The Study On Quasi-distributed FBG Sensor For Leaking Oil Detection And Its Sensitive Material

The detection of leakage of petroleum and liquefied petroleum is very important in many fields such as petrochemical industry and environmental monitoring. Quasi-distributed FBG sensor has unique advantages such as simple structural mutli-piont detection and location with one fiber, besides other advantages possessed by general fiber sensors such as intrinsic safety, high sensitivity, quick response, and anti-disturbance of electromagnetism. Therefore, the researches of the sensor have gotten attention of people in recent years. In this thesis, emphasizes are attached on the researches of selecting and making the sensor's sensitive material and determining optimal size of sensitive material, and of designing sensing heads and mensurating sensing head's performance .Major content of this work includes three aspects as follows:1. Selecting sensitive material: By referring to many data and comparing the performances of many rubbers, we find Rubber ethylene-propylene-diene-monomer (EPDM) is perfect sensitive material. EPDM doesn't only have perfect swellable performance for petroleum and liquefied petroleum, but also have better performances such as excellent anti-aging property, smaller cubage expansion coefficient and good processing property. Conclusions as above are proved by our experiments.2. Making sensitive material: made in non-sulfur vulcanization system with the formula : EPDM 100kg, Dicumylperoxide(DCP) 2kg as cross-linking agent, Stearic Acid 1kg as processing aid, Oxidized Zinc (ZnO) 3kg as accelerant, wax oil 10kg as lubricant; and made in vulcanizing condition: vulcanizing temperature 170 C, vulcanizing time 15minutes, vulcanizing pressure 3 MPa , the vulcanized EPDM is optimal sensitive material for petrol. The sensing head equipped with the vulcanized rubber possesses two qualities: better swelling response and better anti-interfere against temperature variation.3. mensurating the sensing head's performance: The sensing head with mechanical protecting equipment has better comprehensive performance as follows: good swelling response , the excellent ability of anti-interfere against temperature variation, and fine safety property for use. When the sensing head equipped with Rubber 4# with diameter of 8mm and length of 12mm is pressed and its incipient wavelength shifts 0.5-lnm, its alarming level can be set as 1nm, and its response tune for petrol is 5 minutes.