Fiber Refined Oil Level Automatic Measuring Device

In this thesis, a novel optical fiber liquid level sensor system is given, which combines the advantages of high sensitivity of the optical fiber sensor based total internal-reflection and high positioning accuracy of stepping motor system driven by the single chip computer(SCC). By using this system, level of many kinds of liquids can be measured automatically and accurately.The design and implementation procedure of the system were described in detail, including the device selections for the light source and photo-detector, the designs of hardware and software parts. The sensor head was made of two standard multi-mode fibers with the same parameters. The reflective light intensity of sensor head depends on refractive index of medium surrounding sensor head. When sensor head was moved to the interface of two mediums, the reflective light intensity would be changed obviously due to the difference of refractive index. In this system, the SCC is the core of intellectual control system. The data sampling, processing, display and control of the stepping motor are realized by the SCC. According to users'operation, the position of liquid level and situation will be display on the liquid crystal display. Using the stepping motor which is controlled by a SCC to drive the fiber head, the liquid level can be real-time traced and displayed. The automatic tracking measurement system of liquid level was realized by this approach.The sensor head and the optical fiber are integrated. The system has some merits, such as simple structure, high sensitivity, strong reliability, good stability. The range of the system is 0.5m, the distinguishable survey length reaches 0.7mm and absolute error reaches 0.187mm. A new method is supplied to measure the level of many kinds of liquids, including gasoline, diesel oil, and organic solvent. It can be widely applied in the petroleum chemical industry system to automatically measure and trace, and it is suitable for the small vessel high accuracy especially. Key Words: Liquid level sensor; frustrated total internal reflection; multi-mode fiber...