The Research On Measurement Method And Automatic Design Of Oil Colorimeter

Oil is not only the essential nutrients that people take from their diet,but also the important raw material for food processing and various manufacturing industries.As one of the key indicators of oil quality testing,oil color not only plays a crucial role in improving the oil quality,but also is the most direct appearance factors for oil pricing and consumers to choose.The domestic market mainly uses Lovibond visual colorimeter to measure oil color,but the measurement process of visual method is easily affected by the subjective factor of the operator,and the operation is cumbersome and heavy workload,so,the accuracy of the measurement is not very high.However foreign countries use the PFX995 series high precision automatic colorimeter to measure oil color,the measurement results is accurate,but the import price is very expensive.Therefore,it is imperative to develop an automatic oil colorimeter with simple operation,low price and no human operation error.Firstly,by analyzing the measurement principle and system composition of Lovibond colorimeter,we build the hardware system of our automatic colorimeter,which is mainly divided into three parts:color signal generation module,signal transmission module and signal acquisition module.In the signal generating module,light emitted by the tungsten lamp light source passing through the sample slot generate oil color spectral signals.The optical element's selection for each module are determined by their respective optical properties.Secondly,based on the research of automatic oil color measurement methods such as spectrophotometry and photoelectric integration in recent years,this paper proposes the use of CIE color coordinate method to calculate the Lovibond value of oil color.Using Lovibond standard filters to generate mapping database for Lovibond value and CIE color coordinate.The minimum error analysis method is used to match Lovibond value in the database.Through the measurement and experimental analysis,it is found that the CIE color coordinate method requires higher computing speed.However,the logarithmic spectral analysis method can improve the computing speed and efficiency of the system.In addition,the paper focuses on the overall function and design process of the oil color and luster monitor system,and expounds the principle,design process and concrete realization method of each function module in detail.Finally,through analysis of the measurement results of different kinds of oil,the stability of the automatic colorimeter and the reliability of the measurement results are verified.