Under the condition that bed materials are not distributed on the air distribution plate, start the induced draft fan, the primary fan and adjust the air quantity of the primary fan, record the pressure of  water-cooling chamber  and the pressure of bed of lower part of the dense-phase zone inside the boiler, the difference between the two pressure is the resistance of the air distribution plate. Based on these data, draw the relation resistance curve of air quantity in cold-state and the resistance of air distribution plate. Corrected by temperature correction, the relation curve of the primary air quantity in hot-state and the  resistance of air distribution plate can be obtained, this process is called resistance test of empty bed.