IEC 60721-2-5:1991 pdf download.Classification of environmental conditions Part 2: Environmental conditions appearing in nature Section 5: Dust, sand, salt mist.
This section of lEG 721-2 is intended to be used as part of the background information when selecting appropriate seventies of parameters relating to dust, sand and salt mist for product application. The seventies given in lEG 721-1 should be applied.
More detailed information on dust, sand and salt mist characteristics may be obtained from specialist documentation, some of which is given in the list of references in annex B.
This section of lEG 72 1-2 presents characteristics of dust, sand and salt mist appearing in nature, and describes the Influences from these environmental factors to which products are liable to be exposed during storage, transportation and use. Although the effect of these factors is often closely associated with and at times enhanced by wind, the environmental factor of wind is not dealt with in this section but In lEG 721-2-2.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this section of lEG 721-2. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this section of IEC 721-2 are encouraged to Investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards.
The dust and sand environment is Influenced or controlled by such factors as terrain, wind, temperature, humidity and precipitation. None of these factors alone will dictate whether an area has a dust problem or not; a critical combination of two or more is usually required. In the most severe, naturally occurring situations, such as in desert areas, all factors generally have seventies in the range leading to heavy concentrations of dust and sand. The physical features of the terrain can encourage strong winds of sufficient speed to cause dust and sand storms. A topographic feature such as a mountain gap increases wind velocity substantially as air is forced through the constriction.
Sand is distributed widely over the land surface of the globe. The major deserts listed in table 4 are the primary sources of naturally occurring windblown dust and sand. The major deserts constitute about one fifth of the total land area. All continents have sandy beaches of various widths, and there are large deposits of sand at or near the surface in many inland areas formerly covered by water.
The constituent parts of a saline atmosphere are approximately equal to those found In the sea. The salt content of natural sea-water may be taken as 3,4 %, varying above and below this figure according to geographical location and dimatic factors. For example, a value of about 4 % occurs in the Red Sea.
Salinity is defined as the total amount of solid material in grams, contained in 1 kg of sea-water, when all the bromine and iodine have been replaced by the equivalent amount of chlorine, all the carbonate converted to oxide and all organic matter has been completely oxidized.
The principle constituents of sea-water are shown In table 6.IEC-60721-2-5-1991