The flow of grannular solids through apertures has been studied under the followingthree conditions: (1) with no pressure differential

(2) under positive pressure differential and (3) under negative pressure differential. The influence of various related factors upon the solid flow rate has been measured. Based upon the correlation of 665 sets of data obtained the following equations for calculating solid flow rate and sealing pressure difference gradient of vertical stand-pipe. With no pressure differential : C1 - 0.66. when G0 expressed in [kg/cek] Under positive pressure differential : C2 = 2.3×10~4 when (G1 - G0) expressed in [kg/cek]. Under negative pressure differential (before the critical point) : for sand C3 - 5.04

for coal C3 = 9.84 The sealing pressure difference gradient of vertical stand-pipe :