EN ISO 14111:1999
(Main)Natural gas - Guidelines to traceability in analysis (ISO 14111:1997)
Natural gas - Guidelines to traceability in analysis (ISO 14111:1997)
Migrated from Progress Sheet (TC Comment) (2000-07-10): See mail from P. Pieters dated on 98-03-31 (BL)
Erdgas - Leitlinien für die Rückführbarkeit in der Analytik (ISO 14111:1997)
Diese Internationale Norm enthält allgemeine Leitlinien für die Umsetzung und Anwendung von Konzepten zur Rückführbarkeit in der Erdgasanalytik. Ihr Zweck besteht darin, die Grundlagen für die Entwicklung spezifischer Verfahrensanweisungen zur Rückführung in anderen Internationalen Normen der Erdgasanalytik festzuschreiben. Anmerkung: Neben der Analyse von Erdgas könnte diese Internationale Norm auch für andere Bereiche der Gasanalyse und verwandte Gebiete, so z.B. Luftgütemessung, Kraftfahrzeug-Abgasanalyse und Referenzgasherstellung von Nutzen sein.
Gaz naturel - Lignes directrices pour la traçabilité en analyse (ISO 14111:1997)
Zemeljski plin - Smernice za sledljivost pri analizah (ISO 14111:1997)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2000
Zemeljski plin - Smernice za sledljivost pri analizah (ISO 14111:1997)
Natural gas - Guidelines to traceability in analysis (ISO 14111:1997)
Erdgas - Leitlinien für die Rückführbarkeit in der Analytik (ISO 14111:1997)
Gaz naturel - Lignes directrices pour la traçabilité en analyse (ISO 14111:1997)
Ta slovenski standard je istoveten z: EN ISO 14111:1999
ICS:
75.060 Zemeljski plin Natural gas
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
INTERNATIONAL IS0
STANDARD 14111
First edition
1997-03-15
Natural gas - Guidelines to traceability
in analysis
Gaz na turel - Lignes directrices pour la traCabilit6 en analyse
Reference number
IS0 14111 :I 997(E)
IS0 14111:1997(E)
Page
Contents
............................................................................................ 1
1 Scope
2 Normative references .
3 Definitions .
4 Fundamental principles of metrological traceability . 4
5 Elaboration of the traceability concept . 6
6 Chemical composition and the SI system . 7
7 Traceability in natural-gas analysis . 10
Hierarchy of reference gas mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9 Role of traceability in uncertainty assessment
10 Implementation of traceability in International Standards for
...................................................................... 17
natural-gas analysis
11 Examples .
12 Summary .
Annexes
A Supplementary terms and definitions . 23
............................. 26
B Example of typical interlaboratory test results
.................................................................................. 28
C Bibliography
0 IS0 1997
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 the publisher.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet: central@iso.ch
x.400: c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
IS0 14111:1997(E)
@ IS0
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
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.
International Standard IS0 14111 was prepared by Technical Committee
lSO/TC 193, Natural gas, Subcommittee SC 1, Analysis of natural gas.
Annexes A to C of this International Standard are for information only.
@ IS0
IS0 14111:1997(E)
Introduction
At a time when assurances of measurement accuracy in natural-gas
analyses are increasingly being sought, every analytical chemist
responsible for the design and operation of systems used in such analyses
needs to be aware of, and adopt, suitable means by which he or she will
be able to provide these assurances. This implies that the analyst must
employ validated methods in which each result is securely linked, through
a series of reference materials (reference gas mixtures), to accepted
metrological standards. The formal structure which the analyst creates in
doing this constitutes what is called a traceability chain. Only by this
means will the analyst be able to secure and support a proper estimate of
measurement accuracy (uncertainty).
This seemingly simple concept is elaborated in considerable detail in this
International Standard. The practical considerations involved in the
establishment of a satisfactory traceability chain give rise to challenging
problems, particularly in natural-gas analysis, but relevant and useful
advice is provided.
At present, traceability of measurement is universally defined through the
existence of unbroken calibration chains ending at the level of international
or national measurement standards realizing appropriate SI units. This
concept originates from the field of physical metrology, where it has been
implemented with apparent success. Transfer of the metrological scheme
to chemical analysis and other domains in the field of testing is, however,
a highly difficult task, for which standard methods are not yet available.
Therefore it is not possible, at present, to standardize the implementation
of measurement traceability in natural-gas analysis, or in other areas of
chemical analysis.
For the reasons indicated above, this International Standard does not give
any specific traceability protocols. Instead, its purpose is to
- clarify fundamental concepts involved in chemical traceability;
identify basic problems in the application of metrology in chemistry;
indicate feasible solutions on a reference material basis;
implementations using reference gas
- assist in the design of practical
mixtures;
- serve as a reference document for the application of the traceability
concept in other International Standards for natural-gas analysis.
iv
IS0 14111:1997(E)
INTERNATIONAL STANDARD @ IS0
- Guidelines to traceability in analysis
Natural gas
1 Scope
This International Standard provides general guidelines on the implementation and application of traceability
concepts in the analysis of natural gas. Its purpose is to lay down the foundations for the development of specific
traceability protocols in other International Standards for natural-gas analysis.
NOTE - Besides the field of natural-gas analysis, this International Standard could also be useful as a guidance document in
other areas of gas analysis and in related fields such as air quality measurement, vehicle emission monitoring and reference-
gas mixture preparation.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
- Part 1: Probability and general statistical terms.
IS0 3534-l : 1993, Statistics - Vocabulary and symbols
IS0 5168:- 1) , Measurement of fluid flow - Evaluation of uncertainties.
IS0 5725-l :I 994, Accuracy (trueness and precision) of measurement methods and results - Part I: General
principles and definitions.
IS0 5725-2: 1994, Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method.
IS0 5725-3:1994, Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate
measures of the precision of a measurement method.
IS0 5725-4:1994, Accuracy (trueness and precision) of measurement methods and results - Part 4: Basic
methods for the determination of the trueness of a standard measurement method.
IS0 5725-6:1994, Accuracy (trueness and precision) of measurement methods and results - Part 6: Use in
practice of accuracy values.
Preparation of calibration gas mixtures - Weighing methods (including addendum 1).
IS0 6142:1981, Gas analysis -
1) To be published. (Revision of IS0 5168:1978)
@ IS0
IS0 14111:1997(E)
Determination of composition of calibration gas mixtures - Comparison methods.
IS0 6143:1981, Gas analysis -
Checking of calibration gas mixtures by a comparison method.
IS0 6711 :I 981, Gas analysis -
Determination of composition with defined uncertainty by gas chromatography -
IS0 6974-l :- *), Natural gas -
Part I: Guidelines for tailored analysis.
Determination of composition with defined uncertainty by gas chromatography -
I SO 6974-2:- *), Natural gas -
Part 2: Measuring-s ys tern characteristics and statistics for data processing.
IS0 6976: 1995, Natural gas - Calculation of calorific values, density, relative density and Wobbe index from
composition.
Model for quality assurance in design, development, production, installation and
IS0 9001 :I 994, Quality systems -
servicing.
Part 1: Metrological confirmation
IS0 10012-I :I 992, Quality assurance requirements for measuring equipment -
s ys tern for measuring equipment.
IS0 10723:1995, Natural gas - Performance requirements for on-line analytical s ys terns.
IS0 Guide 30:1992, Terms and definitions used in connection with reference materials.
IS0 Guide 33:1989, Uses of certified reference materials.
General and statistical principles.
IS0 Guide 35:1989, Certification of reference materials -
BIPM/IEC/IS0/0IML/IFCC/IUPAC. International vocabulary of basic and general terms in metrology (VIM), second
edition, 1993.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 traceability: A property of the result of a measurement or the value of a standard whereby it can be related
to stated references, usually national or international standards, through an unbroken chain of comparisons all
having stated uncertainties.
NOTES
1 The concept is often expressed by the adjective “traceable ”.
2 The unbroken chain of comparisons is called a “traceability chain ”. [VIM]
3.2 (measurement) standard, etalon: A material measure, measuring instrument, reference material or
measuring system intended to define, realize, conserve or reproduce a unit or one or more values of a quantity to
serve as a reference.
EXAMPLES
a) 1 kg mass standard;
b) 100 &I standard resistor;
standard ammeter;
c)
d) caesium frequency standard;
e) standard hydrogen electrode;
f) reference solution of cortisol in human serum having a certified concentration. [VIM]
2) To be published. (Revision, in parts, of IS0 6974:1984)
@ IS0
IS0 14111:1997(E)
3.3 reference material: A material or substance one or more of whose property values are sufficiently
homogeneous and well established to be used for the calibration of an apparatus, the assessment of a
measurement method or for assigning values to materials.
A reference material may be in the form of a pure or mixed gas, liquid or solid. Examples are water for the
NOTE -
calibration of viscometers, sapphire as a heat-capacity calibrant in calorimetry, and solutions used for calibration in chemical
analysis. [ISO Guide 301
34 . Terms related to accuracy and uncertainty
NOTE - Since traceability essentially serves the purpose of assessment and control of accuracy, viz the uncertainty of
measurement, the following terms relating to accuracy and uncertainty are also key terms of this document. The definitions,
taken from IS0 3534-1, have been adapted to usage in the field of measurement instead of testing, by substitution of
corresponding terms ( “measurement result” instead of “test result ”, and “true value” instead of “accepted reference value ”).
In some cases, the notes to the definitions have also been modified.
3.4.1 accuracy: The closeness of agreement between a measurement result and the true value of the
measurand.
NOTE - The term accuracy, whe n applied to a set of measurement results, describes a combination of random components
bias corn pone nt. [Adapted from IS0 3534-I]
and a corn mon systematic error or
3.4.2 trueness: The clo seness of ag reement b etween the average value obtained from a large series of
the true value of the m ea surand.
meas urement results and
NOTES
The measure of trueness is usually expressed in terms of bias.
2 Until recently, “accuracy” was used with the meaning of “trueness ”. This usage no longer conforms with international
standardization. [Adapted from IS0 3534-l I
3.4.3 precision: The closeness of agreement between independent measurement results obtained under
presc ribed conditions.
NOTES
1 Precision depends only on the distribution of random errors and does not relate to the true value.
2 Precision is a qualitative term relating to the dispersion between the results of measurements of the same measurand,
carried out under specified conditions of measurement. Quantitative measures of precision such as variance or standard
deviation critically depend on the variation implied by the specified measurement conditions. Repeatability and reproducibility
are two particular concepts of precision, relating to the endpoints on the scale of variability in measurement conditions.
[Adapted from IS0 3534-l 1
.
measurement result which characterizes the range of values within
3.4.4 uncertainty . An estimate a ttach
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.