SIST EN ISO 6974-6:2005

Natural gas - Determination of composition with defined uncertainty by gas chromatography - Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C1 to C8 hydrocarbons using three capillary columns (ISO 6974-6:2002)

ISO 6974-6:2002 describes a gas chromatographic method for the quantitative determination of the content of helium, hydrogen, oxygen, nitrogen, carbon dioxide and C1 to C8 hydrocarbons in natural gas samples using three capillary columns. This method is applicable to the determination of these gases within the mole fraction ranges varying from 0,000 1 % to 40 %, depending on the component analysed, and is commonly used for laboratory applications. However, it is only applicable to methane within the mole fraction range of 40 % to 100 %. These ranges do not represent the limits of detection, but the limits within which the stated precision of the method applies. Although one or more components in a sample may not be present at detectable levels, the method can still be applicable.
ISO 6974-6:2002 is only applicable if used in conjunction with ISO 6974-1:2000 and ISO 6974-2:2001.
This method can also be applicable to the analysis of natural gas substitutes. Additional information on the applicability of this method to the determination of natural gas substitutes is also given where relevant.

Erdgas - Bestimmung der Zusammensetzung mit definierter Unsicherheit durch Gaschromatographie - Teil 6: Bestimmung des Wasserstoffs, Heliums, Sauerstoffs, Stickstoffs, Kohlenstoffdioxids und der Kohlenwasserstoffe C1 bis C8 mit drei Kapillarsäulen (ISO 6974-6:2002)

Dieser Teil von ISO 6974 beschreibt ein gaschromatographisches Verfahren mit drei Kapillarsäulen zur
quantitativen Bestimmung des Gehalts an Wasserstoff, Helium, Sauerstoff, Stickstoff, Kohlenstoffdioxid und
C 1 - bis C 8 -Kohlenwasserstoffen in Erdgasproben. Das Verfahren gilt für die Analyse von Gasen, die Bestand-
teile mit den in Tabelle 1 angegebenen Bereichen des Stoffmengenanteils enthalten, und wird üblicherweise
für Laboranwendungen genutzt. Diese Bereiche stellen nicht die Nachweisgrenzen dar, sondern die
Grenzwerte, innerhalb denen die für das Verfahren angegebene Präzision gilt. Auch wenn ein oder mehrere
Komponenten in einer Probe nicht mit nachweisbaren Konzentrationsniveaus vorliegen, kann das Verfahren
trotzdem angewendet werden.
Dieser Teil von ISO 6974 gilt nur in Verbindung mit den Teilen 1 und 2 von ISO 6974.
Dieses Verfahren kann auch für die Analyse von Erdgasaustauschgasen angewendet werden.
ANMERKUNG Zusätzliche Informationen über die Anwendbarkeit dieses Verfahrens zur Bestimmung von Erdgasaus-
tauschgasen werden an relevanter Stelle ebenfalls gegeben.

Gaz naturel - Détermination de la composition avec une incertitude définie par chromatographie en phase gazeuse - Partie 6: Détermination de l'hydrogene, de l'hélium, de l'oxygene, de l'azote, du dioxyde de carbone et des hydrocarbures C1 a C8 en utilisant trois colonnes capillaires (ISO 6974-6:2002)

L'ISO 6974-6:2002 décrit une méthode par chromatographie en phase gazeuse pour la détermination quantitative des teneurs en hydrogène, hélium, oxygène, azote, dioxyde de carbone et hydrocarbures C1 à C8 d'échantillons de gaz naturel, en utilisant trois colonnes capillaires. Elle est applicable à l'analyse de gaz contenant des constituants dont la fraction molaire est comprise dans les intervalles donnés dans le Tableau 1, et elle est couramment mise en oeuvre en laboratoire. Ces intervalles ne représentent pas les limites de détection, mais les limites dans lesquelles la fidélité fixée par la méthode s'applique. Bien qu'un ou plusieurs composants d'un échantillon puissent ne pas être présents à des teneurs détectables, la méthode reste applicable.
L'ISO 6974-6:2002 n'est applicable que si elle est utilisée conjointement avec les parties 1 et 2 de l'ISO 6974.
L'ISO 6974-6:2002 peut également être applicable à l'analyse des substituts du gaz naturel.

Zemeljski plin – Določevanje sestave z določeno negotovostjo s plinsko kromatografijo – 6. del: Določevanje vodika, helija, kisika, dušika, ogljikovega dioksida in C1 do C8 ogljikovodikov z uporabo treh kapilarnih kolon (ISO 6974-6:2002)

General Information

• Status: Published
• Publication Date: 31-Aug-2005
• ICS: 75.060 - Natural gas
• Technical Committee: NAD - Petroleum products, lubricants and related products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Sep-2005
• Due Date: 01-Sep-2005
• Completion Date: 01-Sep-2005
• Ref Project: EN ISO 6974-6:2005 - Natural gas - Determination of composition with defined uncertainty by gas chromatography - Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C1 to C8 hydrocarbons using three capillary columns (ISO 6974-6:2002)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 6974-6:2005
01-september-2005
Zemeljski plin – Določevanje sestave z določeno negotovostjo s plinsko
kromatografijo – 6. del: Določevanje vodika, helija, kisika, dušika, ogljikovega
dioksida in C1 do C8 ogljikovodikov z uporabo treh kapilarnih kolon (ISO 6974-
6:2002)
Natural gas - Determination of composition with defined uncertainty by gas
chromatography - Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon
dioxide and C1 to C8 hydrocarbons using three capillary columns (ISO 6974-6:2002)
Erdgas - Bestimmung der Zusammensetzung mit definierter Unsicherheit durch
Gaschromatographie - Teil 6: Bestimmung des Wasserstoffs, Heliums, Sauerstoffs,
Stickstoffs, Kohlenstoffdioxids und der Kohlenwasserstoffe C1 bis C8 mit drei
Kapillarsäulen (ISO 6974-6:2002)
Gaz naturel - Détermination de la composition avec une incertitude définie par
chromatographie en phase gazeuse - Partie 6: Détermination de l'hydrogene, de
l'hélium, de l'oxygene, de l'azote, du dioxyde de carbone et des hydrocarbures C1 a C8
en utilisant trois colonnes capillaires (ISO 6974-6:2002)
Ta slovenski standard je istoveten z: EN ISO 6974-6:2005
ICS:
75.060 Zemeljski plin Natural gas
SIST EN ISO 6974-6:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 6974-6:2005

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SIST EN ISO 6974-6:2005
EUROPEAN STANDARD
EN ISO 6974-6
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2005
ICS 75.060
English version
Natural gas - Determination of composition with defined
uncertainty by gas chromatography - Part 6: Determination of
hydrogen, helium, oxygen, nitrogen, carbon dioxide and C1 to
C8 hydrocarbons using three capillary columns (ISO 6974-
6:2002)
Gaz naturel - Détermination de la composition avec une Erdgas - Bestimmung der Zusammensetzung mit
incertitude définie par chromatographie en phase gazeuse - definierter Unsicherheit durch Gaschromatographie - Teil 6:
Partie 6: Détermination de l'hydrogène, de l'hélium, de Bestimmung des Wasserstoffs, Heliums, Sauerstoffs,
l'oxygène, de l'azote, du dioxyde de carbone et des Stickstoffs, Kohlenstoffdioxids und der Kohlenwasserstoffe
hydrocarbures C1 à C8 en utilisant trois colonnes C1 bis C8 mit drei Kapillarsäulen (ISO 6974-6:2002)
capillaires (ISO 6974-6:2002)
This European Standard was approved by CEN on 19 May 2005.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6974-6:2005: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------
SIST EN ISO 6974-6:2005
EN ISO 6974-6:2005 (E)






Foreword



The text of ISO 6974-6:2002 has been prepared by Technical Committee ISO/TC 193 "Natural
gas” of the International Organization for Standardization (ISO) and has been taken over as EN
ISO 6974-6:2005 by CMC.

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 December 2005, and conflicting national
standards shall be withdrawn at the latest by December 2005.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.


Endorsement notice

The text of ISO 6974-6:2002 has been approved by CEN as EN ISO 6974-6:2005 without any
modifications.

2

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SIST EN ISO 6974-6:2005


INTERNATIONAL ISO
STANDARD 6974-6
First edition
2002-10-15


Natural gas — Determination of
composition with defined uncertainty by
gas chromatography —
Part 6:
Determination of hydrogen, helium,
oxygen, nitrogen, carbon dioxide and
C to C hydrocarbons using three
1 8
capillary columns
Gaz naturel — Détermination de la composition avec une incertitude
définie par chromatographie en phase gazeuse —
Partie 6: Détermination de l'hydrogène, de l'hélium, de l'oxygène, de
l'azote, du dioxyde de carbone et des hydrocarbures (C à C ) en utilisant
1 8
trois colonnes capillaires




Reference number
ISO 6974-6:2002(E)
©
 ISO 2002

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
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All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
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ii © ISO 2002 – All rights reserved

---------------------- Page: 6 ----------------------
SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
Contents
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Principle . 3
3.1 Analysis of natural gas samples . 3
3.2 Analysis of natural gas substitutes. 3
4 Materials. 3
5 Apparatus. 4
6 Procedure. 9
6.1 Operating conditions . 9
6.2 Performance requirements. 11
6.3 Determination . 11
7 Calculation . 14
8 Precision . 14
9 Test report. 14
Annex A (informative) Typical precision values. 15
Bibliography. 16

© ISO 2002 – All rights reserved iii

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
The main task of technical committees is to prepare International Standards. Draft International Standards adopted
by the technical committees are circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 6974 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 6974-6 was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1, Analysis of
natural gas.
This first edition of ISO 6974-6, together with ISO 6974-1, ISO 6974-2, ISO 6974-3, ISO 6974-4 and ISO 6974-5,
cancels and replaces ISO 6974:1984 which specified only one method.
ISO 6974 consists of the following parts, under the general title Natural gas — Determination of composition with
defined uncertainty by gas chromatography:
 Part 1: Guidelines for tailored analysis
 Part 2: Measuring-system characteristics and statistics for processing of data
 Part 3: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hydrocarbons up to C using
8
two packed columns
 Part 4: Determination of nitrogen, carbon dioxide and C to C and C hydrocarbons for a laboratory and
1 5 6+
on-line measuring system using two columns
 Part 5: Determination of nitrogen, carbon dioxide and C to C and C hydrocarbons for a laboratory and
1 5 6+
on-line process application using three columns
 Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C to C hydrocarbons using
1 8
three capillary columns
Annex A of this part of ISO 6974 is for information only.
iv © ISO 2002 – All rights reserved

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
Introduction
This part of ISO 6974 describes a precise and accurate method for the analysis of natural gas, which permits the
determination of the composition of natural gas. The compositional data obtained are used for the calculation of
calorific value, relative density and Wobbe index.
This method requires the use of three columns which are put in two gas chromatographs.
Due to the high separation power of the capillary columns used, components, generally not present in natural gas
but in some natural gas substitutes, can also be detected using this method. For the analysis of natural gas
substitutes, a methanizer is used in addition.
This part of ISO 6974 provides one of the methods that may be used for determining the composition of natural gas
in accordance with parts 1 and 2 of ISO 6974.
© ISO 2002 – All rights reserved v

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SIST EN ISO 6974-6:2005

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SIST EN ISO 6974-6:2005
INTERNATIONAL STANDARD ISO 6974-6:2002(E)

Natural gas — Determination of composition with defined
uncertainty by gas chromatography —
Part 6:
Determination of hydrogen, helium, oxygen, nitrogen, carbon
dioxide and C to C hydrocarbons using three capillary columns
1 8
1 Scope
This part of ISO 6974 describes a gas chromatographic method for the quantitative determination of the content of
hydrogen, helium, oxygen, nitrogen, carbon dioxide and C to C hydrocarbons in natural gas samples using three
1 8
capillary columns. It is applicable to the analysis of gases containing constituents within the mole fraction ranges
given in Table 1 and is commonly used for laboratory applications. These ranges do not represent the limits of
detection, but the limits within which the stated precision of the method applies. Although one or more components
in a sample may not be present at detectable levels, the method can still be applicable.
This part of ISO 6974 is only applicable if used in conjunction with parts 1 and 2 of ISO 6974.
This method can also be applicable to the analysis of natural gas substitutes.
NOTE Additional information on the applicability of this method to the determination of natural gas substitutes is also given
where relevant.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 6974. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 6974 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 6142, Gas analysis — Preparation of calibration gas mixtures — Gravimetric method
ISO 6143, Gas analysis — Comparison methods for determining and checking the composition of calibration gas
mixtures
ISO 6974-1:2000, Natural gas — Determination of composition with defined uncertainty by gas chromatography —
Part 1: Guidelines for tailored analysis
ISO 6974-2, Natural gas — Determination of composition with defined uncertainty by gas chromatography —
Part 2: Measuring-system characteristics and statistics for processing of data
ISO 7504, Gas analysis — Vocabulary
© ISO 2002 – All rights reserved 1

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
Table 1 — Application ranges
Mole fraction
Component Formula
%
Helium He 0,002to 0,5
Hydrogen H 0,001to 0,5
2
Oxygen O 0,007to 5
2
Nitrogen N 0,007to 40
2
Methane CH 40to 100
4
a
Carbon monoxide  CO 0,001 to 1
Carbon dioxide CO 0,001to 10
2
a
Ethyne (Acetylene) C H 0,001to 0,5
2 2
a
Ethene C H 0,001to 0,5
2 4
Ethane C H 0,002to 15
2 6
a b
Propene C H 0,001to 0,5
3 6
b
Propane C H 0,001to 5
3 8
i-Butane C H 0,000 1 to 1
4 10
n-Butane C H 0,000 1 to 1
4 10
2,2-Dimethylpropane (Neopentane) C H 0,000 1 to 0,5
5 12
2-Methylbutane (i-Pentane) C H 0,000 1 to 0,5
5 12
n-Pentane C H 0,000 1 to 0,5
5 12
Cyclopentane C H 0,000 1 to 0,5
5 10
2,2-Dimethylbutane C H 0,000 1 to 0,5
6 14
2,3-Dimethylbutane C H 0,000 1 to 0,5
6 14
2-Methylpentane C H 0,000 1 to 0,5
6 14
3-Methylpentane C H 0,000 1 to 0,5
6 14
n-Hexane C H 0,000 1 to 0,5
6 14
Benzene C H 0,000 1to 0,5
6 6
Cyclohexane C H 0,000 1 to 0,5
6 12
c
Heptanes C H 0,000 1 to 0,5
7 16
Methylcyclohexane C H 0,000 1 to 0,5
7 14
Toluene C H 0,000 1to 0,5
7 8
d
Octanes C H 0,000 1 to 0,5
8 18
e
Xylenes C H 0,000 1 to 0,5
8 10
NOTE The analysis may be extended under specific conditions (e.g. greater sample volume) to
hydrocarbons heavier than C , if present in mole fractions > 1 µmol/mol.
8
a
These components are generally not present in natural gas, but in natural gas substitute.
b
The separation of propane from propene is critical. Depending on the column in use this separation may
not be achieved.
c
Components included: n-heptane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane,
2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2,3-trimethylbutane. Not all isomers can be
separated from each other.
d
Components included: n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane,
dimethylcyclohexanes, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane,
3,3-dimethylhexane, 3,4-dimethylhexane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane (i-octane),
2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 2,2,3,3-tetramethylbutane. Not all isomers can be separated
from each other.
e
Components included: o-xylene, m-xylene, p-xylene. m- and p-xylene will not be separated from each
other.

2 © ISO 2002 – All rights reserved

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
3 Principle
3.1 Analysis of natural gas samples
Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hydrocarbons from C to C by gas
1 8
1)
chromatography using three capillary columns. A PLOT precolumn is used for the separation of carbon dioxide
(CO ) and ethane (C H ).
2 2 6
A molecular sieve PLOT column is used for the separation of the permanent gases helium (He), hydrogen (H ),
2
oxygen (O ), nitrogen (N ) and methane (CH ).
2 2 4
2)
A thick film WCOT column coated with an apolar phase is used for the separation of the C to C (and heavier)
3 8
hydrocarbons.
The permanent gases helium (He), hydrogen (H ), oxygen (O ), nitrogen (N ) and methane (CH ) are detected
2 2 2 4
with a thermal conductivity detector (TCD). The C to C hydrocarbons are detected with a flame ionization
2 8
detector (FID).
3.2 Analysis of natural gas substitutes
Carbon monoxide (CO) and carbon dioxide (CO ) are detected using an FID after reduction of the components to
2
CH by a methanizer. Use of a methanizer, makes it possible to detect CO and CO at a mole fractions greater
4 2
than 0,001 %. If the samples do not include CO or CO or if the CO and/or the CO mole fraction exceeds 0,02 %,
2 2
a methanizer is not required. CO and CO may then alternatively be detected with the TCD.
2
When analysing natural gas substitutes, the PLOT column described in 3.1 can also be used for the separation of
ethyne (C H ) and ethene (C H ) and the molecular sieve PLOT column can also be used for the analysis of
2 2 2 4
carbon monoxide (CO).
4 Materials
...

SLOVENSKI STANDARD
SIST EN ISO 6974-6:2005
01-september-2005
=HPHOMVNLSOLQ±'RORþHYDQMHVHVWDYH]GRORþHQRQHJRWRYRVWMRVSOLQVNR
NURPDWRJUDILMR±GHO'RORþHYDQMHYRGLNDKHOLMDNLVLNDGXãLNDRJOMLNRYHJD
GLRNVLGDLQ&GR&RJOMLNRYRGLNRY]XSRUDERWUHKNDSLODUQLKNRORQ,62

Natural gas - Determination of composition with defined uncertainty by gas
chromatography - Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon
dioxide and C1 to C8 hydrocarbons using three capillary columns (ISO 6974-6:2002)
Erdgas - Bestimmung der Zusammensetzung mit definierter Unsicherheit durch
Gaschromatographie - Teil 6: Bestimmung des Wasserstoffs, Heliums, Sauerstoffs,
Stickstoffs, Kohlenstoffdioxids und der Kohlenwasserstoffe C1 bis C8 mit drei
Kapillarsäulen (ISO 6974-6:2002)
Gaz naturel - Détermination de la composition avec une incertitude définie par
chromatographie en phase gazeuse - Partie 6: Détermination de l'hydrogene, de
l'hélium, de l'oxygene, de l'azote, du dioxyde de carbone et des hydrocarbures C1 a C8
en utilisant trois colonnes capillaires (ISO 6974-6:2002)
Ta slovenski standard je istoveten z: EN ISO 6974-6:2005
ICS:
75.060 Zemeljski plin Natural gas
SIST EN ISO 6974-6:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN ISO 6974-6:2005

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SIST EN ISO 6974-6:2005
EUROPEAN STANDARD
EN ISO 6974-6
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2005
ICS 75.060
English version
Natural gas - Determination of composition with defined
uncertainty by gas chromatography - Part 6: Determination of
hydrogen, helium, oxygen, nitrogen, carbon dioxide and C1 to
C8 hydrocarbons using three capillary columns (ISO 6974-
6:2002)
Gaz naturel - Détermination de la composition avec une Erdgas - Bestimmung der Zusammensetzung mit
incertitude définie par chromatographie en phase gazeuse - definierter Unsicherheit durch Gaschromatographie - Teil 6:
Partie 6: Détermination de l'hydrogène, de l'hélium, de Bestimmung des Wasserstoffs, Heliums, Sauerstoffs,
l'oxygène, de l'azote, du dioxyde de carbone et des Stickstoffs, Kohlenstoffdioxids und der Kohlenwasserstoffe
hydrocarbures C1 à C8 en utilisant trois colonnes C1 bis C8 mit drei Kapillarsäulen (ISO 6974-6:2002)
capillaires (ISO 6974-6:2002)
This European Standard was approved by CEN on 19 May 2005.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6974-6:2005: E
worldwide for CEN national Members.

---------------------- Page: 3 ----------------------

SIST EN ISO 6974-6:2005
EN ISO 6974-6:2005 (E)






Foreword



The text of ISO 6974-6:2002 has been prepared by Technical Committee ISO/TC 193 "Natural
gas” of the International Organization for Standardization (ISO) and has been taken over as EN
ISO 6974-6:2005 by CMC.

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 December 2005, and conflicting national
standards shall be withdrawn at the latest by December 2005.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.


Endorsement notice

The text of ISO 6974-6:2002 has been approved by CEN as EN ISO 6974-6:2005 without any
modifications.

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SIST EN ISO 6974-6:2005


INTERNATIONAL ISO
STANDARD 6974-6
First edition
2002-10-15


Natural gas — Determination of
composition with defined uncertainty by
gas chromatography —
Part 6:
Determination of hydrogen, helium,
oxygen, nitrogen, carbon dioxide and
C to C hydrocarbons using three
1 8
capillary columns
Gaz naturel — Détermination de la composition avec une incertitude
définie par chromatographie en phase gazeuse —
Partie 6: Détermination de l'hydrogène, de l'hélium, de l'oxygène, de
l'azote, du dioxyde de carbone et des hydrocarbures (C à C ) en utilisant
1 8
trois colonnes capillaires




Reference number
ISO 6974-6:2002(E)
©
 ISO 2002

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
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ii © ISO 2002 – All rights reserved

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
Contents
Foreword . iv
Introduction. v
1 Scope. 1
2 Normative references. 1
3 Principle . 3
3.1 Analysis of natural gas samples . 3
3.2 Analysis of natural gas substitutes. 3
4 Materials. 3
5 Apparatus. 4
6 Procedure. 9
6.1 Operating conditions . 9
6.2 Performance requirements. 11
6.3 Determination . 11
7 Calculation . 14
8 Precision . 14
9 Test report. 14
Annex A (informative) Typical precision values. 15
Bibliography. 16

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
The main task of technical committees is to prepare International Standards. Draft International Standards adopted
by the technical committees are circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 6974 may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 6974-6 was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1, Analysis of
natural gas.
This first edition of ISO 6974-6, together with ISO 6974-1, ISO 6974-2, ISO 6974-3, ISO 6974-4 and ISO 6974-5,
cancels and replaces ISO 6974:1984 which specified only one method.
ISO 6974 consists of the following parts, under the general title Natural gas — Determination of composition with
defined uncertainty by gas chromatography:
 Part 1: Guidelines for tailored analysis
 Part 2: Measuring-system characteristics and statistics for processing of data
 Part 3: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hydrocarbons up to C using
8
two packed columns
 Part 4: Determination of nitrogen, carbon dioxide and C to C and C hydrocarbons for a laboratory and
1 5 6+
on-line measuring system using two columns
 Part 5: Determination of nitrogen, carbon dioxide and C to C and C hydrocarbons for a laboratory and
1 5 6+
on-line process application using three columns
 Part 6: Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and C to C hydrocarbons using
1 8
three capillary columns
Annex A of this part of ISO 6974 is for information only.
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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
Introduction
This part of ISO 6974 describes a precise and accurate method for the analysis of natural gas, which permits the
determination of the composition of natural gas. The compositional data obtained are used for the calculation of
calorific value, relative density and Wobbe index.
This method requires the use of three columns which are put in two gas chromatographs.
Due to the high separation power of the capillary columns used, components, generally not present in natural gas
but in some natural gas substitutes, can also be detected using this method. For the analysis of natural gas
substitutes, a methanizer is used in addition.
This part of ISO 6974 provides one of the methods that may be used for determining the composition of natural gas
in accordance with parts 1 and 2 of ISO 6974.
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SIST EN ISO 6974-6:2005

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SIST EN ISO 6974-6:2005
INTERNATIONAL STANDARD ISO 6974-6:2002(E)

Natural gas — Determination of composition with defined
uncertainty by gas chromatography —
Part 6:
Determination of hydrogen, helium, oxygen, nitrogen, carbon
dioxide and C to C hydrocarbons using three capillary columns
1 8
1 Scope
This part of ISO 6974 describes a gas chromatographic method for the quantitative determination of the content of
hydrogen, helium, oxygen, nitrogen, carbon dioxide and C to C hydrocarbons in natural gas samples using three
1 8
capillary columns. It is applicable to the analysis of gases containing constituents within the mole fraction ranges
given in Table 1 and is commonly used for laboratory applications. These ranges do not represent the limits of
detection, but the limits within which the stated precision of the method applies. Although one or more components
in a sample may not be present at detectable levels, the method can still be applicable.
This part of ISO 6974 is only applicable if used in conjunction with parts 1 and 2 of ISO 6974.
This method can also be applicable to the analysis of natural gas substitutes.
NOTE Additional information on the applicability of this method to the determination of natural gas substitutes is also given
where relevant.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 6974. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 6974 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 6142, Gas analysis — Preparation of calibration gas mixtures — Gravimetric method
ISO 6143, Gas analysis — Comparison methods for determining and checking the composition of calibration gas
mixtures
ISO 6974-1:2000, Natural gas — Determination of composition with defined uncertainty by gas chromatography —
Part 1: Guidelines for tailored analysis
ISO 6974-2, Natural gas — Determination of composition with defined uncertainty by gas chromatography —
Part 2: Measuring-system characteristics and statistics for processing of data
ISO 7504, Gas analysis — Vocabulary
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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
Table 1 — Application ranges
Mole fraction
Component Formula
%
Helium He 0,002to 0,5
Hydrogen H 0,001to 0,5
2
Oxygen O 0,007to 5
2
Nitrogen N 0,007to 40
2
Methane CH 40to 100
4
a
Carbon monoxide  CO 0,001 to 1
Carbon dioxide CO 0,001to 10
2
a
Ethyne (Acetylene) C H 0,001to 0,5
2 2
a
Ethene C H 0,001to 0,5
2 4
Ethane C H 0,002to 15
2 6
a b
Propene C H 0,001to 0,5
3 6
b
Propane C H 0,001to 5
3 8
i-Butane C H 0,000 1 to 1
4 10
n-Butane C H 0,000 1 to 1
4 10
2,2-Dimethylpropane (Neopentane) C H 0,000 1 to 0,5
5 12
2-Methylbutane (i-Pentane) C H 0,000 1 to 0,5
5 12
n-Pentane C H 0,000 1 to 0,5
5 12
Cyclopentane C H 0,000 1 to 0,5
5 10
2,2-Dimethylbutane C H 0,000 1 to 0,5
6 14
2,3-Dimethylbutane C H 0,000 1 to 0,5
6 14
2-Methylpentane C H 0,000 1 to 0,5
6 14
3-Methylpentane C H 0,000 1 to 0,5
6 14
n-Hexane C H 0,000 1 to 0,5
6 14
Benzene C H 0,000 1to 0,5
6 6
Cyclohexane C H 0,000 1 to 0,5
6 12
c
Heptanes C H 0,000 1 to 0,5
7 16
Methylcyclohexane C H 0,000 1 to 0,5
7 14
Toluene C H 0,000 1to 0,5
7 8
d
Octanes C H 0,000 1 to 0,5
8 18
e
Xylenes C H 0,000 1 to 0,5
8 10
NOTE The analysis may be extended under specific conditions (e.g. greater sample volume) to
hydrocarbons heavier than C , if present in mole fractions > 1 µmol/mol.
8
a
These components are generally not present in natural gas, but in natural gas substitute.
b
The separation of propane from propene is critical. Depending on the column in use this separation may
not be achieved.
c
Components included: n-heptane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane,
2,3-dimethylpentane, 2,4-dimethylpentane, 3,3-dimethylpentane, 2,2,3-trimethylbutane. Not all isomers can be
separated from each other.
d
Components included: n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane,
dimethylcyclohexanes, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane,
3,3-dimethylhexane, 3,4-dimethylhexane, 2,2,3-trimethylpentane, 2,2,4-trimethylpentane (i-octane),
2,3,3-trimethylpentane, 2,3,4-trimethylpentane, 2,2,3,3-tetramethylbutane. Not all isomers can be separated
from each other.
e
Components included: o-xylene, m-xylene, p-xylene. m- and p-xylene will not be separated from each
other.

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SIST EN ISO 6974-6:2005
ISO 6974-6:2002(E)
3 Principle
3.1 Analysis of natural gas samples
Determination of hydrogen, helium, oxygen, nitrogen, carbon dioxide and hydrocarbons from C to C by gas
1 8
1)
chromatography using three capillary columns. A PLOT precolumn is used for the separation of carbon dioxide
(CO ) and ethane (C H ).
2 2 6
A molecular sieve PLOT column is used for the separation of the permanent gases helium (He), hydrogen (H ),
2
oxygen (O ), nitrogen (N ) and methane (CH ).
2 2 4
2)
A thick film WCOT column coated with an apolar phase is used for the separation of the C to C (and heavier)
3 8
hydrocarbons.
The permanent gases helium (He), hydrogen (H ), oxygen (O ), nitrogen (N ) and methane (CH ) are detected
2 2 2 4
with a thermal conductivity detector (TCD). The C to C hydrocarbons are detected with a flame ionization
2 8
detector (FID).
3.2 Analysis of natural gas substitutes
Carbon monoxide (CO) and carbon dioxide (CO ) are detected using an FID after reduction of the components to
2
CH by a methanizer. Use of a methanizer, makes it possible to detect CO and CO at a mole fractions greater
4 2
than 0,001 %. If the samples do not include CO or CO or if the CO and/or the CO mole fraction exceeds 0,02 %,
2 2
a methanizer is not required. CO and CO may then alternatively be detected with the TCD.
2
When analysing natural gas substitutes, the PLOT column described in 3.1 can also be used for the separation of
ethyne (C H ) and ethene (C H ) and the molecular sieve PLOT column can also be used for the analysis of
2 2 2 4
carbon monoxide (CO).
4 Materials
4.
...