Development of resistance type moisture measuring device for grains

Abstract

The paper presents a study aimed at developing an indigenous moisture measuring device from locally available materials for grains based on the principle of resistance change of the material with corresponding change in moisture during drying. The developed device has four copper electrode cups positions in which both gauging and dummy copper electrode cups were placed to form Wheatstone bridge circuits of full, half and quarter for four, two and one gauging copper electrode cups respectively, while the remaining positions were used as dummies. These circuits were used to measure the resistances and hence obtaining the moisture content of the grains used. Grains of paddy rice, guinea corn and millet were used to test the device and it was observed that for full bridge circuits of each of the grains, paddy rice have a negative coefficient of correlation of -0.95, -0.99 for guinea corn and -0.99 for millet. The results obtained from predictive empirical equations when compared with the direct oven method, showed that the device can be used to predict or measure moisture content once calibrated.