ISO 19230:2020
(Main)Gas analysis — Sampling guidelines
Gas analysis — Sampling guidelines
This document specifies the general provisions and gives the basic definitions of terms relating to sampling for gas analysis, including sampling devices, sampling methods, sampling technical considerations, and sampling safety. This document applies to both direct and indirect sampling of gas in pressure receptacles and pipelines, including pure gases and gas mixtures. Compressed and liquefied gases are both considered. This document applies to the sampling of processed gases and does not involve gas treatment processes. The sampling procedures specified are not intended for the sampling of special products which are the subject of other International Standards, such as liquefied petroleum gases (see ISO 4257) and gaseous natural gases (see ISO 10715).
Analyse des gaz — Lignes directrices pour le prélèvement des échantillons
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 19230
First edition
2020-11
Gas analysis — Sampling guidelines
Analyse des gaz — Lignes directrices pour le prélèvement des
échantillons
Reference number
ISO 19230:2020(E)
©
ISO 2020
---------------------- Page: 1 ----------------------
ISO 19230:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 19230:2020(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling plan . 5
5 Sampling classification . 6
5.1 Sampling classification of gases . 6
5.2 Sampling classification of liquefied gas . 7
6 Technical specifications . 8
6.1 Overview . 8
6.2 General considerations for gas sampling . 8
6.2.1 Adsorption, reaction and permeation of sampling system . 8
6.2.2 Leaks and atmospheric diffusion in the sampling system . 8
6.2.3 Leak testing of the sampling system . 8
6.2.4 Purging of the sampling system . 9
6.2.5 Homogeneity of gas .12
6.2.6 Inert-gas purging .12
6.3 Possible condensation during compressed gas sampling.12
6.4 Main considerations for liquefied gas sampling .13
6.5 Samples that are not feasible in containers or cannot be used for analysis directly .13
7 Safety guidance in sampling .13
7.1 Overview .13
7.2 General recommendation .13
7.3 Specific recommendation for sampling a certain substance .14
8 Sampling devices .14
8.1 General provision .14
8.2 Sample container .14
8.2.1 Sample container material .14
8.2.2 Structure of sample container .16
8.2.3 Volume of sample container .18
8.3 Sample probe .18
8.4 Pressure reducer and flow controller .19
8.5 Sample pump .19
8.6 Sample line .19
8.6.1 Material of sample line .19
8.6.2 Length and diameter of sample line .20
8.7 Connecters and seals .20
8.8 Cleaning and drying of the sampling device .20
8.9 Connection of sampling devices .20
9 Sampling .21
9.1 Sampling method block diagram .21
9.1.1 Overview .21
9.1.2 Block diagram of compressed gas sampling method .21
9.1.3 Block diagram of liquefied gas sampling method .21
9.2 Quality assessment of the sampling system .22
9.3 Sampling from the gaseous phase and sampling after evaporation of liquefied gas .22
9.4 Direct sampling .23
9.4.1 General provisions.23
9.4.2 Direct sampling of gas in pressure receptacles .23
9.4.3 Direct sampling of gas in pipelines .23
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ISO 19230:2020(E)
9.5 Indirect sampling .23
9.5.1 Indirect sampling of gas in pressure receptacles .23
9.5.2 Indirect sampling of gas in pipelines .24
9.5.3 Leakage test of sample container .25
9.5.4 Storage of samples . . .25
9.6 Sampling records .25
Annex A (informative) Examples of estimation of the purging time and purging cycles for
sampling system . .26
Annex B (informative) Direct sampling for gas in pressure receptacles .27
Annex C (informative) Direct sampling of gas in pipelines .30
Annex D (informative) Fill-empty sampling method .32
Annex E (informative) Evacuated-container sampling .34
Annex F (informative) Evacuated-system sampling .39
Annex G (informative) Indirect sampling using floating piston cylinders .41
Bibliography .43
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ISO 19230:2020(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 158, Analysis of gases.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 19230:2020(E)
Introduction
The determination of gas composition, impurity concentration and physical properties depend, to a
large extent, on sampling technique. The use of correct sampling techniques is an important safety and
quality critical step in gas analysis. The design, construction and selection of the sampling equipment
to avoid hazardous situations and sampling errors are important and directly influence the results
obtained. Any slight carelessness, inexactitude or mistake will seriously influence safety and the results
obtained.
Gaseous products are stored and transported in pressure receptacles in the form of compressed or
liquefied gas or through gas pipelines. The sampling methods used differ depending upon the package,
composition and delivery methods.
This document provides technical guidelines for the sampling of gases in pressure receptacles and
pipelines for analytical purposes.
vi © ISO 2020 – All rights reserved
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INTERNATIONAL STANDARD ISO 19230:2020(E)
Gas analysis — Sampling guidelines
WARNING — The use of this document can involve a number of hazards. This document does not
specify all the safety issues associated with its use. Users of this document are responsible for
establishing measures to ensure safety while gas sampling.
1 Scope
This document specifies the general provisions and gives the basic definitions of terms relating
to sampling for gas analysis, including sampling devices, sampling methods, sampling technical
considerations, and sampling safety.
This document applies to both direct and indirect sampling of gas in pressure receptacles and pipelines,
including pure gases and gas mixtures. Compressed and liquefied gases are both considered.
This document applies to the sampling of processed gases and does not involve gas treatment processes.
The sampling procedures specified are not intended for the sampling of special products which are the
subject of other International Standards, such as liquefied petroleum gases (see ISO 4257) and gaseous
natural gases (see ISO 10715).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 3165, Sampling of chemical products for industrial use — Safety in sampling
ISO 16664, Gas analysis — Handling of calibration gases and gas mixture — Guidelines
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
gas
materials which are present completely in gaseous form at a temperature of 20 °C under the absolute
pressure of 0,101 3 MPa
Note 1 to entry: The materials here include single mediums and mixtures.
3.2
compressed gas
gas (3.1) which, when packaged under pressure for transport, is entirely gaseous at all temperatures
above −50 °C
Note 1 to entry: This category includes all gases with a critical temperature less than or equal to −50 °C.
[SOURCE: ISO 10286:2015, 705, modified — Modified to include all temperatures above −50 °C.]
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ISO 19230:2020(E)
3.3
liquefied gas
gas (3.1) which, when packaged under pressure for transport, is partially liquid at temperatures
above −50 °C
[SOURCE: ISO 10286:2015, 706, modified — Modified to specify that gas is packaged under pressure.]
3.4
high pressure liquefied gas
gas (3.1) with a critical temperature between −50 °C and +65 °C
[SOURCE: ISO 10286:2015, 708]
3.5
low pressure liquefied gas
gas (3.1) with a critical temperature above +65 °C
[SOURCE: ISO 10286:2015, 707]
3.6
toxic gas
gas (3.1) which is known to be so toxic or corrosive to humans to pose a health hazard or which is
presumed to be toxic or corrosive to humans because it has a lethal concentration 50 (3.38) value for
3
acute toxicity equal to or less than 5 000 ml/m (ppm)
Note 1 to entry: Other risks, such as tissue corrosiveness, are sometimes associated.
[SOURCE: ISO 10286:2015, 716]
3.7
gas in pressure receptacles
gas stored in closed cylinders, tube, pressure drums, tanks and other pressure receptacles
3.8
gas in pipelines
gas delivered in pipelines during the production process
3.9
sampling device
components that comprise the sampling system (3.10) mainly includes sample lines (3.26), pressure
regulators/reducers, flow controllers, connectors and sample containers
3.10
sampling system
gas transmission and control system constructed by gas storage container or sample point of gas in
pipelines (3.8) and various sampling devices (3.9)
3.11
representative sample
sample assumed to have the same composition as the material sampled when the latter is considered as
a homogeneous whole
[SOURCE: ISO 6206:1979, 3.3]
3.12
direct sampling
sampling in situations where there is a direct connection between the gas to be sampled and the
analytical unit
[SOURCE: ISO 10715:1997, 2.1, modified — The word "natural" has been omitted from the definition.]
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ISO 19230:2020(E)
3.13
indirect sampling
sampling in situations where there is no direct connection between the gas to be sampled and the
analytical unit
[SOURCE: ISO 10715:1997, 2.7, modified — The word "natural" has been omitted from the definition.]
3.14
sampling plan
planned procedure of selection, withdrawal and preparation of a sample or samples from a lot to yield
the required knowledge of the characteristic(s) from the final sample so that a decision can be made
regarding the lot
[SOURCE: ISO 6206:1979, 3.1.5]
3.15
spot sampling
indirect sampling (3.13) from a specific part of the stream of material with a certain volume at a
specific time
3.16
incremental sampling
indirect sampling (3.13) by collecting a series of spot samples into a combined sample
3.17
continuous sampling
direct sampling (3.12) taken continuously from a stream of material with a constant flow rate in a
certain period of time
3.18
intermittent sampling
direct sampling (3.12) from a stream of material with predetermined intervals
3.19
ullage
outage
space in the container not occupied by the material, or the distance between the material surface and a
fixed reference point at the top of the container
Note 1 to entry: This volume allows room for expansion.
[SOURCE: ISO 6206:1979, 3.3.14]
3.20
sampling error
part of the total estimation error of a characteristic due to known and acceptable deficiencies in the
sampling plan (3.14)
[SOURCE: ISO 6206:1979, 3.4.10]
3.21
incremental sampler
sampler which accumulates a series of spot samples into one composite sample
[SOURCE: ISO 10715:1997, 2.6]
3.22
low-pressure gas
gases with a pressure between 0 MPa and 0,2 MPa at sampling temperature
Note 1 to entry: Except for special provisions, all pressures mentioned in this standard are gauge pressures.
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ISO 19230:2020(E)
3.23
high-pressure gas
gases with a pressure exceeding 0,2 MPa at sampling temperature
3.24
lag time
time taken for a representative sample (3.11) to enter the instrument
[SOURCE: ISO 11042-2:1996, 3.5.1.1]
3.25
sample container
container for collecting the gas sample when indirect sampling (3.13) is necessary
[SOURCE: ISO 10715:1997, 2.14]
3.26
sample line
conduit to transfer a sample of gas from the sample place to the analytical unit or sample container (3.25)
Note 1 to entry: Another word used for sample line is transfer line.
[SOURCE: ISO 14532:2014, 2.3.2.5]
3.27
sample probe
device inserted into the gas pipelines so that a representative sample (3.11) of the flowing gas can be taken
Note 1 to entry: The sample probe will have a conduit to convey the sample from the flowing gas to a point
external to the pipeline.
[SOURCE: ISO 14532:2014, 2.3.2.6, modified — The second sentence has been formatted as a note to entry.]
3.28
sampling point
point in the gas stream where a representative sample (3.11) can be collected
[SOURCE: ISO 10715:1997, 2.17]
3.29
filling ratio
ratio of the mass of gas to the mass of water at 15 °C that would fill completely a pressure receptacle
fitted ready for use
Note 1 to entry: Synonyms are filling factor and filling degree, often expressed in kg/l or similar.
[SOURCE: ISO 10286:2015, 747]
3.30
continuous purging method
purging method by continually purging the sampling system (3.10) with sample gases
3.31
fill-empty cycle purging method
purging method by sequentially filling and emptying the sampling system (3.10) repeatedly with the gas
to be taken
3.32
evacuation-gas purging cycles
purging method by sequentially evacuating and pressurizing the sampling system (3.10) with the
sample to be taken
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ISO 19230:2020(E)
3.33
sampling from the gaseous phase
process that takes a sample from the gaseous phase of the liquefied gases (3.3)
3.34
sampling from the liquid phase
process that takes a sample from the liquid phase of the liquefied gases (3.3)
3.35
sampling in liquid form
process that takes a sample in liquid form directly from the liquid phase of the liquefied gas (3.3)
3.36
sampling after evaporation
process that takes a sample in gaseous form by vaporizing the sample from the liquid phase of the
liquefied gas (3.3)
3.37
liquid valve
device with an internal fixed sample loop, fitted to an analyser for the direct sampling (3.12) of liquefied
gas (3.3) in liquid form, which can keep the liquefied gas to be collected completely in the liquid phase
3.38
lethal concentration 50
LC
50
concentration of a substance in air exposure to which, for a specified length of time, it is expected to
cause the death of 50 % of the entire defined experimental animal population after a defined time period
[SOURCE: ISO 10298:2018, 3.1]
3.39
corrosive gas
gas (3.1) which, when dissolved in water or other liquid, causes corrosion of metal
[SOURCE: ISO 13703:2000, 3.1.4]
3.40
floating piston cylinder
sample container (3.25) that has a moving piston separating the sample from a precharge gas
Note 1 to entry: The pressures are in balance on both sides of the piston.
[SOURCE: ISO 14532:2014, 2.3.2.1, modified — The container has been specified as a "sample container"
and the second sentence was formatted as a note to entry.]
4 Sampling plan
A feasible and complete sampling plan should be developed before sampling as shown in Figure 1.
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ISO 19230:2020(E)
Figure 1 — Scheme of sampling plan
5 Sampling classification
5.1 Sampling classification of gases
In this document, the sampling classification is based on whether the gas is directly fed to the analyser
or not. In addition, the sampling methods vary among different gas packaging, storage methods and
sampling purposes.
Direct sampling, if possible, is strongly recommended. In the case of indirect sampling, the potential
loss of component during the time between sampling and analysis should be studied and incorporated
in the uncertainty budget.
In general, for gas in pressure receptacles, the internal composition is relatively uniform and constant.
For gases in pipelines, the purpose and controls required dictate the type of sampling used. The design
of a sampling plan should consider whether the objectives of sampling are to:
— determine the instantaneous gaseous composition;
— determine an average composition over a specified time interval;
— establish changes in concentration by repeated sampling over a specified time;
— pass continuous samples into the analyser to measure both limit and average composition.
A flow chart detailing the gas sampling classification is shown in Figure 2.
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ISO 19230:2020(E)
Figure 2 — Gas sampling classification
5.2 Sampling classification of liquefied gas
When sampling liquefied gases, a representative sample is obtained by sampling from the liquid phase,
however, it can also occasionally be necessary to sample the vapour phase.
Sampling from the liquid phase is further subdivided into sampling in liquid form or sampling after
evaporation. The method of sampling used is normally determined by a review of the physical
properties of the liquefied gas such as vapour pressure, etc. Generally, high pressure liquefied gases
require evaporation whereas low pressure liquefied gases may be sampled in liquid phase.
For the liquefied gas sampling classification, see Figure 3 which details the sampling methods that
should be used. Then, follow 5.1 to determine the specific sampling type.
Figure 3 — Liquefied gas sampling classification
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ISO 19230:2020(E)
6 Technical specifications
6.1 Overview
For gas sampling, attention should be paid to but not limited to the following technical aspects in order
to collect sufficient representative sample.
6.2 General considerations for gas sampling
6.2.1 Adsorption, reaction and permeation of sampling system
Such problems can be minimized by choosing sampling devices of suitable materials (see Clause 8 for
details).
However, some slight adsorption is difficult to overcome. In this case, the sampling system should be
heated or continuously purged for a long period of time. Quality assessment of the sampling system
should be carried out according to 9.2. The adsorption shall be considered in the uncertainty budget.
6.2.2 Leaks and atmospheric diffusion in the sampling system
Leaks in the sampling system not only result in a loss of gas from the system but also allow air to diffuse
into the system (the partial pressure of the component determines the direction of the diffusion)
thereby affecting the composition of the sample.
The sampling system should be leak tested (see 6.2.3) prior to use to ensure the sample will not be
contaminated, the composition changed, or hazardous conditions created by the ingress of air.
Furthermore, the back-diffusion of air into gas venting lines should be avoided by, for example, using
longer venting lines.
6.2.3 Leak testing of the sampling system
All connections and welds shall be tested prior to fi
...
DRAFT INTERNATIONAL STANDARD
ISO/DIS 19230
ISO/TC 158 Secretariat: NEN
Voting begins on: Voting terminates on:
2020-01-15 2020-04-08
Gas analysis — Sampling guidelines
Analyse des gaz — Lignes directrices pour le prélèvement des échantillons
ICS: 71.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 19230:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020
---------------------- Page: 1 ----------------------
ISO/DIS 19230:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/DIS 19230:2020 (E)
Contents
Foreword . v
Introduction. vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling plan . 5
5 Sampling classification . 6
5.1 Sampling classification of gases . 6
5.2 Sampling classification of liquified gas . 7
6 Technical specifications . 8
6.1 Overview . 8
6.2 General considerations for gas sampling . 8
6.2.1 Adsorption, reaction and permeation of sampling system . 8
6.2.2 Leaks and atmospheric diffusion in the sampling system . 8
6.2.3 Leak testing of the sampling system . 8
6.2.4 Purging of sampling system . 9
6.2.5 Homogeneity of gas . 12
6.2.6 Inert-gas purging . 12
6.3 Possible condensation during compressed gas sampling . 12
6.4 Main condensations for liquefied gas sampling . 13
6.5 Samples that are not feasible in containers or cannot be used for analysis directly . 13
7 Safety guidance in sampling . 13
7.1 Overview . 13
7.2 General recommendation . 13
7.3 Specific recommendation for sampling a certain substance . 14
8 Sampling devices. 14
8.1 General provision . 14
8.2 Sample container . 15
8.2.1 Sample container material . 15
8.2.2 Structure of sample container . 16
8.2.3 Volume of sample container . 19
8.3 Sample probe . 19
8.4 Pressure reducer and flow controller . 19
8.5 Sample pump . 20
8.6 Sample line . 20
8.6.1 Material of sample line . 20
8.6.2 Length and diameter of sample line . 20
8.7 Connecters and seals . 20
8.8 Cleaning and drying of the sampling device . 21
8.9 Connection of sampling devices . 21
9 Sampling . 21
9.1 Sampling method block diagram . 21
9.1.1 Overview . 21
9.1.2 Block diagram of compressed gas sampling method . 21
9.1.3 Block diagram of liquefied gas sampling method. 23
9.2 Quality assessment of the sampling system . 24
9.3 Sampling from the gaseous phase and sampling after evaporation of liquefied gas . 24
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ISO/DIS 19230:2020(E)
9.4 Direct sampling . 24
9.4.1 General provisions . 24
9.4.2 Direct sampling of gas in pressure receptacles . 25
9.4.3 Direct sampling of gas in pipelines . 25
9.5 Indirect sampling . 25
9.5.1 Indirect sampling of gas in pressure receptacles . 25
9.5.2 Indirect sampling of gas in pipelines . 26
9.5.3 Leakage test of sample container . 26
9.5.4 Storage of samples . 26
9.6 Sampling records . 27
Annex A (informative) Examples of estimation of the purging time and purging cycles for
sampling system . 28
Annex B (informative) Direct sampling for gas in pressure receptables . 30
Annex C (informative) Direct sampling of gas in pipelines . 33
Annex D (informative) Fill-empty sampling method . 35
Annex E (informative) Evacuated-container sampling . 37
Annex F (informative) Evacuated-system sampling . 41
Bibliography . 43
iv © ISO 2020 – All rights reserved
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ISO/DIS 19230:2020 (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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 158 Analysis of Gases.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/DIS 19230:2020(E)
Introduction
The determination of gas composition, impurity concentration and physical properties depends to a
large extent on sampling technique. The use of correct sampling techniques is an important safety and
quality critical step in gas analysis. The design, construction and selection of the sampling equipment to
avoid hazardous situations and sampling errors are important and directly influence the results
obtained. Any slight carelessness, in exactitude or mistake will seriously influence safety and the
results obtained.
Gaseous products are stored and transported in pressure receptacles in the form of compressed or
liquefied gas or through gas pipelines. The sampling methods used differ depending upon the package,
composition and delivery methods.
This document provides technical guidelines for the sampling of gases in pressure receptacles and
pipelines for analytical purposes.
vi © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/DIS 19230:2020 (E)
Gas Analysis— Sampling Guidelines
1 Scope
This document gives the basic definitions of terms and general provisions relating to sampling for
gas analysis, including sampling devices, sampling methods, sampling technical considerations, and
sampling safety.
This document applies to both direct and indirect sampling of gas in pressure receptacles and
pipelines, including pure gases and gas mixtures. Compressed and liquefied gases are both
considered.
This document applies to the sampling of processed gases and does not involve gas treatment
processes.
The sampling procedures specified are not intended for the sampling of special products which are the
subject of other International Standards, such as liquefied petroleum gases (ISO 4257) and gaseous
natural gases (ISO 10715).
Warning — The use of this document may involve a number of hazards. This document does
not specify all the safety issues associated with the use of the standard. Users of this
document are responsible for establishing measures to ensure safety whilst gas sampling. All
sampling activities should comply with national and local safety regulations.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 3165, Sampling of chemical products for industrial use — Safety in sampling
ISO 16664, Gas analysis — Handling of calibration gases and gas mixture — Guidelines
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
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3.1
gas
all materials which are present completely in gaseous form at a temperature of 20 ° C under the
absolute pressure of 0,1013 MPa
Note 1 to entry: The materials here include single mediums and mixtures.
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3.2
compressed gas
gas which, when packaged under pressure for transport, is entirely gaseous at all temperatures
above − 50 °C
Note 1 to entry: This category includes all gases with a critical temperature less than or equal to − 50 °C.
[SOURCE: ISO 10286:2015, 705]
3.3
liquified gas
gas which, when packaged under pressure for transport, is partially liquid at temperatures
above − 50 °C
[SOURCE: ISO 10286:2015, 706]
3.4
high pressure liquefied gas
gas with a critical temperature between − 50 °C and + 65 °C
[SOURCE: ISO 10286:2015, 708]
3.5
low pressure liquefied gas
gas with a critical temperature above + 65 °C
[SOURCE: ISO 10286:2015, 707]
3.6
toxic gas
gas which is known to be so toxic or corrosive to humans to pose a health hazard or which is presumed
to be toxic or corrosive to humans because it has a LC50 value for acute toxicity equal to or less than
3
5000 ml/m (ppm)
Note 1 to entry: Other risks such as tissue corrosiveness are sometimes associated.
[SOURCE: ISO 10286:2015, 716]
3.7
gas in pressure receptacles
gas stored in cylinders, tube, pressure drums, tanks and other pressure receptacles, and no fresh gas
replenished into the receptacles
3.8
gas in pipelines
gas delivered in pipelines during the production process
3.9
sampling device
components that comprise the sampling system mainly include sample lines, pressure
regulators/reducers, flow controllers, connectors and sample containers
3.10
sampling system
gas transmission and control system constructed by gas storage container or sample point of gas in
pipelines and various sampling devices
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3.11
representative sample
a sample assumed to have the same composition as the material sampled when the latter is considered
as a homogeneous whole
[SOURCE: ISO 6206:1979, 3.1.4]
3.12
direct sampling
sampling in situations where there is a direct connection between the gas to be sampled and the
analytical unit
[SOURCE: ISO 10715:1997, 2.1]
3.13
indirect sampling
sampling in situation where there is no direct connection between the gas to be sampled and the
analytical unit
[SOURCE: ISO 10715:1997, 2.7]
3.14
sampling plan
the planned procedure of selection, withdrawal and preparation of a sample or samples from a lot to
yield the required knowledge of the characteristic(s) from the final sample so that a decision can be
made regarding the lot
[SOURCE: ISO 6206:1979, 3.1.5]
3.15
spot sampling
indirect sampling from a specific part of the stream of material with a certain volume at a specific time
3.16
incremental sampling
indirect sampling by collecting a series of spot samples into a combined sample
3.17
continuous sampling
direct sampling taken continuously from a stream of material with a constant flow rate in a certain
period of time
3.18
intermittent sampling
direct sampling from a stream of material with predetermined intervals
3.19
ullage/outage
the space in the container not occupied by the material, or the distance between the material surface
and a fixed reference point at the top of the container
NOTE 1 to entry: This volume allows room for expansion.
[SOURCE: ISO 6206:1979, 3.3.14]
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3.20
sampling error
that part of the total estimation error of a characteristic due to known and acceptable deficiencies in the
sampling plan
[SOURCE: ISO 6206:1979, 3.4.10]
3.21
incremental sampler
a sampler which accumulates a series of spot samples into one composite sample
[SOURCE: ISO 10715:1997, 2.6]
3.22
low-pressure gas
gases with a pressure between 0 and 0,2 MPa at sampling temperature
NOTE 1 to entry: Except for special provisions, all pressures mentioned in this standard are gauge pressures.
3.23
high-pressure gas
gases with a pressure exceeding 0,2 MPa at sampling temperature
3.24
lag time
time taken for a representative sample to enter the instrument
[SOURCE: ISO 11042-2:1996, 3.5.1.1]
3.25
sample container
a container for collecting the gas sample when indirect sampling is necessary
[SOURCE: ISO 10715:1997, 2.14]
3.26
sample line
conduit to transfer a sample of gas from the sample place to the analytical unit or sample container
Note 1 to entry: Another word used for sample line is transfer line.
[SOURCE: ISO 14532:2014, 2.3.2.5]
3.27
sample probe
device inserted into the gas pipelines so that a representative sample of the flowing gas can be taken.
The sample probe will have a conduit to convey the sample from the flowing gas to a point external to
the pipeline
[SOURCE:ISO 14532:2014,2.3.2.6]
3.28
sampling point
a point in the gas stream where a representative sample can be collected
[SOURCE: ISO 10715:1997, 2.17]
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3.29
filling ratio
ratio of the mass of gas to the mass of water at 15 °C that would fill completely a pressure receptacle
fitted ready for use
Note 1 to entry: Synonyms are filling factor and filling degree, often expressed in kg/l or similar.
[SOURCE: ISO 10286:2015, 747]
3.30
continuous purging method
purging method by continually purging the sampling system with sample gases
3.31
fill-empty cycle purging method
purging method by sequentially filling and emptying the sampling system repeatedly with the gas to be
sampled
3.32
evacuation-gas purging cycles
purging method by evacuating the sampling system
3.33
sampling from the gaseous phase
sampling from the gaseous phase of the liquefied gas
3.34
sampling from the liquid phase
sampling from the liquid phase of the liquefied gas
3.35
sampling in liquid form
the process that takes a sample in liquid form directly from the liquid phase of the liquefied gas
3.36
sampling after evaporation
the process that takes a sample in gaseous form by vaporizing the sample from the liquid phase of the
liquefied gas
3.37
liquid valve
a device fitted to an analyser for the direct sampling of liquefied gas in liquid form, which can keep the
liquefied gas to be collected in completely liquid phase
4 Sampling plan
A feasible and complete sampling plan should be developed before sampling.
For a sampling plan, first determine the sampling type (clause 5), then consider techniques of sampling
(clause 6), to determine the appropriate sampling process (clause 9) and sampling devices (clause 8)
and sampling safety (clause 7), and then sampling (clause 9).
The scheme for sampling plan is shown in Figure 1.
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Figure 1 —Scheme of sampling plan
5 Sampling classification
5.1 Sampling classification of gases
In this document, the sampling classification is based on whether the gas is connected to the analyser.
In addition, the sampling methods vary among different gas packaging, storage methods and sampling
purposes.
Direct sampling, if possible, is strongly recommended. In the case of indirect sampling, the potential loss
of component during the time between sampling and analysis should be studied and incorporated in the
uncertainty budget.
In general, for gas in pressure receptacles the internal composition is relatively uniform and constant.
For gases in pipelines the purpose and controls required dictate the type of sampling used. The design
of a sampling plan should consider whether the objectives of sampling are to:
• Determine the instantaneous gaseous composition
• Determine an average composition over a specified time interval
• Establish changes in concentration by repeated sampling over a specified time
• Pass continuous samples into the analyser to measure both limit and average composition
A flow chart detailing the gas sampling classification is shown in Figure 2.
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Figure 2 — Gas sampling classification
5.2 Sampling classification of liquified gas
When sampling liquefied gases, a representative sample is obtained by sampling from the liquid phase,
however occasionally it may also be necessary to sample the vapour phase, e.g. the gas phase
composition is frequently required in the preparation of calibration gas mixtures.
Sampling from the liquid phase is further sub-divided into sampling in liquid form or sampling after
evaporation. The method of sampling used is normally determined by a review of the physical
properties of the liquefied gas such as vapour pressure etc. Generally low temperature liquefied gases
and high pressure liquefied gases require evaporation whereas low pressure liquefied gases may be
sampled in liquid phase.
For the liquefied gas sampling classification see Figure 3 which details the sampling methods that
should be used, then follow 5.1 to determine the specific sampling type.
Liquefied gas sampling
Sampling from the liquid phase
Sampling from the gaseous phase
Sampling in liquid form Sampling after evaporation
Figure 3 — Liquified gas sampling classification
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6 Technical specifications
6.1 Overview
For gas sampling, attention should be paid to but not limited to the following considerations to collect
sufficient representative sample.
6.2 General considerations for gas sampling
6.2.1 Adsorption, reaction and permeation of sampling system
Such problems can be minimized by choosing sampling devices of suitable materials (see clause 8 for
details).
However, some slight adsorption is difficult to overcome. In this case, the sampling system should be
heated or continuously purged for a long period of time, and quality assessment of the sampling system
should be carried out according to 9.2. The adsorption shall be considered in the uncertainty budget.
6.2.2 Leaks and atmospheric diffusion in the sampling system
Leaks in the sampling system not only result in a loss of gas from the system but also allow air to diffuse
into the system (the partial pressure of the component determines the direction of the diffusion)
thereby affecting the composition of the sample.
The sampling system should be leak tested (see 6.2.3) prior to use to ensure the sample will not be
contaminated, the composition changed, or hazardous conditions created by the ingress of air.
Furthermore, the back-diffusion of air into gas venting lines should be avoided by, for example, using
longer venting lines.
6.2.3 Leak testing of the sampling system
All connections and welds shall be tested prior to first use. During subsequent re-use of the sampling
system re-connected parts should be retested for leaks. Other parts of the system should be regularly
retested, this is particularly important for corrosive gases. When sampling toxic gases leak testing shall
be performed before each use of the sampling system. The integrity of the sampling containers and their
connection with the sampling system should also be tested.
The following test methods can be used:
a) Pressurization of the system, followed by monitoring of the static pressure with respect to time.
A pressure drop indicates a leak.
b) Evacuation of the system and monitoring the vacuum achieved. A deterioration in the vacuum
resulting in an increase in pressure indicates a leak.
c) Pressurize the system and check all connections with a leak detection solution. Following the
use of leak detection solution, the system should be purged out to ensure dryness prior to use.
d) Use of a leak detector (e.g. mass spectrometry, where the system is filled with helium and the
presence of helium outside the system is detected with the mass spectrometer).
The correct selection of a leak detection method depends upon the system requirements. For example,
leak detection solution may not detect small leaks, however,
...
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