The ‘Holmen’ pellet tester (Major, 1984; Fig. 8) simulates a more rigorous treatment
of pellets by pneumatic handling. In this apparatus, a 100-g sieved sample of pellets is
introduced in a stream of air. For a standard time (0.5 to 2 min) this air together with
pellets is circulated through right-angled bends, impinging repeatedly on hard surfaces.
Pellet attrition will then occur. After treatment, the product is sieved again using a sieve
with an opening of approximately 80% of the pellet diameter. Standards have been
developed for the testing time in relation to the pellet diameter under investigation.