Solid biofuels - Determination of calorific value (ISO 18125:2017)

ISO 18125:2017 specifies a method for the determination of the gross calorific value of a solid biofuel at constant volume and at the reference temperature 25 °C in a bomb calorimeter calibrated by combustion of certified benzoic acid.
The result obtained is the gross calorific value of the analysis sample at constant volume with all the water of the combustion products as liquid water. In practice, biofuels are burned at constant (atmospheric) pressure and the water is either not condensed (removed as vapour with the flue gases) or condensed. Under both conditions, the operative heat of combustion to be used is the net calorific value of the fuel at constant pressure. The net calorific value at constant volume may also be used; formulae are given for calculating both values.
General principles and procedures for the calibrations and the biofuel experiments are presented in the main text, whereas those pertaining to the use of a particular type of calorimetric instrument are described in Annexes A to C. Annex D contains checklists for performing calibration and fuel experiments using specified types of calorimeters. Annex E gives examples to illustrate some of the calculations.

Biogene Festbrennstoffe - Bestimmung des Heizwertes (ISO 18125:2017)

Dieses Dokument legt ein Verfahren zur Bestimmung des Brennwertes eines biogenen Festbrennstoffes bei konstantem Volumen und bei einer Referenztemperatur von 25 °C in einem Bombenkalorimeter fest, das durch die Verbrennung zertifizierter Benzoesäure kalibriert wurde.
Das erhaltene Ergebnis ist der Brennwert einer Analysenprobe bei konstantem Volumen, wobei das gesamte Wasser in den Verbrennungsprodukten in flüssigem Zustand vorliegt. In der Praxis werden biogene Brennstoffe bei konstantem (atmosphärischem) Druck verbrannt, wobei eine Kondensation des Wassers entweder nicht stattfindet (d. h. Wasser wird als Wasserdampf zusammen mit den Abgasen abgeführt) oder stattfindet. In beiden Fällen ist die anzuwendende wirksame Verbrennungswärme der Heizwert des Brennstoffes bei konstantem Druck. Der Heizwert bei konstantem Volumen darf ebenfalls angewendet werden; im vorliegenden Dokument sind Gleichungen zur Berechnung beider Werte angegeben.
Die bei den Kalibrierungen und Prüfungen von biogenen Brennstoffen allgemein angewendeten Prinzipien und Verfahren sind im Hauptteil dieses Dokuments dargelegt, während Prinzipien und Verfahren im Zusammenhang mit der Anwendung spezieller Kalorimeter Typen in den Anhängen A bis C beschrieben sind. Anhang D enthält eine Checkliste zur Durchführung der Kalibrierungen und Brennstoffprüfungen unter Anwendung bestimmter Kalorimeter Typen. Im Anhang E sind Berechnungsbeispiele angegeben.

Biocombustibles solides - Détermination du pouvoir calorifique (ISO 18125:2017)

ISO 18125:2017 spécifie une méthode de détermination du pouvoir calorifique supérieur à volume constant d'un biocombustible solide et à une température de référence de 25 °C dans une bombe calorimétrique étalonnée par combustion d'acide benzoïque certifié.
Le résultat obtenu est le pouvoir calorifique supérieur de l'échantillon pour analyse à volume constant avec toute l'eau des produits de combustion à l'état liquide. En pratique, les biocombustibles sont soumis à combustion à pression (atmosphérique) constante et l'eau est condensée ou non (s'évapore avec les gaz de combustion). Dans les deux cas, la chaleur effective de la combustion à utiliser est le pouvoir calorifique inférieur du combustible à pression constante. Le pouvoir calorifique inférieur à volume constant peut également être utilisé; des formules sont indiquées pour le calcul des deux données.
Les principes et les modes opératoires généraux relatifs aux essais d'étalonnage et aux essais sur les biocombustibles sont présentés dans le corps du texte du présent document, alors que ceux relevant de l'utilisation d'un type particulier d'instrument calorimétrique sont décrits aux Annexes A à C. L'Annexe D spécifie des listes de contrôle pour réaliser l'étalonnage et les essais sur les combustibles à l'aide de modèles de calorimètres spécifiés. L'Annexe E fournit une série d'exemples illustrant certains des calculs.

Trdna biogoriva - Določevanje kalorične vrednosti (ISO 18125:2017)

Ta mednarodni standard določa metodo za ugotavljanje bruto kalorične vrednosti trdnega biogoriva pri konstantni prostornini in referenčni temperaturi 25 °C v bombnem kalorimetru, ki je kalibriran s postopkom zgorevanja certificirane benzojske kisline. Rezultat je bruto kalorična vrednost analiznega vzorca pri konstantni prostornini, pri čemer je vsa voda produktov zgorevanja v obliki tekoče vode. V praksi biogoriva izgorevajo pri konstantnem (atmosferskem) tlaku, pri čemer voda ni kondenzirana (odstranjena v obliki hlapov z dimnimi plini) ali je kondenzirana. Pri obeh pogojih je delovna toplota zgorevanja, ki bo uporabljena, neto kalorična vrednost goriva pri konstantnem tlaku. Uporabi se lahko tudi neto kalorična vrednost goriva pri konstantnem tlaku. Podane so enačbe za izračun obeh vrednosti.

General Information

Status
Published
Publication Date
16-May-2017
Technical Committee
Drafting Committee
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Due Date
17-May-2017
Completion Date
17-May-2017

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SLOVENSKI STANDARD
SIST EN ISO 18125:2017
01-julij-2017
1DGRPHãþD
SIST EN 14918:2010
7UGQDELRJRULYD'RORþHYDQMHNDORULþQHYUHGQRVWL ,62
Solid biofuels - Determination of calorific value (ISO 18125:2017)
Biogene Festbrennstoffe - Bestimmung des Heizwertes (ISO 18125:2017)
Biocombustibles solides - Détermination du pouvoir calorifique (ISO 18125:2017)
Ta slovenski standard je istoveten z: EN ISO 18125:2017
ICS:
75.160.40 Biogoriva Biofuels
SIST EN ISO 18125:2017 en,fr,de

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

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SIST EN ISO 18125:2017
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SIST EN ISO 18125:2017
EN ISO 18125
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2017
EUROPÄISCHE NORM
ICS 75.160.40; 27.190 Supersedes EN 14918:2009
English Version
Solid biofuels - Determination of calorific value (ISO
18125:2017)

Biocombustibles solides - Détermination du pouvoir Biogene Festbrennstoffe - Bestimmung des Heizwertes

calorifique (ISO 18125:2017) (ISO 18125:2017)
This European Standard was approved by CEN on 6 April 2017.

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: Avenue Marnix 17, B-1000 Brussels

© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 18125:2017 E

worldwide for CEN national Members.
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SIST EN ISO 18125:2017
EN ISO 18125:2017 (E)
Contents Page

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

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SIST EN ISO 18125:2017
EN ISO 18125:2017 (E)
European foreword

This document (EN ISO 18125:2017) has been prepared by Technical Committee ISO/TC 238 "Solid

biofuels" in collaboration with Technical Committee CEN/TC 335 “Solid biofuels” the secretariat of

which is held by SIS.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by November 2017, and conflicting national standards

shall be withdrawn at the latest by November 2017.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent

rights.
This document supersedes EN 14918:2009.

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 18125:2017 has been approved by CEN as EN ISO 18125:2017 without any modification.

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SIST EN ISO 18125:2017
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SIST EN ISO 18125:2017
INTERNATIONAL ISO
STANDARD 18125
First edition
2017-04
Solid biofuels — Determination of
calorific value
Biocombustibles solides — Détermination du pouvoir calorifique
Reference number
ISO 18125:2017(E)
ISO 2017
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SIST EN ISO 18125:2017
ISO 18125:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST EN ISO 18125:2017
ISO 18125:2017(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

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

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

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

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

4.1 Gross calorific value ............................................................................................................................................................................ 2

4.2 Net calorific value ................................................................................................................................................................................. 3

5 Reagents ........................................................................................................................................................................................................................ 3

6 Apparatus ..................................................................................................................................................................................................................... 4

7 Preparation of test sample ......................................................................................................................................................................... 7

8 Calorimetric procedure ................................................................................................................................................................................. 8

8.1 General ........................................................................................................................................................................................................... 8

8.2 Preparing the bomb for measurement ............................................................................................................................10

8.2.1 General procedure .......................................................................................................................................................10

8.2.2 Using combustion aid ...............................................................................................................................................10

8.3 Assembling the calorimeter ......................................................................................................................................................11

8.4 Combustion reaction and temperature measurements ....................................................................................11

8.5 Analysis of products of combustion ...................................................................................................................................12

8.6 Corrected temperature rise θ ................................................................................................................................................ 12

8.6.1 Observed temperature rise ..................................................................................................................................12

8.6.2 Isoperibol and static-jacket calorimeters ................................................................................................12

8.6.3 Adiabatic calorimeters .............................................................................................................................................14

8.6.4 Thermometer corrections ....................................................................................................................................14

8.7 Reference temperature .................................................................................................................................................................14

9 Calibration ...............................................................................................................................................................................................................14

9.1 Principle .....................................................................................................................................................................................................14

9.2 Calibrant ....................................................................................................................................................................................................15

9.2.1 Certification conditions...........................................................................................................................................15

9.2.2 Calibration conditions ..............................................................................................................................................15

9.3 Valid working range of the effective heat capacity ε............................................................................................15

9.4 Ancillary contributions .................................................................................................................................................................16

9.5 Calibration procedure ....................................................................................................................................................................16

9.6 Calculation of effective heat capacity for the individual experiment ....................................................17

9.6.1 Constant mass-of-calorimeter-water basis ............................................................................................17

9.6.2 Constant total-calorimeter-mass basis ......................................................................................................17

9.7 Precision of the mean value of the effective heat capacity ε ....................................................................... 18

9.7.1 Constant value of ε ..................................................................................................................................................... 18

9.7.2 ε as a function of the observed temperature rise .............................................................................19

9.8 Redetermination of the effective heat capacity .......................................................................................................19

10 Gross calorific value .......................................................................................................................................................................................19

10.1 General ........................................................................................................................................................................................................19

10.2 Combustion .............................................................................................................................................................................................20

10.3 Calculation of gross calorific value .....................................................................................................................................20

10.3.1 General...................................................................................................................................................................................20

10.3.2 Constant mass-of-calorimeter-water basis ............................................................................................20

10.3.3 Constant total-calorimeter-mass basis ......................................................................................................22

10.3.4 ε as a function of the observed temperature rise .............................................................................23

10.4 Expression of results .......................................................................................................................................................................23

10.5 Calculation to other bases ..........................................................................................................................................................23

11 Performance characteristics .................................................................................................................................................................24

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11.1 Repeatability limit .............................................................................................................................................................................24

11.2 Reproducibility limit .......................................................................................................................................................................24

12 Calculation of net calorific value at constant pressure .............................................................................................24

12.1 General ........................................................................................................................................................................................................24

12.2 Calculations .............................................................................................................................................................................................24

13 Test report ................................................................................................................................................................................................................25

Annex A (normative) Adiabatic bomb calorimeters .........................................................................................................................26

Annex B (normative) Isoperibol and static-jacket bomb calorimeters.........................................................................30

Annex C (normative) Automated bomb calorimeters ......................................................................................................................36

Annex D (informative) Checklists for the design and procedures of combustion experiments ..........39

Annex E (informative) Examples to illustrate the main calculations used in this document

when an automated bomb calorimeter is used for determinations ............................................................44

Annex F (informative) List of symbols used in this document ................................................................................................48

Annex G (informative) Default values of most used solid biofuels for the calculations of

calorific values .....................................................................................................................................................................................................51

Annex H (informative) Flow chart for a routine calorific value determination ...................................................52

Bibliography .............................................................................................................................................................................................................................53

Index ................ ..............................................................................................................................................................................................................................54

iv © ISO 2017 – All rights reserved
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SIST EN ISO 18125:2017
ISO 18125:2017(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 on 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 the following URL:

www . i so .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 238, Solid biofuels.
© ISO 2017 – All rights reserved v
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SIST EN ISO 18125:2017
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SIST EN ISO 18125:2017
INTERNATIONAL STANDARD ISO 18125:2017(E)
Solid biofuels — Determination of calorific value
1 Scope

This document specifies a method for the determination of the gross calorific value of a solid biofuel at

constant volume and at the reference temperature 25 °C in a bomb calorimeter calibrated by combustion

of certified benzoic acid.

The result obtained is the gross calorific value of the analysis sample at constant volume with all

the water of the combustion products as liquid water. In practice, biofuels are burned at constant

(atmospheric) pressure and the water is either not condensed (removed as vapour with the flue gases)

or condensed. Under both conditions, the operative heat of combustion to be used is the net calorific

value of the fuel at constant pressure. The net calorific value at constant volume may also be used;

formulae are given for calculating both values.

General principles and procedures for the calibrations and the biofuel experiments are presented in

the main text, whereas those pertaining to the use of a particular type of calorimetric instrument

are described in Annexes A to C. Annex D contains checklists for performing calibration and fuel

experiments using specified types of calorimeters. Annex E gives examples to illustrate some of the

calculations.
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 651, Solid-stem calorimeter thermometers
ISO 652, Enclosed-scale calorimeter thermometers
ISO 1770, Solid-stem general purpose thermometers
ISO 1771, Enclosed-scale general purpose thermometers
ISO 14780, Solid biofuels — Sample preparation
ISO 16559, Solid biofuels — Terminology, definitions and descriptions

ISO 18134-3, Solid biofuels — Determination of moisture content — Oven dry method — Part 3: Moisture

in general analysis sample
ISO 18135, Solid biofuels — Sampling
3 Terms and definitions

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

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
© ISO 2017 – All rights reserved 1
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SIST EN ISO 18125:2017
ISO 18125:2017(E)
3.1
gross calorific value at constant volume

absolute value of the specific energy of combustion, in joules, for unit mass of a solid biofuel burned in

oxygen in a calorimetric bomb under the conditions specified

Note 1 to entry: The products of combustion are assumed to consist of gaseous oxygen, nitrogen, carbon dioxide

and sulphur dioxide, of liquid water (in equilibrium with its vapour) saturated with carbon dioxide under the

conditions of the bomb reaction, and of solid ash, all at the reference temperature (3.4).

3.2
net calorific value at constant volume

absolute value of the specific energy of combustion, in joules, for unit mass of the biofuel burned

in oxygen under conditions of constant volume and such that all the water of the reaction products

remains as water vapour (in a hypothetical state at 0,1 MPa), the other products being as for the gross

calorific value, all at the reference temperature (3.4)
3.3
net calorific value at constant pressure

absolute value of the specific heat (enthalpy) of combustion, in joules, for unit mass of the biofuel

burned in oxygen at constant pressure under such conditions that all the water of the reaction products

remains as water vapour (at 0,1 MPa), the other products being as for the gross calorific value, all at the

reference temperature (3.4)
3.4
reference temperature

international reference temperature for thermochemistry of 25 °C is adopted as the reference

temperature for calorific values
Note 1 to entry: See 8.7.

Note 2 to entry: The temperature dependence of the calorific value of biofuels is small [less than 1 J/(g × K)].

3.5
effective heat capacity of the calorimeter
amount of energy required to cause unit change in temperature of the calorimeter
3.6
corrected temperature rise

change in calorimeter temperature caused solely by the processes taking place within the

combustion bomb

Note 1 to entry: The corrected temperature rise is the total observed temperature rise corrected for heat

exchange, stirring power, etc. (8.6).

Note 2 to entry: The change in temperature may be expressed in terms of other units: resistance of a platinum or

thermistor thermometer, frequency of a quartz crystal resonator, etc., provided that a functional relationship is

established between this quantity and a change in temperature. The effective heat capacity of the calorimeter (3.5)

may be expressed in units of energy per such an arbitrary unit. Criteria for the required linearity and closeness

in conditions between calibrations and fuel experiments are given in 9.3.

Note 3 to entry: A list of the symbols used and their definitions is given in Annex F.

4 Principle
4.1 Gross calorific value

A weighed portion of the analysis sample of the solid biofuel is burned in high-pressure oxygen in a bomb

calorimeter under specified conditions. The effective heat capacity of the calorimeter is determined in

calibration experiments by combustion of certified benzoic acid under similar conditions, accounted

for in the certificate. The corrected temperature rise is established from observations of temperature

2 © ISO 2017 – All rights reserved
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SIST EN ISO 18125:2017
ISO 18125:2017(E)

before, during and after the combustion reaction takes place. The duration and frequency of the

temperature observations depend on the type of calorimeter used. Water is added to the bomb initially

to give a saturated vapour phase prior to combustion (see 8.2.1 and 9.2.2), thereby allowing all the

water formed, from the hydrogen and moisture in the sample, to be regarded as liquid water.

The gross calorific value is calculated from the corrected temperature rise and the effective heat

capacity of the calorimeter, with allowances made for contributions from ignition energy, combustion of

the fuse(s) and for thermal effects from side reactions such as the formation of nitric acid. Furthermore,

a correction is applied to account for the difference in energy between the aqueous sulphuric acid

formed in the bomb reaction and gaseous sulphur dioxide, i.e. the required reaction product of sulphur

in the biofuel. The corresponding energy effect between aqueous and gaseous hydrochloric acid can be

neglected due to the usually low value for the correction regarding solid biofuels.

4.2 Net calorific value

The net calorific value at constant volume and the net calorific value at constant pressure of the

biofuel are obtained by calculation from the gross calorific value at constant volume determined on

the analysis sample. The calculation of the net calorific value at constant volume requires information

about the moisture and hydrogen contents of the analysis sample. In principle, the calculation of the net

calorific value at constant pressure also requires information about the oxygen and nitrogen contents

of the analysis sample.
5 Reagents

5.1 Oxygen, at a pressure high enough to fill the bomb to 3 MPa, pure with an assay of at least a volume

fraction of 99,5 %, and free from combustible matter.

Oxygen made by the electrolytic process may contain up to a volume fraction of 4 % of hydrogen.

5.2 Fuse.

5.2.1 Ignition wire, of nickel-chromium 0,16 mm to 0,20 mm in diameter, platinum 0,05 mm to

0,10 mm in diameter, or another suitable conducting wire with well-characterized thermal behaviour

during combustion.

5.2.2 Cotton fuse, of white cellulose cotton, or equivalent, if required (see 8.2.1).

5.3 Combustion aids of known gross calorific value, composition and purity, like benzoic acid,

n-dodecane, paraffin oil, combustion bags or capsules may be used.

5.4 Standard volumetric solutions and indicators, only for use when analysis of final bomb solutions

is required.
5.4.1 Barium hydroxide solution, c[Ba(OH) ] = 0,05 mol/l.
5.4.2 Sodium carbonate solution, c(Na C0 ) = 0,05 mol/l.
2 3
5.4.3 Sodium hydroxide solution, c(NaOH) = 0,1 mol/l.
5.4.4 Hydrochloric acid solution, c(HCI) = 0,1 mol/l.
5.4.5 Screened methyl orange indicator, 1 g/l solution.

Dissolve 0,25 g of methyl orange and 0,15 g of xylene cyanol FF in 50 ml of a volume fraction of 95 %

ethanol and dilute to 250 ml with water.
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ISO 18125:2017(E)
5.4.6 Phenolphthalein, 10 g/l solution.

Dissolve 2,5 g of phenolphthalein in 250 ml of a volume fraction of 95 % ethanol.

5.5 Benzoic acid, of calorimetric-standard quality, certified by (or with certification unambiguously

traceable to) a recognized standardizing authority.

Benzoic acid is the sole substance recommended for calibration of an oxygen-bomb calorimeter. For

the purpose of checking the overall reliability of the calorimetric measurements, test substances, e.g.

n-dodecane, are used. Test substances are mainly used to prove that certain characteristics of a sample

...

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