EN ISO 9225:2012

SLOVENSKI STANDARD
01-maj-2012
1DGRPHãþD
SIST EN 12500:2000
Korozija kovin in zlitin - Korozivnost v atmosferskem okolju - Merjenje okoljskih
parametrov, ki vplivajo na korozivnost atmosfer (ISO 9225:2012)
&RUURVLRQRIPHWDOVDQGDOOR\V&RUURVLYLW\RIDWPRVSKHUHV0HDVXUHPHQWRI
HQYLURQPHQWDOSDUDPHWHUVDIIHFWLQJFRUURVLYLW\RIDWPRVSKHUHV,62
PHDVXUHPHQWRIHQYLURQPHQWDOSDUDPHWHUVDIIHFWLQJLQGRRUFRUURVLYLW\
Korrosion von Metallen und Legierungen - Korrosivität von Atmosphären - Messung der
die Korrosivität von Atmosphären beeinflussenden Umweltparameter (ISO 9225:2012)
Corrosion des métaux et alliages - Corrosivité des atmosphères - Mesurage des
paramètres environnementaux affectant la corrosivité des atmosphères (ISO 9225:2012)
Ta slovenski standard je istoveten z: EN ISO 9225:2012
ICS:
77.060 Korozija kovin Corrosion of metals
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 9225
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2012
ICS 77.060 Supersedes EN 12500:2000
English Version
Corrosion of metals and alloys - Corrosivity of atmospheres -
Measurement of environmental parameters affecting corrosivity
of atmospheres (ISO 9225:2012)
Corrosion des métaux et alliages - Corrosivité des Korrosion von Metallen und Legierungen - Korrosivität von
atmosphères - Mesurage des paramètres Atmosphären - Messung der die Korrosivität von
environnementaux affectant la corrosivité des atmosphères Atmosphären beeinflussenden Umweltparameter (ISO
(ISO 9225:2012) 9225:2012)
This European Standard was approved by CEN on 22 January 2012.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9225:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 9225:2012) has been prepared by Technical Committee ISO/TC 156 "Corrosion of
metals and alloys" in collaboration with Technical Committee CEN/TC 262 “Metallic and other inorganic
coatings” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by August 2012, and conflicting national standards shall be withdrawn at
the latest by August 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12500:2000.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 9225:2012 has been approved by CEN as a EN ISO 9225:2012 without any modification.

INTERNATIONAL ISO
STANDARD 9225
Second edition
2012-02-01
Corrosion of metals and alloys —
Corrosivity of atmospheres —
Measurement of environmental
parameters affecting corrosivity of
atmospheres
Corrosion des métaux et alliages — Corrosivité des atmosphères —
Mesurage des paramètres environnementaux affectant la corrosivité
des atmosphères
Reference number
ISO 9225:2012(E)
©
ISO 2012
ISO 9225:2012(E)
©  ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 9225:2012(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 1
3  Principle . 1
4  Humidity and temperature parameters . 2
4.1  Relative humidity . 2
4.2  Temperature . 2
5  Airborne contaminants . 2
5.1  Principle . 2
5.2  Placement of measurement equipment . 3
5.3  Measurement methods and duration . 3
Annex A (normative) Determination of sulfur dioxide deposition rate on lead dioxide sulfation
plates . 6
Annex B (normative) Determination of sulfur dioxide deposition rate on lead dioxide sulfation
cylinder . 9
Annex C (normative) Determination of sulfur dioxide deposition rate on alkaline surfaces . 12
Annex D (normative) Determination of chloride deposition rate by the wet candle method . 14
Annex E (normative) Determination of chloride deposition rate by dry plate method . 18
Annex F (normative) Comparison of chlorides and sulfur dioxide deposition rates determined by
different methods . 21
Bibliography . 22

ISO 9225:2012(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9225 was prepared by Technical Committee ISO/TC 156, Corrosion of metals and alloys.
This second edition cancels and replaces the first edition (ISO 9225:1992), which has been technically revised.
iv © ISO 2012 – All rights reserved

ISO 9225:2012(E)
Introduction
The ability of an atmosphere to cause corrosion of metals and alloys is controlled by the following factors: the
temperature-humidity complex and pollution. A basic requirement for the estimation of the corrosivity of
atmospheres is standardized measurement of the important parameters describing the correlation between
the corrosion and the environmental characteristics.
The methods included in this International Standard have been chosen for their easy applicability and good
comparability of results. It is important to stress that the methods for estimation of the atmospheric corrosivity
given in ISO 9223 are based on the measurement methods described in this International Standard.

INTERNATIONAL STANDARD ISO 9225:2012(E)

Corrosion of metals and alloys — Corrosivity of atmospheres —
Measurement of environmental parameters affecting corrosivity
of atmospheres
WARNING — Some of the procedures included in this International Standard entail the use of
potentially hazardous chemicals. lt is emphasized that all appropriate safety precautions should be
taken.
1 Scope
This International Standard specifies methods for measuring the parameters needed for corrosivity estimation
used for classification of the corrosivity of atmospheres in ISO 9223.
This International Standard specifies methods for the measurement of environmental parameters for
 normative corrosivity estimation based on calculated first-year corrosion rates of standard metals, and
 informative corrosivity estimation based on characterization of the exposure environment.
This International Standard does not describe the usual analytical techniques for the measured parameters
since this depends on the available analytical techniques used in laboratories. Specific methods for deposition

measurement of SO and Cl deposition rates and conversional factors for comparison of different measuring
methods are presented in Annexes A, B, C, D, E and F.
For methods pertaining to the characterization of the atmospheric exposure site in general, see ISO 8565.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 9223, Corrosion of metals and alloys — Corrosivity of atmospheres — Classification, determination and
estimation
ISO 11844-3, Corrosion of metals and alloys — Classification of low corrosivity of indoor atmospheres —
Part 3: Measurement of environmental parameters affecting indoor corrosivity
3 Principle
Different environmental parameters and their combinations affect the corrosivity of the atmosphere. Two
methods for corrosivity estimation (normative and informative) are specified in ISO 9223.
In general, two groups of parameters are obtained or measured for standardized procedures of corrosivity
estimation:
 humidity and temperature;
 airborne contaminants.
ISO 9225:2012(E)
Standardized corrosivity estimation is based on information on levels of the dominating environmental
parameters: the temperature-humidity complex, and pollution with SO and airborne chlorides. Measurements
of these parameters are mandatory for the purpose of corrosivity estimation.

Contaminants other than SO and Cl , such as NO , O , H S, HNO , can also exert an effect on the
2 x 3 2 3
2  
corrosion rate. Corrosion active components of dust deposits (SO , NO , Cl ) react with metals in the
4 3
presence of humidity. These factors are considered as accompanying factors (see ISO 9223). These
environmental parameters, which contribute to the effect on corrosion of standard metals in multi-pollutant
situations, are not included as mandatory parameters for corrosivity estimation in ISO 9223. Information on
levels of these parameters can help in informative corrosivity estimation.
Methods for the measurement of environmental parameters to be used specifically for the estimation of low
corrosivity of indoor atmospheres (IC) are given in ISO 11844-3.
4 Humidity and temperature parameters
4.1 Relative humidity
Reliable long-term average values for relative humidity can often be obtained from the meteorological
authorities in the country. Several types of measuring devices can be used if collection of new data for the
locality is needed. There are several continuous measuring devices, such as hygrographs,
thermohygrographs or logging hygrometers, available on the market.
The period of measurement is preferably one year in order to cover seasonal variations and because the
classification system is based on yearly average values. The data shall be expressed as yearly mean values.
4.2 Temperature
Reliable long-term average values for temperature can often be obtained from the meteorological authorities
in the country. Several types of measuring devices can be used if collection of new data for the locality is
needed. There are several continuous measuring devices, such as thermohygrographs or logging
thermometers, available on the market.
The period of measurement is preferably one year in order to cover seasonal variations and because the
classification system is based on yearly average values. The data shall be expressed as yearly mean values.
5 Airborne contaminants
5.1 Principle
The gas concentration or deposition rate may be measured using several techniques:
 continuous gas concentration measuring instruments;
 average gas concentration with active sampler and air pump;
 average gas concentration with diffusive (passive) sampler;
 average deposition rate equipment.
The results from concentration measurements are typically given in micrograms per cubic metre (µg/m ) and,
for deposition measurements, in milligrams per square metre per day [mg/(md)].
2 © ISO 2012 – All rights reserved

ISO 9225:2012(E)
5.2 Placement of measurement equipment
5.2.1 Continuous gas concentration measurement instruments
The instrument shall be located in a place that is sheltered from the rain and protected from unauthorized
people. Preferably, the instrument should be placed indoors with a tube leading out to the ambient air.
Polyethylene or PTFE tubing is recommended and the length of the tubing should not exceed 2 m. The inlet
shall be facing down with a wider hood at the inlet to reduce the risk of sucking particulates into the tube.
5.2.2 Measurement instruments with active sampler
The active sampler equipment shall be placed according to the same rules as the continuous gas-measuring
instrument.
5.2.3 Measurement instruments with diffusive sampler
The sampling device shall be placed with the open end facing downward under appropriate shelter. The air
flow influences the gas diffusion in the sampler.
5.2.4 Deposition rate equipment
The equipment shall be sheltered from setting particles and from washing out by rain for outdoor deposition
measurements. The air flow influences the deposition rate.
5.3 Measurement methods and duration
5.3.1 Continuous measurement
The measurements shall preferably be carried out for one year in order to record the seasonal variation of the
gas pollutants. The data from continuous measuring instruments shall be recorded as monthly average values.
For the corrosivity estimation, the data shall be expressed as yearly mean values.
5 6
Standard instruments have detection limits in a range from 4  10 volume fractions to 1  10 volume
fractions.
5.3.2 Measurement with active sampler
The methods are based on pumping air through an absorption unit with a reactive surface or liquid, with
subsequent laboratory analysis of the amount absorbed. The sampling period shall be one week. The data
shall be collected over the sampling periods and summarized to monthly average values. The result is given
as an average concentration for the measuring period.
The measuring period is preferably one year or at least one month for each season of the year. For the
corrosivity estimation, the data shall be expressed as yearly mean values.
NOTE The detection limits for air concentrations depend on the sensitivity of the analysing instruments and the
duration of the sampling. For an analytical instrument with normal sensitivity, it is possible to obtain weekly average values
with a detection limit better than 0,1 µg/m .
5.3.3 Measurement with diffusive sampler
Mean gas concentrations can be calculated using diffusive sampling devices. The principle used for diffusive
sampling is shown in Figure 1. The recommended sampling period is one month, but can be extended to three
months, corresponding to one measurement for each season of the year. The measurement period is
preferably one year.
ISO 9225:2012(E)
Key
1 absorbent
2 tube
3 permeable screen for gases
C ambient concentration of gas
C concentration of gas at the absorbent equal zero
Figure 1 — Principle of concentration calculation for a diffusive sampler

NOTE Normal sensitivity for weekly mean values is down to 0,1 µg/m for SO , but higher for other gases. Generally
the detection limit decreases with increasing sampling time.
The general calculation model is specified in ISO 11844-3.
The data shall be expressed as yearly mean values.
5.3.4 Measurement of deposition rate of pollution
The deposition takes place on an absorbing or collecting surface similar to the surfaces used for diffusive
sampling devices. In the deposition method standardized for SO deposition measurements, the gas reacts
when it reaches the lead dioxide surface or alkaline surface (see Annexes A, B and C). In the methods
standardized for airborne salinity measurements, particles (aerosol) are deposited on a wet or dry surface
designed to collect this pollutant (see Annexes D and E). Since the collecting system is open, the deposition
rate depends on the movement of the air.
NOTE The use of lead compounds can be restricted in some countries.
SO deposition measurements performed by the lead dioxide plates and by the lead dioxide cylinder differ
with regard to the kind and shape of the deposition surface. Both measurements give values with low
correlation for monthly sampling periods due to the greater variation in weather characteristics. A high
correlation exists for annual average values (see Annex F). Capture of sulfuric acid aerosols and
sulfur-bearing species from precipitation and sea salt deposition can occur.
The SO deposition values used for the derivation of the dose-response functions given in ISO 9223 are either
based on deposition measurements on alkaline surfaces or converted values based on concentration
measurements.
Chloride deposition rates determined by the dry plate method and by the wet candle method differ because
the kind and shape of deposition surface are different (wet/dry surfaces, cylindrical/plate format of the
deposition surface). There is little difference in the deposition rates determined by the two methods at
locations with very low deposition rates, i.e. 10 mg/(md). On the other hand, at higher chloride deposition
rates, the wet candle method gives deposition rates that are approximately twice as high as those given by the
dry plate method. Both these measurements give values with low correlation for monthly sampling periods due
to the great variation in weather characteristics. A high correlation exists for annual average values (see
Annex F).
4 © ISO 2012 – All rights reserved

ISO 9225:2012(E)
The chloride deposition values used for the derivation of the dose-response functions given in ISO 9223 are
based on measurements with the wet candle method. If the chloride deposition is measured with the dry plate
method (see Annex E), it is necessary that the transformation factor given in Annex F be applied before using
the dose-response functions.
ISO 9225:2012(E)
Annex A
(normative)
Determination of sulfur dioxide deposition rate
on lead dioxide sulfation plates
A.1 Principle
Atmospheric sulfur dioxide (SO ) reacts with the lead dioxide (PbO ) to form lead sulfate (PbSO ). The plates
2 2 4
are withdrawn after exposure and sulfate analysis is performed on the contents to determine the extent of
sulfur dioxide capture. The deposition rate of sulfur dioxide is expressed in milligrams per square metre per
day [mg/(md)].
The lead dioxide reagent used in this method can also convert other sulfur-bearing compounds, such as
hydrogen sulfide (H S) and mercaptans (C H SH), to sulfate.
2 2 5
The inverted position of the disc is intended to minimize sulfur capture from acid precipitation
...