Uncertainty evaluation of conductance moisture meters for rough grain

Conductance moisture meters are generally easy to operate and respond rapidly. They are widely used for determining the moisture content of rough rice. In order to ensure the accuracy of moisture meters, the measurement uncertainty for two designs of meters, the farm-type sample-cell (CD-5) and inspection-type single-grain (CTR-E200) were evaluated in this study. The standard moisture content of rough rice was maintained using reference materials. The source of uncertainty included the predicted values of calibration equation, the source of reference materials, the effects of temperature variation, nonlinear and repeatability and resolution source. The study also dealt with the effect of calibration equations on uncertainty. The uncertainty analysis showed that predicted uncertainty is the main source for combined uncertainty. No significant difference was found in the uncertainty between the linear and polynomial calibration equations for the CD-5 meter. However, the polynomial calibration equation had better predictive performance than the linear equation for the CTR-E200 meter.