ISO 11844-3:2020 pdf free.Corrosion of metals and alloys一Classification of low corrosivity of
indoor atmospheres一Measurement of environmental parameters affecting indoor corrosivity.
4 Principle
Different combinations of parameters affect the corrosivity of indoor atmospheres. Knowledge about
possible sources of environmental effects shall be obtained before decisions regarding the type
of measurements needed are taken. The characterization of indoor atmospheric corrosivity using
environmental parameters is more complicated than measuring the corrosivity with metal specimens.
However, in many cases, the measurement of environmental parameters can give a good indication of how to establish the corrosivity of an environment and will, in combination with the information given in ISO 11844-1, give a good indication of the corrosivity categories for the materials in the selected environment.
5 Environmental parameters
In indoor atmospheres, corrosion processes are characterized by a more complex group of parameters than in outdoor atmospheres. In general, three groups of parameters should be measured:
a) humidity and temperature;
b) airborne contaminants, such as gases and particles, which in turn are affected by c);
c) dry deposition velocity and air flow.
Fluctuation in temperature and humidity, particularly at higher humidity levels, can cause condensation on cooler surfaces. The frequency and time of condensation is an important factor for indoor corrosion. The corrosion effects from these groups of parameters are usually interdependent. A particular level of humidity is needed before corrosion begins, and this can vary for different contaminants. Combinations of contaminants can accelerate the corrosion processes.
Methods for sampling and analysis of various air pollutants in indoor atmospheres are described in the ISO 16000 series. Of specific relevance is ISO 16000-1, which describes a general measurement strategy for measuring indoor air pollution and specific standards for measuring selected compounds such as volatile organic compounds (see ISO 16000-5) and nitrogen dioxide (see ISO 16000-15).
NOTE ISO 16000 (all parts) is mainly devoted to compounds hazardous to human health and the environment and not to compounds resulting in high corrosivity of the environment.
6 Humidity and temperature parameters
6.1 Relative humidity
Use continuous measuring devices, such as hygrographs, thermohygrographs or logging hygrometers. The measuring period is preferably one year, to cover seasonal variations. If shorter measuring periods are needed, select a measuring period where large variations in the relative humidity are expected. The period shall be at least one month per season. The data shall be reported as monthly values. The average, maximum and minimum values for each month shall be reported.
The calculation of time with relative humidity in given intervals represents useful information.
6.2 Temperature Use continuous measuring devices, such as thermohygrographs or logging thermometers. The measuring period is preferably one year, to cover seasonal variations. If shorter measuring periods are needed, select a measuring period where large variations in the temperature are expected. The period shall be at least one month per season. The data shall be reported as monthly values. The average, maximum and minimum values for each month shall be reported.
The calculation of time with temperature in given intervals represents useful information.6.3 Temperature-humidity complex Continuous measurements of temperature and humidity give data for the calculation of frequency and time with condensation.ISO 11844-3 pdf download.