BS ISO 19862:2015 pdf free

BS ISO 19862:2015 pdf free.Buildings and civil engineering works一Sealants 一Durability to extension compression cycling under accelerated weathering
In the immersion technique, the test specimens are placed in a chamber that is periodically flooded with re-circulated water. During immersion, the specimens are completely covered by water. The water temperature is measured below the water surface with the black standard thermometer. The immersion spray water can be at a higher temperature. The uncontrolled temperature of the re-circulated immersion water during operation of the weathering device is typically (40±5) °C. It can be controlled by heating the water to a higher temperature. However, heating is not desirable because the water immersion temperature would then differ to a larger extent from the spray water temperature.
NOTE 1 Adequate heat transfer between the test specimen and the environment is essential during the lower temperature period in the fluorescent UV/condensation device in order for condensation on the sealant to occur. This places restrictions on the thermal mass and, consequently, on the dimensions of a specimen. No experimental data have been generated on the time-of-wetness of sealant test specimens of the kind specified in this International Standard when placed in fluorescent UV/condensation device operating at conditions specified in this International Standard. However, testing conducted by ASTM C24 on ISO 8339 specimens appears to suggest that the condensation process provided in the fluorescent UV/condensation apparatus is generally not applicable to the type of sealant specimens tested. Therefore, wetting in this International Standard is carried out by water spray on the exposed specimen surface (default method). However, the front surface water spray accessory was not designed for this purpose and requires an unreasonable amount of pure water for the wet period specified. Therefore, often the equipment is modified to allow re-circulation of the water during the exposure period. Some fluorescent UV equipment have adaptable spray manifolds, which allow installation of lower flow type nozzles, thus reducing the amount of pure water used.
NOTE 2 Data generated with these two methods of water exposure (spray or immersion) in a round robin test on a set of sealants for revision of ISO 11431 showed acceptable correlation, although contributions to the various degradation mechanisms acting in the specimens (e.g. hydrolysis, thermal shock, leaching of formulation components, et cetera) can differ between these exposures. The degree of correlation between these two methods thus may vary depending on the specific sealant tested.BS ISO 19862 pdf free.