Testing oxygen sensors

In 1957, Ethyl Corp. announced anew antiknock compound, methylcyclopentadienyknanganese tricarbonyl [12108-13-3] (MMT). MMT is almost as effective as lead on a per gram of metal basis, but because manganese was more expensive than lead, MMT was not widely used until limits were placed on the lead content of gasoline. MMT was used in unleaded fuel between 1975 and 1978. After a large fleet test suggested that MMT could increase exhaust emissions because it interfered with catalysts and oxygen sensors, EPA banned its use in unleaded fuel in 1978. MMT is used in Canada in unleaded fuel. 

Fig. 5.39 Resistivity-change based (Ga203-) oxygen sensor in humidity saturated test gas.

L. C. Clark first suggested in 1956 that the test solution be separated from an amperometric oxygen sensor by a hydrophobic porous membrane, permeable only for gases (for a review of the Clark electrode see [88]). The first potentiometric sensor of this type was the Severinghaus CO2 electrode [150], with a glass electrode placed in a dilute solution of sodium hydrogenocarbonate as the internal sensor (see fig. 4.10). As an equilibrium pressure of CO2, corresponding to the CO2 concentration in the test solution, is established in the... 

USE OF OXYGEN SENSORS AS A SURROGATE GLUCOSE SENSOR FOR IN VIVO TESTING AND IMPORTANT ISSUES RELATED TO IN VITRO SENSOR CALIBRATION... 

Lin JT. Testing of planar thick film fabricated oxygen sensor with galvanostatic techniques. PhD thesis, University of California San Diego, La Jolla, CA, 2000. 

The uncertainty of commercial calibration gas mixtures is typically 1% of the amount fraction, and the contribution of this to the overall measurement uncertainty is much greater than the intrinsic error of the oxygen sensor for amount fractions of oxygen that are 0.1 ppm and above [2]. Consequently, test procedures that require calibrated gas mixtures will be limited by the uncertainty of those gas mixtures, and therefore carmot be used to test the accuracy of oxygen and other zirconia-based gas sensors, assuming the uncertainty of the sensor calibration is no worse than that of the test mixtures. At present, the uncertainty of commercial calibration gas mixtures is a limitation to verifying the accuracy of these gas sensors. 

A schematic of the oxygen sensor is shown in Fig. 5.1(a). Figure 5.1(b) shows the device had a strong response when it was tested at 120°C in pure... 

Several optical sensors have already been introduced that selectively respond to oxygen in the atmosphere or water. A calorimetric oxygen sensor has been tested using a solid polymer membrane or coating involving a picketfence... 

These tests have been carried out with three sensors located at the level of the turbo-pump which ensures the injection of the gaseous hydrogen (sensor 1), at the level of the turbo-pump which ensures the injection of the gaseous oxygen (sensor 2) and at the level of the inflows of the two gases (see Figure 9.37). 

A function check, or bump test, means using simple tests (such as exposing sensors to calibration gas or exhaling into the oxygen sensor) to show that the instrument will respond to the chemicalfs) of concern and that aU alarms operate as they were designed. Functional Safety Assessment... 

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