The Study Of New Oil Fatty Acid Freezing Point Test System

We have a lot of methods to test the freezing points, many institutions have established the corresponding detection methods, such as International Standard Organization, American Society Testing and Materials, and the China National Standardization Management Committee.At present, the test standard of inspection and quarantine system is the SN/T0801.17-1999"Animal and vegetable oils and fats import and export-Method for the determination of solidifying point of fatty acid".These methods and the testing equipment have many shortcomings,high labor intensity, the low testing precision and efficiency, poor data repeatability and so on, so we have the urgent need to improve. In view of the above problems, this paper proposes a novel detection method and develops the equipment,In recent years, with the development of computer and electronic technology, detection equipment increases ceaselessly, the use of new equipment to replace manual testing is a general trend.This paper has developed the new freezing point test device, mainly in the following three aspects:1. It Proposes a mechanical structure design method of the testing system for freezing point. The mechanical part is mainly composed of freezing point testing sensor, water bath, oil tube clamping device,360automatic turntable, PC and so on,which is simple structure and convenient operation;2. It gives an implementation scheme of hardware circuit for freezing point test. This part of hardware circuit consists of the core chip ATmegal6L, temperature sensor DS18B20, step motor driving chip L298N and RS232serial communication bus. Among them, the sensor uses a single digital temperature sensor DS18B20produced by DALLAS company in USA, temperature range of-55℃～125℃,0.0625℃accuracy, response time of750ms.The main role in the whole testing device is:after receiving the test command from the computer, the step motor will drive the temperature sensor probe into the oil liquid, and then read the signal of the temperature sensor, after the temperature conversion and processing, and the data will be sent to the computer through the serial port and displayed on the computer;3. It developmens a freezing point test application software system. First of all, writes a freezing point testing program " freepoint" with Microsoft VC++6.0, real-time samples and records the temperature. After the sampling is finished, do the image processing using the software " matlab6.5", realizing the analysis of the peak value and freezing point determination, comparison and so on.It is proved that this instrument has replaced the traditional manual testing method. It reduces the testing error, increases the high stability, makes convenient data of comparison and traceability. Besides, it greatly reduces the labor intensity and improves the efficiency.