ISO 22762-1:2018 pdf free

ISO 22762-1:2018 pdf free.Elastomeric seismic-protection isolators
Some elastomers are susceptible to crystallization if the ambient temperature is low over a prolonged period. High-damping compounds of these elastomers can be more susceptible than conventional low-damping ones. The crystallization process involves a nucleation period, during which little change in rubber stiffness occurs, followed by rapid stiffening as the crystallites grow. The nucleation period shortens as the temperature is lowered to that at which the rate of crystallization is highest. The minimum test temperatures specified for natural rubber and chloroprene rubber are those at which the rate of crystallization is highest. To ensure that the performance of the isolator is not compromised, it is necessary that the nucleation period not be greatly exceeded during any continuous exposure to low temperatures. Crystallites melt when the ambient temperature of the isolators is raised sufficiently,and thus the effects are completely reversible. If chloroprene rubber is used, crystallization resistant grades should be chosen where low temperature conditions are to be encountered.
NOTE The service temperature can be taken as that occurring at the isolator location averaged over a 24 h period. The bulk of an isolator does not usually experience shorter term fluctuations of temperature. For isolators installed outside, the temperature experienced at the site in a normal year can be used, unless the structure is regarded as critically important.
The machine shown schematically in Figure 4 shall be capable of compressing the elastomeric isolator under controlled conditions. It shall also provide a method of measuring the compressive force and compressive displacement to an accuracy of less than or equal to 1 % of the maximum values recorded.
The force calibration shall be based on ISO 7500-1. The machine shall maintain the parallelism of the upper and lower loading platens for the test piece attachment during the test. A Class 1 machine, as defined in Clause 7 of ISO 7500-1:2018, is recommended.ISO 22762-1 pdf download.