Expression of performance of sample handling systems for process analyzers

Specifies the tests which should be carried out to determine the functional performance of sample handling systems. In addition, specifies the information to be provided by the manufacturers and users of such systems. Applies to systems handling of gaseous or liquid samples for process analysers.

Angabe zum Betriebsverhalten von Probenhandlungssystemen für Prozeßanalysengeräte

Expression des qualités de fonctionnement des systèmes de manipulation d'échantillon pour analyseurs de processus

Spécifie les essais qui doivent être effectués pour déterminer les qualités de fonctionnement d'un système de manipulation d'échantillon ainsi que les informations qui doivent être fournies par les utilisateurs et les constructeurs de tels systèmes. S'applique aux systèmes de manipulation d'échantillons liquides ou gazeux.

Expression of performance of sample handling systems for process analyzers (IEC 61115:1992)

General Information

Status
Published
Publication Date
11-Oct-1993
Current Stage
6060 - Document made available
Start Date
12-Oct-1993
Completion Date
12-Oct-1993

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SLOVENSKI STANDARD
SIST EN 61115:1998
01-november-1998
Expression of performance of sample handling systems for process analyzers
(IEC 61115:1992)
Expression of performance of sample handling systems for process analyzers
Angabe zum Betriebsverhalten von Probenhandlungssystemen für
Prozeßanalysengeräte

Expression des qualités de fonctionnement des systèmes de manipulation d'échantillon

pour analyseurs de processus
Ta slovenski standard je istoveten z: EN 61115:1993
ICS:
19.020 Preskuševalni pogoji in Test conditions and
postopki na splošno procedures in general
SIST EN 61115:1998 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
NORME CEI
INTERNATIONALE IEC
1115
INTERNATIONAL
Première
édition
STANDARD
First edition
1992-03
Expression des qualités de fonctionnement
des systèmes de manipulation d'échantillon
pour analyseurs de processus
Expression of performance of sample
handling systems for process analyzers
© CEI 1992 Droits de reproduction réservés — Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized

utilisée sous quelque forme que ce soit et par aucun procédé, in any form or by any means, electronic or mechanical,

électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission

microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher

Bureau central de la Commission Electrotechnique Inte rnationale 3, rue de Varembé Genève Suisse

Commission Electrotechnique Internationale CODE PRIX
International Electrotechnical Commission PRICE CODE
IEC
MemayHapoAHae 3netcrpoTexHH4eclan HOMHCCHH
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 2 ----------------------
IEC 1115©IEC — 3 —
CONTENTS
Page
FOREWORD 5
INTRODUCTION 7
Clause
1. Scope and object 9
1.1 Scope 9
11
1.2 Object
11
2 Normative references
13
2.1 IEC standards
13
2.2 ISO standards
13
3 Definitions
13
3.1 General definitions
rtation and storage 25
3.2 Terms related to conditions of operation, transpo
rformance of sample handling
3.3 Terms related to the specification of the pe
27
systems and sample handling system components
37
4 Procedures for statements
39
Statements concerning the requirements for a sample handling system (user)
4.1
4.2 Statements concerning the requirements for a sample handling system
(manufacturer of process analyzer) 41
4.3 Statements concerning sample handling system components (manufacturer
43 of sample handling system components)
Statements concerning sample handling systems (manufacturer of sample
4.4
43
handling systems)
45
rformance characteristics 4.5 Statements on special pe
Annexes
49
Purpose, functions and properties of sample handling systems A
rt 59
B Operating groups and limit ranges of operation, storage and transpo
65
C Verification of time constants of a measuring system for process analysis
67
D Index of definitions
71
E Bibliography
---------------------- Page: 3 ----------------------
IEC1115©IEC - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
EXPRESSION OF PERFORMANCE OF
SAMPLE HANDLING SYSTEMS
FOR PROCESS ANALYZERS
FOREWORD

1) The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on

which all the National Committees having a special interest therein are represented, express, as nearly as

possible, an international consensus of opinion on the subjects dealt with.

They have the form of recommendations for international use and they are accepted by the National

Committees in that sense.

3) In order to promote international unification, the IEC expresses the wish that all National Committees

should adopt the text of the IEC recommendation for their national rules in so far as national conditions will

the lEC recommendation and the corresponding national rules should, as
permit. Any divergence between
far as possible, be clearly indicated in the latter.
This International Standard has been prepared by Sub-Committee 66D: Analyzing
equipment, of IEC Technical Committee No. 66: Electrical and electronic test and
measuring instruments, systems and accessories.
The text of this standard is based on the following documents:
DIS Report on Voting
66D(CO)12 66 D(CO)15

Full information on the voting for the approval of this standard can be found in the Voting

Report indicated in the above table.
Annexes A, B and C are normative and annexes D and E are informative.
In this standard, the following print types are used:
requirements and definitions: in roman type;
NOTES: in smaller roman type;
- terms used throughout this standard which have been defined in clause 3: bold
roman type.
---------------------- Page: 4 ----------------------
— 7 —
IEC 1115©IEC
INTRODUCTION

Most process or environmental analyzers are designed to work within specified limits of

the properties of the sample fluid (e.g. pressure, dew-point) at the sample inlet as well as

the outlet [1,2]. Moreover, process analyzers may need auxiliary fluids or other utilities for

their correct function.

It is the purpose of a sample handling system to connect one or more process analyzers

with one or more source fluids and the environment, so that the requirements of the

analyzer are met, and so that it is possible for the analyzer to work properly over an

acceptable period of time with an economically justified amount of maintenance work.

(See annex A for the description of the purpose, functions and properties of sample

handling systems.)
Sample handling systems may fulfill the following functions [1]:
sample extraction;
sample transpo rt ;
sample conditioning;
exhaust stream disposal;
supply of utilities;
sample stream switching;
performance monitoring and control.

Some of the functions can be completely or partly fulfilled by components which are

integral parts of an analyzer or which are external to the sample handling system. For the

rt of the sample handling
purpose of this standard these components are not considered pa
system.

The design of a sample handling system depends on the properties of the source fluid, the

process analyzer, and the disposal points. Furthermore, the design depends on the proper-

ties required for the complete measuring device. Testing a sample handling system is very

impo rtant. Due to the variety of system configurations and requirements for a system,

many different test procedures are applied in practice, but in this standard only the test

procedures which are used in most cases are specified. User and manufacturer may agree

on additional test procedures, but these are not covered in this standard.
---------------------- Page: 5 ----------------------
IEC 1115© IEC — 9 —
EXPRESSION OF PERFORMANCE OF
SAMPLE HANDLING SYSTEMS
FOR PROCESS ANALYZERS
1 Scope and object
1.1 Scope

This International Standard specifies the tests which should be carried out to determine

ormance of sample handling systems. In addition it specifies the infor-
the functional pe rf
mation to be provided by the manufacturers and users of such systems.
It is applicable to:
a) systems handling gaseous or liquid samples for process analyzers used for any
ultimate purpose, e.g. process control, emission, ambient air monitoring, etc.;
b) complete systems and system components;

c) power supplies and instrumentation for providing and controlling other utilities

necessary for process analyzers or sample handling system components, only in so far

as they are a functional part of the system;
d) facilities for maintaining system performance;
ormance of the process analyzer if these are part of
e) facilities for maintaining the pe rf
the sample handling system and not the analyzer.
NOTES

This standard has been prepared in accordance with the general principles set out in IEC 359.

2 Requirements for general principles concerning quantities, units and symbols are given in ISO 1000

and recommendations for the use of their multiples and of certain other units in ISO 31.

1.1.1 Aspects excluded from scope
This standard does not cover:

- general aspects of process analyzers (see IEC 746 for electrochemical analyzers);

NOTE - An IEC standard is in preparation for gas analyzers.
electric safety requirements (see IEC 348);
---------------------- Page: 6 ----------------------
-11 -
IEC1115©IEC
safety aspects concerning explosive or toxic hazards;

- aspects concerning applications where regulations or legal metrology are involved,

such as atmospheric pollution. For such aspects more elaborate work going on inside

ISO such as ISO 6712 applies;
requirements for output signals (see IEC 381-1 and IEC 381-2);
influence of environmental conditions (see IEC 68).
1.1.2 Equipment excluded from scope
This standard does not apply to:
systems for handling solid samples;
equipment intended for use in explosive gas atmospheres (see IEC 79 parts 0 to
12).
1.2 Object
This standard is intended

- to specify and to unify the general aspects in the terminology and definitions related

to the functional performance of sample handling systems for process analyzers;

- to specify the tests which, in most cases, should be performed to determine the

ormance of sample handling systems;
functional pe rf
- to specify what information should be available for the manufacturer of sample

handling systems. This information may be provided by the user or the manufacturer of

process analyzers or by the manufacturer of sample handling system components;

- to specify what information should be available for the user of sample handling

systems.
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 ISO maintain

registers of currently valid International Standards.
---------------------- Page: 7 ----------------------
IEC1115©IEC - 13 --
2.1 IEC standards

IEC 359: 1987, Expression of the performance of electrical and electronic measuring

equipment.
2.2 ISO standards
ISO 31: Quantities and units - Parts 0 to 13.
SI units and recommendations for the use of their multiples and certain
ISO 1000: 1981,
other units.
NOTE - See annex E for informative references of ISO and IEC standards.
3 Definitions
3.1 General definitions

(See annex A and figures A.1 and A.2 for a description of sample handling systems.)

3.1.1 Process analyzer

An analytical instrument connected to a source fluid that automatically provides output

signals giving information in relation to a quantity of one or more components present in a

fluid mixture or in relation to physical or chemical properties of a fluid which depend on its

composition.

NOTE - For on-line or extractive process analyzers a sample stream is extracted from the source fluid and

analyzer the measurement is performed within the
transported to the analyzer. With an in-line or in situ
source fluid.
3.1.2 Sample handling system

A system which connects one or more process analyzers with the source fluid, disposal

points and utilities.
NOTES

1 A sample handling system may extract the required sample stream from one or more source fluids and

condition it in order to meet all the input requirements of the process analyzer so that an accurate measure-

ment of the properties under investigation is possible. The system may also ensure the appropriate

disposal of exhaust streams and the supply of utilities as necessary. Instrumentation for ensuring the

proper function of a sample handling system component or for facilitating maintenance work is considered

part of the sample handling system if it is a functional part of it.

2 See annex A and figures A.1 and A.2 for a description of sample handling systems.

3 Figure 1 gives a schematic example for the use of terms describing the functions of sample transport

and exhaust stream disposal.
3.1.3 Sample extraction
s of a sample handling system which extract the required sample
The function of those pa rt
stream from the source fluid.

NOTE - The sample stream should be extracted in such a way that it is truly representative of the source fluid.

---------------------- Page: 8 ----------------------
IEC1115©IEC - 15 -
3.1.3.1 Source fluid

The source fluid (gas or liquid) from which the sample stream is extracted and of which the

composition or properties are to be measured.
NOTES

1 The source fluid may flow through a process line or fill a volume. Ambient air may also be the source

fluid.

2 The source fluid and the sample fluid in the sample line may consist of a combination of the following

components:
components to be measured;
irrelevant components;
obstructive components;
interfering components.
3.1.3.2 Component to be measured

The component or group of components of which a quantity (e.g. concentration) is to be

measured by the process analyzer.
3.1.3.3 Property to be measured

The physical or chemical property which is to be measured by the analyzer and which

depends on the composition of the source fluid.
3.1.3.4 Irrelevant components

The components which are not to be measured and which do not affect the performance of

the analyzer or of the sample handling system.
3.1.3.5 Obstructive components

The components which adversely affect the performance of the analyzer or of sample

handling system components.
The effect may be:
- physical (e.g. by dirtying windows in optical analyzers), or
- chemical (e.g. by corrosion), or
- by causing unacceptable errors (e.g. bubbles in a liquid sample stream for a
photometer).
Obstructive components can be solid, liquid or gaseous.
Interfering components
3.1.3.6
The components which give rise to interference errors in the analyzer.
---------------------- Page: 9 ----------------------
IEC1115©IEC - 17 -
3.1.3.7 Sampling point
The point where the sample stream is extracted from the source fluid.

NOTE - It may be necessary to have a combination of sampling points at the inlet of a sample handling

system. The sample streams from different sampling points can be mixed or measured separately.

3.1.4 Sample transpo rt

The function of those pa rts of a sample handling system which transfer the sample fluid

from the sampling point to the inlet of the process analyzer.
3.1.4.1 Sample line

The connection from the sampling point(s) to the analyzer inlet in which a stream is

allowed to flow.

NOTE - Filters, coolers, pumps, flowmeters, etc. may be part of the sample line (see annex A, figure A.2).

3.1.4.2 Sample stream
The fluid stream in the sample line.
NOTES

1 Other streams may be branched off the sample stream (e.g. bypass streams) or be injected into it (e.g.

dilution streams).

The composition and the physical state of the fluid in the sample line shall be allowed to change only

in a predictable way.

3 The properties of the conditioned sample stream at the inlet of an analyzer have to meet the require-

ments of the analyzer.
3.1.4.3 Bypass stream
A fluid stream which is branched off the sample stream.
NOTES

1 It is frequently the purpose of bypass streams to reduce the delay time of the sample handling system.

2 The term "bypass stream" is also used for process lines. So the sample stream may be extracted from

a bypass stream of a process stream.
---------------------- Page: 10 ----------------------
IEC 1115 © IEC — 19 —
Exhaust stream
o o^
Possible sampling
points
Exhaust st ream
Sampling point o
Disposal points
Sample line
Sample stream
Exhaust stream
Process
analyzer
Bypass stream, exh aust stream
fEC 216192
Figure 1 - Schematic example for the use of terms describing the functions
of sample transpo rt and exhaust stream disposal
Sample conditioning
3.1.5

The function of those parts of a sample handling system which change the physical and/or

chemical properties of the sample stream to suit the process analyzer without changing

the composition unless this is done in a predictable way.
NOTES

1 In sample conditioning the sample stream is treated in a predictable way whereby obstructive and inter-

fering components are removed or converted as far as necessary.

2 The requirements the sample conditioning has to meet depend on the physical and chemical properties

of the source fluid as well as on the admissible inlet conditions of the process analyzer.

3.1.5.1 Conditioned sample fluid
The sample fluid suitably conditioned for the analysis.
3.1.6 Exhaust stream disposal
rts of a sample handling system which connect the outlet of the
The function of those pa

process analyzer or another point in the sample handling system with a disposal point.

NOTES

This function should be so realized that the requirements for the analyzer outlet or for other points in

the sample handling system are met as well as those for the disposal point.

2 The instrumentation for exhaust stream disposal depends very much on the physical state (liquid or

gaseous) of the exhaust stream. One sample handling system may give rise to exhaust streams of different

physical states.
---------------------- Page: 11 ----------------------
- 21 -
IEC 1115© IEC
3.1.6.1 Disposal point
The point at which exhaust streams leave the complete system.

NOTE - A disposal point can be in the open air, the inlet to a process line or volume, or the inlet to a

disposal system external to the sample handling system.
3.1.6.2 Exhaust stream

A fluid stream from the process analyzer outlet or from another point in the sample

handling system to a disposal point.
3.1.7 Supply of utilities

The function of those pa rts of a sample handling system which supply the process

analyzer or components of the sample handling system with utilities (e.g. pressurized air,

water for cooling, steam for heating, test fluids for calibration, electric power).

3.1.7.1 Calibration fluid (Test fluid)
A fluid with known quantities or properties to be measured.
Sample stream switching
3.1.8

The function of those parts of a sample handling system which sequentially connect the

process analyzer automatically or manually to different sampling points.

NOTE - The electronics or pneumatics which control valves used for sample stream switching are con-

sidered part of the sample stream switching if they are a functional part of the sample handling system.

Performance monitoring and control
3.1.9
rformance of the
The function of those parts of a sample handling system by which the pe

system or the process analyzer can be checked, maintained or re-established either auto-

matically or manually.
NOTES

1 Sample handling system components as well as analyzers may include elements which serve the

performance monitoring and control.

2 Equipment which serves the maintainability of the sample handling system or of the analyzer (e.g.

ormance

valves for draining off condensate or facilities for re-calibration) are considered part of the pe rf

monitoring and control (see example in Figure A.2 of annex A).

3 Equipment in which signals from measuring instruments or sensors or any sample handling system

components are processed for maintenance or reliability reasons and which are an integral part of the

sample handling system are considered part of the performance monitoring and control.

---------------------- Page: 12 ----------------------
IEC 1115©IEC - 23 -
3.1.10 Sample handling system component

Any device which is used for performing the functions of a sample handling system.

3.1.10.1 Filter

A device which removes solid particles and/or liquid droplets from a fluid stream.

NOTE - Filtering may be done mechanically, by coalescing or with electric precipitators.

3.1.10.2 Separator
A device in which one phase is separated from another.
3.1.10.3 Absorber

A device which separates components from a fluid stream by sorption, ion exchange or

chemical reaction.
3.1.10.4 Converter

A device in which the chemical constitution of one or more components in a stream is

changed.

NOTE - A converter may convert an obstructive or interfering component into an irrelevant one or a

component to be measured into a measurable one.
3.1.10.5 Scrubber

A device in which a gaseous stream is passed through a liquid for washing out solids or

droplets or gaseous components.
3.1.10.6 Cooler (Heater)
A device in which one or more sample streams are cooled (heated).
3.1.10.7 Pump
A device for actively transferring fluids.
Phase exchanger
3.1.10.8

A device in which a component or group of components to be measured and present in a

fluid of one physical state is at least partly transferred into a fluid of a different physical

state.

NOTE - A device for transferring a component or group of components from a liquid into a gas stream is

frequently called a stripper.
3.1.10.9 Vaporizer
A device for totally converting a liquid into a gas.
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IEC1115©IEC - 25 -
3.1.10.10 Sampling probe

A device to be inserted into a process stream or volume for the purpose of extracting a

sample stream.

NOTE - A sampling probe may comprise parts for sample conditioning (e.g. a filter).

Performance
3.1.11

The degree to which the intended functions of a sample handling system or of a sample

handling system component are accomplished.
3.1.11.1 Performance characteristic

One of the quantities assigned to a sample handling system or a sample handling system

component in order to define by values, tolerances, ranges, etc. the performance of the

system or component.
3.1.12
Influence quantity

Any quantity, generally external to a sample handling system or sample handling system

component which may affect the performance of the system or component. (Examples:

ambient temperature, ambient pressure, corrosive atmosphere.)
3.1.13 Specified range, specified value

The range (value) of a quantity to be measured, observed, supplied or set where a sample

handling system or system component works within the limits of performance charac-

teristics as stated by the manufacturer.
Terms related to conditions of operation, transportation and storage
3.2
3.2.1 Specified operating conditions
The whole of
effective ranges and values of performance characteristics;
specified ranges of use;

specified ranges and values for source fluid conditions at the sampling point(s) (see

4.1.1);

- specified ranges and values for exhaust stream conditions at the disposal point(s)

(see 4.1.2) and
- specified ranges and values for utilities (see 4.1.3)
within which the sample handling system is specified.
3.2.1.1 Specified range of use (refer to annex B)

The range of values for an influence quantity within which the sample handling system or

system component works within the limits of pe rformance characteristics as stated by the

manufacturer.
---------------------- Page: 14 ----------------------
- 27 -
IEC1115©lEC
(refer to annex B)
3.2.2 Reference conditions

A set of values with tolerances or restricted ranges of influence quantities specified for

making comparison tests.
(refer to annex B)
3.2.3 Limit conditions of operation
ormance characteristics
The whole of the ranges of values for influence quantities and pe

(beyond the specified ranges of use and effective ranges respectively) within which the

apparatus can function without resulting in damage or degradation of performance when it

is afterwards operated under rated operating conditions.
Limit conditions of storage and transport (refer to annex B)
3.2.4

All the conditions of temperature, humidity, air pressure, vibration, shock, etc. within which

an apparatus may be stored or transported in an inoperative condition, without causing

damage or degradation of performance when the apparatus is afterwards operated under

specified operating conditions.

3.3 Terms related to the specification of the performance of sample handling systems

and sample handling system components

Tests shall be performed with the sample handling system or the sample handling system

component ready for use, after start-up time (if necessary) and after performing adjust-

ments according to the manufacturer's instructions.
(see figure 2)
3.3.1 Time constants
For test procedures see 4.5.1.
3.3.1.1 Delay time (T10)

The time interval from the instant a step change occurs in the concentration or property to

be measured at the inlet, to the instant when the change in the analyzer inlet passes and

remains beyond 10 % of its steady-state difference, with the sample flow kept at its

specified value.

NOTE - In sample handling systems the delay time frequently depends on the time needed to transport

the sample from the sampling point to the analyzer inlet. This sample transpo rt time can be determined with

an analyzer with small time constants together with suitable test fluid.
3.3.1.2 Rise (Fall) time (Tr, Tf)

The time interval within which the concentration or property to be measured passes from

10 % to (and remains beyond) 90 % of its steady-state difference at the analyzer inlet after

a step increase (decrease) in the concentration or property to be measured at the inlet,

with the sample flow kept at its specified value.
3.3.1.3 90 %time (T90)
The sum of the delay time and the rise or fall time, whichever is larger.
---------------------- Page: 15 ----------------------
IEC 1115 © IEC
— 29 —
Too
T^o ,
10%
90 %
100 %
IEC 217192
Figure 2 - Time constants and relation between T10 , Tr (Tf T90
) and
3.3.1.4 Cycle time

For sample handling systems equipped with devices for automatic sample stream switch-

ing, the cycle time is the time between two consecutive starts of the sampling period on

the sample stream from the same sampling point.
NOTES
1 The cycle time is not necessarily identical for all sampling points.

2 If the time between two consecutive starts on any sample is less than the 90 % time of that part of the

system between switching valve and process analyzer, special precautions are necessary for the interpre-

tation of the output signal of the analyzer.

For sample handling systems with discontinuously working sample extraction, sample

transport

or sample conditioning, the cycle time is the time between two consecutive starts

of these operations.
3.3.1.5 Time constants of sample handling systems with automatic sample stream
switching (see 4.5.2)

For sample handling systems with automatic sample stream switching, the time constants

for sampling on one sample stream depend on:
---------------------- Page: 16 ----------------------
IEC1115©IEC -31 -

- the time constants of the system between sampling point and switching valve, and

- the time constants of the system between switching valve and process analyzer.

Additionally these constants depend on the time-lag between the occurrence of a concen-

tration change at the sampling point and the start of the sampling period on the sample

stream from that sampling point.
3.3.1.6 Start-up time

The time interval between switching on the power and other utilities, and the beginning of

the sample handling system or system component working within the stated limits of

performance characteristics.
3.3.2 Leak rate (see 4.5.3)

The amount of unwanted fluid which enters (e.g. ambient air) or leaves the sample

handling system or system component per time unit with the system or component within

its specified range of operating pressure.
Maintenance requirements (see 4.5.4)
3.3.3

The work which foreseeably has to be done to maintain the specified operating conditions

of a sample handling system or system component. This may also include the
re-calibration procedure.
3.3.4 Status signal

Externally available binary signal which describes the status of a sample handling system

component or of a sampling system.
3.3.5 Special performance characteristics

NOTE - In sample conditioning the composition of the sample fluid may change, and the changes may

affect the measurement [1, 2, 4, 5, 6]. Their effect may be corrected by calculation or by compensation by

appropriate calibration procedures, but errors specific for sample handling systems can remain. Exclusively

absolute errors are dealt with in the following.
Volume effect (Enrichment effect)
3.3.5.1

The effect on the concentration to be measured which results from removing components

from the sample stream so that the concentration of the components to be measured is

increased in the conditioned sample fluid.
NOTES

A typical example for increasing the concentration of the component to be measured is the removal of

vapours for dry analysis.

2 The volume effect depends on the concentration of the components to be removed in the source fluid

and in the conditioned sample fluid (if the removal is not complete). If these concentrations are known the

volume effect can be calculated [6] using the formula:
---------------------- Page: 17 ----------------------
IEC 1115 © IEC - 33 -
(1)
where
Cm is the concentration of the component to be measured in the source fluid,

C'm is the concentration to be measured in the conditioned sample fluid (measured by the process

analyzer),
Cr is the concentration of the components to be removed in the source fluid, and

C'r is the concentration of these components remaining in the conditioned sample fluid,

whereby the concentrations are given as volume fractions.

If necessary the correction for the volume effect can be based on estimates for the mean concentrations of

Cr and C'r
3.3.5.2 Volume error (Enrichment error)

The difference between the concentration measured by the process analyzer in the condi-

tioned sample fluid (possibly corrected by using formula (1)) and the conce
...

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