BS EN IEC 60721-2-4:2018

What is BS EN IEC 60721-2-4:2018  about?
BS EN IEC 60721-2-4:2018   presents a broad division into types of solar radiation areas. It is intended to be used as part of the background material when selecting appropriate severities of solar radiation for product applications. All types of geographical areas are covered, except areas with altitudes above 5,000 m. This document also serves to define limiting severities of solar radiation to which products are liable to be exposed during transportation, storage and use.  Solar radiation can affect products primarily by the heating of material and their environment or by photochemical degradation of material. Solar radiation, especially its ultraviolet content, causes photochemical degradation of most organic materials. Elasticity and plasticity of certain rubber compounds and plastic materials are affected. Optical glass may become opaque. Solar radiation bleaches out colours in paints, textiles, paper, etc. This can be of importance, for example for the colour-coding of components. The heating of material is a consequence of exposure to solar radiation. The presentation of severities of solar radiation is therefore related to the power density radiated towards a surface, or irradiance, expressed in W/m2. An object subjected to solar radiation will attain a temperature that depends primarily on the surrounding air temperature, the energy radiated from the Sun, and the incidence angle of the radiation on the object. Other factors, for example wind and heat conduction to mountings, can be of importance. In addition, the absorptance αs of the surface for the solar spectrum is of importance. An artificial air temperature ts may be defined, which, under steady-state conditions, results in the same surface temperature of an object as the combination of the actual air temperature tu and the solar radiation of th...