Designing a Cylindrical Capacitive Based Sensor for Monitoring the Table Salt’s Moisture Content during Iodization

Abstract

Coaxial cylinder capacitive moisture sensor for determination of moisture content of table salts has been fabricated. The CMS method for determination of moisture content of table salts overcomes the effect of evaporation of iodine in table salt which results from heating in the oven drying method. The CMS overcomes the polarization effect result from the resistive methods of moisture content determination and it is non expensive to construct and it has high accuracy since measurements involves programming system in interpretation of the results. In this research, moisture content sensor based on capacitive principal created using two coaxial cylinders with height 5.207 cm, and different diameters of 4.303 cm and 1.198 cm embedded inside one another. The input signal of the CMS system was provided by the AC signal from the sensor capacitor, the capacitance of the sensor capacitor is directly proportional to the moisture content of the salt sample placed between the two coaxial cylinders of the sensor capacitor. The moisture content was obtained from the model m=6.6145×10-4c+4.54044 for calibration of the CMS by using the OVD as a reference method for determination of moisture content in the table salts. The model was then validated by constructing the comparison plot of OVD and CMS moisture contents. The comparison graph of OVD and CMS MC against test had conceding error bars between OVD and CMS MC. The coefficient of determination of 0.94 was obtained and the correlation plot was a linear relation expressed as y=0.971x+0.773. The model was then validated by solving for moisture content from measured values of capacitance.