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Abstract
Several procedures for the sampling of powders before particle-size analysis have been described, but little information is available as to the merits of the various techniques. In the present work the relative efficiencies of scoop sampling, cone and quartering, the chute riffler, and the spinning riffler have been investigated. Of these, scoop sampling is especially prone to error, since the whole of the powder does not pass through the sampling device and the previous history of the powder is important. The special problems of scoop sampling have been studied in some detail; it is concluded that training of the operator could improve sampling efficiency, but that, in general, this sampling technique should be avoided. The efficiency of the spinning-riffler technique proved far superior to any other, provided that the time for one revolution of the ring of containers was only a small fraction of the total time required for the powder to flow through the sampling device.
Notes
* Manuscript rcceived 15 January 1962.