Three model cyclones were tested at four trash loading rates. Cyclone collection efficiency for over-sized cyclones was slightly less than the efficiency of a standard-sized cyclone, averaging 98.63 and 98.42%, respectively. Cyclone collection efficiency increased as trash loading rate increased, with average values ranging from 97.93% at a trash loading rate of 0.88 grain/ft³ (2 g/m³) to an average of 98.95% at a trash loading rate of 7.0 grain/ft³ (16 g/m³). Cyclone pressure drops for over- sized cyclones were much less than pressure drops for standard-sized cyclones, with the pressure drop in an over-sized cyclone averaging 28% of the value for pressure drop in a standard-sized cyclone. The authors concluded that, with their lower pressure drop, over-sized cyclones are more compatible than standard-sized cyclones on airflow systems that use axial- flow fans. Collection efficiency of over-sized cyclones was just slightly less than that of standard-sized cyclones.