IEC 60721-2-5:1991 pdf download.Classification of environmental conditions – Part 2: Environmental conditions appearing in nature – Section 5: Dust, sand, salt mist.
IEC 60721-2-5:1991 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 lEC 721-2-2.
2 NormatIve references
The following standards contain provisions which, through reference in this text, constitute provisions of this section of lEC 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.
IEC 721-1: 1990-12, Classification of environmental conditions – Part 1: Environmental parameters and their Se verities.
IEC 721 -2-2: 1988, Classification of environmental conditions – Part 2: Environmental conditions appearing in nature – Section 2: Precipitation and wind.
3 General
Dust, sand, salt mist and related wind can have an effect on products in various ways, the most important being:
– ingress of dust Into enclosures and encapsulations;
– deterioration of electrical characteristics, e.g. faulty contact, change of contact resistance, change of track resistance;
– seizure or disturbance in motion of bearings, axles, shafts and other moving parts;
– surface abrasion (erosion, corrosion);
– clouding of optical surfaces;
– contamination of lubricants;
– reduction of thermal conductivity;
– clogging of ventilating openings, bushings, pipes, filters, apertures necessary for operation, etc.
The presence of dust and sand in combination with other environmental factors such as water vapour can have harmful effects on products, e.g. corrosion and mould growth. Damp heat atmospheres cause corrosion in connection with chemically aggressive dust, and similar effects are caused by salt mist contained In the air.
Effects of ion-conducting and corrosive dusts, e.g. de-icing salts, may have to be considered.
4 Natural dust and sand environments
4.1 Classification of dust and sand
The following definitions of dust and sand are based on different aerodynamic behaviour:
– dust may be defined as particulate matter of unspecified origin or composition and of size ranging from 1 im to 150 Itm. Particles of less than 75 pm diameter can remain suspended in the atmosphere for very long periods by natural turbulence of the air;IEC 60721-2-5:1991 pdf download.