ALGORITHM FOR TEMPERATURE CORRECTION OF VIBRATION DENSITY METERS
Abstract
In this article additional temperature error of vibration density meters in liquids and gases is reviewed. Particularly scrutinized are the effects of change in the temperature of the medium on the vibration frequency of the density vibration transducers. Main principle of operation and advantages of vibration density meters is described. The article analyzes and describes the existing algorithms of calculating density and active temperature compensation as well as the disadvantages of those algorithms. It points out to the significant limitations of temperature calibration diapason of the existing methods which relate to the necessity of using distilled water. Basing on the previous vibration transducer simulation and on the established main function of the elastic modules of the metal’ temperature properties a new thermal compensation algorithm, which does not involve liquid compensators, was introduced. Main advantages of the new algorithm are demonstrated. Those advantages emerge due to using vacuum as a medium surrounding the vibration transducer. One of the most notable benefits is significant extension of the calibrated temperature range. A possibility of applying the algorithm for calibrating density meters in extreme temperatures is introduced. Furthermore, formulas for calculatingthe value of the oscillation period of the converter which account for temperature changes (thermal compensation period) are presented. The advantages of using second order polynomial with zero linear term as a calibration function are also provided. Methodology behind conducting the experiments, types of equipment and measuring instruments are described in detail. Resul ting experimental data for vibration transducers made of three different metals is presented. The obtained data is analyzed, which led to a conclusion that application of suggested algorithm of thermal compensation of liquid and gases density meters’ vibration transducers is feasible and expedient.
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