In its practical application, electrochemical oxygen sensors have problems such as climate impact, life and reliability, and residual current. For these specific problems, we have adopted different methods to solve them in practical applications. 1. Impact of climate on oxygen sensors Under normal conditions, changes in climatic conditions (fluctuations in temperature, humidity, and pressure) can have varying degrees of impact on the stability of oxygen sensor performance. The change in temperature affects the oxygen permeability of the oxygen permeable membrane, thereby affecting the diffusion current. The thermistor compensation can compensate for the deviation caused by a part of the temperature fluctuation, making it 1/2 to 1/3 of the original. There are also some gas-permeable membranes on the surface of the oxygen sensor that have strong ability to adhere to moisture. The oxygen permeability will decrease with increasing humidity, which will reduce the performance of the oxygen sensor. Therefore, when selecting the gas-permeable membrane of the oxygen sensor, the viscosity of the moisture should be selected. A gas permeable membrane that is not strong in adhesion and has a relatively stable adhesion to moisture. Atmospheric pressure fluctuations can cause sensor performance fluctuations simultaneously. Many countries are currently studying ways to eliminate the effects of atmospheric pressure fluctuations on the performance of oxygen sensors. One of the methods is to use the wall of the pool to install a pressure buffer. This pressure buffer is essentially a A gas permeable membrane that utilizes the cushioning properties of this membrane to reduce the effects of atmospheric pressure fluctuations on the performance of the oxygen sensor. 2, the life and reliability of chemical oxygen sensors Due to the influence of electrode structure, electrolyte material and production process, the reliability of electrochemical oxygen sensor is low, which can not meet the requirements of use. To objectively reflect the ability of electrochemical oxygen sensor to maintain its performance index, analyze and evaluate the electrochemical oxygen sensor. Reliability, it is important to establish the relationship between the model of sensor reliability and time and the relationship between characteristic parameters. One of the practices is to randomly sample from the same batch of products, first test the service life, and then perform statistical inference and failure analysis based on the test data. The main indicators of failure analysis are sensitivity, measurement range and measurement accuracy. According to the enterprise standard Q / UN2585 - 298, when the oxygen sensor measurement accuracy is < ± 1%, the sensitivity change and the measurement range change can be reflected by the measurement accuracy. Therefore, the detection parameter in the life test is determined as the measurement accuracy. If the measurement accuracy of the sensor exceeds ± 1%, the sensor is judged to be invalid. 3, residual current problem When the oxygen content of the gas sample is zero, the diffusion current of the sensor is not zero. This current is called residual current or leakage current (I c ). When the sensor state is new and the electrolyte is pure, I c is small and can be ignored. However, as the sensor is infected by impurities and the pH changes during use, I c gradually becomes larger, which will affect the measurement accuracy of the meter. Therefore, the instrument design should be equipped with residual flow correction (using high-purity nitrogen or ammonia to periodically correct residual flow), so that the instrument can ensure high precision during use. Concerned about surprises Tag: Oxygen sensor Residual flow Practical application Measurement accuracy Chemical formula Previous: Application of grating sensor in automatic displacement measurement system Next: Application of 3D spatial error compensation technology for CNC machine tools
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