An indirect method has been developed to estimate solid velocity in the ver
tical pneumatic conveying of agricultural grains. Experiments on vertical p
neumatic conveying of rough rice, milled rice, and soybean indicated that s
olid velocity is a function of air velocity solid flow rate, solid-to-air r
atio, and grain equivalent diameter An empirical equation has been develope
d to predict dispersed solids density, i.e. concentration of solids in pneu
matic conveying. Knowing the solid flow rate and dispersed solids density,
solid velocity was calculated The method used for determining the solid vel
ocity was validated based on the hypothesis that the average solid velocity
is equal to zero when the limiting value of the air velocity is equal to t
he terminal velocity of the grains. The applicability of the developed rela
tionships for estimating the solid velocity was verified for other agricult
ural grains like corn and mungbean.