There has been increased interest in annular/ring (torsional) type shear cells, for powder failure property measurement with the objective of obtaining an indication of powder flowability for quality control or equipment design. As the first step in the development of a new such tester, this paper presents an overview of the effects of changes in different test procedure variables on the measured failure loci and derived failure function and compares these differences; with repeatability. The variables investigated are, shear displacement/number of measurements, method of curve fitting the loci, shear velocity and depth of the powder sample. (c) 2006 Published by Elsevier B.V.