ISO 6144:2003
(Main)Gas analysis — Preparation of calibration gas mixtures — Static volumetric method
Gas analysis — Preparation of calibration gas mixtures — Static volumetric method
ISO 6144:2003 specifies a method for the preparation of calibration gas mixtures by a static volumetric method and provides a procedure for calculating the volumetric composition of the mixture. It can be used either with binary gas mixtures (containing one calibration component in a complementary gas, which is usually nitrogen or air) or with mixtures containing more than one component in the complementary gas. This International Standard also specifies how the expanded uncertainty in the volume fraction of each calibration component in the mixture is determined by a rigorous evaluation of all the measurement uncertainties involved, including those associated with the apparatus used for the preparation of the gas mixture and those associated with the experimental procedure itself.
Analyse des gaz — Préparation des mélanges de gaz pour étalonnage — Méthode volumétrique statique
Analiza plinov – Priprava kalibrirnih plinskih zmesi – Statična volumetrijska metoda
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2004
$QDOL]DSOLQRY±3ULSUDYDNDOLEULUQLKSOLQVNLK]PHVL±6WDWLþQDYROXPHWULMVND
PHWRGD
Gas analysis -- Preparation of calibration gas mixtures -- Static volumetric method
Analyse des gaz -- Préparation des mélanges de gaz pour étalonnage -- Méthode
volumétrique statique
Ta slovenski standard je istoveten z: ISO 6144:2003
ICS:
71.040.40 Kemijska analiza Chemical analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL ISO
STANDARD 6144
Second edition
2003-02-01
Gas analysis — Preparation of calibration
gas mixtures — Static volumetric method
Analyse des gaz — Préparation des mélanges de gaz pour
étalonnage — Méthode volumétrique statique
Reference number
©
ISO 2003
PDF disclaimer
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accepts no liability in this area.
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parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2003
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2003 — All rights reserved
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Principle .2
5 Apparatus.2
6 Procedure for preparing the calibration gas mixture .4
7 Calculation of the volume fraction of the calibration component in the gas mixture.7
8 Determination of the uncertainty in the concentration of the calibration component in the
gas mixture .9
Annex A (informative) Example of an apparatus suitable for the preparation of calibration gas
mixtures by the static volumetric method.12
Annex B (informative) Example of determination of the volume of metering syringes .15
Annex C (informative) Example of the determination of the uncertainty in the concentration of a
calibration gas mixture prepared by the static volumetric method.17
Annex D (informative) Example of the determination of the stability, as a function of time, of
prepared calibration gas mixtures .22
Bibliography.29
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 6144 was prepared by Technical Committee ISO/TC 158, Analysis of gases.
This second edition cancels and replaces the first edition (ISO 6144:1981), which has been technically
revised.
iv © ISO 2003 — All rights reserved
INTERNATIONAL STANDARD ISO 6144:2003(E)
Gas analysis — Preparation of calibration gas mixtures —
Static volumetric method
1 Scope
This International Standard specifies a method for the preparation of calibration gas mixtures by a static
volumetric method and provides a procedure for calculating the volumetric composition of the mixture. It can
be used either with binary gas mixtures (containing one calibration component in a complementary gas, which
[1, 2]
is usually nitrogen or air ) or with mixtures containing more than one component in the complementary gas.
This International Standard also specifies how the expanded uncertainty in the volume fraction of each
calibration component in the mixture is determined by a rigorous evaluation of all the measurement
uncertainties involved, including those associated with the apparatus used for the preparation of the gas
mixture and those associated with the experimental procedure itself.
NOTE 1 This International Standard is generally applicable to the preparation of calibration gas mixtures containing
−9 −6
calibration components in the concentration range 10 × 10 (10 ppb — parts per billion) to 50 × 10 (50 ppm — parts per
million) by volume. However, gas mixtures may be prepared at larger or smaller volume fractions, provided that the
components used in the static dilution process are selected appropriately.
NOTE 2 A relative expanded uncertainty of not greater than ± 1 % at a level of confidence of 95 % may be achievable
at these concentrations, provided that:
the purities of the parent gases have been determined by analysis and any significant impurities and the uncertainties
in their measured concentrations have been taken into account;
no significant adsorption effects or chemical reactions occur between the gaseous constituents and the internal
surfaces of the apparatus, and there are no reactions between any of the gaseous components, i.e. between the
calibration component and complementary gas or between the calibration components themselves;
all the relevant apparatus used in the preparation of a calibration gas mixture have been calibrated with assigned
measurement uncertainties which are appropriate to calculating the final expanded uncertainty for the calibration gas
mixture prepared.
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 7504, Gas analysis — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7504 apply.
4 Principle
A calibration gas mixture consists of one of more calibration components in a complementary (diluent) gas,
mixed in a suitable gas-mixing chamber. These calibration components are generally pure gases taken from
cylinders, or from pure, volatile liquids that are allowed to evaporate into the gas-mixing chamber. The gas
mixture is prepared using syringes to inject:
either known volumes of gaseous calibration components (each at a pressure of about 1 × 10 Pa);
or known masses or volumes of liquid calibration components;
These are injected into a volume of complementary gas contained in the mixing chamber (which is also at a
pressure of about 1 × 10 Pa). Further complementary gas is then added to increase the overall pressure of
the gas mixture to an accurately measured value above ambient atmospheric pressure. This final (above-
atmospheric) pressure is required so that the calibration gas mixture will subsequently flow out of the mixing
chamber and can be used to calibrate a gas analyser, which is usually operated at ambient pressure.
At each stage in the preparation procedure, the mixture is homogenized, usually by means of a suitable
stirring device, and then left to equilibrate to ambient atmospheric temperature.
The volume fraction of each calibration component in the calibration gas mixture is determined by calculation
of the ratio of the volume of the calibration component to the total volume of the mixture.
5 Apparatus
5.1 Gas-mixing chamber, consisting of the components specified in 5.1.1 to 5.1.8.
NOTE An example of a suitable gas-mixing chamber is described in Annex A.
5.1.1 Vessel, comprising the gas-mixing chamber itself, of sufficient internal volume to deliver the amount
of calibration gas mixture required for any subsequent instrumental calibrations, manufactured of a suitable
material that is inert to all the component gases, and designed both to be evacuable and to withstand the
required above-atmospheric operating pressures. It shall also have vacuum/high-pressure flanges to allow
access to the components that are mounted within the mixing chamber.
3 3 5
NOTE 1 Vessels with internal volumes of 0,1 m to 0,5 m , capable of operating up to pressures of about 2 × 10 Pa
(2 bar) and of maintaining a vacuum of better than 0,1 × 10 Pa (0,1 mbar), have been found to be suitable (see Annex A).
NOTE 2 Mixing chambers manufactured from borosilicate glass or stainless steel have been found to be suitable for
the commonly used gaseous species (e.g. gas mixtures which contain SO , NO, NO , CO and C H as the calibration
2 2 6 6
components). However, care shall be taken in selecting the materials of the mixing chamber, and of the other components
which come into contact with the gas mixtures, so that they do not affect the mixture's stability adversely — particularly
when more reactive gas mixtures are to be prepared.
5.1.2 Vacuum pump, capable of evacuating the mixing chamber and its associated components to a low
pressure, and including a suitable vacuum shut-off valve. This low pressure shall be defined either so that any
gaseous contamination resulting from the residual low pressure has no effect on the accuracy of the
concentration of the gas mixture prepared, or so that a quantitative correction for the effect of this residual low
pressure may be made to the concentration of the mixture.
NOTE The residual gas pressure is generally due mainly to nitrogen from residual air. However, care must be taken
to ensure that other gases that may react with the constituents of the gas mixture are not present at significant
concentrations in this residual gas (e.g. traces of water vapour when acid gases are being used as calibration
components, or traces of oxygen in the case when nitric oxide calibration mixtures are being prepared).
5.1.3 Gas line, used for the injection of the complementary gas, and including appropriate metering and
shut-off valves.
2 © ISO 2003 — All rights reserved
5.1.4 Pressure, vacuum and temperature gauges, used to monitor these parameters inside the mixing
vessel.
5.1.5 Septum, enabling a gas or liquid of known volume or mass to be injected into the mixing chamber
from a metering syringe (5.2).
5.1.6 Motor-driven gas-mixing device, e.g. a fan, enabling the gaseous components in the gas-mixing
chamber to be homogenized, and designed to provide satisfactory mixing of all the gaseous components to a
given degree of homogeneity within a specified time. Experimental tests shall be carried out to demonstrate
that the mixing device is able to achieve the required homogeneity within the specified time.
5.1.7 Pressure relief valve, used to ensure that the maximum internal safe working pressure specified for
the mixing vessel and its associated components is not exceeded.
5.1.8 Outlet-gas sampling line, enabling the gas mixture prepared to be used for calibration purposes,
and having a device for equalizing the internal pressure of the gas mixture in the mixing chamber with
atmospheric pressure so as to enable the gas mixture to be determined at ambient pressure for calibration
purposes.
5.2 Calibrated metering syringe, which can be used to inject, by means of a
...
INTERNATIONAL ISO
STANDARD 6144
Second edition
2003-02-01
Gas analysis — Preparation of calibration
gas mixtures — Static volumetric method
Analyse des gaz — Préparation des mélanges de gaz pour
étalonnage — Méthode volumétrique statique
Reference number
©
ISO 2003
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2003
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2003 — All rights reserved
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Principle .2
5 Apparatus.2
6 Procedure for preparing the calibration gas mixture .4
7 Calculation of the volume fraction of the calibration component in the gas mixture.7
8 Determination of the uncertainty in the concentration of the calibration component in the
gas mixture .9
Annex A (informative) Example of an apparatus suitable for the preparation of calibration gas
mixtures by the static volumetric method.12
Annex B (informative) Example of determination of the volume of metering syringes .15
Annex C (informative) Example of the determination of the uncertainty in the concentration of a
calibration gas mixture prepared by the static volumetric method.17
Annex D (informative) Example of the determination of the stability, as a function of time, of
prepared calibration gas mixtures .22
Bibliography.29
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 6144 was prepared by Technical Committee ISO/TC 158, Analysis of gases.
This second edition cancels and replaces the first edition (ISO 6144:1981), which has been technically
revised.
iv © ISO 2003 — All rights reserved
INTERNATIONAL STANDARD ISO 6144:2003(E)
Gas analysis — Preparation of calibration gas mixtures —
Static volumetric method
1 Scope
This International Standard specifies a method for the preparation of calibration gas mixtures by a static
volumetric method and provides a procedure for calculating the volumetric composition of the mixture. It can
be used either with binary gas mixtures (containing one calibration component in a complementary gas, which
[1, 2]
is usually nitrogen or air ) or with mixtures containing more than one component in the complementary gas.
This International Standard also specifies how the expanded uncertainty in the volume fraction of each
calibration component in the mixture is determined by a rigorous evaluation of all the measurement
uncertainties involved, including those associated with the apparatus used for the preparation of the gas
mixture and those associated with the experimental procedure itself.
NOTE 1 This International Standard is generally applicable to the preparation of calibration gas mixtures containing
−9 −6
calibration components in the concentration range 10 × 10 (10 ppb — parts per billion) to 50 × 10 (50 ppm — parts per
million) by volume. However, gas mixtures may be prepared at larger or smaller volume fractions, provided that the
components used in the static dilution process are selected appropriately.
NOTE 2 A relative expanded uncertainty of not greater than ± 1 % at a level of confidence of 95 % may be achievable
at these concentrations, provided that:
the purities of the parent gases have been determined by analysis and any significant impurities and the uncertainties
in their measured concentrations have been taken into account;
no significant adsorption effects or chemical reactions occur between the gaseous constituents and the internal
surfaces of the apparatus, and there are no reactions between any of the gaseous components, i.e. between the
calibration component and complementary gas or between the calibration components themselves;
all the relevant apparatus used in the preparation of a calibration gas mixture have been calibrated with assigned
measurement uncertainties which are appropriate to calculating the final expanded uncertainty for the calibration gas
mixture prepared.
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 7504, Gas analysis — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7504 apply.
4 Principle
A calibration gas mixture consists of one of more calibration components in a complementary (diluent) gas,
mixed in a suitable gas-mixing chamber. These calibration components are generally pure gases taken from
cylinders, or from pure, volatile liquids that are allowed to evaporate into the gas-mixing chamber. The gas
mixture is prepared using syringes to inject:
either known volumes of gaseous calibration components (each at a pressure of about 1 × 10 Pa);
or known masses or volumes of liquid calibration components;
These are injected into a volume of complementary gas contained in the mixing chamber (which is also at a
pressure of about 1 × 10 Pa). Further complementary gas is then added to increase the overall pressure of
the gas mixture to an accurately measured value above ambient atmospheric pressure. This final (above-
atmospheric) pressure is required so that the calibration gas mixture will subsequently flow out of the mixing
chamber and can be used to calibrate a gas analyser, which is usually operated at ambient pressure.
At each stage in the preparation procedure, the mixture is homogenized, usually by means of a suitable
stirring device, and then left to equilibrate to ambient atmospheric temperature.
The volume fraction of each calibration component in the calibration gas mixture is determined by calculation
of the ratio of the volume of the calibration component to the total volume of the mixture.
5 Apparatus
5.1 Gas-mixing chamber, consisting of the components specified in 5.1.1 to 5.1.8.
NOTE An example of a suitable gas-mixing chamber is described in Annex A.
5.1.1 Vessel, comprising the gas-mixing chamber itself, of sufficient internal volume to deliver the amount
of calibration gas mixture required for any subsequent instrumental calibrations, manufactured of a suitable
material that is inert to all the component gases, and designed both to be evacuable and to withstand the
required above-atmospheric operating pressures. It shall also have vacuum/high-pressure flanges to allow
access to the components that are mounted within the mixing chamber.
3 3 5
NOTE 1 Vessels with internal volumes of 0,1 m to 0,5 m , capable of operating up to pressures of about 2 × 10 Pa
(2 bar) and of maintaining a vacuum of better than 0,1 × 10 Pa (0,1 mbar), have been found to be suitable (see Annex A).
NOTE 2 Mixing chambers manufactured from borosilicate glass or stainless steel have been found to be suitable for
the commonly used gaseous species (e.g. gas mixtures which contain SO , NO, NO , CO and C H as the calibration
2 2 6 6
components). However, care shall be taken in selecting the materials of the mixing chamber, and of the other components
which come into contact with the gas mixtures, so that they do not affect the mixture's stability adversely — particularly
when more reactive gas mixtures are to be prepared.
5.1.2 Vacuum pump, capable of evacuating the mixing chamber and its associated components to a low
pressure, and including a suitable vacuum shut-off valve. This low pressure shall be defined either so that any
gaseous contamination resulting from the residual low pressure has no effect on the accuracy of the
concentration of the gas mixture prepared, or so that a quantitative correction for the effect of this residual low
pressure may be made to the concentration of the mixture.
NOTE The residual gas pressure is generally due mainly to nitrogen from residual air. However, care must be taken
to ensure that other gases that may react with the constituents of the gas mixture are not present at significant
concentrations in this residual gas (e.g. traces of water vapour when acid gases are being used as calibration
components, or traces of oxygen in the case when nitric oxide calibration mixtures are being prepared).
5.1.3 Gas line, used for the injection of the complementary gas, and including appropriate metering and
shut-off valves.
2 © ISO 2003 — All rights reserved
5.1.4 Pressure, vacuum and temperature gauges, used to monitor these parameters inside the mixing
vessel.
5.1.5 Septum, enabling a gas or liquid of known volume or mass to be injected into the mixing chamber
from a metering syringe (5.2).
5.1.6 Motor-driven gas-mixing device, e.g. a fan, enabling the gaseous components in the gas-mixing
chamber to be homogenized, and designed to provide satisfactory mixing of all the gaseous components to a
given degree of homogeneity within a specified time. Experimental tests shall be carried out to demonstrate
that the mixing device is able to achieve the required homogeneity within the specified time.
5.1.7 Pressure relief valve, used to ensure that the maximum internal safe working pressure specified for
the mixing vessel and its associated components is not exceeded.
5.1.8 Outlet-gas sampling line, enabling the gas mixture prepared to be used for calibration purposes,
and having a device for equalizing the internal pressure of the gas mixture in the mixing chamber with
atmospheric pressure so as to enable the gas mixture to be determined at ambient pressure for calibration
purposes.
5.2 Calibrated metering syringe, which can be used to inject, by means of a piston, a known volume of
gas or liquid through a needle. The syringe shall have gastight seals to ensure that no significant leakage of
the gas or liquid takes place.
NOTE 1 Glass syringes having polytetrafluoroethene (PTFE) bushings as seals, and with internal volumes of 10 ml,
5 ml, 1 ml, 0,5 ml and 0,1 ml, have been found to be suitable when used with mixing chambers of volumes which are in
practical use, and when used to prepare gas mixtures for the calibration of ambient-air analysers.
NOTE 2 It is recommended that the internal volume of the syringe be measured experimentally with a maximum
relative uncertainty of ± 1 % (at a level of confidence of 95 %). In addition, the syringe should have a maximum leak rate of
2 –2
10 × 10 Pa (10 mbar) per hour after evacuation to 5 Pa (5 × 10 mbar), in order that it has satisfacto
...
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