Structure Reliability Design For The Flexible Magnetostrictive Liquid Level Sensor

In the petrochemical industry,a high-precision liquid level sensor with great measuring range is required for monitoring the oil level of large-scale oil tanks.For various reasons,the conventional liquid level sensors do not meet requirements of monitoring the oil level of large-scale oil tank.And a flexible magnetostrictive liquid level sensor is the best choice.However,the results of actual operation showed that the flexible magnetostrictive liquid level sensors sometimes failed which affected its normal operation.The causes of failures are necessary to be found out by studying and analyzing how the sensors worked,and then to optimize the design accordingly and enhance the reliability and stability of the sensors.This thesis is to find out that the unreasonable structure designs were causes for some failures,including that there was no output at low temperature operation,the sensor was corroded,and leakage occurred during operation.The unreasonable assembly scheme is found to be the reason why there was no output at low temperature operation;The sensor was corroded was because the material for the outer tube was not correctly chosen;And leakage occurred was because the welding technique for the end cap of the outer tube was not qualified.According to the analysis above,the structure design of the flexible magnetostrictive liquid level sensor has been optimized by using better glass tube to improve the assembly scheme,by replacing material for the outer tube with excellent anticorrosion polyethylene glycol propylene tube,and by enhancing the welding technique for the end cap of the polyethylene glycol propylene tube.After optimizing the structure design,the testing results indicated that the data were normal and met the design requirements.The tests included performance test of the glass fiber tube at high temperature and low temperature,coil test,vibration test,and performance test for the whole sensor,Hence perfectly solved the problems of failures mentioned above.After a long time of use,the sensors worked stably and were approved by customers.The structure reliability design for the flexible magnetostrictive liquid level sensor solved a series of problems occurred in the product operation and therefore enhanced the product's reliability and stability.