SIST EN ISO 15403:2005
(Main)Natural gas - Designation of the quality of natural gas for use as a compressed fuel for vehicles (ISO 15403:2000)
Natural gas - Designation of the quality of natural gas for use as a compressed fuel for vehicles (ISO 15403:2000)
2009-12-02 ANP: Due to an error in the CEN database, the above listed standard had not been given the status of "Withdrawn" after publication of the superseding standard.
Erdgas - Bestimmung der Beschaffenheit von Erdgas als verdichteter Kraftstoff für Fahrzeuge (ISO 15403:2000)
Ziel dieser Internationalen Norm ist die Bereitstellung von Daten zur Beschaffenheit von Kraftstoff für Erdgasfahrzeuge (NGV), die Hersteller, Fahrzeugbetreiber, Tankstellenbetreiber und andere Beteiligte der Industrie für mit verdichtetem Erdgas angetriebene Fahrzeuge benötigen, um Geräte für diese Fahrzeuge erfolgreich zu entwickeln und zu betreiben.
Kraftstoff, der die Anforderungen dieser Internationalen Norm erfüllt, sollte:
a) den sicheren Betrieb des Fahrzeugs und damit verbundener Geräte für Kraftstoffversorgung und Instandhaltung gewährleisten;
b) das Kraftstoffsystem vor den schädlichen Einflüssen von Korrosion, Vergiftung sowie der Ablagerung von flüssigen und festen Stoffen schützen;
c) eine zufrieden stellende Leistung des Fahrzeugs unter allen klimatischen Bedingungen und Fahrerfordernissen gewährleisten.
Einige Aspekte dieser internationalen Norm können ebenfalls für die Anwendung auf Erdgas in ortsfesten Verbrennungsmotoren zutreffen.
Gaz naturel - Désignation de la qualité de gaz naturel pour usage comme carburant comprimé pour véhicules (ISO 15403:2000)
Zemeljski plin – Označevanje kakovosti zemeljskega plina, ki se uporablja za komprimirano gorivo za vozila (ISO 15403:2000)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 15403:2005
01-julij-2005
=HPHOMVNLSOLQ±2]QDþHYDQMHNDNRYRVWL]HPHOMVNHJDSOLQDNLVHXSRUDEOMD]D
NRPSULPLUDQRJRULYR]DYR]LOD ,62
Natural gas - Designation of the quality of natural gas for use as a compressed fuel for
vehicles (ISO 15403:2000)
Erdgas - Bestimmung der Beschaffenheit von Erdgas als verdichteter Kraftstoff für
Fahrzeuge (ISO 15403:2000)
Gaz naturel - Désignation de la qualité de gaz naturel pour usage comme carburant
comprimé pour véhicules (ISO 15403:2000)
Ta slovenski standard je istoveten z: EN ISO 15403:2005
ICS:
75.060 Zemeljski plin Natural gas
SIST EN ISO 15403:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 15403:2005
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SIST EN ISO 15403:2005
EUROPEAN STANDARD
EN ISO 15403
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2005
ICS 75.060
English version
Natural gas - Designation of the quality of natural gas for use as
a compressed fuel for vehicles (ISO 15403:2000)
Gaz naturel - Désignation de la qualité de gaz naturel pour
usage comme carburant comprimé pour véhicules (ISO
15403:2000)
This European Standard was approved by CEN on 17 April 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 15403:2005: E
worldwide for CEN national Members.
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SIST EN ISO 15403:2005
EN ISO 15403:2005 (E)
Foreword
The text of ISO 15403:2000 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 15403:2005 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 November 2005, and conflicting national
standards shall be withdrawn at the latest by November 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 15403:2000 has been approved by CEN as EN ISO 15403:2005 without any
modifications.
2
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SIST EN ISO 15403:2005
INTERNATIONAL ISO
STANDARD 15403
First edition
2000-06-01
Natural gas — Designation of the quality of
natural gas for use as a compressed fuel
for vehicles
Gaz naturel — Désignation de la qualité de gaz naturel pour usage comme
carburant comprimé pour véhicules
Reference number
ISO 15403:2000(E)
©
ISO 2000
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
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ii © ISO 2000 – All rights reserved
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Symbols and abbreviations .9
5 Gas composition requirements.10
6 Gas properties.11
7 Driveability.12
8 Test methods.12
9 Sampling.13
Annex A (informative) Propane and butane content.14
Annex B (informative) Wobbe index range .16
Annex C (informative) Engine knock.18
Annex D (informative) Methane number and octane number .19
Annex E (informative) Water content of natural gas.22
Bibliography .23
© ISO 2000 – All rights reserved iii
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SIST EN ISO 15403:2005
ISO 15403:2000(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.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 15403 was prepared by Technical Committee ISO/TC 193, Natural gas.
Annexes A to E of this International Standard are for information only.
iv © ISO 2000 – All rights reserved
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
Introduction
Natural gas has been used to some extent as a fuel for internal combustion engines in compressor stations, co-
generation systems, and vehicles of various types for many years now. However, the prerequisites for growth, i.e.
economic viability and fuel availability, were generally not satisfied. Now, with the natural gas industry well
established, supplying 20 % of the world's primary energy, and the need for alternative, low-emission fuels, the
situation has improved considerably. During the past decade, natural gas vehicles have become a viable option with
some one million units now in use around the world. Growth is continuing as many governments actively promote
this clean-burning fuel with its environmental benefits. Many fleet operators are converting their vehicles, and
vehicle manufacturers are developing and marketing dedicated natural gas equipment.
In the context of this standard, natural gas vehicles (NGVs) utilize compressed natural gas stored "on-board". The
pressure of the gas stored in multiple containers is up to a maximum 25 000 kPa. Although the pressure has to be
reduced before combustion, compression and storage gives NGVs an adequate range. While NGVs were initially
equipped with converted gasoline or diesel engines, high-performance, dedicated natural gas engines are now
being extensively developed and produced. Liquefied natural gas (LNG) may also be stored in the fuel tanks of
natural gas vehicles. This, however, will be the subject of a separate International Standard.
This International Standard for the quality designation of compressed natural gas is designed to stipulate the
international requirements placed on the natural gas used as a motor fuel. Engine and vehicle manufacturers must
know these requirements so they can develop high-performance equipment which runs on compressed natural gas.
A technical report giving detailed data on the gas compositions used in ISO 15403 has been drafted and is being
circulated as an addendum.
© ISO 2000 – All rights reserved v
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SIST EN ISO 15403:2005
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SIST EN ISO 15403:2005
INTERNATIONAL STANDARD ISO 15403:2000(E)
Natural gas — Designation of the quality of natural gas for use as a
compressed fuel for vehicles
1 Scope
The aim of this International Standard is to provide manufacturers, vehicle operators, fuelling station operators and
others involved in the compressed-natural-gas vehicle industry with information on the fuel quality for natural gas
vehicles (NGVs) required to develop and operate compressed-natural-gas vehicle equipment successfully.
Fuel meeting the requirements of this International Standard should:
a) provide for the safe operation of the vehicle and associated equipment needed for its fuelling and maintenance;
b) protect the fuel system from the detrimental effects of corrosion, poisoning, and liquid or solid deposition;
c) provide satisfactory vehicle performance under any and all conditions of climate and driving demands.
Some aspects of this International Standard may also be applicable for the use of natural gas in stationary
combustion engines.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard 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 6326-1:1989, Natural gas — Determination of sulfur compounds — Part 1: General introduction.
1)
ISO 6326-2:— , Natural gas — Determination of sulfur compounds — Part 2: Gas chromatographic method using
an electrochemical detector.
ISO 6326-3:1989, Natural gas — Determination of sulfur compounds — Part 3: Determination of hydrogen sulfide,
mercaptan sulfur and carbonyl sulfide sulfur by potentiometry.
ISO 6326-4:1994, Natural gas — Determination of sulfur compounds — Part 4: Gas chromatographic method using
a flame photometric detector for the determination of hydrogen sulfide, carbonyl sulfide and sulfur-containing
odorants.
ISO 6326-5:1989, Natural gas — Determination of sulfur compounds — Part 5: Lingener combustion method.
ISO 6327:1981, Gas analysis — Determination of the water dew point of natural gas — Cooled surface
condensation hygrometers.
1) To be published. (Revision of ISO 6326-2:1981)
© ISO 2000 – All rights reserved 1
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
ISO 6570-1:1983, Natural gas — Determination of potential hydrocarbon liquid content — Part 1: Principles and
general requirements.
ISO 6570-2:1984, Natural gas — Determination of potential hydrocarbon liquid content — Part 2: Weighing method.
ISO 6974 (all parts), Natural gas — Determination of composition with defined uncertainty by gas chromatography.
ISO 6976:1995, Natural gas — Calculation of calorific values, density, relative density and Wobbe index from
composition.
ISO 10101-1:1993, Natural gas — Determination of water by the Karl Fischer method — Part 1: Introduction.
ISO 10101-2:1993, Natural gas — Determination of water by the Karl Fischer method — Part 2: Titration procedure.
ISO 10101-3:1993, Natural gas — Determination of water by the Karl Fischer method — Part 3: Coulometric
procedure.
ISO 11541:1997, Natural gas — Determination of water content at high pressure.
ISO 13734:1998, Natural gas — Organic sulfur compounds used as odorants — Requirements and test methods.
2)
ISO 14532:— , Natural gas — Terminology.
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply. Definitions were taken
from ISO 14532 whenever possible.
3.1
natural gas
complex mixture of hydrocarbons, primarily methane, but generally also including ethane, propane and higher
hydrocarbons in much smaller amounts and some non-combustible gases, such as nitrogen and carbon dioxide
NOTE 1 Natural gas generally also includes minor amounts of trace constituents.
NOTE 2 Natural gas is produced and processed from the raw gas or liquefied natural gas and, if required, blended to the
extent suitable for direct use (for example as gaseous fuel).
NOTE 3 Natural gas remains in the gaseous state under the temperature and pressure conditions normally found in service.
NOTE 4 Natural gas consists predominantly of methane (mole fraction greater than 0,70), and has a superior calorific value
3 3
normally within the range 30 MJ/m to 45 MJ/m . It contains also ethane (typically up to 0,10 mole fraction), propane, butanes
and higher alkanes in steadily decreasing amounts. Nitrogen and carbon dioxide are the principal non-combustible
components, each present at levels which typically vary from less than 0,01 mole fraction to 0,20 mole fraction.
Natural gas is processed from the raw gas so as to be suitable for use as industrial, commercial, residential fuel or as a
chemical feedstock. The processing is intended to reduce the contents of potentially corrosive components, such as hydrogen
sulfide and carbon dioxide, and of other components, such as water and higher hydrocarbons, potentially condensable in the
transmission and distribution of the gas. Hydrogen sulfide, organic sulfur compounds and water are then reduced to trace
amounts, and high carbon dioxide contents are likely to be reduced to below 0,05 mole fraction.
Natural gas is normally technically free from aerosol, liquid and particulate matter.
2) To be published.
2 © ISO 2000 – All rights reserved
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
In some circumstances natural gas may be blended with town gas or coke oven gas, in which case hydrogen and carbon
monoxide will be present in amounts up to 0,10 mole fraction and 0,03 mole fraction respectively. In this case, small amounts
of ethylene may also be present.
3)
Natural gas may also be blended with LPG /air mixtures, in which case oxygen will be present, and the levels of propane and
butanes will be considerably enhanced.
NOTE 5 Pipeline quality natural gas is one which has been processed so as to be suitable for direct use as industrial,
commercial, residential fuel or as a chemical feed stock.
The processing is intended to reduce the corrosive and toxicity effects of certain components, and to avoid condensation of
water or hydrocarbons in the transmission and distribution of the gas.
Hydrogen sulfide and water should only be present in trace amounts, and high carbon dioxide content is likely to be reduced.
[ISO 14532]
3.2
substitute natural gas
manufactured or blended gas which is interchangeable in its properties with natural gas
NOTE Manufactured gas is sometimes called synthetic natural gas.
[ISO 14532]
3.3
compressed natural gas
natural gas used as a fuel for vehicles, typically compressed up to 20 000 kPa in the gaseous state [ISO 14532]
NOTE The maximum pressure for natural gas stored in a container is 25 000 kPa.
3.4
gas quality
attribute of natural gas defined by its composition and its physical properties [ISO 14532]
3.5
normal reference conditions
reference conditions of pressure, temperature and humidity (state of saturation) equal to: 101,325 kPa and
273,15 K for a real, dry gas
3.6
standard reference conditions
reference conditions of pressure, temperature and humidity (state of saturation) equal to: 101,325 kPa and
288,15 K for a real, dry gas
NOTE 1 Good practice requires that the reference conditions are incorporated as part of the symbol, and not of the unit, for
the physical quantity represented.
EXAMPLE
�
��
Hp ,,T Vp ,T
��
Scrc crc mrc mrc
��
where
�
H superior calorific value on volumetric basis;
S
3) LPG = liquefied petroleum gas
© ISO 2000 – All rights reserved 3
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
T temperature of the combustion reference conditions;
crc
p pressure of the combustion reference conditions;
crc
V(p , T ) volume at temperature and pressure of the metering reference conditions.
mrc mrc
NOTE 2 Standard reference conditions are also referred to as metric standard conditions.
NOTE 3 The abbreviation s.t.p. (standard temperature and pressure) replaces the abbreviation N.T.P. (Normal Temperature
and Pressure), as formerly used, and is defined as the condition of pressure and temperature equal to: 101,325 kPa and
288,15 K. No restriction is given on the state of saturation.
[ISO 14532]
3.7
superior calorific value
energy released as heat by the complete combustion in air of a specified quantity of gas, in such a way that the
pressure p at which the reaction takes place remains constant, and all the products of combustion are returned to
1
the same specified temperature T as that of the reactants, all of these products being in the gaseous state except
1
for water formed by combustion, which is condensed to the liquid state at T [ISO 14532]
1
NOTE 1 Where the quantity of gas is specified on a molar basis, the calorific value, expressed in MJ/mol, is designated as:
Hp ,T
��
S1 1
On a mass basis the calorific value, expressed in MJ/kg, is designated as:
ˆ
Hp��,T
S1 1
3
Where the quantity of gas is specified on a volumetric basis, the calorific value, expressed in MJ/m , is designated as:
�
��
Hp,,TVp,T
��
S1 1 2 2
��
where p and T are the gas volume (metering) reference conditions.
2 2
The volumetric based calorific value should be specified to normal or standard reference conditions.
NOTE 2 The terms gross, higher, upper and total calorific value, or heating value, are synonymous with superior calorific
value.
NOTE 3 The calorific value should be specified to the combustion conditions.
NOTE 4 The calorific value is normally stated as dry.
�
EXAMPLEHp ,T designates the superior calorific value, specified on a volumetric basis, at standard reference
��
S,w src src
conditions and stated as wet. For simplicity, the combustion conditions are not specified.
3.8
inferior calorific value
energy released as heat by the complete combustion in air of a specified quantity of gas, in such a way that the
pressure p at which the reaction takes place remains constant, and all the products of combustion are returned to
1
the same specified temperature T as that of the reactants, all of these products being in the gaseous state
1
4 © ISO 2000 – All rights reserved
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
NOTE 1 Superior calorific value differs from inferior calorific value by the heat of condensation of water formed by
combustion.
NOTE 2 Where the quantity of gas is specified on a molar basis, the calorific value, expressed in MJ/mol, is designated as:
Hp��,T
I1 1
On a mass basis the calorific value, expressed in MJ/kg, is designated as:
ˆ
Hp ,T
��
I1 1
3
Where the quantity of gas is specified on a volumetric basis, the calorific value, expressed in MJ/m , is designated as:
�
��
Hp,,TV p,T
��
I1 1 2 2
��
where p and T are the gas volume (metering) reference conditions.
2 2
NOTE 3 The terms net and lower calorific value, or heating value, are synonymous with inferior calorific value.
NOTE 4 Superior and inferior calorific values can also be stated as dry or wet (denoted by the subscript "w") depending on
the water vapour content of the gas prior to combustion.
The effects of water vapour on the calorific values, either directly measured or calculated, are described in annex F of
ISO 6976:1995.
NOTE 5 Normally the calorific value is expressed as the superior, dry value specified on volumetric basis under normal or
standard reference conditions.
[ISO 14532]
3.9
density
mass of gas divided by its volume at specified conditions of pressure and temperature
NOTE In a mathematical representation the density is given by:
m
� pT, �
��
Vp,T
��
[ISO 14532]
3.10
relative density
quotient of the mass of a gas, contained within an arbitrary volume, and the mass of dry air of standard composition
(defined in ISO 6976:1995) which would be contained in the same volume at the same reference conditions
NOTE 1 An equivalent definition is given by the ratio of the density of the gas � to the density of dry air of standard
g
composition � at the same reference conditions.
a
� pT,
� �
g
src src
d �
� pT,
��
a src src
NOTE 2 Density can be expressed in terms of the real gas law:
Mp�
� �
ZR��T
© ISO 2000 – All rights reserved 5
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
With this relation the relative density, when both gas and air are considered as real fluids, becomes:
Mp�
gsrc
Zp�,,T ��RT M �Z �p T
� �
g src src src g a src src
d��
Mp�
MZp� ,T
a src � �
ag src src
Zp ,T ��RT
� �
a src src src
For ideal gas behaviour of the gases, when both gas and air are considered as fluids which obey the ideal gas law, the relative
density becomes:
M
g
d �
M
a
NOTE 3 In former times, the above ratio M /M was called specific gravity of a gas, which has the same value as the
g a
relative density if ideal behaviour of the gases is assumed. The term relative density should now replace the term specific
gravity.
[ISO 14532]
3.11
Wobbe index
calorific value, on a volumetric basis, at specified reference conditions, divided by the square root of the relative
density at the same specified metering reference conditions
NOTE 1 The volume is stated at normal or standard reference conditions.
NOTE 2 The Wobbe index is specified as superior (denoted the subscript "S") or inferior (denoted the subscript "I"),
depending on the calorific value, and as dry or wet (denoted by the subscript "w") depending on the calorific value and the
corresponding density.
EXAMPLE
Wobbe index, superior, specified on a volumetric basis, at standard reference conditions and stated as wet (denoted by the
supscript "w")
�
Hp ,T
� �
S,w src src
Wp ,T �
��
Ssrc src
dp� ,T
�
wsrc src
NOTE 3 The Wobbe index is a measure of heat input to gas appliances derived from the orifice flow equation. Heat input for
different natural gas compositions is the same if they have the same Wobbe index, and operate under the same gas pressure
(see ISO 6976).
[ISO 14532]
3.12
compression factor
quotient of the actual (real) volume of an arbitrary mass of gas, at a specified pressure and temperature, and the
volume of the same gas, under the same conditions, as calculated from the ideal gas law
NOTE 1 The terms compressibility factor and Z-factor are synonymous with compression factor.
NOTE 2 The formula for the compression factor is as follows:
V (real)
m
Z �
V (ideal)
m
6 © ISO 2000 – All rights reserved
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
where
RT�
V (ideal) �
m
p
Thus
pV� ()y
m
Zp(,T,y) �
RT�
where
p absolute pressure;
T thermodynamic temperature;
y set of parameters which uniquely characterizes the gas;
V molar volume;
m
R molar gas constant in coherent units;
Z compression factor.
In principle, y may be the complete molar composition (see ISO 12213-2, reference [1] in the Bibliography) or a distinctive set
of dependent physico-chemical properties (see ISO 12213-3, reference [2]).
NOTE 3 Compression factor is a dimensionless quantity usually close to unity near standard or normal reference conditions.
Within the range of pressures and temperatures encountered in gas transmission, compression factor can significantly differ
from unity.
NOTE 4 The supercompressibility factor is defined as the square root of the ratio of the compression factor at reference
conditions to the compression factor of the same gas at the conditions of interest:
Z
b
f �
Zp(,T,y)
where
Z compression factor at base conditions of pressure and temperature.
b
Base conditions are temperature and pressure conditions at which natural gas volumes are determined for purpose of custody
transfer. In natural gas measurements the properties of interest are temperature, pressure and composition. Assuming ideal
gas properties, for simplicity, tables of pure compounds can be prepared for use in calculating gas properties for any
composition at "base conditions". These "base conditions" are chosen near ambient.
In the IGU Dictionary of the Gas Industry the supercompressibility factor is defined as:
1
f �
Zp(,T,y)
The supercompressibility factor is used with measurements made by flow instruments. The volume obtained with a flow meter
must be multiplied by "f" to obtain the corrected volume.
The compression factor is used with measurements made by displacement methods. In this case the volume must be
multiplied by "1/Z" to obtain the correct volume.
© ISO 2000 – All rights reserved 7
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SIST EN ISO 15403:2005
ISO 15403:2000(E)
3.13
water dew point
temperature above which no condensation of water occurs at a specified pressure
NOTE For any pressure lower than the specified pressure there is no condensation at this dew-point temperature.
[ISO 14532]
3.14
hydrocarbon dew point
temperature above which no condensation of hydrocarbons occurs at a specified pressure
NOTE 1 At a given dew point temperature there is a pressure range within which condensation occurs because of
retrograde behaviour. The cricondentherm defines the maximum temperature at which condensation can occur.
NOTE 2 The dew point line is the locus of pressure and temperature points which separate the single phase gas from the
gas-hydrocarbon
...
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