Content Handbook Q

Outline of method

Fine particles and dust from storage and transport of the sample are removed by sieving before the sample is attrited with or without glass beads depending on the type of formulation.

The test involves rolling a cylinder filled with granules/tablets, which results in a cascading wave-like motion. The relative speed between adjacent granules/tablets produces friction and causes surface attrition. In the presence of glass beads, friction and resulting surface attrition can be higher. Using glass beads allows to distinguish products with more attrition resistant surfaces.

Generated fine particles and dust are separated and the percentage larger than 125 μm is reported.

Scope

The method is intended for measuring the resistance to attrition during normal transport, storage and handling of loosely packed granules or tablets. The method is applicable to granular formulations including ready baits and tablets which are packed in bulk and have a characteristic length of less than 1 cm (Note 1).

Reason for the revision

The objective of this revision was to combine MT 178 and MT 178.2 into a single method for granular products and to include loosely packed tablets. The procedure was simplified, editorial changes have been made and obsolete references have been removed. 

Important note

Where same conditions are used, results obtained with MT 178 and MT 178.2 are equivalent to those obtained with MT 178.3. 

MT 178.3 supersedes MT 178 and MT 178.2.