Bubble behavior in fluidized beds is being studies. The objectives of this work are: (1) to develop a measurement method for the maximum peaks of prevailing force which randomly and transiently occur in fluidized beds, and synchronize these data with the bubbling image analysis data obtained by the capacitance method at METC, and (2) to obtain the above defined forces under various operating conditions in conjunction with the bubble image analysis data generated by the capacitance method at METC. Preliminary experimental data of the prevailing forces were obtained in an identical size fluidized bed as used at METC (6 inch I.D) by using three different measurement methods, e.g. piezoelectric, fracture-sensitive and gas pressure fluctuation methods. 19 refs., 7 figs.