An investigation was undertaken to determine the effects of system parameters on vertical jet penetration in fluidized beds. The study was conducted in a 12-in.-diameter semicircular, transparent column over a pressure range of 50 to 750 psig. Three different jet penetrations were measured in the investigation corresponding to the phenomena observed. The effect of bed fluidizing velocity on jet penetration was determined by measuring the jet penetration at three different fluidization velocities. The effects of particle density and particle size on jet penetration were also studied. An investigation was undertaken to determine the effect of pressure on jet penetration. Existing correlations to predict jet penetration were compared with the experimental data to determine how well the correlations predicted the effect of system pressure. The effect of jet nozzle size and configuration on jet penetration length were also determined. The second area studied in this investigation was the effect of standpipe length on solids flow rate from hoppers. Two different modes of standpipe flow were observed in these tests. With no restriction at the bottom of the pipe, the solids moved in a dilute, streaming type of flow in the standpipe. With a restriction at the bottom, however, the solids were in a dense-phase moving packed-bed flow in the pipe. In general, the solids flow rate through the pipe increased with increasing pipe length for the dilute-phase flow mode.