SIST ISO 7935:1996

Stationary source emissions -- Determination of the mass concentration of sulfur dioxide -- Performance characteristics of automated measuring methods

Applies to extractive and non-extractive automated sulfur dioxide measuring methods. Specifies 4 main performance characteristics: detection limit, effect of interfering substances, response time, integral performance. Annex A describes determination of the main performance characteristics, annex B lists additional performance characteristics.

Émissions de sources fixes -- Détermination de la concentration en masse de dioxyde de soufre -- Caractéristiques de performance des méthodes de mesurage automatiques

Emisije nepremičnih virov - Ugotavljanje masne koncentracije žveplovega dioksida - Delovne karakteristike avtomatskih merilnih metod

General Information

• Status: Published
• Publication Date: 30-Sep-1996
• ICS: 13.040.40 - Stationary source emissions
• Technical Committee: KAZ - Air quality
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Oct-1996
• Due Date: 01-Oct-1996
• Completion Date: 01-Oct-1996
• Ref Project: ISO 7935:1992 - Stationary source emissions — Determination of the mass concentration of sulfur dioxide — Performance characteristics of automated measuring methods

Standards Content (Sample)

INTERNATIONAL
ISO
STANDARD
7935
First edition
19924 2-I 5
Stationary Source emissions -
Determination of the mass concentration
of Sulfur dioxide - Performance
characteristics of automated measuring
methods
Emissions de sources fixes
- Determination de Ia concen tra tion en
masse de dioxyde de soufre
- Caractbristiques de Performance des
methodes de mesurage automa tiques
Reference number
ISO 79357 992(E)

---------------------- Page: 1 ----------------------
ISO 7935:1992(E)
Contents
Page
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 2
3 Definitions ,.,.,.~. 2
4 Description of the automated measuring Systems . . . . . . . . . . . . . . . . . . 3
5 Numerital values of Performance characteristics and their
applica bility .,.,,.*.*. 4
Annexes
A Determination of main Performance characteristics of automated
measuring Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
B Additional Performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.~. 11
C Bibliography
0 ISO 1992
All rights reserved. No patt of this publication may be reproduced or utilized in any ferm or
by any means, electronie or mechanical, including photocopying and microfilm, without per-
mission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii

---------------------- Page: 2 ----------------------
ISO 7935: 1992(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. Esch 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.
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 ISO 7935 was prepared by Technical Committee
lSO/TC 146, Air quality, Sub-Committee SC 1, Stationary Source
emissions.
Annex A forms an integral part of this Internationa Standard. Annexes B
and C are for information only.

---------------------- Page: 3 ----------------------
ISO 7935:1992(E)
Introduction
Sulfur dioxide tan arise in considerable quantities from combustion of
fossil fuels used for energy generation, industrial activities processing
Sulfur or Sulfur containing material, and from combustion of Sulfur con-
taining waste. The waste gas from these processes, containing Sulfur di-
Oxide, is usually discharged into the ambient atmosphere, via a duct or a
chimney.
For evaluating the mass concentration of Sulfur dioxide present in the
waste gas of stationary Source emissions, a number of highly developed
methods of integrated sampling and subsequent determination by chemi-
cal analysis and automated measuring Systems are available. Considerable
experience exists on their application under plant conditions. One of these
methods is standardized as ISO 7934.
ISO 7934 is used for example in comparative measurements, where the
automated measuring methods are involved. The automated technique is
capable of continuous measurement of the mass concentration of Sulfur
dioxide.
For methods where Performance characteristics are given, the values of
Performance characteristics are used to decide whether a method is suit-
able for a given measuring task (see ISO 6879:1983, clause 1). Values of
the main Performance characteristics of automated measuring Systems,
capable of determining the mass concentration of Sulfur dioxide present
in waste gas stationary emission sources, are given in clause 5.
Additional Performance characteristics are given in informative annex B.
The procedure for evaluating the values of the Performance characteristics
listed in clause 5, is described in normative annex A.
IV

---------------------- Page: 4 ----------------------
ISO 7935:1992(E)
INTERNATIONAL STANDARD
Staticpnary Source emissions - Determination of the
mass concentration of Sulfur dioxide - Performance
characteristics of automated measuring methods
NOTE 2 Although it is impossible to give precise testing
1 Scope
details, the requirements and testing principles are also ap-
plicable to non-extractive Systems.
This International Standard specifies a complete set
of values of Performance characteristics for auto-
mated measuring Systems for the continuous
Table 1 - Main Performance characteristics
measurement of the mass concentrations of Sulfur
dioxide in stationary Source emissions. Performance Numerital Test
characteristics value methods
(see
annex A)
NOTE 1 If the Performance characteristics of an auto-
mated measuring System are listed according to table 1, this
Detection Iimit 2 % '1 A.4.2.1 .l
ensures that the automated measuring System is reliable
and gives satisfactory continuous results.
Effect of interfering
+ 2 % 1) 2) A.4.2.1.2
substances
The set of data listed in table 1 refers to the perform-
Response time < 200 s 3) A.4.2.1.3
ante characteristics of measurement methods, in-
Integral Performance
~t: 2,5 % 1) 4) A.4.2.2
cluding all Steps from sampling to recording and, if
( SA >
necessary, storage of data.
1) Related to the upper limit of measurement.
2) The main interfering substances in the flue gas from
This International Standard is applicable to extractive
combustion plants are CO*, CO, NO, H,O and, in
and non-extractive automated Sulfur dioxide measur-
smaller concentrations, NO, and NH,. If the water va-
ing methods. For both methods it implies the appli-
pour is not removed from the flue gas of coal and waste
cability of Zero and calibration gas and the availability fired incinerators, HCI and HN may also interfere. In
special cases there may be other interfering substances
of comparable samples. The automated measuring
(e.g. cyanide).
System tan be calibrated with calibration gases, by
applying the manual method described in ISO 7934,
3) Assuming an integration time of 30 min.
or by applying an automated measuring System pre-
4) See 3.7.
viously verified according to this International Stan-
dard using a different principle of detection. The value
of the integral Performance (3.7) is determined by
using ISO 7934 or an automated measuring System
The facilities at which the values of the Performance
verified according to this International Standard with
characteristics given in table 1 have been verified ac-
a different principle of detection. At present, the range
cording to this International Standard in the appropri-
over which this specification applies is between
ate ranges are listed in table 2.
0 g/m3 to 0,l g/m3 and 0 g/m3 to 8 g/m3 (see table 2
for details).

---------------------- Page: 5 ----------------------
ISO 7935:1992(E)
3.5 comparative measurements: Measurements
Table 2 - Facilities and measuring ranges
that are performed in the Same chimney in the same
-
sampling plane for the same period of time.
Measuring range
g/m3 of SO2 1)
3.6 manual method: The test method defined in
ISO 7934 for the manual sampling and analysis 0%
Furnaces for hard coal O-l toO-8
stationary Source emissions containing Sulfur dioxide.
Furnaces for hard coal with
0 to 0,l
Stack gas desulfuration plant
Furnaces for brown coal 0 - 0,l to 0 - 3,0
3.7 integral Performance, SA: The integral perform-
Furnaces for heavy fuel oil 0 - 0,l to 0 - 5,0 ante is a measure of the working accuracy of the
AMS. lt is calculated according to the formula for
Refuse incinerator 0 - 0,4 to 0 - 1 ,o
Standard deviations.
Coke oven 0 to 1
Calcar with heavy fuel oil 0 to 5
The integral Performance is derived from the differ-
ence in the pairs of measured values of Sulfur dioxide
Sulfuric acid recovery plant 0 to 1
by the AMS under investigation, and by an ISO man-
I
ual method or a verified AMS of different measuring
1) Related to 101,3 kPa, 273 K and dry gas.
I
principle on the basis of a sufficient number of com-
1
parative measurements spread over the period of un-
attended Operation (see annex A).
2 Normative references
NOTES
The following Standards contain provisions which,
3 lt is not possible to determine the Standard deviation of
through reference in this text, constitute provisions
an AMS under repeatable working conditions because
of this International Standard. At the time of publi-
cation, the editions indicated were valid. All Standards
- commercially available calibration gas mixtures contain-
are subject to revision, and Parties to agreements
ing Sulfur dioxide do not have all the properties of actual
based on this International Standard are encouraged
waste gas and do not cover all possible influences;
to investigate the possibility of applying the most re-
cent editions of the Standards indicated below.
- the mass concentration of Sulfur dioxide in waste gas
Members of IEC and ISO maintain registers of cur-
usually varies with time;
rently valid International Standards.
- it is not possible to maintain the properties of a waste
gas present in the waste gas flue when it is transferred
ISO 6879:1983, Air quality - Performance character-
into a vessel.
istics and related concepts for air quality measuring
methods.
4 The reason that the integral Performance is defined as
a measure of the working accuracy, is that it contains, in
ISO 7934: 1989, Stationary Source emissions - De-
addition to random errors, all the effects of interfering sub-
termination o f the mass concentration of Sulfur diox-
stances, changes in temperature and power line as well as
- Hydrogen peroxide/barium perchlora te/Thorin
ide
zero drifts and span drifts. lt also includes the Standard de-
me thod.
viation of the ISO manual method or the verified AMS using
a different principle of detection, which tan be determined
separately and eliminated if necessary. Furthermore, it in-
3 Definitions
cludes the effects, for the different methods, of a different
response time to variations in the composition of the waste
For the purposes of this Internationa gas.
I Standard, the
following definitions apply.
The integral Performance defined in this subclause is an
upper limiting value for the AMS. Relevant systematic errors
3.1 automated measuring System (AMS): A com-
of the measured values of the ISO manual method, or the
plete System that may be attached to a chimney to
verified AMS using a different principle of detection, have
continuously measure and record the mass concen-
to be known and taken into account.
tration of Sulfur dioxide passing through the chimney.
3.2 analyser: Analytical part in an extractive AMS.
3.8 chimney: Stack or final exit duct on a stationary
process used for the dispersion of residual process
3.3 verified AMS: AMS previously verified in
gases.
ISO 7935.
3.4 calibration gas: A gas of known and reliable 3.9 mass concentration: The concentration of a
composition that may be used to check the response substance in an emission, expressed in milligrams per
of an AMS. cubic metre or grams per cubic metre.
2

---------------------- Page: 6 ----------------------
3.10 stationary Source emissions: Those waste
- an analytical part.
gases that have been emitted from a stationary plant
Certain extractive methods also include Sample di-
or process and are exhausted to a chimney for dis-
lution.
persion into the atmosphere.
The Sample probe is placed inside the duct containing
4 Description of the automated
The choice of locations may
gaseous effluents.
sometimes be difficult, since the measurement to be
measuring Systems
made needs to be representative and calibration
should be possible.
4.1 Introduction
The design of the Sample probe and the gas con-
There are two types of automated measuring sys-
ditioning System essentially depends on physico-
tems:
Chemical characteristics (composition of the gaseous
Phase, particle concentration, temperature, water
- extractive methods;
dew Point, etc.) of the effluents to be analysed and
the principle of the analyser used. Since particulate
- non-extractive methods, known as in-situ or
matter and humidity may influence the measurement,
Cross-duct measuring methods.
the line contains a particulate filter and a humidity
elimination device.
Examples of the components of these Systems are
given in figures 1 and 2.
In Order to limit Sulfur dioxide losses and inconsistent
readings, the line is frequently heated.
Using the extractive method, the representative gas
Sample is taken from the Stack with a sampling probe
The analytical detection methods most commonly
and conveyed to the analyser through the Sample line
used are absorption, using infrared or ultraviolet radi-
and Sample gas conditioning System. The values de-
ation, fluorescence, using ultraviolet radiation,
termined are often recorded or stored by means of
interferometry and conductometry.
electronie data processing.
4.3 Non-extractive methods
The non-extractive method does not require any
Sample processing. In addition, it takes into consider-
For in-situ or Cross-duct methods, an Optical device is
ation a larger part of the waste gas. Most of the
used which is positioned directly in the duct of
methods described in 4.2 and 4.3 are able to deter-
gaseous effluents. lt consists of two modules, one
mine Sulfur dioxide specifically. Methods which rely
being a radiation emittor, the other a receptor of the
on conductometry determine total Sulfur oxides.
radiation which has passed through the gases con-
taining Sulfur dioxide.
4.2 Extractive methods
Installation of these two modules, in relation to the
The extractive methods enable Separation of the
duct, depends on the apparatus used.
sampling and analysis Parts, thereby facilitating main-
tenance operations.
The Signals from the receptor are subsequently pro-
cessed, in Order to convert the data into concen-
The main Parts are
tration, expressed as V/V or in milligrams per cubic
metre.
- a Sample probe;
NOTE 5 When comparing the results from dry extractive
- a Sample line;
methods and non-extractive methods, it is necessary to
know the water content of the flue gases for correction of
- a gas conditioning System; the in-situ value to a value on a dry gas basis.

---------------------- Page: 7 ----------------------
ISO 7935:1992(E)
1 2 3 4 10
5 6 7 8 9
KeY
1 Gas sampling probe
2 Particulate filter
3 Heating jacket or heating bandage
4 Cooler with condensate-separator
5 Sampling pump
6 Filter
7 Needle valve
8 Flowmeter
9 Analyser
IO Recorder
11 Inlet for
a) calibration gas mixtures containing Sulfur dioxide
b) zero samples
i
Figure 1 - Example of the components for the extractive method
1
1 Absorption-Ce11 for calibration gas mixtures
2 Inlet for calibration gas mixtures
3 Optical receiver
4 Electronie module
5 Recorder
Figure 2 - Example of the components for the non-extractive method
4

---------------------- Page: 8 ----------------------
ISO 7935: 1992(E)
automated measuring System is handled and maintained
5 Numerital values of Performance
properly. Checks with calibration gas mixtures containing
characteristics and their applicability
Sulfur dioxide are carried out and the interfering effect of
changes in atmospheric pressure are taken into account.
When measured in accordance with the respective
methods given in annex A, the Performance charac- 8 The Performance characteristics given in tables 1 and
B.1 are based on many measurements carried out with
teristics shall meet the requirements given in table 1.
complete extractive measuring Systems under plant con-
Together with the measuring ranges from table2, the ditions using the non-dispersive infrared (NDIR), non-
dispersive ultraviolet (NDUV) and conductometric methods
values of table 1 show the state of the art of Source
and on results obtained with non-extractive methods. The
emission measurement of Sulfur dioxide.
value of the integral Performance was obtained on the basis
of 50 comparative measurements performed according to
ISO 7934.
NOTES
9 The response time, t G ZOO s, indicated in table
...

SLOVENSKI STANDARD
SIST ISO 7935:1996
01-oktober-1996
(PLVLMHQHSUHPLþQLKYLURY8JRWDYOMDQMHPDVQHNRQFHQWUDFLMHåYHSORYHJDGLRNVLGD
'HORYQHNDUDNWHULVWLNHDYWRPDWVNLKPHULOQLKPHWRG
Stationary source emissions -- Determination of the mass concentration of sulfur dioxide
-- Performance characteristics of automated measuring methods
Émissions de sources fixes -- Détermination de la concentration en masse de dioxyde de
soufre -- Caractéristiques de performance des méthodes de mesurage automatiques
Ta slovenski standard je istoveten z: ISO 7935:1992
ICS:
13.040.40 (PLVLMHQHSUHPLþQLKYLURY Stationary source emissions
SIST ISO 7935:1996 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST ISO 7935:1996

---------------------- Page: 2 ----------------------

SIST ISO 7935:1996
INTERNATIONAL
ISO
STANDARD
7935
First edition
19924 2-I 5
Stationary Source emissions -
Determination of the mass concentration
of Sulfur dioxide - Performance
characteristics of automated measuring
methods
Emissions de sources fixes
- Determination de Ia concen tra tion en
masse de dioxyde de soufre
- Caractbristiques de Performance des
methodes de mesurage automa tiques
Reference number
ISO 79357 992(E)

---------------------- Page: 3 ----------------------

SIST ISO 7935:1996
ISO 7935:1992(E)
Contents
Page
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 2
3 Definitions ,.,.,.~. 2
4 Description of the automated measuring Systems . . . . . . . . . . . . . . . . . . 3
5 Numerital values of Performance characteristics and their
applica bility .,.,,.*.*. 4
Annexes
A Determination of main Performance characteristics of automated
measuring Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
B Additional Performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.~. 11
C Bibliography
0 ISO 1992
All rights reserved. No patt of this publication may be reproduced or utilized in any ferm or
by any means, electronie or mechanical, including photocopying and microfilm, without per-
mission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii

---------------------- Page: 4 ----------------------

SIST ISO 7935:1996
ISO 7935: 1992(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. Esch 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.
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 ISO 7935 was prepared by Technical Committee
lSO/TC 146, Air quality, Sub-Committee SC 1, Stationary Source
emissions.
Annex A forms an integral part of this Internationa Standard. Annexes B
and C are for information only.

---------------------- Page: 5 ----------------------

SIST ISO 7935:1996
ISO 7935:1992(E)
Introduction
Sulfur dioxide tan arise in considerable quantities from combustion of
fossil fuels used for energy generation, industrial activities processing
Sulfur or Sulfur containing material, and from combustion of Sulfur con-
taining waste. The waste gas from these processes, containing Sulfur di-
Oxide, is usually discharged into the ambient atmosphere, via a duct or a
chimney.
For evaluating the mass concentration of Sulfur dioxide present in the
waste gas of stationary Source emissions, a number of highly developed
methods of integrated sampling and subsequent determination by chemi-
cal analysis and automated measuring Systems are available. Considerable
experience exists on their application under plant conditions. One of these
methods is standardized as ISO 7934.
ISO 7934 is used for example in comparative measurements, where the
automated measuring methods are involved. The automated technique is
capable of continuous measurement of the mass concentration of Sulfur
dioxide.
For methods where Performance characteristics are given, the values of
Performance characteristics are used to decide whether a method is suit-
able for a given measuring task (see ISO 6879:1983, clause 1). Values of
the main Performance characteristics of automated measuring Systems,
capable of determining the mass concentration of Sulfur dioxide present
in waste gas stationary emission sources, are given in clause 5.
Additional Performance characteristics are given in informative annex B.
The procedure for evaluating the values of the Performance characteristics
listed in clause 5, is described in normative annex A.
IV

---------------------- Page: 6 ----------------------

SIST ISO 7935:1996
ISO 7935:1992(E)
INTERNATIONAL STANDARD
Staticpnary Source emissions - Determination of the
mass concentration of Sulfur dioxide - Performance
characteristics of automated measuring methods
NOTE 2 Although it is impossible to give precise testing
1 Scope
details, the requirements and testing principles are also ap-
plicable to non-extractive Systems.
This International Standard specifies a complete set
of values of Performance characteristics for auto-
mated measuring Systems for the continuous
Table 1 - Main Performance characteristics
measurement of the mass concentrations of Sulfur
dioxide in stationary Source emissions. Performance Numerital Test
characteristics value methods
(see
annex A)
NOTE 1 If the Performance characteristics of an auto-
mated measuring System are listed according to table 1, this
Detection Iimit 2 % '1 A.4.2.1 .l
ensures that the automated measuring System is reliable
and gives satisfactory continuous results.
Effect of interfering
+ 2 % 1) 2) A.4.2.1.2
substances
The set of data listed in table 1 refers to the perform-
Response time < 200 s 3) A.4.2.1.3
ante characteristics of measurement methods, in-
Integral Performance
~t: 2,5 % 1) 4) A.4.2.2
cluding all Steps from sampling to recording and, if
( SA >
necessary, storage of data.
1) Related to the upper limit of measurement.
2) The main interfering substances in the flue gas from
This International Standard is applicable to extractive
combustion plants are CO*, CO, NO, H,O and, in
and non-extractive automated Sulfur dioxide measur-
smaller concentrations, NO, and NH,. If the water va-
ing methods. For both methods it implies the appli-
pour is not removed from the flue gas of coal and waste
cability of Zero and calibration gas and the availability fired incinerators, HCI and HN may also interfere. In
special cases there may be other interfering substances
of comparable samples. The automated measuring
(e.g. cyanide).
System tan be calibrated with calibration gases, by
applying the manual method described in ISO 7934,
3) Assuming an integration time of 30 min.
or by applying an automated measuring System pre-
4) See 3.7.
viously verified according to this International Stan-
dard using a different principle of detection. The value
of the integral Performance (3.7) is determined by
using ISO 7934 or an automated measuring System
The facilities at which the values of the Performance
verified according to this International Standard with
characteristics given in table 1 have been verified ac-
a different principle of detection. At present, the range
cording to this International Standard in the appropri-
over which this specification applies is between
ate ranges are listed in table 2.
0 g/m3 to 0,l g/m3 and 0 g/m3 to 8 g/m3 (see table 2
for details).

---------------------- Page: 7 ----------------------

SIST ISO 7935:1996
ISO 7935:1992(E)
3.5 comparative measurements: Measurements
Table 2 - Facilities and measuring ranges
that are performed in the Same chimney in the same
-
sampling plane for the same period of time.
Measuring range
g/m3 of SO2 1)
3.6 manual method: The test method defined in
ISO 7934 for the manual sampling and analysis 0%
Furnaces for hard coal O-l toO-8
stationary Source emissions containing Sulfur dioxide.
Furnaces for hard coal with
0 to 0,l
Stack gas desulfuration plant
Furnaces for brown coal 0 - 0,l to 0 - 3,0
3.7 integral Performance, SA: The integral perform-
Furnaces for heavy fuel oil 0 - 0,l to 0 - 5,0 ante is a measure of the working accuracy of the
AMS. lt is calculated according to the formula for
Refuse incinerator 0 - 0,4 to 0 - 1 ,o
Standard deviations.
Coke oven 0 to 1
Calcar with heavy fuel oil 0 to 5
The integral Performance is derived from the differ-
ence in the pairs of measured values of Sulfur dioxide
Sulfuric acid recovery plant 0 to 1
by the AMS under investigation, and by an ISO man-
I
ual method or a verified AMS of different measuring
1) Related to 101,3 kPa, 273 K and dry gas.
I
principle on the basis of a sufficient number of com-
1
parative measurements spread over the period of un-
attended Operation (see annex A).
2 Normative references
NOTES
The following Standards contain provisions which,
3 lt is not possible to determine the Standard deviation of
through reference in this text, constitute provisions
an AMS under repeatable working conditions because
of this International Standard. At the time of publi-
cation, the editions indicated were valid. All Standards
- commercially available calibration gas mixtures contain-
are subject to revision, and Parties to agreements
ing Sulfur dioxide do not have all the properties of actual
based on this International Standard are encouraged
waste gas and do not cover all possible influences;
to investigate the possibility of applying the most re-
cent editions of the Standards indicated below.
- the mass concentration of Sulfur dioxide in waste gas
Members of IEC and ISO maintain registers of cur-
usually varies with time;
rently valid International Standards.
- it is not possible to maintain the properties of a waste
gas present in the waste gas flue when it is transferred
ISO 6879:1983, Air quality - Performance character-
into a vessel.
istics and related concepts for air quality measuring
methods.
4 The reason that the integral Performance is defined as
a measure of the working accuracy, is that it contains, in
ISO 7934: 1989, Stationary Source emissions - De-
addition to random errors, all the effects of interfering sub-
termination o f the mass concentration of Sulfur diox-
stances, changes in temperature and power line as well as
- Hydrogen peroxide/barium perchlora te/Thorin
ide
zero drifts and span drifts. lt also includes the Standard de-
me thod.
viation of the ISO manual method or the verified AMS using
a different principle of detection, which tan be determined
separately and eliminated if necessary. Furthermore, it in-
3 Definitions
cludes the effects, for the different methods, of a different
response time to variations in the composition of the waste
For the purposes of this Internationa gas.
I Standard, the
following definitions apply.
The integral Performance defined in this subclause is an
upper limiting value for the AMS. Relevant systematic errors
3.1 automated measuring System (AMS): A com-
of the measured values of the ISO manual method, or the
plete System that may be attached to a chimney to
verified AMS using a different principle of detection, have
continuously measure and record the mass concen-
to be known and taken into account.
tration of Sulfur dioxide passing through the chimney.
3.2 analyser: Analytical part in an extractive AMS.
3.8 chimney: Stack or final exit duct on a stationary
process used for the dispersion of residual process
3.3 verified AMS: AMS previously verified in
gases.
ISO 7935.
3.4 calibration gas: A gas of known and reliable 3.9 mass concentration: The concentration of a
composition that may be used to check the response substance in an emission, expressed in milligrams per
of an AMS. cubic metre or grams per cubic metre.
2

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SIST ISO 7935:1996
3.10 stationary Source emissions: Those waste
- an analytical part.
gases that have been emitted from a stationary plant
Certain extractive methods also include Sample di-
or process and are exhausted to a chimney for dis-
lution.
persion into the atmosphere.
The Sample probe is placed inside the duct containing
4 Description of the automated
The choice of locations may
gaseous effluents.
sometimes be difficult, since the measurement to be
measuring Systems
made needs to be representative and calibration
should be possible.
4.1 Introduction
The design of the Sample probe and the gas con-
There are two types of automated measuring sys-
ditioning System essentially depends on physico-
tems:
Chemical characteristics (composition of the gaseous
Phase, particle concentration, temperature, water
- extractive methods;
dew Point, etc.) of the effluents to be analysed and
the principle of the analyser used. Since particulate
- non-extractive methods, known as in-situ or
matter and humidity may influence the measurement,
Cross-duct measuring methods.
the line contains a particulate filter and a humidity
elimination device.
Examples of the components of these Systems are
given in figures 1 and 2.
In Order to limit Sulfur dioxide losses and inconsistent
readings, the line is frequently heated.
Using the extractive method, the representative gas
Sample is taken from the Stack with a sampling probe
The analytical detection methods most commonly
and conveyed to the analyser through the Sample line
used are absorption, using infrared or ultraviolet radi-
and Sample gas conditioning System. The values de-
ation, fluorescence, using ultraviolet radiation,
termined are often recorded or stored by means of
interferometry and conductometry.
electronie data processing.
4.3 Non-extractive methods
The non-extractive method does not require any
Sample processing. In addition, it takes into consider-
For in-situ or Cross-duct methods, an Optical device is
ation a larger part of the waste gas. Most of the
used which is positioned directly in the duct of
methods described in 4.2 and 4.3 are able to deter-
gaseous effluents. lt consists of two modules, one
mine Sulfur dioxide specifically. Methods which rely
being a radiation emittor, the other a receptor of the
on conductometry determine total Sulfur oxides.
radiation which has passed through the gases con-
taining Sulfur dioxide.
4.2 Extractive methods
Installation of these two modules, in relation to the
The extractive methods enable Separation of the
duct, depends on the apparatus used.
sampling and analysis Parts, thereby facilitating main-
tenance operations.
The Signals from the receptor are subsequently pro-
cessed, in Order to convert the data into concen-
The main Parts are
tration, expressed as V/V or in milligrams per cubic
metre.
- a Sample probe;
NOTE 5 When comparing the results from dry extractive
- a Sample line;
methods and non-extractive methods, it is necessary to
know the water content of the flue gases for correction of
- a gas conditioning System; the in-situ value to a value on a dry gas basis.

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SIST ISO 7935:1996
ISO 7935:1992(E)
1 2 3 4 10
5 6 7 8 9
KeY
1 Gas sampling probe
2 Particulate filter
3 Heating jacket or heating bandage
4 Cooler with condensate-separator
5 Sampling pump
6 Filter
7 Needle valve
8 Flowmeter
9 Analyser
IO Recorder
11 Inlet for
a) calibration gas mixtures containing Sulfur dioxide
b) zero samples
i
Figure 1 - Example of the components for the extractive method
1
1 Absorption-Ce11 for calibration gas mixtures
2 Inlet for calibration gas mixtures
3 Optical receiver
4 Electronie module
5 Recorder
Figure 2 - Example of the components for the non-extractive method
4

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SIST ISO 7935:1996
ISO 7935: 1992(E)
automated measuring System is handled and maintained
5 Numerital values of Performance
properly. Checks with calibration gas mixtures containing
characteristics and their applicability
Sulfur dioxide are carried out and the interfering effect of
changes in atmospheric pressure are taken into account.
When measured in accordance with the respective
methods given in annex A, the Performance charac- 8 The Performance characteristics given in tables 1 and
B.1 are based on many measurements carried
...