Gaseous oxygen sensor

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). 

Membrane oxygen electrodes are the most convenient oxide-ion sensors for measurements of ionic melt basicity, since their use is not connected to pollution by foreign admixtures of the melt studied, or with passing gaseous oxygen through the melt. This excludes the drawbacks that are characteristic of other kinds of oxygen electrodes. 

PSi and porous polymer substrates for optical chemical sensors are discussed by Hajj-Hassan et al. (2010). They were used as substrates to encapsulate gaseous oxygen (O2) responsive luminophores in their nanostructured pores. These substrate materials behave as optical interference filters that allow efficient and selective detection of the wavelengths of interest in optical sensors. 

We note that the above-mentioned sensors usually operate in mixed-potential mode. That takes place because more than one electtochemical reaction usually occurs at an electtode. hi particular, in such reactions, gaseous oxygen and CO present in the atmosphere can participate simultaneously with the target gas. In this case, the resulting electrode potential becomes a mixed potential which is generated from competition of the various reactions occurring at the electtode. 

FIGURE 6.18 Time Trace of Temperature Sensors and Differential Pressure Transducer with Corresponding Images of Screen using (a) Gaseous Helium and (b) Gaseous Oxygen as Pressurants. 

Fig. 12.12 Portable (battery-powered) electrochemical sensors for gaseous oxygen, (a) A typical application for the device is monitoring the atmosphere during welding or cutting or grinding operations on metal in confined spaces. Other uses include atmospheric monitoring during inspection and repair of tanks (e.g. ballast tanks on-board ship) and pipelines, e.g. sewers, (b) Similar devices may be used to monitor a boiler system. (Courtesy Neotronics Ltd.)...

A fairly efficient method of selective detection of active forms of oxygen by means of sensors is the preliminary separation of their mixture with the aid of filters designed for the purpose, filters that vigorously de-excite this or that form of oxygen. It has been mentioned in Section 5.4 that freshly atomized films of Ag efficiently absorb O-atoms from the gaseous phase, mildly de-excite 02 molecules. To de-excite the singlet oxygen molecules proper, use should be made of filters with... 

Table 17. Sensor chemistry for gaseous and aqueous oxygen.

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