IEC 60068-2-60:2015

IEC 60068-2-60 ®
Edition 3.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-60: Tests – Test Ke: Flowing mixed gas corrosion test

Essais d'environnement –
Partie 2-60: Essais – Essai Ke: Essai de corrosion dans un flux de mélange de
gaz
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IEC 60068-2-60 ®
Edition 3.0 2015-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Environmental testing –
Part 2-60: Tests – Test Ke: Flowing mixed gas corrosion test

Essais d'environnement –
Partie 2-60: Essais – Essai Ke: Essai de corrosion dans un flux de mélange de

gaz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 19.040 ISBN 978-2-8322-2747-3

– 2 – IEC 60068-2-60:2015 © IEC 2015
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references. 5
3 Test apparatus . 5
4 Severities . 6
5 Preconditioning . 6
6 Initial measurements . 6
7 Testing . 7
7.1 General . 7
7.2 Test specimens . 7
7.3 Corrosivity monitoring materials . 7
7.4 Testing procedure . 7
8 Recovery . 9
9 Final measurements . 9
10 Information to be given in the relevant specification . 9
11 Information to be given in the test report . 10
Annex A (normative) Corrosion monitoring copper coupons . 11
A.1 General . 11
A.2 Nature and dimension . 11
A.3 Cleaning procedure . 11
Annex B (informative) Description of test apparatus . 12
B.1 General . 12
B.2 Climatic system . 12
B.3 Test enclosure . 13
B.4 Gas delivery system . 14
B.5 Analysing system . 14
B.5.1 Temperature and humidity . 14
B.5.2 Gases . 14
B.6 Other corrosion monitoring methods . 15
B.6.1 Mass increase . 15
B.6.2 Surface analysis of monitoring coupons . 15
B.6.3 Visual examination . 16
B.7 Calibration of the chamber . 16
Annex C (informative) Guide to the selection of methods and test duration . 17
C.1 Introductory remarks . 17
C.2 Function of corrosive gases used in the tests . 17
C.3 Use of the different test methods . 17
Bibliography . 19

Figure B.1 – Example of test apparatus . 12

Table 1 – Test conditions . 6

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ENVIRONMENTAL TESTING –
Part 2-60: Tests – Test Ke: Flowing mixed gas corrosion test

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60068-2-60 has been prepared by IEC technical committee 104:
Environmental conditions, classification and methods of test.
This third edition cancels and replaces the second edition, published in 1995, and constitutes
a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– updated IEC format;
– updated normative references list;
– addition of information of the working volume;
– revision of the test procedure;
– revision of the figures in Annex B.

– 4 – IEC 60068-2-60:2015 © IEC 2015
The text of this standard is based on the following documents:
FDIS Report on voting
104/655/FDIS 104/656/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60068 series, published under the general title Environmental
testing, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
ENVIRONMENTAL TESTING –
Part 2-60: Tests – Test Ke: Flowing mixed gas corrosion test

1 Scope
This part of IEC 60068-2 determines the corrosive influence of operating and storage indoor
environments on electrotechnical products components, equipment and materials, particularly
contacts and connections, considered separately, integrated into a subassembly or
assembled as a complete equipment.
It provides test methods giving information, on a comparative basis, to aid the selection of
materials, choice of production processes and component design, with regard to corrosion
resistance. A guide to the selection of methods and test duration is provided in Annex C.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60512-2-1, Connectors for electronic equipment – Tests and measurements – Part 2-1:
Electrical continuity and contact resistance tests – Test 2a: Contact resistance – Millivolt level
resistance method
IEC 60512-3-1, Connectors for electronic equipment – Tests and measurements – Part 3-1:
Insulation tests – Test 3a: Insulation resistance
ISO 431, Copper refinery shapes
3 Test apparatus
The test apparatus consists of a climatic system, test enclosure, gas delivery system and
means for measuring gas concentration.
Details of design and construction are optional but shall be such that the conditions specified
for each method are fulfilled throughout the working volume and shall comply with the
following requirements:
– water droplets or aerosols shall not be injected into the test enclosure;
– air and water used shall be sufficiently clean in order not to affect performance of the test;
– the test atmosphere shall flow through the enclosure in such a manner as to ensure
uniform test conditions within the working volume;
– the sampling point for gas analysis shall be in the working volume of the test enclosure;
– the exhaust gases shall be treated in accordance with the relevant regulatory stipulations;
– the wet bulb pod shall be placed in the test chamber in such a manner not to exceed
0,1 % of the cross-section of the test chamber.

– 6 – IEC 60068-2-60:2015 © IEC 2015
Because of the strong synergistic effect and the so called “memory effect” (i.e., it is difficult to
fully remove the chlorine compounds from the chamber, tubes, etc.), it is recommended that
enclosures and tubing used for tests that incorporate chlorine only be used for chlorine tests.
The working volume is the volume within which the individual corrosion (mass increase of
copper coupons expressed in mg/( dm × day) according to Annex A) at each location differs
by a maximum of 15 % from the average corrosion of all coupons within the working volume.
4 Severities
The test severity shall be given in the relevant specification. It is defined by
– the test method, chosen from Table 1,
– the test duration.
Preferred durations, in days, are 4, 7, 10, 14 and 21.
Four methods are defined. The different parameters for each method are summarized in the
following Table 1. A guidance for the use of each method is given in Clause C.3.
Table 1 – Test conditions
Parameters Method 1 Method 2 Method 3 Method 4
−9
H S (10 vol/vol) 100 ± 20 10 ± 5 100 ± 20 10 ± 5
−9
NO (10 vol/vol)
200 ± 50 200 ± 50 200 ± 20
−9
Cl (10 vol/vol)
10 ± 5 20 ± 5 10 ± 5
−9
SO (10 vol/vol)
500 ± 100 200 ± 20
a
Temperature (°C) 25 ± 1 30 ± 1 30 ± 1 25 ± 1
a
RH (%) 75 ± 3 70 ± 3 75 ± 3 75 ± 3
Rate of ventilations 3 to 10 3 to 10 3 to 10 3 to 10
per hour
Mass increase of 1,0 to 2,0 0,3 to 1,3 1,2 to 2,2 1,2 to 2,4
copper coupons
mg/(dm × day)
according to Annex A
NOTE Since the nature of the corrosive attack is different for test Methods 1 to 4, neither their numbering nor
the corresponding mass increase of copper coupons reflect their severity.
a
Different temperature and humidity values (e.g. 40 °C and 80 %RH) may be used based upon mutual
agreement between the interested parties. The mass increase may be different from the given values.

5 Preconditioning
The relevant specification may require preconditioning of specimens, for example cleaning or
mechanical operation.
6 Initial measurements
Initial measurements shall be carried out as required by the relevant specification.
Generally, these measurements are:

– contact resistance measurements for electromechanical product components (see
IEC 60512-2-1);
– insulation resistance measurements (see IEC 60512-3-1).
7 Testing
7.1 General
Samples exposed in the tests shall be
– the specimens being evaluated,
– corrosion monitor materials.
7.2 Test specimens
The relevant product specification shall define the conditions of the specimens during the test,
for example mated or unmated for connectors; contacts open or closed for switches, operated
or electrically loaded.
The duration of the operation or loading of heat-dissipating specimens, shall be such that the
temperature and the relative humidity in the working volume remain within the specified
tolerances.
The conditions of the specimens and the test chamber shall be such that condensation on the
specimens shall not occur when they are introduced into the test chamber.
The total volume of the test specimens should not exceed 10 % of the volume of the working
area of the test chamber. If the total volume of the test specimens exceed 10 %, the amount
exceeding 10 % shall be included in the test report.
The total surface area of the test specimens should not exceed 10 % of the surface area of
the working area of the test chamber. If the total surface of the test specimens exceed 10 %,
the amount exceeding 10 % shall be included in the test report.
A minimum space between specimens might be 10 mm so as not to disturb the uniform air
flow.
7.3 Corrosivity monitoring materials
Copper coupons shall be exposed with the test specimens in order to verify the conformance
of the test condition.
A minimum of five test coupons of copper, prepared in accordance with Annex A, shall be
exposed with the test specimens for the same duration. Their mass increase during the test,
measured by a balance with a resolution of 0,01 mg, shall be taken as a measure of the
corrosion and as a monitor of the reproducibility and repeatability of the test.
Other vehicles, for example, gold-plated coupons or other specimens (see B.6.3) can be used
in addition to the copper coupons.
7.4 Testing procedure
One of the following test procedures shall be used:

– 8 – IEC 60068-2-60:2015 © IEC 2015
Test procedure 1
When the test atmosphere does not contain chlorine (Method 1) or when the method for
measuring chlorine concentration does not suffer interference from the other gases present in
the test atmosphere, the following procedure shall be used:
– after the specified temperature is stabilized, start the flow of humid air, allow to stabilize
and adjust temperature and humidity not to accumulate the condensation on the inner wall
of the test chamber and the test specimen;
– start the flow of the gases into the humid air stream and allow to stabilize;
– measure and adjust gas concentrations. Allow to stabilize. When it is necessary to
measure chlorine concentration, total chlorine (not only chlorine gas, Cl ) present in the
test atmosphere is taken as a measure of chlorine gas concentration. The chlorine added
to the test atmosphere shall still only be in the form of chlorine gas, Cl ;
– introduce the test specimens and the corrosion monitoring materials as prescribed in 7.3.
The copper coupons shall be exposed with the test specimens for the first 4 days during a
test duration. The copper coupons might be exposed another 4 days during a test
duration, if necessary. It shall be included in the test report. The test specimens and the
corrosion monitoring materials shall be distributed uniformly in the working volume. They
shall not come in contact with one another nor shield one another from the test
atmosphere. The test specimens shall be in the condition (for example, mated/unmated,
electrically loaded or operated) as stated in the relevant specification. The test duration
shall be measured from this point;
– allow the test conditions to stabilize, which may require considerable time. Measure and
adjust, if necessary, temperature, humidity and gas concentrations. During these
adjustments, any overshooting of gas concentration shall be avoided. Maximum allowed
duration of this period of stabilization and adjustments, to prescribed values, is 24 h;
– during the course of testing, temperature, humidity and gas concentrations shall be kept
within the prescribed limits. The chamber is allowed to be opened during the test.
The number of openings shall be limited.
No opening is allowed for a test duration shorter than 4 days.
One opening is allowed for a test duration of between 4 and 10 days.
One opening per week is allowed for a test duration exceeding 10 days.
The duration of these openings shall be limited to the time necessary to remove and
introduce specimens and/or copper coupons;
– at the end of the test period, remove the specimens and the corrosion monitoring
materials.
Test procedure 2
When chlorine is present in the test atmosphere (Methods 2 to 4) and when the method for
measuring chlorine suffers interference from other gases in the test atmosphere, the following
procedure shall be used:
– after the specified temperature is stabilized, start the flow of humid air, allow to stabilize
and adjust temperature and humidity so as not to accumulate the condensation on the
inner wall of the test chamber and the test specimen;
– start the flow of chlorine into the humid air stream and allow to stabilize;
– measure and adjust the chlorine concentration. Allow to stabilize;
– introduce the test specimens and the corrosion monitor materials as prescribed in 7.2. The
copper coupons shall be exposed with the test specimens for the first 4 days during a test
duration. The copper coupons might be exposed another 4 days during a test duration, if
necessary. It shall be included in the test report. The test specimens and the corrosion
monitoring materials shall be distributed uniformly in the working volume. They shall not
come in contact with one another nor shield one another from the test atmosphere. The

test specimens shall be in the condition (for example, mated/unmated, electrically loaded
or operated) as stated in the relevant specification;
– allow temperature, humidity and chlorine concentration to stabilize, which may require
considerable time due to initially high reaction or adsorption rates of chlorine with surfaces.
If necessary, measure and adjust the chlorine concentration. During this adjustment, any
overshooting of gas concentration shall be avoided. The chlorine concentration shall
remain stable for 2 h minimum. The maximum allowed duration of this period of chlorine
stabilization and adjustments, to prescribed values, is 24 h;
– start the flow of the remaining gases and allow to stabilize. Measure and adjust, if
necessary, temperature, humidity and gas concentrations, excluding chlorine. During
these adjustments, any overshooting of gas concentration shall be avoided. The maximum
allowed duration of this period of stabilization and adjustments, to prescribed values, is
24 h. The test duration is measured from the moment when all gases are present in the
test atmosphere;
– during the course of testing, temperature, humidity and gas concentrations shall be kept
within the prescribed limits. Chlorine concentration, however, cannot be controlled during
the test. The way to ensure that values remain within the set limits is to carry out the
chlorine measurement after finishing the test (see below). The chamber is allowed to be
opened during the test.
The number of openings shall be limited.
No opening is allowed for a test duration shorter than 4 days.
One opening is allowed for a test duration of between 4 and 10 days.
One opening per week is allowed for a test duration exceeding 10 days.
The duration of these openings shall be limited to the time necessary to remove and
introduce specimens and/or copper coupons;
– at the end of the test period, stop the flow of gases except chlorine which shall remain
running. Allow sufficient time to empty the chamber of the other gases, to an extent
sufficient to avoid interference with chlorine analyses;
– measure the chlorine concentration which shall be within the limits prescribed in order for
the test to be valid;
– remove the test specimens and the corrosion monitoring materials.
8 Recovery
After removal of the specimens from the test chamber, they shall be stored in accordance with
the relevant specification prior to final measurements.
9 Final measurements
The final measurements shall be carried out as required by the relevant specification which
may also require a visual examination of the specimens after the test.
The relevant specification shall provide the criteria upon which the acceptance or rejection of
the specimen is to be based.
If the necessary measurements cannot be made within the specified time, the period of
storage under recovery conditions may be extended to a maximum of one week. Such an
extension shall be mentioned in the test report.
10 Information to be given in the relevant specification
When this test is included in a relevant specification, the following details shall be given, in so
far as they are applicable. The relevant specification shall supply information as required in

– 10 – IEC 60068-2-60:2015 © IEC 2015
the clauses listed below, paying particular attention to the items marked with an asterisk (*) as
this information is always required.
Clause
a) Method* 4
b) Test duration* 4
c) Preconditioning of the specimens 5
d) Initial measurements* 6
e) Conditions of the specimens during the test* 7
f) Operation and loading during testing 7
g) Recovery and duration* 8
h) Final measurements* and possible visual examination 9
i) Criteria of acceptance or rejection* 9
11 Information to be given in the test report
Information to be given in the test report is as follows:
– test method;
– test duration;
– preconditioning;
– method and results of initial measurement;
– conditions and duration of test;
– operation and loading during test;
– recovery and duration;
– method and results of final measurement;
– individual mass increase of copper coupon in mg/(dm × day);
– any deviation from the standard.

Annex A
(normative)
Corrosion monitoring copper coupons
A.1 General
Copper coupons are exposed with the test specimen in order to verify the conformance of the
test to the limits set out in this standard. The mass increase of the coupons shall be taken as
a measure of this conformity.
A.2 Nature and dimension
The coupons shall be made from half hard OFHC copper (Cu-OF according to ISO 431) sheet,
2 2
maximum thickness of 0,5 mm, and have a total surface area of 0,1 dm to 0,2 dm each. The
surface of the coupon is an essentially faultless surface (free from pores, marks, scratches
and any light colouration) and a matt finish (arithmetically mean deviation of the profile
Ra = 0,15 µm ± 0,1 µm).
A.3 Cleaning procedure
Before the start of the test, the copper coupons shall be cleaned, as described below,
weighed by a balance with a resolution of 0,01 mg and stored for a maximum of 120 h in a
desiccator with non-corrosive dehydrating agent.
The cleaning procedure of the copper coupons shall be as follows:
– cathodic degrease in 1 N NaOH, for 15 s to 30 s, at 5 V to 10 V, using a stainless steel
anode or platinium anode;
– rinse with tap water;
– rinse with demineralized water;
– activate by dipping in 10 % H SO , for 20 s to 30 s;
2 4
– rinse with tap water;
– rinse with demineralized water;
– rinse with alcohol: denatured ethyl alcohol or isopropyl alcohol;
– dry with warm air (about 50 °C).
All solutions shall be prepared with demineralized water, of at least the same quality as used
in the climatic system.
– 12 – IEC 60068-2-60:2015 © IEC 2015
Annex B
(informative)
Description of test apparatus
B.1 General
The test apparatus consists of a climatic system, a test enclosure, a gas delivery system and
gas analysing systems. An example of test apparatus is shown in Figure B.1.
IEC
Key
1 Gas source 7 Conditioning chamber
2 Flow controller 8 Test chamber
3 Air supply 9 Working volume
4 Gas analysing system 10 Chemical filter
5 Gas mixing chamber 11 Pump
6 Humidity source
Figure B.1 – Example of test apparatus
B.2 Climatic system
The climatic system supplies humidified air to the test enclosure. A common way is to bubble
pressurized air through a water bath held at a temperature above the dew point of the

humidified air needed. When calculating the temperature any additional adding of dry air to
the test atmosphere should be taken into account. The relative humidity of the air in the test
enclosure should be periodically checked and the temperature of the water bath adjusted
accordingly.
Pressurized air should be cleaned from oil and pollutants. One or several oil traps, oil filters
and chemical filters, such as a combination of dry active carbon and a molecular sieve, should
be used and regenerated at regular intervals. Alternatively, synthetic air can be used. Water
should be distilled or deionized.
The humidified air can be introduced into the test enclosure by the method shown in
Figure B.1. In this case, the air from the test enclosure is exhausted by suction thereby
producing a lower pressure in the test enclosure than in the outer chamber. This humidified
air from the outer chamber is sucked into the test enclosure through a hole, the size of which
affects the pressure difference. The flow rate of the air out of the enclosure is adjusted to
obtain the specified number of volume changes per hour. The lower pressure within the test
enclosure, as compared with the ambient, may however cause difficulties when using certain
instruments for gas analysis.
B.3 Test enclosure
The constituents of the test atmosphere are chemically active and hence liable to adsorb,
absorb or react with the materials of construction of the test enclosure and of tubes. Materials
recommended for test enclosures are glass, polymethylmetacrylate (PMMA), polytetrafluoro-
ethylene (PTFE), polyvinylidenfluorid (PVDF) and an austenitic stainless steel of the 18 % Cr,
10 % Ni type with added Mo, Ti, Nb or other resistant materials, in order to increase the
resistance to chlorine compounds, essential for this application. Higher amounts of the gases
than specified are often added, especially regarding chlorine, in order to obtain specified
concentrations in the working volume. When using some types of stainless steel, corrosion of
the enclosure will occur. A “burn-in” period, during which gas adsorption rates will be
unusually high, might be necessary for new chambers.
The minimum volume of the test enclosure is recommended to be 0,1 m .
The test enclosure may be of any shape. A cylindrical shape generally produces a more
uniform air flow and a larger working volume relative to the volume of the enclosure as
compared to a cubical shape.
It is recommended that the test enclosure enables the samples to be exposed only
incidentally to sunlight or other light sources.
The design of the chamber should allow easy and thorough cleaning of walls and other parts
within the enclosure. Walls may be heated, to specified temperature or slightly higher, in
order to avoid condensation; normally an air jacket (may be an outer chamber) or a water
jacket is used.
The enclosure should be fitted with suitable gas-tight seals to enable electrical measurements
and all electrical and mechanical operations to be performed during the test.
The test atmosphere is preferably injected through opening(s) in the bottom of the chamber
and exhausted through opening(s) in the opposite wall (top of the chamber). Baffles in front of
the opening(s) can be used in order to improve uniformity of the air flow.
Tubes for the exhaust can be heated in order to avoid condensation and corrosion.
Forced movement of the air is allowed, in order to improve uniformity, provided the
requirements in Table 1 are met. Forced movement of the air can be achieved by the use of

– 14 – IEC 60068-2-60:2015 © IEC 2015
fans or by moving the test objects slowly through the atmosphere by using a carousel. In
general, fans produce turbulent air movement which tends to increase the rate of corrosion.
To avoid that, the air velocity to the test specimen shall be as low as possible. Uniform air
velocity when using carousels is only produced at a constant diameter. When using fans or
carousels, power dissipation from this equipment should be taken into account. Fans can
normally be placed far from the test objects so that heat dissipation does not affect test
performance. For carousels, the motor is normally positioned outside the chamber to avoid
heat dissipation within the test enclosure. The effect of fans or a carousel can be investigated
prior to use (see Clause B.7).
B.4 Gas delivery system
The gas supply system, tubing, valves etc., should not adsorb or absorb gases to an extent
affecting the performance of the test. PTFE is a generally used material in tubings. Valves,
etc., are generally manufactured from acid proof steel, preferably coated with PTFE on the
surfaces in contact with the gas. Chlorine, in particular, attacks acid proof steel in the
presence of humidity.
Gases used can be supplied by permeation tubes with purified air, synthetic air or nitrogen as
carrier gas. An alternative method is to use gas cylinders, preferably with diluted gas (usually
in nitrogen).
Gases used should be clean enough not to affect performance of the test. The recommended
purity level for active gases other than the specified gas is a maximum concentration of 0,1 %
of the active gas concentration; gas such as nitrogen monoxide in nitrogen dioxide is allowed
at higher concentrations to a maximum of 10 % of the specified gas.
For regulating gas flow dosing pumps, orifices or mass flow meters can be used. Mass flow
meters are recommended for regulating the diluted corrosive gases.
Before introducing the corrosive gases in the test enclosure, it is recommended to use a
mixing chamber. The concentration of the individual corrosive gases, when mixing with other
corrosive gases, should avoid unwanted reactions between the gases.
B.5 Analysing system
B.5.1 Temperature and humidity
For measuring temperature and humidity, methods unaffected by corrosive gases present can
be used. Humidity and temperature may be controlled before mixing with diluted corrosive gas.
In test apparatus, according to Figure B.1, this would be in the outer chamber. In this case,
the settings are adjusted according to the mixing with the diluted corrosive gases. The
correlation between the true humidity and temperature in the test enclosure and the
temperature and humidity normally measured outside should be checked periodically
(normally twice per year). This exposure of instruments to the corrosive environment in the
test enclosure is recommended to be limited.
B.5.2 Gases
In order to avoid condensation in sampling tubes, these tubes can be heated. Relative
humidity in the tubes should be 80 % maximum, preferably lower.
Possible effects of the pressure difference between the test enclosure and outside of the
chamber on the function of the gas analysing instruments should be checked thoroughly. Most
instruments require gas samples of ambient pressure. When having a negative pressure in
the test enclosure, some instruments may have difficulties evacuating the air out of the
enclosure, thus giving too low readings. A positive pressure is more easily managed, in this
case measures in order to reduce pressure to ambient can easily be taken.

Examples of instrument types which can be used for sulphur dioxide are UV-fluorescence,
conductometry and colorimetry.
For hydrogen sulphide, UV-fluorescence, gas chromatography with flame photometric
detection, adsorption on gold film sensor (interference by NO ), conductometry or colorimetry
may be used.
For nitrogen dioxide, chemiluminiscence or colorimetry may be used.
Chlorine gas (Cl ) can be measured using electrochemical methods or colorimetry. Both
methods are affected by the other corrosive gases used in the test atmosphere. The chlorine
analysis can accordingly only be conducted when the other gases are absent.
After mixing all gases, total chlorine may be analysed using ionic chromatography. Chlorine
content using this method is taken as a measure of Cl concentration.
Instruments used should be calibrated according to the manufacturer’s instructions.
Additionally, all instruments should be periodically calibrated using gas calibration sources.
When using UV-fluorescence type instruments, air should be used as carrier gas in the gas
calibration source since different readings are obtained when using nitrogen as compared to
when using air.
It is also important to note that many instruments (for example, UV-fluorescence for SO
analysis) are affected by relative humidity. The same relative humidity in the carrier gas, from
the calibration unit, as in the sampling tube may be difficult to achieve. In this case, readings
using pure air from the chamber, using the same temperature, humidity, flow and the same
heating of tubes as when taking gas samples, are taken and compared with readings for pure
carrier gas from the calibration unit. When analysing the corrosive gas from the chamber, the
reading is adjusted accordingly.
B.6 Other corrosion monitoring methods
B.6.1 Mass increase
For the mass increase of copper, a balance with a resolution of 0,01 mg should be used.
Immediately before weighing the corrosion monitoring coupons, the balance should be
calibrated.
For monitoring of corrosion by determining mass gain of copper or silver, a quartz
microbalance can be used. Since the copper-coated quartz crystals cannot be cleaned using
the method described in Annex A, the method should be calibrated by comparing with mass
gain measurements for copper coupons cleaned according to the standard and weighed on a
normal analytical balance.
B.6.2 Surface analysis of monitoring coupons
Investigation of the corrosion layers produced on the surface of the coupons exposed in any
of the four methods described by this standard, gives additional information regarding the
nature, chemical composition, layer structure and thickness of the corrosion products.
Appropriate methods such as coulometric reduction, cyclic voltametry, X-ray microanalysis
(SEM EDS, WDS or microprobe), Auger electron spectroscopy (AES), secondary ion mass
spectrometry (SIMS), electron spectroscopy for chemical analysis (ESCA), are available
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