scope:

This part of ISO 2631 addresses human exposure to mechanical multiple shocks measured at the seat pad when a person is seated. The adverse health effects of prolonged exposure to vibration that includes multiple shocks are related to dose measures. The method described in this part of ISO 2631 is generally applicable in cases where adverse health effects in the lumbar spine are concerned. The calculation of the lumbar spine response described in this part of ISO 2631 assumes that the person subjected to the vibration is seated in an upright position and does not voluntarily rise from the seat during the exposure. Different postures can result in different responses in the spine. The limitations of the lumbar spine response models used in this part of ISO 2631 are given in 5.2. Caution is necessary when applying the method to extreme shock conditions. This International Standard specifies a method of determining the stress cracking resistance of polyethylene materials in any environment. The test is carried out on notched test specimens cut from compressionmoulded sheet or finished products, as applicable. The test specimen is subjected to a static tensile load when immersed in an environment such as a surfactant solution held at a specified temperature, and the time to failure measured. The method has been specifically developed for polyethylene materials but can be used to evaluate PE extrusions, such as pipe segments, PE fusion welds/fittings and blow-moulded PE containers to study the effect of aggressive environments, i.e. dangerous goods/chemicals. The method may also be adapted for other thermoplastic materials, e.g. polypropylene (PP). In this case, care must be taken in interpreting the results as the processing stresses/orientation in finished products may have an effect.