EN ISO 20023:2018

SLOVENSKI STANDARD
01-februar-2019
Trdna biogoriva - Varnost peletov trdnega biogoriva - Varno ravnanje in
shranjevanje lesnih peletov za uporabo v stanovanjskih in drugih manjših
napravah (ISO 20023:2018)
Solid biofuels - Safety of solid biofuel pellets - Safe handling and storage of wood pellets
in residential and other small-scale applications (ISO 20023:2018)
Biogene Festbrennstoffe - Sicherheit von biogenen Festbrennstoffen - Sicherer Umgang
und Lagerung von Holzpellets in häuslichen- und anderen kleinen Feuerstätten (ISO
20023:2018)
Biocombustibles solides - Sécurité des granulés de biocombustible solide - Manutention
et stockage en toute sécurité des granulés de bois dans des applications résidentielles et
autres applications à petite échelle (ISO 20023:2018)
Ta slovenski standard je istoveten z: EN ISO 20023:2018
ICS:
75.160.40 Biogoriva Biofuels
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20023
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2018
EUROPÄISCHE NORM
ICS 27.190; 75.160.40
English Version
Solid biofuels - Safety of solid biofuel pellets - Safe
handling and storage of wood pellets in residential and
other small-scale applications (ISO 20023:2018)
Biocombustibles solides - Sécurité des granulés de Biogene Festbrennstoffe - Sicherheit von biogenen
biocombustible solide - Manutention et stockage en Festbrennstoffen - Sicherer Umgang und Lagerung von
toute sécurité des granulés de bois dans des Holzpellets in häuslichen- und anderen kleinen
applications résidentielles et autres applications à Feuerstätten (ISO 20023:2018)
petite échelle (ISO 20023:2018)
This European Standard was approved by CEN on 5 October 2018.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, 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
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20023:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 20023:2018) 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 June 2019, and conflicting national standards shall be
withdrawn at the latest by June 2019.
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.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 20023:2018 has been approved by CEN as EN ISO 20023:2018 without any modification.

INTERNATIONAL ISO
STANDARD 20023
First edition
2018-10
Solid biofuels — Safety of solid biofuel
pellets — Safe handling and storage of
wood pellets in residential and other
small-scale applications
Biocombustibles solides — Sécurité des granulés de biocombustible
solide — Manutention et stockage en toute sécurité des granulés
de bois dans des applications résidentielles et autres applications à
petite échelle
Reference number
ISO 20023:2018(E)
©
ISO 2018
ISO 20023:2018(E)
© ISO 2018
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 20023:2018(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Terms related to transportation and delivery . 2
3.3 Terms related to storage . 3
4 General . 3
4.1 Product requirements . 3
4.2 Hazards associated with amounts of pellets ≤100 t . 3
4.3 General requirements for storage and handling of pellets . 4
5 Requirements for safe transport and delivery of pellets . 4
5.1 General . 4
5.2 Requirements for bulk delivery by blower trucks . 5
5.2.1 Transport vehicles and their operation . 5
5.2.2 Filling end-user storage systems . 6
5.3 Pellets delivered in bulk tipped into troughs or bunkers . 8
5.4 Pellets delivered in big bags . 8
5.5 Pellets delivered in small bags on pallets . 8
6 Requirements for bulk storage systems . 8
6.1 General requirements . 8
6.1.1 Location of pellet store . 8
6.1.2 Quality control of installation . 9
6.1.3 Construction requirements . 9
6.1.4 Measures to reduce the accumulation of fines . 9
6.1.5 Protection against moisture and water . 9
6.1.6 Prevention of dust movement . 9
6.1.7 Noise protection . 9
6.1.8 Installation .10
6.1.9 Fire protection .10
6.1.10 Explosion prevention .10
6.1.11 Protection and measures against burn-back and back gassing . .10
6.1.12 Extraction systems .11
6.1.13 Fill connectors and piping .11
6.1.14 Electrical outlet for suction fan .12
6.1.15 Ventilation .12
6.1.16 Safety instructions .15
6.1.17 Access to storage .15
6.2 Individual custom-made pellet stores .15
6.2.1 Construction requirements .15
6.2.2 Fill connectors .17
6.2.3 Impact protection mat .18
6.2.4 Sloping floor .18
6.2.5 Access hatch/door to pellet store .18
6.3 Pre-fabricated storage systems .19
6.3.1 General.19
6.3.2 Requirements regarding the site, indoor systems .20
6.3.3 Requirements regarding the siting of outdoor installations .20
6.3.4 Ground connection (earth) .20
6.3.5 Filling instructions .20
6.3.6 Fabric store .20
ISO 20023:2018(E)
6.3.7 Underground store .21
7 Health protection aspects .21
7.1 Entering a pellet store .21
7.1.1 General.21
7.1.2 Requirements for small pellet stores up to 15 t .22
7.1.3 Requirements for pellet stores >15 t and/or underground stores .22
7.2 Stationary CO monitors .22
7.3 Equipment used in stores .23
Annex A (informative) Hazards associated with pellets .24
Annex B (informative) Model calculation for different cases of store ventilation .30
Annex C (informative) Examples for store designs .34
Annex D (normative) Minimum requirements of a hand-over document .42
Annex E (informative) Example of a checklist for filling of store .46
Bibliography .48
iv © ISO 2018 – All rights reserved

ISO 20023:2018(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.
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.
ISO 20023:2018(E)
Introduction
There is a continuous global growth in production, storage, handling, bulk transport and use of solid
biofuels especially in the form of pelletized biofuels.
The specific physical and chemical characteristics of solid biofuels, their handling and storage can lead
to a risk of fire and/or explosion, as well as health risks such as intoxication due to exposure to carbon-
monoxide, asphyxiation due to oxygen depletion or allergic reactions.
There is a risk of injury or death associated with pellet storage, so safety measures shall be implemented.
The possibility of fire and explosion incidents is a clear indicator that safety needs to be prioritized,
first of all for human safety but also because interruptions in energy supply can have significant
consequences. The market confidence in solid biofuels as a secure energy source may be jeopardized
and financial losses due to business interruptions could occur. Difficulty to obtain insurance coverage
will also increase.
As part of the determination and the assessment of risks for solid biofuels, defined test methods
and standards are established or need to be developed. However, the ageing and degradation due to
handling and storage of solid biofuels in particular environments will affect the characteristics. The
consequence of this change of characteristics is that safety margins need to be established in relation to
the actual analysis results.
For small scale applications and handling of small quantities of pellets up to 100 t, requirements of this
standard support end-users not educated in safety aspects or requirements of solid biofuel handling.
Health risks are associated with the quality of the fuel and therefore controlling the fuel quality reduces
the risks, particularly of dust emissions. Logistics and the handling of the pellets play a major part in
maintaining quality and are therefore also addressed in this standard.
Generally, facilities at end users with a storage capacity <100 t are covered by this document and larger
1)
stores will be covered by ISO 20024 . However, storage capacity alone is not a good enough parameter
on which to decide which standard to apply. A trader or larger end user might have a number of small
storage facilities but may have a greater throughput of pellets during the entire year but with frequent
filling and reclaiming or packaging. Depending on the characteristics of a specific facility, all of the
principles covered in this document should be considered but all or only some parts of the systems/
equipment described in ISO 20024 will be relevant.
A competent assessor should have knowledge and experience commensurate with the complexity of the
facility (knowledge of solid biofuels is required) before selecting which standard and which clauses are
applicable to the facility being considered.
1)  Under preparation. Stage at the time of publication ISO/CD 20024:2018.
vi © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 20023:2018(E)
Solid biofuels — Safety of solid biofuel pellets — Safe
handling and storage of wood pellets in residential and
other small-scale applications
1 Scope
This document provides principles and requirements for the safe handling and storage of wood pellets
in residential and other small-scale applications. It covers the supply chain from loading of the delivery
truck, requirements of delivery trucks, connections to the end-user's store and the delivery process.
It also covers the design and construction of pellet storage systems. This document addresses risks
of fires, dust explosions, off-gassing, oxygen depletion, damage to appliances and buildings through
swelling of pellets and other health risks. It is applicable to wood pellets according to ISO 17225-2.
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 16559, Solid biofuels — Terminology, definitions and descriptions
ISO 17225-2, Solid biofuels — Fuel specifications and classes — Part 2: Graded wood pellets
IEC 60529, Degrees of protection provided by enclosures (IP Code)
EN 13237, Potentially explosive atmospheres — Terms and definitions for equipment and protective systems
intended for use in potentially explosive atmospheres
3 Terms and definitions
For the purposes of this document, terms and definitions given in ISO 16559 and EN 13237, 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 General terms
3.1.1
combustible dust
finely divided solid particles, with a particle size of 500 μm or less in nominal size, which may form
explosive mixtures with air at standard atmospheric pressure and temperatures
Note 1 to entry: This includes dust and grit as defined in ISO 4225.
Note 2 to entry: The term 'solid particles' is intended to address particles in the solid phase but does not preclude
a hollow particle.
[SOURCE: ISO/IEC 80079-20-2:2016, 3.1]
ISO 20023:2018(E)
3.1.2
fines
F
small sized particles in fuel below a certain pre-defined size, here less than 3,15 mm
Note 1 to entry: The amount of fines can be different after completion of production, bagging, transportation,
unloading, distribution etc.
[SOURCE: ISO 16559:2014, 4.90, modified — “usually” replaced by “here” to indicate exact limit.]
3.2 Terms related to transportation and delivery
3.2.1
bulk transport
pellets transported loose, typically in tippers, walking floor trucks, other trucks with closed cargo area
or blower trucks (3.2.2)
3.2.2
blower truck
vehicle with a pneumatic discharge system using compressed air
Note 1 to entry: Examples of blower trucks include silo-trucks and rotary feeder trucks.
3.2.3
silo truck
fully pneumatic blower truck (3.2.2) where pellets are loaded into special pressurised compartments
emptied by applying compressed air and using compressed air for pellet conveying
3.2.4
rotary feeder truck
truck where pellets are discharged by gravity via a rotary valve (or star valve) into the stream of
compressed air for pellet conveying
3.2.5
day hopper
hopper directly linked to the automatically stoked heating boiler
Note 1 to entry: Typically a day hopper holds a few days of pellet fuel up to 1 t. The filling of the hopper is a batch
operation.
3.2.6
closing cap
cap made of metal or plastic, which seals the connectors (3.2.7)
3.2.7
connector
permanently installed coupling made of aluminium-alloys or steel, with a gasket ring for pressure and
suction operation, which functions in the filling of the pellet store (3.3.2)
Note 1 to entry: There are different uses for connectors, such as filling and suction.
3.2.8
delivery hose
temporary connection between the pellet blower truck (3.2.2) and the fill connector of the pellet store
during the pneumatic delivery process
2 © ISO 2018 – All rights reserved

ISO 20023:2018(E)
3.3 Terms related to storage
3.3.1
sloping floor
construction in the store that allows the fuel to be fed by gravity to the conveying system
Note 1 to entry: The aim is to achieve storage that completely drains without any intervention.
3.3.2
pellet store
room, container or other place where pellets are stored by the end-user before combustion
Note 1 to entry: Pellet stores can be self-built or pre-fabricated.
3.3.3
small pellet store
pellet store with a capacity of less than 15 t
3.3.4
individual customized store
pellet store that is individual custom-made into a building often including existing structures like walls
Note 1 to entry: Individual customized stores may be self-built by end-users.
3.3.5
pre-fabricated store
storage system built by specialist companies, erected at the end-user's premises
3.3.6
fill pipe
connecting pipe, which connects the fill connector (3.2.7) with the pellet store
3.3.7
small bag
bag for pellets with a typical filling weight between 8 kg and 25 kg
3.3.8
big bag
flexible intermediate bulk container (FIBC) made of flexible fabric that is designed for storing and
transporting bulk materials with a capacity of 500 l and above
4 General
4.1 Product requirements
This document was developed to promote the safe handling, storage and combustion of pellets
conforming to the fuel properties of ISO 17225-2, Classes A1, A2 and B. If other fuel types are used the
principles contained herein might not apply.
A data sheet for wood pellets issued by the manufacturer/supplier may provide more specific
information with regards to the product delivered, quality, safety and health aspects during handling
and storage.
4.2 Hazards associated with amounts of pellets ≤100 t
Pellets react in their environment in different ways, especially with air and moisture and they are also
sensitive to mechanical stress. To avoid hazards it is important to store and handle pellets accordingly.
ISO 20023:2018(E)
The hazards associated with pellet storage in small-scale applications can be summarized, but are not
limited to the following categories:
a) intoxication or oxygen depletion caused by volatile components that may accumulate through
biological degradation or originate from backflow of flue gases;
b) risk of explosions and fire due to accumulation of dust and fines as a result of physical stress and
decomposition;
c) risk of fire and smouldering due to self-ignition processes or burn-back;
d) damage to storage structures and buildings due to swelling of pellets caused by water.
More information concerning the listed hazards is compiled in Annex A.
4.3 General requirements for storage and handling of pellets
All handling and transport equipment shall be designed to minimise damage to the pellets. Abrasion of
pellets and consequential formation of fines shall be minimized.
Dust emissions to the environment shall be kept as low as possible. Fines and dust accumulate on flat
and inclined surfaces. These surfaces and other places where fines may accumulate shall be minimized.
Unavoidable areas where fines may accumulate shall be cleaned regularly, see 6.1.4.
Accumulation of carbon monoxide (CO) and volatiles in closed storage facilities shall be avoided by
proper ventilation of the facilities.
Wood pellets shall be protected against humidity and moisture. They shall be kept dry at all times.
If pellets of other quality or diameter are used, the vehicles, conveyors and storage containers shall be
thoroughly cleaned of any previously handled products.
NOTE Requirements for large storage facilities (>100 t), packing and loading systems are provided in
ISO 20024.
5 Requirements for safe transport and delivery of pellets
5.1 General
The requirements will differ depending on how the pellets are delivered to the end-user:
a) Bulk pellets for residential and other small-scale applications are typically delivered by blower
trucks. For requirements for this type of delivery, see 5.2.
b) If bulk pellets are delivered by tippers or walking floor trucks and are unloaded at the end-
customer into a trough or a bunker, see 5.3.
c) If other vehicles are used for bulk transport the suitability of the transport system shall be
evaluated.
d) If pellets are delivered in big bags, see 5.4.
e) If pellets are delivered in small bags, see 5.5.
In all cases the pellets shall be protected against moisture (e.g. rain, snow or condensate) throughout
the transportation process as well as during loading and unloading.
Loading of trucks is only permitted when the pellet temperature is less than 40 °C. If the ambient
temperature exceeds 35 °C, a pellet temperature up to but not exceeding 45 °C is acceptable. Heating of
pellets in the truck shall be minimized e.g. by using bright/reflective surface on the outside of the truck.
Heating can also be caused by using hot compressed air, which raises the temperature of the pellets.
4 © ISO 2018 – All rights reserved

ISO 20023:2018(E)
The specification of the pellets shall be in accordance with ISO 17225-2 and shall be stated on all
delivery documentation and invoices.
All pellet handling areas shall be strictly non-smoking areas and have no open flames.
5.2 Requirements for bulk delivery by blower trucks
5.2.1 Transport vehicles and their operation
To help the understanding of the following paragraphs, see Figure 1.
Key
1 compressor 6 end-user’s pellet store
2 pressurisation of storage cell 7 suction fan with filter sock to extract the blower air
3 pressure gauge measures pressure in the discharge and create a slightly negative pressure in the pellet
pipe or in the storage cell store
4 coupling on blower truck 8 exhaust air
5 delivery hose
Figure 1 — Operating principle of the blowing process using a silo truck
Mechanical damage of pellets caused by transport vehicles shall be minimized. Blower trucks shall be
equipped with a low abrasion blowing feed system. Low abrasion may be obtained by using coated
hoses. Sharp edges between hoses shall be avoided. The trucks should be equipped with a compressor
that provides air for blowing the pellets. Where required, blower trucks shall have a mobile fan to
extract the supply air from the storage facility during blowing. Explosion protection for the mobile
fan is not required if only used outdoors. The capacity of this suction fan shall exceed the capacity
of the blowing system of the vehicle. The extracted air shall be filtered (e.g. by fabric filter) to limit
dust emissions to the environment. The connected filter bag shall be checked for fouling and shall be
protected from rain or be made from water resistant material in order to ensure a necessary negative
pressure in the pellet store during the blowing process.
Some stores do not need suction of the blowing air. Filling instructions provided by the manufacturer of
these stores shall be followed. Where no suction is required, the blowing air (<1 500 m /h) has to exit
through windows, doors or other openings, so that the pressure in the room where the pellet store is
located does not increase significantly. Openings should have a size of at least 400 cm .
A blower truck shall be constructed so that the increase in fines is as low as possible. While testing the
suitability of a truck the increase of fines shall be less than 2 % where:
— the pellets have a mechanical durability of 98,5 % (±0,3 %),
ISO 20023:2018(E)
— the delivery hose shall be 18 m long and there is one 45° bend (radius = 2,5 times the pipe diameter)
in the fill pipe,
— the distance between the tube end in the store/test facility and the opposite wall is 3 m,
— the impact mat is 50 cm in front of the rear wall,
— the delivery rate has a mass flow of 15 t/h (±1 t),
— the minimum quantity of fuel to be blown for this test is 500 kg.
The actual fines content in the end-user's store depends on many additional factors to those during
testing (e.g. impact of driver/operating staff competence, blowing distance, height differences, bends,
construction and dimensions of the pellet store) and can exceed the 2 % increase limit expected from
the testing of the transportation vehicle.
Locally used reducing and connecting couplings should be part of the equipment on board the truck. The
hose couplings shall be free from obstructions that would cause damage to the pellets. Only electrically
conductive delivery hoses shall be used for the filling. Where the delivery hoses have a coating, the
breakdown voltage shall be below 4 kV. The delivery and vent hoses shall dissipate static (earth leakage
resistance R << 10 Ω). Hoses shall be marked or be clearly visible when crossing traffic areas like
E
sidewalks or bicycle paths.
The blower truck shall be equipped with an earthing system. Blower truck doing part deliveries of the
loaded pellets to end-users shall be equipped with calibrated certified on-board weighing system.
The truck storage cells shall be securely closed immediately after loading the truck.
Only trucks properly operated, maintained and with well-kept blowers/compressors shall be deployed.
Storage cells, hoses, fans, filters and other equipment shall be clean and shall be inspected regularly by
the operating staff according to the manufacturer’s instructions and good practice.
In difficult delivery situations where high temperatures in the blowing air and pellets can cause
problems such as long distances between the truck and fill connector and/or high ambient temperatures
(>30 °C), the blower trucks should use cooled air. The blower trucks should either use cooled air as a
technical measure (compressor cooler) or optimize the temperature through organizational measures
(e. g. delivery in the early morning when it is still cool).
5.2.2 Filling end-user storage systems
When filling a pellet store there are two options:
a) When the customer is on-site or deliverer has been provided with access:
— If required by the filling instructions of the manufacturer, the customer shall turn off the
combustion system in appropriate time before the delivery of the pellets. This needs to be
confirmed by the customer before delivery.
— The exact period of time before the delivery takes place should be given in the boiler instructions.
— The customer will confirm to the driver that the boiler has been turned off for the required period.
b) When the customer is absent:
— The customer can give a written instruction that delivery can be made safely without turning
the boiler off.
— Where the delivery operative has no information on the length of time the boiler has been
turned off and there is no written instruction from the end-user to carry out the delivery the
pellet supplier shall not fill the pellet store.
To help the understanding of the described options when filling a pellet store, see Figure 2.
6 © ISO 2018 – All rights reserved

ISO 20023:2018(E)
Figure 2 — Filling of end-user store
Before filling an end-user pellet store a checklist shall be filled in by the delivery staff, see an example of
a checklist in Annex E. The checklist shall include at least the following information:
a) Boiler switched off; YES/NO/UNKNOWN. If the boiler has not been turned off, and there is no
written instruction that delivery can be made safely without turning the boiler off, no delivery
shall be performed.
b) Pellet store inspected; YES/NO.
c) Nature and estimated amount of remaining pellets in the store, if possible.
d) Obvious defects and observations which may cause safety hazards.
e) Suction fan used; YES/NO.
f) Fill connectors are properly earthed; YES/NO/UNKNOWN. If proper earthing is not ensured at the
connectors, the earthing system of the blower truck shall be used.
g) Length of hose used (in metres).
The checklist shall be included in the delivery documents and may be included in the delivery note.
The filling instruction for the pellet store shall be clearly visible for the pellet deliverer.
ISO 20023:2018(E)
If local arrangements are unfavourable e.g. too many bends in the filling lines, blowing distances >30 m
or disadvantageous layout of pellet store, excessive fines can arise. Such issues shall be documented on
the checklist and should be explained to the customer.
NOTE Particle segregation will occur during storage and delivery, and the results can be seen on the slope in
the lower area of the storage. The appearance of a dusty surface of the pile is not an indication for the total fines
content in a pile.
5.3 Pellets delivered in bulk tipped into troughs or bunkers
When pellets are delivered by tippers or walking floor trucks into a trough or bunker, the reception
facility shall meet the following requirements:
a) be covered except during delivering of pellets;
b) be at least 0,5 m wider on either side of the tail gate of the discharge chute to collect all pellets
during unloading;
c) where grating is used it shall be constructed of bars with rounded edges.
5.4 Pellets delivered in big bags
Pellets may be delivered in big bags (FIBC) with or without a discharge spout. Preferably bags with four
lifting loops should be used. Forks used for handling big bags shall have rounded edges to avoid damage
to the bag.
Big bags without a discharge spout delivered to an end-customer will usually be emptied manually
by taking out small amounts. They shall be closed between withdrawals to protect the pellets from
moisture and contamination.
Big bags with a discharge spout shall have a discharge spout with a diameter ≤300 mm. The lacing
cord for closing the discharge spout shall be connected to the big bag and shall not be cut open to avoid
contamination of the pellets with cord ends. These bags may also be used as a fuel store that feeds
directly into the heating system.
5.5 Pellets delivered in small bags on pallets
Pellets in small bags on pallets shall not be stored outdoors in direct sunlight. Pallets shall be covered
with a protective covering and be recovered after withdrawal of bags from the stack.
Outdoor storage in direct sunlight may be done if the packaging material is UV resistant and
weatherproof. A loaded pallet with pellets may be damaged by animals, e.g. birds, foxes and rats, when
stored outdoors.
Pellet bags shall be stored unopened. Bagged pellets are safe from gaseous emissions in terms of health
impacts if one bag is opened at a time and loaded into the pellet store or day hopper.
6 Requirements for bulk storage systems
6.1 General requirements
6.1.1 Location of pellet store
The blower truck shall be able to get sufficiently close to the connectors to minimize damage to the
pellets during the filling process. The access route shall be adequate for the kind of transport vehicles
that are used. The minimum road width and minimum clearances for heavy trucks according to national
regulations shall be guaranteed. The turning radius, gross weight of the vehicle, the gradient of the
roads and winter conditions should be considered.
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ISO 20023:2018(E)
When filling the pellet store with a blower truck, a hose length of 30 m shall not be exceeded. The total
pipework including hose, connectors and pipework in the facility should not exceed 35 m. Connectors
shall be easily accessible.
6.1.2 Quality control of installation
Pellet stores shall be installed and operated according to this standard and the manufacturer´s
instructions. It is recommended that the installer of the heating system also installs the pellet store and
is therefore responsible for smooth operation of the whole system. Even if the pellet store is not built by
the installer, he shall check the pellet store before the first pellet delivery. The results of the check shall
be handed over to the end user, as given in Annex D.
6.1.3 Construction requirements
Walls and all construction elements shall be designed to withstand the load in all directions (horizontal
as well as vertical). For calculating loadings the m
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