Suchergebnisse

ABSTRACT At present there is no generally accepted test available for characterizing the friability of granular filter media in the context of its ability to withstand handling and placing, as distinct from abrasion resistance during backwashing – which is the subject of other, existing, test methods. Most existing procedures tend to be grinding tests and have little meaning. The approach selected in this work was to adapt the ring shear test, in which a sample (large enough to be analysed by sieving) is subjected to shear under a known compression load and the change in the undersize fraction is assessed. A representative selection of dry media was submitted to the test and the results proved to be reproducible and capable of distinguishing (clearly) between friable and non‐friable resistant types. The procedure is likely to become the basis of a standard test.