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SIST EN ISO 12213-1:2009
01-november-2009
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SIST EN ISO 12213-1:2005
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Natural gas - Calculation of compression factor - Part 1: Introduction and guidelines (ISO
12213-1:2006)
Erdgas - Berechnung von Realgasfaktoren - Teil 1: Einführung und Leitfaden (ISO 12213
-1:2006)
Gaz naturel - Calcul du facteur de compression - Partie 1: Introduction et lignes
directrices (ISO 12213-1:2006)
Ta slovenski standard je istoveten z: EN ISO 12213-1:2009
ICS:
75.060 Zemeljski plin Natural gas
SIST EN ISO 12213-1:2009 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 12213-1:2009
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SIST EN ISO 12213-1:2009
EUROPEAN STANDARD
EN ISO 12213-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2009
ICS 75.060 Supersedes EN ISO 12213-1:2005
English Version
Natural gas - Calculation of compression factor - Part 1:
Introduction and guidelines (ISO 12213-1:2006)
Gaz naturel - Calcul du facteur de compression - Partie 1: Erdgas - Berechnung von Realgasfaktoren - Teil 1:
Introduction et lignes directrices (ISO 12213-1:2006) Einführung und Leitfaden (ISO 12213-1:2006)
This European Standard was approved by CEN on 13 August 2009.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12213-1:2009: E
worldwide for CEN national Members.
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SIST EN ISO 12213-1:2009
EN ISO 12213-1:2009 (E)
Contents Page
Foreword .3
2
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SIST EN ISO 12213-1:2009
EN ISO 12213-1:2009 (E)
Foreword
The text of ISO 12213-1:2006 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 12213-1:2009.
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 March 2010, and conflicting national standards shall be withdrawn at
the latest by March 2010.
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 ISO 12213-1:2005.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 12213-1:2006 has been approved by CEN as a EN ISO 12213-1:2009 without any
modification.
3
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SIST EN ISO 12213-1:2009
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SIST EN ISO 12213-1:2009
INTERNATIONAL ISO
STANDARD 12213-1
Second edition
2006-11-15
Natural gas — Calculation of
compression factor —
Part 1:
Introduction and guidelines
Gaz naturel — Calcul du facteur de compression —
Partie 1: Introduction et lignes directrices
Reference number
ISO 12213-1:2006(E)
©
ISO 2006
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SIST EN ISO 12213-1:2009
ISO 12213-1:2006(E)
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Published in Switzerland
ii © ISO 2006 – All rights reserved
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SIST EN ISO 12213-1:2009
ISO 12213-1:2006(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 2
3 Terms and definitions. 2
4 General principles. 4
5 Guidelines. 5
5.1 Pipeline quality natural gases . 5
5.2 Other gases and other applications. 8
Annex A (normative) Symbols and units. 11
Annex B (informative) Computer program. 12
Bibliography . 13
© ISO 2006 – All rights reserved iii
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SIST EN ISO 12213-1:2009
ISO 12213-1:2006(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 2.
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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12213-1 was prepared by Technical Committee ISO/TC 193, Natural gas, Subcommittee SC 1, Analysis
of natural gas.
This second edition cancels and replaces the first edition (ISO 12213-1:1997), of which it constitutes a minor
revision (the year of publication of Reference [5] in the Bibliography has been corrected).
ISO 12213 consists of the following parts, under the general title Natural gas — Calculation of compression
factor:
⎯ Part 1: Introduction and guidelines
⎯ Part 2: Calculation using molar-composition analysis
⎯ Part 3: Calculation using physical properties
iv © ISO 2006 – All rights reserved
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SIST EN ISO 12213-1:2009
INTERNATIONAL STANDARD ISO 12213-1:2006(E)
Natural gas — Calculation of compression factor —
Part 1:
Introduction and guidelines
1 Scope
ISO 12213 specifies methods for the calculation of compression factors of natural gases, natural gases
containing a synthetic admixture and similar mixtures at conditions under which the mixture can exist only as a
gas.
It is divided into three parts: this part of ISO 12213 gives an introduction and provides guidelines for the
methods of calculation described in ISO 12213-2 and ISO 12213-3.
Part 2 gives a method for use where the detailed molar composition of the gas is known. Part 3 gives a
method for use where a less detailed analysis, comprising superior calorific value (volumetric basis), relative
density, carbon dioxide content and (if non-zero) hydrogen content, is available.
Both methods are applicable to dry gases of pipeline quality within the range of conditions under which
transmission and distribution, including metering for custody transfer or other accounting purposes, are
normally carried out. In general, such operations take place at temperatures between about 263 K and 338 K
(approximately −10 °C to 65 °C) and pressures not exceeding 12 MPa (120 bar). Within this range, the
uncertainty of prediction of both methods is about ± 0,1 % provided that the input data, including the relevant
pressure and temperature, have no uncertainty.
NOTE Pipeline quality gas is used in this International Standard as a concise term for gas which has been processed
so as to be suitable for use as industrial, commercial or domestic fuel. Although there is no formal international agreement
upon the composition and properties of a gas which complies with this concept, some quantitative guidance is provided
in 5.1.1. A detailed gas quality specification is usually a matter for contractual arrangements between buyer and seller.
The method given in Part 2 is also applicable (with increased uncertainty) to broader categories of natural gas,
including wet or sour gases, within a wider range of temperatures and to higher pressures, for example for
reservoir or underground storage conditions or for vehicular (NGV) applications.
The method given in Part 3 is applicable to gases with a higher content of nitrogen, carbon dioxide or ethane
than normally found in pipeline quality gas. The method may also be applied over wider ranges of temperature
and pressure but with increased uncertainty.
For the calculation methods described to be valid, the gas must be above its water and hydrocarbon
dewpoints at the prescribed conditions.
This International Standard gives all of the equations and numerical values needed to implement both
methods. It is planned to make verified computer programs available (see Annex B).
© ISO 2006 – All rights reserved 1
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SIST EN ISO 12213-1:2009
ISO 12213-1:2006(E)
2 Normative references
The following referenced documents are indispensable for the application 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 6976, Natural gas — Calculation of calorific values, density, relative density and Wobbe index from
composition
ISO 13443, Natural gas — Standard reference conditions
3 Terms and definitions
For the purposes of the various parts of this International Standard, the following terms and definitions apply.
3.1
compression factor
Z
ratio of the volume of an arbitrary mass of gas, at a specified pressure and temperature, to the volume of the
same mass of gas under the same conditions as calculated from the ideal-gas law, as follows:
Z = V (real)/V (ideal) (1)
m m
where
V (ideal) = RT/p (2)
m
NOTE 1 Thus
Z(p, T, y) = pV (p, T, y)/(RT) (3)
m
where
p is the absolute pressure;
T is the thermodynamic temperature;
y is a set of parameters which uniquely characterizes the gas (in principle, the latter may be the complete molar
composition or a distinctive set of dependent physico-chemical properties, or a mixture of both);
V is the molar volume of the gas;
m
R is the molar gas constant, in coherent units.
NOTE 2 The compression factor is a dimensionless quantity usually close to unity.
NOTE 3 The terms “compressibility factor” and “Z-factor” are synonymous with compression factor.
3.2
density
ρ
mass of a given quantity of gas divided by its volume at specified conditions of pressure and temperature
3.3
molar composition
term used when the proportion of each component in a homogeneous mixture is expressed as a mole (or
molar) fraction, or mole (molar) percentage, of the whole
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SIST EN ISO 12213-1:2009
ISO 12213-1:2006(E)
NOTE 1 Thus the mole fraction x of component i is the ratio of the number of moles of component i in a given volume
i
of a mixture to the total number of moles of all the components in the same volume of the mixture. One mole of any
chemical species is the amount of substance which contains the relative molecular mass in grams. A table of
recommended values of relative molecular masses is given in ISO 6976.
NOTE 2 For an ideal gas, the mole fraction (or percentage) is identical to the volume fraction (or percentage), but this
is not in general a sufficiently accurate approximation to real-gas behaviour for the purposes of this International Standard.
3.4
molar calorific value
H
amount of heat which would be released by the complete combustion in air of the hydrocarbons in one mole of
natural gas in such a way that the pressure at which the reaction takes place remains constant and all the
products of combustion are returned to the same specified temperature as that of the reactants, all of these
products being in the gaseous state except for water formed by combustion, which is condensed to the liquid
state at the specified temperature
NOTE 1 The molar calorific value only includes the hydrocarbons in the natural gas, i.e. inert components (primarily
nitrogen, carbon dioxide and helium) and other combustible components (such as hydrogen and carbon monoxide) are
excluded.
NOTE 2 The specified temperature is 298,15 K (25 °C) and the reference pressure is 101,325 kPa.
NOTE 3 The term “molar heating value” is synonymous with “molar calorific value”.
3.5
superior calorific value (volumetric basis)
H
S
amount of heat which would be released by the complete combustion in air of all the combustible components
in unit volume of natural gas in such a way that the pressure at which the reaction takes place remains
constant and all the products of combustion are returned to the same specified temperature as that of the
reactants, all of these products being in the gaseous state except for water formed by combustion, which is
condensed to the liquid state at the specified temperature
NOTE 1 The superior calorific value includes all the combustible components in the natural gas.
NOTE 2 The reference temperature at which the volume is measured is 273,15 K (0 °C) and the specified temperature
at which combustion takes place is 298,15 K (25 °C). The reference pressure is 101,325 kPa.
NOTE 3 Annex D of ISO 12213-3:2006 gives conversion factors which enable superior calorific values and relative
densities determined at other reference or specified temperatures, and other reference pressures, including the ISO
standard reference conditions (see ISO 13443), to be used as input data for the calculation method described.
NOTE 4 The terms “gross”, “higher”, “upper” and “total calorific value” and “heating value” are synonymous with
“superior calorific value”.
3.6
relative density
d
ratio of the mass of a given volume of natural gas to the mass of dry air of standard composition which would
be contained in the same volume at the same reference conditions of pressure and temperature
NOTE 1 The relative density includes all the components of the natural gas.
NOTE 2 The standard composition of dry air is given in ISO 6976.
NOTE 3 In this International Standard, the reference temperature is 273,15 K (0 °C) and the reference pressure is
101,325 kPa (see Note 3 to 3.5).
NOTE 4 The term “specific gravity” is synonymous with “relative density”.
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SIST EN ISO 12213-1:2009
ISO 12213-1:2006(E)
3.7
uncertainty of a predicted compression factor
± ∆Z
range of values Z − ∆Z to Z + ∆Z within which the (unknown) true value is expected to lie with a confidence
level of 95 %
NOTE 1 This uncertainty may be expressed either as an absolute value or as a percentage.
NOTE 2 Estimates of the 95 % confidence limits are, to the extent that this is practicable, established by comparison of
test data of low uncertainty with calculated values of Z.
4 General principles
The methods recommended use equations which are based on the concept that any natural gas may be
uniquely characterized for calculation of its volumetric properties either by component analysis or by an
appropriate and distinctive set of measurable physical properties. These characteristics, together with the
pressure and temperature, are used as input data for the methods.
In the sense that the volumetric behaviour of a gas mixture derives directly from the numbers and types of
molecular interactions (collisions) which take place, a method which explicitly recognizes each molecular
constituent of the mixture, and its proportion of the whole, is to some degree more fundamental than
alternatives.
The method given in Part 2 of this International Standard uses a detailed molar-composition analysis in which
all constituents present in amounts exceeding a mole fraction of 0,000 05 should be represented. The sum of
the mole fractions used should be unity to within 0,000 1. For a typical distributed (pipeline quality) gas, this
includes all alkane hydrocarbons up to about C or C together with nitrogen, carbon dioxide and helium. For
7 8
gases containing a synthetic admixture, hydrogen, carbon monoxide and ethylene are also likely to be
significant components. For broader categories of gas, other components such as water vapour and hydrogen
sulfide need to be taken into consideration.
The equation recommended is known as the AGA8 detailed characterization equation, and will be referred to
[1]
hereafter as the AGA8-92DC equation (see Bibliography). It is a revision of the equation described in AGA
[2]
Report No. 8 .
The method given in Part 3 of this International Standard uses two distinct physical properties, namely
superior calorific value and relative density, together with the carbon dioxide content.
NOTE In principle, any three from superior calorific value, relative density, carbon dioxide content and nitrogen
content may be used, the calculation methods being essentially equivalent. However, the set comprising the first three is
preferred for this International Standard. The reader interested in the use of alternative input variables is referred to the
[3]
GERG TM5 documentation .
Th
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