Solid biofuels - Determination of off-gassing and oxygen depletion characteristics - Part 1: Laboratory method for the determination of off-gassing and oxygen depletion using closed containers (ISO/TS 20048-1:2020)

This international standard specifies analytical methods for the determination of off-gassing from and oxygen depletion by solid biofuel pellets. The standard specifies the applicability and use of analytical methods. It further establishes special procedures for sampling and sample handling of solid biofuels pellets prior to the analysis of off-gassing and oxygen depletion. Guidance on the applicability and use of the data on off-gassing and oxygen depletion from the analytical methods is given.

Biogene Festbrennstoffe - Bestimmung von Ausgasungs- und Sauerstoffverarmungseigenschaften - Teil 1: Laboratoriumsverfahren zur Bestimmung von Ausgasung und Sauerstoffverarmung (ISO/TS 20048-1:2020)

Biocombustibles solides - Détermination des dégagements gazeux et de l’appauvrissement en oxygène - Partie 1: Titre manque (ISO/TS 20048-1:2020)

Le présent document définit une méthode de détermination des dégagements gazeux (gaz permanents) et de l'appauvrissement en oxygène de la biomasse ligneuse et non ligneuse, y compris les matériaux densifiés tels que les granulés et les briquettes, ainsi que les matériaux non densifiés tels que les plaquettes. La méthode est également applicable aux matériaux traités thermiquement, y compris les matériaux torréfiés et carbonisés.
Le facteur d'émission et d'appauvrissement et le taux d'émission et d'appauvrissement de diverses espèces gazeuses émises par un échantillon dans un récipient d'essai fermé sont déterminés par chromatographie en phase gazeuse.
Le facteur d'émission et d'appauvrissement et le taux d'émission et d'appauvrissement donnent des indications sur les exigences de ventilation pour maintenir les concentrations de gaz en dessous des niveaux d'exposition admissibles (PEL) dans les espaces où les travailleurs peuvent être exposés à l'atmosphère confinée.

Trdna biogoriva - Določanje značilnosti odvajanja plinov in pomanjkanja kisika - 1. del: Laboratorijska metoda za določanje uhajanja plinov in zmanjšanja kisika z uporabo zaprtih posod (ISO/TS 20048-1:2020)

General Information

Status
Published
Public Enquiry End Date
28-Feb-2022
Publication Date
08-May-2022
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
20-Apr-2022
Due Date
25-Jun-2022
Completion Date
09-May-2022

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SLOVENSKI STANDARD
SIST-TS CEN ISO/TS 20048-1:2022
01-junij-2022

Trdna biogoriva - Določanje značilnosti odvajanja plinov in pomanjkanja kisika - 1.

del: Laboratorijska metoda za določanje uhajanja plinov in zmanjšanja kisika z
uporabo zaprtih posod (ISO/TS 20048-1:2020)

Solid biofuels - Determination of off-gassing and oxygen depletion characteristics - Part

1: Laboratory method for the determination of off-gassing and oxygen depletion using

closed containers (ISO/TS 20048-1:2020)
Biogene Festbrennstoffe - Bestimmung von Ausgasungs- und

Sauerstoffverarmungseigenschaften - Teil 1: Laboratoriumsverfahren zur Bestimmung

von Ausgasung und Sauerstoffverarmung (ISO/TS 20048-1:2020)
Biocombustibles solides - Détermination des dégagements gazeux et de
l’appauvrissement en oxygène - Partie 1: Titre manque (ISO/TS 20048-1:2020)
Ta slovenski standard je istoveten z: CEN ISO/TS 20048-1:2022
ICS:
75.160.40 Biogoriva Biofuels
SIST-TS CEN ISO/TS 20048-1:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN ISO/TS 20048-1:2022
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SIST-TS CEN ISO/TS 20048-1:2022
CEN ISO/TS 20048-1
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
April 2022
TECHNISCHE SPEZIFIKATION
ICS 27.190; 75.160.40
English Version
Solid biofuels - Determination of off-gassing and oxygen
depletion characteristics - Part 1: Laboratory method for
the determination of off-gassing and oxygen depletion
using closed containers (ISO/TS 20048-1:2020)

Biocombustibles solides - Détermination des Biogene Festbrennstoffe - Bestimmung von

dégagements gazeux et de l'appauvrissement en Ausgasungs- und Sauerstoffverarmungseigenschaften -

oxygène - Partie 1: Méthode de laboratoire pour la Teil 1: Laboratoriumsverfahren zur Bestimmung von

détermination des dégagements gazeux et de Ausgasung und Sauerstoffverarmung (ISO/TS 20048-

l'appauvrissement en oxygène dans des récipients 1:2020)
fermés (ISO/TS 20048-1:2020)

This Technical Specification (CEN/TS) was approved by CEN on 27 March 2022 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to

submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS

available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in

parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 20048-1:2022 E

worldwide for CEN national Members.
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SIST-TS CEN ISO/TS 20048-1:2022
CEN ISO/TS 20048-1:2022 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST-TS CEN ISO/TS 20048-1:2022
CEN ISO/TS 20048-1:2022 (E)
European foreword

The text of ISO/TS 20048-1:2020 has been prepared by Technical Committee ISO/TC 238 "Solid

biofuels” of the International Organization for Standardization (ISO) and has been taken over as

CEN ISO/TS 20048-1:2022 by Technical Committee CEN/TC 335 “Solid biofuels” the secretariat of

which is held by SIS.

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.

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 announce this Technical Specification: 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/TS 20048-1:2020 has been approved by CEN as CEN ISO/TS 20048-1:2022 without any

modification.
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SIST-TS CEN ISO/TS 20048-1:2022
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SIST-TS CEN ISO/TS 20048-1:2022
TECHNICAL ISO/TS
SPECIFICATION 20048-1
First edition
2020-03
Solid biofuels — Determination of
off-gassing and oxygen depletion
characteristics —
Part 1:
Laboratory method for the
determination of off-gassing and
oxygen depletion using closed
containers
Reference number
ISO/TS 20048-1:2020(E)
ISO 2020
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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 2020 – All rights reserved
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Apparatus ..................................................................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Test containers ........................................................................................................................................................................................ 3

5.3 Gas sampler................................................................................................................................................................................................ 5

5.4 Ovens ............................................................................................................................................................................................................... 5

5.5 Gas chromatograph (GC) analyser ......................................................................................................................................... 5

6 Biomass sampling and sample preparation ............................................................................................................................ 6

6.1 General ........................................................................................................................................................................................................... 6

6.2 Test sample characterization ...................................................................................................................................................... 6

6.3 Test sample size ..................................................................................................................................................................................... 6

7 Procedure..................................................................................................................................................................................................................... 6

7.1 Determination of porosity in biomass test sample .................................................................................................. 6

7.2 Filling of test containers ................................................................................................................................................................. 7

7.3 Test container arrangement and test gas sampling volume ............................................................................ 7

7.4 Operation of temperature-controlled ovens ................................................................................................................. 8

7.5 Gas sampling procedure ................................................................................................................................................................. 8

7.6 Gas analysis ................................................................................................................................................................................................ 9

8 Calculation .................................................................................................................................................................................................................. 9

9 Test report ................................................................................................................................................................................................................13

Annex A (normative) Quantification of gas species using chromatography ............................................................14

Annex B (informative) Estimation of ventilation requirements for enclosed spaces ....................................16

Annex C (informative) Determination of gas species concentration in open storage space ...................19

Bibliography .............................................................................................................................................................................................................................20

© ISO 2020 – All rights reserved iii
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(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.
A list of all parts in the ISO 20048 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 2020 – All rights reserved
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(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.

Emission from pellets or biomass stored in enclosed space represents a significant health risk due to

exposure to carbon-monoxide (CO) and oxygen depletion. It is important to be able to assess the risk by

quantifying the emission of CO in combination with oxygen level. This document describes a method for

estimating the propensity of a particular quality of pellets or biomass to emit CO, CO , CH as well as the

2 4

depletion of oxygen within the stored environment. In a confined space, the gas composition can result

in a toxic as well as explosive atmosphere.

Biomass species, age of the material as well as the ambient temperature impacts the dynamics of the gas

emissions. Unless the level of CO and oxygen levels are well understood in an operating environment,

there are inherent risk for workers, which have implications for liability.

This document specifies the methodology for measuring the emission and depletion factor and emission

and depletion rate of off-gassing in combination with oxygen depletion for permanent gases emitted in

an enclosed storage for biomass.

NOTE A method to be used in preliminary screening of CO for operational planning is currently under

development within ISO/TC 238/WG 7. Stage at the time of publication ISO/CD 20048-2:2018.

The method described in this document uses highly sensitive gas chromatography to be able to identify

the spectrum of gases and their relative concentration to predict the potential for unhealthy conditions

during indoor storage of biomass. The sensitivity for detection of gas species and concentrations is

only limited by the sensitivity of the chromatographic instrument. The method allows for estimation

of emission and depletion factor and emission and depletion rate for each gas species of biomass at

different storage temperatures.

The gas instrument analysis part of the method also allows for identification of gas species and

determination of concentrations of gases sampled in open storage spaces for occupational hygiene

purposes (Annex C).
© ISO 2020 – All rights reserved v
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SIST-TS CEN ISO/TS 20048-1:2022
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SIST-TS CEN ISO/TS 20048-1:2022
TECHNICAL SPECIFICATION ISO/TS 20048-1:2020(E)
Solid biofuels — Determination of off-gassing and oxygen
depletion characteristics —
Part 1:
Laboratory method for the determination of off-gassing
and oxygen depletion using closed containers
1 Scope

This document defines a method for determination of off-gassing (permanent gases) and oxygen

depletion from woody as well as non-woody biomass, including densified materials such as pellets and

briquettes, as well as non-densified materials such as chips. The method is also applicable for thermally

treated materials, including torrefied and carbonized materials.

The emission and depletion factor and emission and depletion rate for various gas species emitted from

sample within a closed test container is determined by means of gas chromatography.

The emission and depletion factor and emission and depletion rate provide guidance for ventilation

requirements to keep gas concentrations below Permissible Exposure Levels (PEL) in spaces where

workers can be exposed to the enclosed atmosphere.
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 18135, Solid biofuels — Sampling
ISO 14780, Solid biofuels — Sample preparation

ISO 17827-2, Solid biofuels — Determination of particle size distribution for uncompressed fuels — Part 2:

Vibrating screen method using sieves with aperture of 3,15 mm and below
ISO 17828, Solid biofuels — Determination of bulk density

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 18846, Solid biofuels — Determination of fines content in quantities of pellets

ISO 18847, Solid biofuels — Determination of particle density of pellets and briquettes

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 16559 and the following apply.

© ISO 2020 – All rights reserved 1
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)

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
emission factor

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram of the substance emitting at a given temperature
3.2
depletion factor

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram of the substance depleting at a given temperature
3.3
emission rate

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram per day of the substance emitting at a given temperature
3.4
depletion rate

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram per day of the substance depleting at a given temperature
3.5
ppmv
parts per million on volume basis
3.6
gas chromatograph

instrument used in analytical chemistry for separating and analysing compounds that can be

vapourized without decomposition
3.7
Permissible Exposure Level
PEL
regulatory limit on the amount or concentration of a substance in the air

Note 1 to entry: This is usually based on an eight-hour time weighted average, but some are based on short-term

exposure limits.
4 Principle

One or more test container(s) sealed with an air-tight lid and partly filled with biomass test sample are

placed in oven with controlled temperature such as 20 °C, 30 °C, 40 °C or 50 °C. Gas samples are drawn

by means of a syringe through the sampling port of the container(s) and the relative concentration

of gas species is quantified by means of a gas chromatograph. The concentration is converted from

a volume fraction in % relative to other gases in the test container and expressed as emission and

depletion factor in gram per kilogram of biomass at a given temperature. The emission and depletion

rate are expressed as gram of gas species per kilogram of biomass per day at a given temperature.

A method for converting emission and depletion factor (ppmv) concentration and calculating the

number of air exchanges in a space with controlled ventilation is provided in Annex B.

2 © ISO 2020 – All rights reserved
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)
5 Apparatus
5.1 General

All equipment holding biomass samples and gas samples extracted during the determination shall be

free of any contaminants, well ventilated and dry before the off-gassing test starts.

NOTE Containers and fittings can be dried overnight at low temperature around 30 °C.

5.2 Test containers

The test container(s) shall preferably be made of glass, not plastic, due to the risk of contaminating

gases from plastic materials at higher temperatures. Since the containers shall only be filled to 75 %

with biomass to be tested, it is an advantage to be able to see the level of biomass from the outside.

Figure 1 a) to 1 c) show photos of the test container with sampling port and Figure 2 shows a schematic

of the test container and sampling port.
a) Test container of glass with sampling port
b) Sampling port, from the side
© ISO 2020 – All rights reserved 3
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)
c) Sampling port, from above
Figure 1 — Example of test container of glass with sampling port
Key
1 septum
2 nipple
3 sampling port
4 container lid
5 air-tight seal
6 test container
Figure 2 — Schematic of test container with sampling port

The headspace in an enclosed container shall contain sufficient oxygen to sustain oxidation of test

[1][2]

sample to reach a peak (plateau) and allow determination of the emission and depletion factor . The

25 % headspace of enclosed air volume under roof in a typical large-scale storage facility such as a silo

when fully loaded is typical and is therefore selected for this test method.
4 © ISO 2020 – All rights reserved
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)

The seal between the lid and the container as well as the sampling port nipple (septum) shall be made

of polytetrafluoroethylene (PTFE) or neoprene, which are non-reactive materials at the temperatures

recommended for the off-gassing tests. Gas samples shall be drawn using a syringe (see 5.3) piercing

through the septum.

The effective gas volume in a test container can be expressed in accordance with Formula (1).

VV=+VV=×02, 5 +V (1)
hv cv
where
V is the effective gas volume in test container when filled with biomass;
V =×02, 5 V is the selected headspace volume;
h c
V is the volume of void between the biomass particles;
V is the volume of empty test container.
EXAMPLE

The effective gas volume (V) for a test container with a volume of 3 500 ml (V ) loaded to 75 % with wood pellets

and with a volume of void of 50 % can be calculated as follows:
V = 0,25 × 3 500 [ml]+0,75 × 3 500 [ml] × 0,5 = 3 500 [ml] × 0,625 = 2 188 ml

Guidance for selecting container size in relation to gas sample size required by the GC for a selected gas

depletion volume is provided in 7.3.
5.3 Gas sampler

A gas-tight GC syringe shall be used for drawing gas test samples through septum in the container

sampling port nipple. It is recommended that the capacity of the syringe be at least 3 times the volume

of the sampling tube and sampling loop of the GC or as recommended by the manufacturer of the GC

(see 5.5). The syringe shall have a scale with a resolution of 1 ml and a valve to secure the sample after

drawing. It is best to use needles that have a hole on the side rather than the tip to prevent silicone or

neoprene material blocking the hole while sampling.

The gas sample is injected directly from the sampler syringe into the GC sample port.

5.4 Ovens

The temperature within the test containers shall be controlled by placing the containers in ovens

automatically controlling the temperature in the range of 20 °C to 50 °C ± 1 °C. A separate oven is

required for each temperature selected for testing. The ovens shall be able to hold the size of containers

required to achieve the necessary accuracy of the off-gassing determination.
[4]

Since temperature of biomass under test has a propensity to self-generate heat at testing temperatures

above 40 °C, particularly if the moisture in the material is high, a thermocouple should be placed

inside the material in one of the containers. A thermocouple in the centre of the test volume will help

monitoring the uniformity of the temperature.
5.5 Gas chromatograph (GC) analyser

The detection limit for each gas species and related concentrations is determined by the type of column

in the GC. The manufacturer of the GC should be consulted. GC with thermal conductivity detector (TCD)

shall be used to detect and quantify permanent gases and light hydrocarbons. Packed and capillary

© ISO 2020 – All rights reserved 5
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)

columns could be used with TCD to measure permanent gases. A combination of TCD and FID (flame

ionization detector) could also be used for gas measurements depending on the GC configuration.

NOTE 1 Helium (He) is usually used as carrier gas but, e.g., nitrogen or argon are other possible alternatives.

NOTE 2 PEL for CO is in the range of 25 ppmv to 100 ppmv depending on jurisdiction and on the duration of

the exposure. Gas chromatography allows identification of a large number of non-condensable like CO, CO , CH ,

2 4

N , H , and O . The PEL for those compounds can be found in occupational hygiene databases. The occupational

2 2 2
health lower limit for oxygen is 19,5 %.
Annex A provides a generic orientation of operation and calibration of a GC.
6 Biomass sampling and sample preparation
6.1 General

Sampling and sample preparation of biomass shall be done in accordance with ISO 18135 and ISO 14780

respectively.
6.2 Test sample characterization

The test sample characterization shall be done in accordance with the following international standards;

a) Moisture ISO 18134-1 or ISO 18134-2
b) Particle size distribution ISO 17827-2
c) Fines content ISO 18846
d) Bulk density ISO 17828
e) Particle density ISO 18847

If available, note the origin, species and age of the test sample in the test report (Clause 9).

6.3 Test sample size

The total sample size depends on the test container configuration selected (7.3). At least three test

sample fractions shall be prepared; one for test sample characterization (6.2) and the others for off-

gassing/oxygen depletion tests.
EXAMPLE

Volume of material required per temperature test is V × 4 plus required volume for characterization depending

on the selected test under 6.2. Material for each additional test temperature requires V × 4.

7 Procedure
7.1 Determination of porosity in biomass test sample

The characteristics of the biomass test sample can vary depending on shape and size of the material as

well as amount of entrained dust.
[7]

For pellets the bed porosity (or bulk porosity of the bed) is determined using Formula (2) :

ε=−1 (2)
where
6 © ISO 2020 – All rights reserved
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SIST-TS CEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)
ρ is the bulk density (ISO 17828) and
ρ is the single particle density (ISO 18847) of wood pellet.
7.2 Filling of test containers
Mark the test con
...

SLOVENSKI STANDARD
kSIST-TS FprCEN ISO/TS 20048-1:2022
01-februar-2022

Trda biogoriva - Določanje značilnosti odvajanja plinov in pomanjkanja kisika - 1.

del: Laboratorijska metoda za določanje uhajanja plinov in zmanjšanja kisika z
uporabo zaprtih posod (ISO/TS 20048-1:2020)

Solid biofuels - Determination of off-gassing and oxygen depletion characteristics - Part

1: Laboratory method for the determination of off-gassing and oxygen depletion using

closed containers (ISO/TS 20048-1:2020)
Biogene Festbrennstoffe - Bestimmung von Ausgasungs- und

Sauerstoffverarmungseigenschaften - Teil 1: Laboratoriumsverfahren zur Bestimmung

von Ausgasung und Sauerstoffverarmung (ISO/TS 20048-1:2020)
Biocombustibles solides - Détermination des dégagements gazeux et de
l’appauvrissement en oxygène - Partie 1: Titre manque (ISO/TS 20048-1:2020)
Ta slovenski standard je istoveten z: FprCEN ISO/TS 20048-1
ICS:
75.160.40 Biogoriva Biofuels
kSIST-TS FprCEN ISO/TS 20048-1:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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kSIST-TS FprCEN ISO/TS 20048-1:2022
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kSIST-TS FprCEN ISO/TS 20048-1:2022
TECHNICAL ISO/TS
SPECIFICATION 20048-1
First edition
2020-03
Solid biofuels — Determination of
off-gassing and oxygen depletion
characteristics —
Part 1:
Laboratory method for the
determination of off-gassing and
oxygen depletion using closed
containers
Reference number
ISO/TS 20048-1:2020(E)
ISO 2020
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kSIST-TS FprCEN ISO/TS 20048-1:2022
ISO/TS 20048-1:2020(E)
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Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Apparatus ..................................................................................................................................................................................................................... 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Test containers ........................................................................................................................................................................................ 3

5.3 Gas sampler................................................................................................................................................................................................ 5

5.4 Ovens ............................................................................................................................................................................................................... 5

5.5 Gas chromatograph (GC) analyser ......................................................................................................................................... 5

6 Biomass sampling and sample preparation ............................................................................................................................ 6

6.1 General ........................................................................................................................................................................................................... 6

6.2 Test sample characterization ...................................................................................................................................................... 6

6.3 Test sample size ..................................................................................................................................................................................... 6

7 Procedure..................................................................................................................................................................................................................... 6

7.1 Determination of porosity in biomass test sample .................................................................................................. 6

7.2 Filling of test containers ................................................................................................................................................................. 7

7.3 Test container arrangement and test gas sampling volume ............................................................................ 7

7.4 Operation of temperature-controlled ovens ................................................................................................................. 8

7.5 Gas sampling procedure ................................................................................................................................................................. 8

7.6 Gas analysis ................................................................................................................................................................................................ 9

8 Calculation .................................................................................................................................................................................................................. 9

9 Test report ................................................................................................................................................................................................................13

Annex A (normative) Quantification of gas species using chromatography ............................................................14

Annex B (informative) Estimation of ventilation requirements for enclosed spaces ....................................16

Annex C (informative) Determination of gas species concentration in open storage space ...................19

Bibliography .............................................................................................................................................................................................................................20

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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.
A list of all parts in the ISO 20048 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.
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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.

Emission from pellets or biomass stored in enclosed space represents a significant health risk due to

exposure to carbon-monoxide (CO) and oxygen depletion. It is important to be able to assess the risk by

quantifying the emission of CO in combination with oxygen level. This document describes a method for

estimating the propensity of a particular quality of pellets or biomass to emit CO, CO , CH as well as the

2 4

depletion of oxygen within the stored environment. In a confined space, the gas composition can result

in a toxic as well as explosive atmosphere.

Biomass species, age of the material as well as the ambient temperature impacts the dynamics of the gas

emissions. Unless the level of CO and oxygen levels are well understood in an operating environment,

there are inherent risk for workers, which have implications for liability.

This document specifies the methodology for measuring the emission and depletion factor and emission

and depletion rate of off-gassing in combination with oxygen depletion for permanent gases emitted in

an enclosed storage for biomass.

NOTE A method to be used in preliminary screening of CO for operational planning is currently under

development within ISO/TC 238/WG 7. Stage at the time of publication ISO/CD 20048-2:2018.

The method described in this document uses highly sensitive gas chromatography to be able to identify

the spectrum of gases and their relative concentration to predict the potential for unhealthy conditions

during indoor storage of biomass. The sensitivity for detection of gas species and concentrations is

only limited by the sensitivity of the chromatographic instrument. The method allows for estimation

of emission and depletion factor and emission and depletion rate for each gas species of biomass at

different storage temperatures.

The gas instrument analysis part of the method also allows for identification of gas species and

determination of concentrations of gases sampled in open storage spaces for occupational hygiene

purposes (Annex C).
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TECHNICAL SPECIFICATION ISO/TS 20048-1:2020(E)
Solid biofuels — Determination of off-gassing and oxygen
depletion characteristics —
Part 1:
Laboratory method for the determination of off-gassing
and oxygen depletion using closed containers
1 Scope

This document defines a method for determination of off-gassing (permanent gases) and oxygen

depletion from woody as well as non-woody biomass, including densified materials such as pellets and

briquettes, as well as non-densified materials such as chips. The method is also applicable for thermally

treated materials, including torrefied and carbonized materials.

The emission and depletion factor and emission and depletion rate for various gas species emitted from

sample within a closed test container is determined by means of gas chromatography.

The emission and depletion factor and emission and depletion rate provide guidance for ventilation

requirements to keep gas concentrations below Permissible Exposure Levels (PEL) in spaces where

workers can be exposed to the enclosed atmosphere.
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 18135, Solid biofuels — Sampling
ISO 14780, Solid biofuels — Sample preparation

ISO 17827-2, Solid biofuels — Determination of particle size distribution for uncompressed fuels — Part 2:

Vibrating screen method using sieves with aperture of 3,15 mm and below
ISO 17828, Solid biofuels — Determination of bulk density

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 18846, Solid biofuels — Determination of fines content in quantities of pellets

ISO 18847, Solid biofuels — Determination of particle density of pellets and briquettes

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 16559 and the following apply.

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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
emission factor

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram of the substance emitting at a given temperature
3.2
depletion factor

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram of the substance depleting at a given temperature
3.3
emission rate

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram per day of the substance emitting at a given temperature
3.4
depletion rate

concentration in percent of a gas species relative to other gases in a volume and expressed in gram per

kilogram per day of the substance depleting at a given temperature
3.5
ppmv
parts per million on volume basis
3.6
gas chromatograph

instrument used in analytical chemistry for separating and analysing compounds that can be

vapourized without decomposition
3.7
Permissible Exposure Level
PEL
regulatory limit on the amount or concentration of a substance in the air

Note 1 to entry: This is usually based on an eight-hour time weighted average, but some are based on short-term

exposure limits.
4 Principle

One or more test container(s) sealed with an air-tight lid and partly filled with biomass test sample are

placed in oven with controlled temperature such as 20 °C, 30 °C, 40 °C or 50 °C. Gas samples are drawn

by means of a syringe through the sampling port of the container(s) and the relative concentration

of gas species is quantified by means of a gas chromatograph. The concentration is converted from

a volume fraction in % relative to other gases in the test container and expressed as emission and

depletion factor in gram per kilogram of biomass at a given temperature. The emission and depletion

rate are expressed as gram of gas species per kilogram of biomass per day at a given temperature.

A method for converting emission and depletion factor (ppmv) concentration and calculating the

number of air exchanges in a space with controlled ventilation is provided in Annex B.

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5 Apparatus
5.1 General

All equipment holding biomass samples and gas samples extracted during the determination shall be

free of any contaminants, well ventilated and dry before the off-gassing test starts.

NOTE Containers and fittings can be dried overnight at low temperature around 30 °C.

5.2 Test containers

The test container(s) shall preferably be made of glass, not plastic, due to the risk of contaminating

gases from plastic materials at higher temperatures. Since the containers shall only be filled to 75 %

with biomass to be tested, it is an advantage to be able to see the level of biomass from the outside.

Figure 1 a) to 1 c) show photos of the test container with sampling port and Figure 2 shows a schematic

of the test container and sampling port.
a) Test container of glass with sampling port
b) Sampling port, from the side
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c) Sampling port, from above
Figure 1 — Example of test container of glass with sampling port
Key
1 septum
2 nipple
3 sampling port
4 container lid
5 air-tight seal
6 test container
Figure 2 — Schematic of test container with sampling port

The headspace in an enclosed container shall contain sufficient oxygen to sustain oxidation of test

[1][2]

sample to reach a peak (plateau) and allow determination of the emission and depletion factor . The

25 % headspace of enclosed air volume under roof in a typical large-scale storage facility such as a silo

when fully loaded is typical and is therefore selected for this test method.
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The seal between the lid and the container as well as the sampling port nipple (septum) shall be made

of polytetrafluoroethylene (PTFE) or neoprene, which are non-reactive materials at the temperatures

recommended for the off-gassing tests. Gas samples shall be drawn using a syringe (see 5.3) piercing

through the septum.

The effective gas volume in a test container can be expressed in accordance with Formula (1).

VV=+VV=×02, 5 +V (1)
hv cv
where
V is the effective gas volume in test container when filled with biomass;
V =×02, 5 V is the selected headspace volume;
h c
V is the volume of void between the biomass particles;
V is the volume of empty test container.
EXAMPLE

The effective gas volume (V) for a test container with a volume of 3 500 ml (V ) loaded to 75 % with wood pellets

and with a volume of void of 50 % can be calculated as follows:
V = 0,25 × 3 500 [ml]+0,75 × 3 500 [ml] × 0,5 = 3 500 [ml] × 0,625 = 2 188 ml

Guidance for selecting container size in relation to gas sample size required by the GC for a selected gas

depletion volume is provided in 7.3.
5.3 Gas sampler

A gas-tight GC syringe shall be used for drawing gas test samples through septum in the container

sampling port nipple. It is recommended that the capacity of the syringe be at least 3 times the volume

of the sampling tube and sampling loop of the GC or as recommended by the manufacturer of the GC

(see 5.5). The syringe shall have a scale with a resolution of 1 ml and a valve to secure the sample after

drawing. It is best to use needles that have a hole on the side rather than the tip to prevent silicone or

neoprene material blocking the hole while sampling.

The gas sample is injected directly from the sampler syringe into the GC sample port.

5.4 Ovens

The temperature within the test containers shall be controlled by placing the containers in ovens

automatically controlling the temperature in the range of 20 °C to 50 °C ± 1 °C. A separate oven is

required for each temperature selected for testing. The ovens shall be able to hold the size of containers

required to achieve the necessary accuracy of the off-gassing determination.
[4]

Since temperature of biomass under test has a propensity to self-generate heat at testing temperatures

above 40 °C, particularly if the moisture in the material is high, a thermocouple should be placed

inside the material in one of the containers. A thermocouple in the centre of the test volume will help

monitoring the uniformity of the temperature.
5.5 Gas chromatograph (GC) analyser

The detection limit for each gas species and related concentrations is determined by the type of column

in the GC. The manufacturer of the GC should be consulted. GC with thermal conductivity detector (TCD)

shall be used to detect and quantify permanent gases and light hydrocarbons. Packed and capillary

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columns could be used with TCD to measure permanent gases. A combination of TCD and FID (flame

ionization detector) could also be used for gas measurements depending on the GC configuration.

NOTE 1 Helium (He) is usually used as carrier gas but, e.g., nitrogen or argon are other possible alternatives.

NOTE 2 PEL for CO is in the range of 25 ppmv to 100 ppmv depending on jurisdiction and on the duration of

the exposure. Gas chromatography allows identification of a large number of non-condensable like CO, CO , CH ,

2 4

N , H , and O . The PEL for those compounds can be found in occupational hygiene databases. The occupational

2 2 2
health lower limit for oxygen is 19,5 %.
Annex A provides a generic orientation of operation and calibration of a GC.
6 Biomass sampling and sample preparation
6.1 General

Sampling and sample preparation of biomass shall be done in accordance with ISO 18135 and ISO 14780

respectively.
6.2 Test sample characterization

The test sample characterization shall be done in accordance with the following international standards;

a) Moisture ISO 18134-1 or ISO 18134-2
b) Particle size distribution ISO 17827-2
c) Fines content ISO 18846
d) Bulk density ISO 17828
e) Particle density ISO 18847

If available, note the origin, species and age of the test sample in the test report (Clause 9).

6.3 Test sample size

The total sample size depends on the test container configuration selected (7.3). At least three test

sample fractions shall be prepared; one for test sample characterization (6.2) and the others for off-

gassing/oxygen depletion tests.
EXAMPLE

Volume of material required per temperature test is V × 4 plus required volume for characterization depending

on the selected test under 6.2. Material for each additional test temperature requires V × 4.

7 Procedure
7.1 Determination of porosity in biomass test sample

The characteristics of the biomass test sample can vary depending on shape and size of the material as

well as amount of entrained dust.
[7]

For pellets the bed porosity (or bulk porosity of the bed) is determined using Formula (2) :

ε=−1 (2)
where
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ρ is the bulk density (ISO 17828) and
ρ is the single particle density (ISO 18847) of wood pellet.
7.2 Filling of test containers
Mark the test container at the 75 % level.

Fill each container to the 85 % level with the biomass test material to be tested. In order to achieve a

representative packing density, expose the test container to shock by means of dropping the container

5 times from a height of 50 mm onto a wooden board on an even horizontal and hard workbench or

floor. Make sure the test container hits the wooden board in a vertical position and that the level of test

material reaches the 75 % level. Refill or remove material if necessary, to reach the 75 % level. This

procedure shall be repeated until the packing density is stable.

If more than one test container is used, mark the containers with different letters A, B, C etc., and weigh

the content of each container to make sure each container has the same weight within 1 % of weight.

If there is dust remaining on the rim of the test container, swipe it off with a cloth.

Apply the lid assembly with the sampling port to the test container and seal it. Tighten all connections.

To make it air-tight, use an extra sealant, such as silicone, around the fittings on the side of the lid that

is exposed to air when the container is closed, No extra sealant shall be used on the inner side of the lid.

Ensure that the sealant chosen can be used in the temperatures it will be exposed to during the test.

The container called PEAK is sampled only once when the sampling is completed. It is to verify the peak

emission value at the end of the test period.
7.3 Test container arrangement and test gas sampling volume

The different gas species evolve at different rates, which mean that the relative ratio of gases can

change slightly over time as the oxygen is consumed. Also, the temperature can affect the relative rate

of evolution of the various gas species. The oxygen content in the containment is depleted as a function

of oxidation of components of the biomass. In order to obtain a representative profile of emissions for

long term storage, emission and depletion factors and emission and depletion rates for gas species shall

be defined over an extended period of time such as 28 to 30 days. Due to this relatively long period

of time, considerations shall be given to testing more than one biomass test material at a time. For

example, reference material and several test samples can be processed in parallel. If testing is done at

various temperatures such as 20 °C/30 °C/40 °C/50 °C there shall be one oven per temperature.

NOTE Using more than one oven per temperature is not recommended since there will be some difference in

the temperature which could affect the results.

Consideration shall be given to maximum allowable gas depletion due to sampling and the number of

days samples should be taken.
Figure 3 illustrates arrangements of four test containers in an oven.
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Key
1 oven with temperature regulator
2 test containers marked A, B and C
3 reference test container marked PEAK
Figure 3 — Schematic of oven and test container configuration
7.4 Operation of temperature-controlled ovens

The temperature of the ovens has to be stabilized at the selected temperature before the test

container(s) are loaded into the ovens. Ideally there should be multiple ovens operated in parallel with

temperatures controlled at 20/30/40/50 °C or other selected temperatures to run the tests in parallel

to save time and to make sure the material is of the same age.

NOTE If the room temperature is fairly stable, the 20 °C test can be done without an oven.

7.5 Gas sampling procedure

Remove the test containers from the oven during the sampling and rotate it along its axis at least

once before the syringe is inserted to draw the gas sample. This will mix the gases and minimize the

potential for un-even distribution of gases within the test container. During sampling the door of the

oven shall be open as short time as possible and the test containers shall not be outside the oven more

than necessary.

After completion of sampling, place the test containers in the oven. Use gloves, protective glasses and

...

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