These two rules are attributed to inventor/scientist John von Neumann, who introduced them in 1947. The whole of the stream of powder should be taken for many short increments of time, in preference to part of the stream being taken for the whole of the time.The powder should be sampled when in motion.That high level of efficiency and accuracy still exists today, when looking at the performance of Gilson Spinning Rifflers and comparing the five common sampling procedures. 3406, 1963).”īased on the suppositions studied and substantiated in the Allen and Khan paper, the spinning riffler then demonstrated greater efficiencies and markedly higher accuracy in comparison to scoop sampling, cone and quartering, table sampling, and chute riffling sampling procedures. What was summarized by Allen and Khan nearly 50 years ago still stands true today: “The spinning riffler is the best technique by far and produces good results, no matter what the previous history of the powder (it samples unmixed just as efficiently as mixed powders).” In conclusion, the pair also said about the spinning riffler, “This is the only technique which will invariably furnish samples to the accuracy required by British Standards for Particle Size Determinations of Fine Powders (B.S. Khan, post-graduate students from the UK’s University of Bradford, statistically validated the higher level of performance of the spinning riffler method over other common sampling techniques. The thesis article, Critical Evaluation of Powder Sampling Properties, written by Terrence Allen and A.A. Since any test result is only as good as the specimen used, accurate sampling should be considered as having primary importance in any testing process.Īlthough they’ve been around since the 1930s, an article published in The Chemical Engineer in 1970 brought an enhanced awareness of spinning rifflers – and their ability to deliver optimal reliability and sampling accuracy. Whether called a Spinning Riffler or Rotary Sample Divider, the premise behind the how and why of this style of widely-used sample divider is the same: it offers a superior and demonstrated capability to produce accurate representative samples efficiently and consistently, with virtually no operator error and little bias.
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