuels" in collaboration with Technical Committee CEN/TC 335 “Solid biofuels” the secretariat of
which is held by SIS.
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 2021, and conflicting national standards
shall be withdrawn at the latest by November 2021.
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 ISO 17225-2:2014.
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 17225-2:2021 has been approved by CEN as EN ISO 17225-2:2021 without any
modification.
INTERNATIONAL ISO
STANDARD 17225-2
Second edition
2021-05
Solid biofuels — Fuel specifications
and classes —
Part 2:
Graded wood pellets
Biocombustibles solides — Classes et spécifications des
combustibles —
Partie 2: Classes de granulés de bois
Reference number
ISO 17225-2:2021(E)
©
ISO 2021
ISO 17225-2:2021(E)
© ISO 2021
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 2021 – All rights reserved

ISO 17225-2:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 3
5 Specification of graded wood pellets . 4
Bibliography . 9
ISO 17225-2:2021(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 238, Solid biofuels.
This second edition cancels and replaces the first edition (ISO 17225-2:2014), which has been technically
revised. The main changes compared to the previous edition are as follows:
— ash melting behaviour as normative and threshold values for DT temperature added for Table 1
— maximum value for bulk density added for Table 1
— particle density and coarse pellet fines added as informative
A list of all parts in the ISO 17225 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 2021 – All rights reserved

ISO 17225-2:2021(E)
Introduction
The objective of the ISO 17225 series is to provide unambiguous and clear classification principles for
solid biofuels; to serve as a tool to enable efficient trading of solid biofuels; to enable good understanding
between seller and buyer as well as a tool for communication with equipment manufacturers. It also
facilitates authority permission procedures and reporting.
This document supports the use of graded wood pellets for residential, small commercial and public
buildings as well as industrial energy generation applications, which require classified pellet quality.
The residential, small and commercial and public building applications require higher quality fuel for
the following reasons:
— Small-scale equipment does not usually have advanced controls and flue gas cleaning.
— Appliances are not generally managed by professional heating engineers.
— Appliances are often located in residential and populated districts.
NOTE 1 Pellets produced according to this document can be used in pellet stoves, which are tested according to
[1] [2]
European Standard EN 14785 , pellet burners tested according to EN 15270 and pellet boilers or integrated-
[3]
pellet burner systems tested according to EN 303–5 .
NOTE 2 For individual contracts, ISO 17225-1 can be used.
Although this document may be obtained separately, they require a general understanding of the
standards based on and supporting ISO 17225-1. It is recommended to obtain and use ISO 17225-1 in
conjunction with these standards.
INTERNATIONAL STANDARD ISO 17225-2:2021(E)
Solid biofuels — Fuel specifications and classes —
Part 2:
Graded wood pellets
1 Scope
This document determines the fuel quality classes and specifications of graded wood pellets for non-
industrial and industrial use. This document covers only wood pellets produced from the following raw
materials (see ISO 17225-1:2021, Table 1):
— 1.1 Forest, plantation and other virgin wood;
— 1.2 By-products and residues from wood processing industry;
— 1.3.1 Chemically untreated used wood.
Thermally treated biomass pellets (e.g. torrefied pellets) are not included in the scope of 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 14780, Solid biofuels — Sample preparation
ISO 16559, Solid biofuels — Terminology, definitions and descriptions
ISO 16948, Solid biofuels — Determination of total content of carbon, hydrogen and nitrogen
ISO 16968, Solid biofuels — Determination of minor elements
ISO 16994, Solid biofuels — Determination of total content of sulfur and chlorine
ISO 17225-1:2021, Solid biofuels — Fuel specifications and classes — Part 1: General requirements
ISO 17828, Solid biofuels — Determination of bulk density
ISO 17829, Solid Biofuels — Determination of length and diameter of pellets
ISO 17830, Solid biofuels — Particle size distribution of disintegrated pellets
ISO 17831-1, Solid biofuels — Determination of mechanical durability of pellets and briquettes — Part 1:
Pellets
ISO 18122, Solid biofuels — Determination of ash content
ISO 18125, Solid biofuels — Determination of calorific value
ISO 18134-1, Solid biofuels — Determination of moisture content — Oven dry method — Part 1: Total
moisture — Reference method
ISO 18134-2, Solid biofuels — Determination of moisture content — Oven dry method — Part 2: Total
moisture — Simplified method
ISO 18135, Solid Biofuels — Sampling
ISO 17225-2:2021(E)
ISO 21404, Solid biofuels — Determination of ash melting behaviour
ISO 21945, Solid biofuels — Simplified sampling method for small scale applications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16559 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
additive
material which has been intentionally introduced into the fuel feed stock to improve quality of fuel (e.g.
combustion or durability properties), to reduce emissions or to make production more efficient
Note 1 to entry: Trace amounts of e.g. grease or other lubricants that are introduced into the fuel processing
stream as part of normal mill operations are not considered as additives.
3.2
biofuel pellet
densified biofuel made with or without additives (3.1) usually with a cylindrical form, random length
typically 5 mm to 40 mm and diameter up to 25 mm and broken ends, produced by compressing biomass
Note 1 to entry: Usually the biomass has been milled before densification.
Note 2 to entry: See also non-woody pellet, wood pellet and pellet from thermally treated biomass.
3.3
chemical treatment
any treatment with chemicals other than air, water or heat
EXAMPLE Glue and paint.
Note 1 to entry: Examples of chemical treatment are listed in ISO 17225-1.
3.4
coarse pellet fines
CPF
particles with a size ranging from ≥ 3,15 mm to < 5,6 mm resulting from breakage of pellets during
production or handling
3.5
commercial application
facility that utilizes solid biofuel burning appliances or equipment that have similar fuel requirements
as residential appliances
Note 1 to entry: Commercial applications should not be confused with industrial applications, which can utilize a
much wider array of materials and have vastly different fuel requirements.
3.6
fines
F
fraction of small sized particles as defined by a specification or end-user
Note 1 to entry: In the solid biofuels standards fines are always defined as particles passing through a 3,15 mm
round hole sieve.
2 © ISO 2021 – All rights reserved

ISO 17225-2:2021(E)
3.7
woody biomass
biomass originating from trees, bushes and shrubs together with their fruit, leaves and needles inherent
to the biomass
Note 1 to
...