Grain flow measurements with X-ray techniques

The use of low energy X-rays, up to 30 keV, densitometry is demonstrated fo r grain flow rate measurements through laboratory experiments. Mass flow ra tes for corn were related to measured X-ray intensity in gray scale units w ith a 0.99 correlation coefficient for flow rates ranging from 2 to 6 kg/s. Larger flow rate values can be measured by using higher energy or a higher tube current. Measurements were done in real time at a 30 Hz sampling rate . Flow rate measurements are relatively independent of grain moisture due t o a negligible change in the X-ray attenuation coefficients at typical mois ture content values from 15 to 25%. Grain flow profile changes did not affe ct measurement accuracy. X-rays easily capture variations in the corn thick ness profile. Due to the low energy of the X-ray photons, biological shield ing can be accomplished with 2-mm-thick lead foil or 5 mm of steel. (C) 200 0 Elsevier Science B.V. All rights reserved.