In this research, the effect of paddy variety (VA), moisture content (MC) and air flow rate (AF) on the performance of negative pressure pneumatic collecting system and the quality of the collected product was examined. The experiments were carried out at two levels of paddy variety, namely Hashemi and Gilaneh, three levels of moisture content (8, 10.5 and 13% w.b.) and four levels of air flow rate (65, 75, 85 and 95 L/s). Parameters for evaluation of pneumatic collecting system were collecting capacity (CC), Power consumption (PC) and collecting efficiency (CE). Also quality of the collected product was evaluated based on percentage change in broken grains (ΔBG). Results showed that collecting capacity of Hashemi variety were significantly less than Gilaneh. However the power consumption for collecting of Hashemi variety was greater. Increasing the air flow rate cause an increase in the collecting capacity, power consumption and the percentage of the broken grains and decrease in the collecting efficiency. Increasing moisture content also leads to an increase in power consumption and a decrease in the collecting capacity and the percentage of broken grains.
